/usr/lib/gcc/x86_64-linux-gnu/5/include/d/std/internal/math/biguintcore.d is in libphobos-5-dev 5.5.0-12ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 | /** Fundamental operations for arbitrary-precision arithmetic
*
* These functions are for internal use only.
*/
/* Copyright Don Clugston 2008 - 2010.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
/* References:
"Modern Computer Arithmetic" (MCA) is the primary reference for all
algorithms used in this library.
- R.P. Brent and P. Zimmermann, "Modern Computer Arithmetic",
Version 0.5.9, (Oct 2010).
- C. Burkinel and J. Ziegler, "Fast Recursive Division", MPI-I-98-1-022,
Max-Planck Institute fuer Informatik, (Oct 1998).
- G. Hanrot, M. Quercia, and P. Zimmermann, "The Middle Product Algorithm, I.",
INRIA 4664, (Dec 2002).
- M. Bodrato and A. Zanoni, "What about Toom-Cook Matrices Optimality?",
http://bodrato.it/papers (2006).
- A. Fog, "Optimizing subroutines in assembly language",
www.agner.org/optimize (2008).
- A. Fog, "The microarchitecture of Intel and AMD CPU's",
www.agner.org/optimize (2008).
- A. Fog, "Instruction tables: Lists of instruction latencies, throughputs
and micro-operation breakdowns for Intel and AMD CPU's.", www.agner.org/optimize (2008).
Idioms:
Many functions in this module use
'func(Tulong)(Tulong x) if (is(Tulong == ulong))' rather than 'func(ulong x)'
in order to disable implicit conversion.
*/
module std.internal.math.biguintcore;
version(D_InlineAsm_X86)
{
import std.internal.math.biguintx86;
}
else
{
import std.internal.math.biguintnoasm;
}
alias multibyteAdd = multibyteAddSub!('+');
alias multibyteSub = multibyteAddSub!('-');
private import core.cpuid;
private import std.traits : Unqual;
shared static this()
{
CACHELIMIT = core.cpuid.datacache[0].size*1024/2;
FASTDIVLIMIT = 100;
}
private:
// Limits for when to switch between algorithms.
immutable size_t CACHELIMIT; // Half the size of the data cache.
immutable size_t FASTDIVLIMIT; // crossover to recursive division
// These constants are used by shift operations
static if (BigDigit.sizeof == int.sizeof)
{
enum { LG2BIGDIGITBITS = 5, BIGDIGITSHIFTMASK = 31 };
alias BIGHALFDIGIT = ushort;
}
else static if (BigDigit.sizeof == long.sizeof)
{
alias BIGHALFDIGIT = uint;
enum { LG2BIGDIGITBITS = 6, BIGDIGITSHIFTMASK = 63 };
}
else static assert(0, "Unsupported BigDigit size");
private import std.exception : assumeUnique;
private import std.traits:isIntegral;
enum BigDigitBits = BigDigit.sizeof*8;
template maxBigDigits(T) if (isIntegral!T)
{
enum maxBigDigits = (T.sizeof+BigDigit.sizeof-1)/BigDigit.sizeof;
}
static immutable BigDigit[] ZERO = [0];
static immutable BigDigit[] ONE = [1];
static immutable BigDigit[] TWO = [2];
static immutable BigDigit[] TEN = [10];
public:
/// BigUint performs memory management and wraps the low-level calls.
struct BigUint
{
private:
pure invariant()
{
assert( data.length >= 1 && (data.length == 1 || data[$-1] != 0 ));
}
immutable(BigDigit) [] data = ZERO;
this(immutable(BigDigit) [] x) pure nothrow @nogc @safe
{
data = x;
}
package(std) // used from: std.bigint
this(T)(T x) pure nothrow @safe if (isIntegral!T)
{
opAssign(x);
}
enum trustedAssumeUnique = function(BigDigit[] input) pure @trusted @nogc {
return assumeUnique(input);
};
public:
// Length in uints
@property size_t uintLength() pure nothrow const @safe @nogc
{
static if (BigDigit.sizeof == uint.sizeof)
{
return data.length;
}
else static if (BigDigit.sizeof == ulong.sizeof)
{
return data.length * 2 -
((data[$-1] & 0xFFFF_FFFF_0000_0000L) ? 1 : 0);
}
}
@property size_t ulongLength() pure nothrow const @safe @nogc
{
static if (BigDigit.sizeof == uint.sizeof)
{
return (data.length + 1) >> 1;
}
else static if (BigDigit.sizeof == ulong.sizeof)
{
return data.length;
}
}
// The value at (cast(ulong[])data)[n]
ulong peekUlong(int n) pure nothrow const @safe @nogc
{
static if (BigDigit.sizeof == int.sizeof)
{
if (data.length == n*2 + 1) return data[n*2];
return data[n*2] + ((cast(ulong)data[n*2 + 1]) << 32 );
}
else static if (BigDigit.sizeof == long.sizeof)
{
return data[n];
}
}
uint peekUint(int n) pure nothrow const @safe @nogc
{
static if (BigDigit.sizeof == int.sizeof)
{
return data[n];
}
else
{
ulong x = data[n >> 1];
return (n & 1) ? cast(uint)(x >> 32) : cast(uint)x;
}
}
public:
///
void opAssign(Tulong)(Tulong u) pure nothrow @safe if (is (Tulong == ulong))
{
if (u == 0) data = ZERO;
else if (u == 1) data = ONE;
else if (u == 2) data = TWO;
else if (u == 10) data = TEN;
else
{
static if (BigDigit.sizeof == int.sizeof)
{
uint ulo = cast(uint)(u & 0xFFFF_FFFF);
uint uhi = cast(uint)(u >> 32);
if (uhi == 0)
{
data = [ulo];
}
else
{
data = [ulo, uhi];
}
}
else static if (BigDigit.sizeof == long.sizeof)
{
data = [u];
}
}
}
void opAssign(Tdummy = void)(BigUint y) pure nothrow @nogc @safe
{
this.data = y.data;
}
///
int opCmp(Tdummy = void)(const BigUint y) pure nothrow @nogc const @safe
{
if (data.length != y.data.length)
return (data.length > y.data.length) ? 1 : -1;
size_t k = highestDifferentDigit(data, y.data);
if (data[k] == y.data[k])
return 0;
return data[k] > y.data[k] ? 1 : -1;
}
///
int opCmp(Tulong)(Tulong y) pure nothrow @nogc const @safe if(is (Tulong == ulong))
{
if (data.length > maxBigDigits!Tulong)
return 1;
foreach_reverse (i; 0 .. maxBigDigits!Tulong)
{
BigDigit tmp = cast(BigDigit)(y>>(i*BigDigitBits));
if (tmp == 0)
if (data.length >= i+1)
{
// Since ZERO is [0], so we cannot simply return 1 here, as
// data[i] would be 0 for i==0 in that case.
return (data[i] > 0) ? 1 : 0;
}
else
continue;
else
if (i+1 > data.length)
return -1;
else if (tmp != data[i])
return data[i] > tmp ? 1 : -1;
}
return 0;
}
bool opEquals(Tdummy = void)(ref const BigUint y) pure nothrow @nogc const @safe
{
return y.data[] == data[];
}
bool opEquals(Tdummy = void)(ulong y) pure nothrow @nogc const @safe
{
if (data.length > 2)
return false;
uint ylo = cast(uint)(y & 0xFFFF_FFFF);
uint yhi = cast(uint)(y >> 32);
if (data.length==2 && data[1]!=yhi)
return false;
if (data.length==1 && yhi!=0)
return false;
return (data[0] == ylo);
}
bool isZero() pure const nothrow @safe @nogc
{
return data.length == 1 && data[0] == 0;
}
size_t numBytes() pure nothrow const @safe @nogc
{
return data.length * BigDigit.sizeof;
}
// the extra bytes are added to the start of the string
char [] toDecimalString(int frontExtraBytes) const pure nothrow
{
auto predictlength = 20+20*(data.length/2); // just over 19
char [] buff = new char[frontExtraBytes + predictlength];
ptrdiff_t sofar = biguintToDecimal(buff, data.dup);
return buff[sofar-frontExtraBytes..$];
}
/** Convert to a hex string, printing a minimum number of digits 'minPadding',
* allocating an additional 'frontExtraBytes' at the start of the string.
* Padding is done with padChar, which may be '0' or ' '.
* 'separator' is a digit separation character. If non-zero, it is inserted
* between every 8 digits.
* Separator characters do not contribute to the minPadding.
*/
char [] toHexString(int frontExtraBytes, char separator = 0,
int minPadding=0, char padChar = '0') const pure nothrow @safe
{
// Calculate number of extra padding bytes
size_t extraPad = (minPadding > data.length * 2 * BigDigit.sizeof)
? minPadding - data.length * 2 * BigDigit.sizeof : 0;
// Length not including separator bytes
size_t lenBytes = data.length * 2 * BigDigit.sizeof;
// Calculate number of separator bytes
size_t mainSeparatorBytes = separator ? (lenBytes / 8) - 1 : 0;
size_t totalSeparatorBytes = separator ? ((extraPad + lenBytes + 7) / 8) - 1: 0;
char [] buff = new char[lenBytes + extraPad + totalSeparatorBytes + frontExtraBytes];
biguintToHex(buff[$ - lenBytes - mainSeparatorBytes .. $], data, separator);
if (extraPad > 0)
{
if (separator)
{
size_t start = frontExtraBytes; // first index to pad
if (extraPad &7)
{
// Do 1 to 7 extra zeros.
buff[frontExtraBytes .. frontExtraBytes + (extraPad & 7)] = padChar;
buff[frontExtraBytes + (extraPad & 7)] = (padChar == ' ' ? ' ' : separator);
start += (extraPad & 7) + 1;
}
for (int i=0; i< (extraPad >> 3); ++i)
{
buff[start .. start + 8] = padChar;
buff[start + 8] = (padChar == ' ' ? ' ' : separator);
start += 9;
}
}
else
{
buff[frontExtraBytes .. frontExtraBytes + extraPad]=padChar;
}
}
int z = frontExtraBytes;
if (lenBytes > minPadding)
{
// Strip leading zeros.
ptrdiff_t maxStrip = lenBytes - minPadding;
while (z< buff.length-1 && (buff[z]=='0' || buff[z]==padChar) && maxStrip>0)
{
++z;
--maxStrip;
}
}
if (padChar!='0')
{
// Convert leading zeros into padChars.
for (size_t k= z; k< buff.length-1 && (buff[k]=='0' || buff[k]==padChar); ++k)
{
if (buff[k]=='0') buff[k]=padChar;
}
}
return buff[z-frontExtraBytes..$];
}
// return false if invalid character found
bool fromHexString(const(char)[] s) pure nothrow @safe
{
//Strip leading zeros
int firstNonZero = 0;
while ((firstNonZero < s.length - 1) &&
(s[firstNonZero]=='0' || s[firstNonZero]=='_'))
{
++firstNonZero;
}
auto len = (s.length - firstNonZero + 15)/4;
auto tmp = new BigDigit[len+1];
uint part = 0;
uint sofar = 0;
uint partcount = 0;
assert(s.length>0);
for (ptrdiff_t i = s.length - 1; i>=firstNonZero; --i)
{
assert(i>=0);
char c = s[i];
if (s[i]=='_') continue;
uint x = (c>='0' && c<='9') ? c - '0'
: (c>='A' && c<='F') ? c - 'A' + 10
: (c>='a' && c<='f') ? c - 'a' + 10
: 100;
if (x==100) return false;
part >>= 4;
part |= (x<<(32-4));
++partcount;
if (partcount==8)
{
tmp[sofar] = part;
++sofar;
partcount = 0;
part = 0;
}
}
if (part)
{
for ( ; partcount != 8; ++partcount) part >>= 4;
tmp[sofar] = part;
++sofar;
}
if (sofar == 0)
data = ZERO;
else
data = trustedAssumeUnique(tmp[0 .. sofar]);
return true;
}
// return true if OK; false if erroneous characters found
// FIXME: actually throws `ConvException` on error.
bool fromDecimalString(const(char)[] s) pure @trusted
{
//Strip leading zeros
int firstNonZero = 0;
while ((firstNonZero < s.length) &&
(s[firstNonZero]=='0' || s[firstNonZero]=='_'))
{
++firstNonZero;
}
if (firstNonZero == s.length && s.length >= 1)
{
data = ZERO;
return true;
}
auto predictlength = (18*2 + 2*(s.length-firstNonZero)) / 19;
auto tmp = new BigDigit[predictlength];
uint hi = biguintFromDecimal(tmp, s[firstNonZero..$]);
tmp.length = hi;
data = trustedAssumeUnique(tmp);
return true;
}
////////////////////////
//
// All of these member functions create a new BigUint.
// return x >> y
BigUint opShr(Tulong)(Tulong y) pure nothrow const if (is (Tulong == ulong))
{
assert(y>0);
uint bits = cast(uint)y & BIGDIGITSHIFTMASK;
if ((y>>LG2BIGDIGITBITS) >= data.length) return BigUint(ZERO);
uint words = cast(uint)(y >> LG2BIGDIGITBITS);
if (bits==0)
{
return BigUint(data[words..$]);
}
else
{
uint [] result = new BigDigit[data.length - words];
multibyteShr(result, data[words..$], bits);
if (result.length > 1 && result[$-1] == 0)
return BigUint(trustedAssumeUnique(result[0 .. $-1]));
else
return BigUint(trustedAssumeUnique(result));
}
}
// return x << y
BigUint opShl(Tulong)(Tulong y) pure nothrow const if (is (Tulong == ulong))
{
assert(y>0);
if (isZero()) return this;
uint bits = cast(uint)y & BIGDIGITSHIFTMASK;
assert ((y>>LG2BIGDIGITBITS) < cast(ulong)(uint.max));
uint words = cast(uint)(y >> LG2BIGDIGITBITS);
BigDigit [] result = new BigDigit[data.length + words+1];
result[0..words] = 0;
if (bits==0)
{
result[words..words+data.length] = data[];
return BigUint(trustedAssumeUnique(result[0..words+data.length]));
}
else
{
uint c = multibyteShl(result[words..words+data.length], data, bits);
if (c==0) return BigUint(trustedAssumeUnique(result[0..words+data.length]));
result[$-1] = c;
return BigUint(trustedAssumeUnique(result));
}
}
// If wantSub is false, return x + y, leaving sign unchanged
// If wantSub is true, return abs(x - y), negating sign if x < y
static BigUint addOrSubInt(Tulong)(const BigUint x, Tulong y,
bool wantSub, ref bool sign) pure nothrow if (is(Tulong == ulong))
{
BigUint r;
if (wantSub)
{ // perform a subtraction
if (x.data.length > 2)
{
r.data = subInt(x.data, y);
}
else
{ // could change sign!
ulong xx = x.data[0];
if (x.data.length > 1)
xx += (cast(ulong)x.data[1]) << 32;
ulong d;
if (xx <= y)
{
d = y - xx;
sign = !sign;
}
else
{
d = xx - y;
}
if (d == 0)
{
r = 0UL;
sign = false;
return r;
}
if (d > uint.max)
{
r.data = [cast(uint)(d & 0xFFFF_FFFF), cast(uint)(d>>32)];
}
else
{
r.data = [cast(uint)(d & 0xFFFF_FFFF)];
}
}
}
else
{
r.data = addInt(x.data, y);
}
return r;
}
// If wantSub is false, return x + y, leaving sign unchanged.
// If wantSub is true, return abs(x - y), negating sign if x<y
static BigUint addOrSub(BigUint x, BigUint y, bool wantSub, bool *sign)
pure nothrow
{
BigUint r;
if (wantSub)
{ // perform a subtraction
bool negative;
r.data = sub(x.data, y.data, &negative);
*sign ^= negative;
if (r.isZero())
{
*sign = false;
}
}
else
{
r.data = add(x.data, y.data);
}
return r;
}
// return x*y.
// y must not be zero.
static BigUint mulInt(T = ulong)(BigUint x, T y) pure nothrow
{
if (y==0 || x == 0) return BigUint(ZERO);
uint hi = cast(uint)(y >>> 32);
uint lo = cast(uint)(y & 0xFFFF_FFFF);
uint [] result = new BigDigit[x.data.length+1+(hi!=0)];
result[x.data.length] = multibyteMul(result[0..x.data.length], x.data, lo, 0);
if (hi!=0)
{
result[x.data.length+1] = multibyteMulAdd!('+')(result[1..x.data.length+1],
x.data, hi, 0);
}
return BigUint(removeLeadingZeros(trustedAssumeUnique(result)));
}
/* return x * y.
*/
static BigUint mul(BigUint x, BigUint y) pure nothrow
{
if (y==0 || x == 0)
return BigUint(ZERO);
auto len = x.data.length + y.data.length;
BigDigit [] result = new BigDigit[len];
if (y.data.length > x.data.length)
{
mulInternal(result, y.data, x.data);
}
else
{
if (x.data[]==y.data[]) squareInternal(result, x.data);
else mulInternal(result, x.data, y.data);
}
// the highest element could be zero,
// in which case we need to reduce the length
return BigUint(removeLeadingZeros(trustedAssumeUnique(result)));
}
// return x / y
static BigUint divInt(T)(BigUint x, T y_) pure nothrow
if ( is(Unqual!T == uint) )
{
uint y = y_;
if (y == 1)
return x;
uint [] result = new BigDigit[x.data.length];
if ((y&(-y))==y)
{
assert(y!=0, "BigUint division by zero");
// perfect power of 2
uint b = 0;
for (;y!=1; y>>=1)
{
++b;
}
multibyteShr(result, x.data, b);
}
else
{
result[] = x.data[];
uint rem = multibyteDivAssign(result, y, 0);
}
return BigUint(removeLeadingZeros(trustedAssumeUnique(result)));
}
static BigUint divInt(T)(BigUint x, T y) pure nothrow
if ( is(Unqual!T == ulong) )
{
if (y <= uint.max)
return divInt!uint(x, cast(uint)y);
if (x.data.length < 2)
return BigUint(ZERO);
uint hi = cast(uint)(y >>> 32);
uint lo = cast(uint)(y & 0xFFFF_FFFF);
immutable uint[2] z = [lo, hi];
BigDigit[] result = new BigDigit[x.data.length - z.length + 1];
divModInternal(result, null, x.data, z[]);
return BigUint(removeLeadingZeros(trustedAssumeUnique(result)));
}
// return x % y
static uint modInt(T)(BigUint x, T y_) pure if ( is(Unqual!T == uint) )
{
uint y = y_;
assert(y!=0);
if ((y&(-y)) == y)
{ // perfect power of 2
return x.data[0] & (y-1);
}
else
{
// horribly inefficient - malloc, copy, & store are unnecessary.
uint [] wasteful = new BigDigit[x.data.length];
wasteful[] = x.data[];
uint rem = multibyteDivAssign(wasteful, y, 0);
delete wasteful;
return rem;
}
}
// return x / y
static BigUint div(BigUint x, BigUint y) pure nothrow
{
if (y.data.length > x.data.length)
return BigUint(ZERO);
if (y.data.length == 1)
return divInt(x, y.data[0]);
BigDigit [] result = new BigDigit[x.data.length - y.data.length + 1];
divModInternal(result, null, x.data, y.data);
return BigUint(removeLeadingZeros(trustedAssumeUnique(result)));
}
// return x % y
static BigUint mod(BigUint x, BigUint y) pure nothrow
{
if (y.data.length > x.data.length) return x;
if (y.data.length == 1)
{
return BigUint([modInt(x, y.data[0])]);
}
BigDigit [] result = new BigDigit[x.data.length - y.data.length + 1];
BigDigit [] rem = new BigDigit[y.data.length];
divModInternal(result, rem, x.data, y.data);
return BigUint(removeLeadingZeros(trustedAssumeUnique(rem)));
}
// return x op y
static BigUint bitwiseOp(string op)(BigUint x, BigUint y, bool xSign, bool ySign, ref bool resultSign)
pure nothrow @safe if (op == "|" || op == "^" || op == "&")
{
auto d1 = includeSign(x.data, y.uintLength, xSign);
auto d2 = includeSign(y.data, x.uintLength, ySign);
foreach (i; 0..d1.length)
{
mixin("d1[i] " ~ op ~ "= d2[i];");
}
mixin("resultSign = xSign " ~ op ~ " ySign;");
if (resultSign)
{
twosComplement(d1, d1);
}
return BigUint(removeLeadingZeros(trustedAssumeUnique(d1)));
}
/**
* Return a BigUint which is x raised to the power of y.
* Method: Powers of 2 are removed from x, then left-to-right binary
* exponentiation is used.
* Memory allocation is minimized: at most one temporary BigUint is used.
*/
static BigUint pow(BigUint x, ulong y) pure nothrow
{
// Deal with the degenerate cases first.
if (y==0) return BigUint(ONE);
if (y==1) return x;
if (x==0 || x==1) return x;
BigUint result;
// Simplify, step 1: Remove all powers of 2.
uint firstnonzero = firstNonZeroDigit(x.data);
// Now we know x = x[firstnonzero..$] * (2^^(firstnonzero*BigDigitBits))
// where BigDigitBits = BigDigit.sizeof * 8
// See if x[firstnonzero..$] can now fit into a single digit.
bool singledigit = ((x.data.length - firstnonzero) == 1);
// If true, then x0 is that digit
// and the result will be (x0 ^^ y) * (2^^(firstnonzero*y*BigDigitBits))
BigDigit x0 = x.data[firstnonzero];
assert(x0 !=0);
// Length of the non-zero portion
size_t nonzerolength = x.data.length - firstnonzero;
ulong y0;
uint evenbits = 0; // number of even bits in the bottom of x
while (!(x0 & 1))
{
x0 >>= 1;
++evenbits;
}
if ((x.data.length- firstnonzero == 2))
{
// Check for a single digit straddling a digit boundary
BigDigit x1 = x.data[firstnonzero+1];
if ((x1 >> evenbits) == 0)
{
x0 |= (x1 << (BigDigit.sizeof * 8 - evenbits));
singledigit = true;
}
}
// Now if (singledigit), x^^y = (x0 ^^ y) * 2^^(evenbits * y) * 2^^(firstnonzero*y*BigDigitBits))
uint evenshiftbits = 0; // Total powers of 2 to shift by, at the end
// Simplify, step 2: For singledigits, see if we can trivially reduce y
BigDigit finalMultiplier = 1UL;
if (singledigit)
{
// x fits into a single digit. Raise it to the highest power we can
// that still fits into a single digit, then reduce the exponent accordingly.
// We're quite likely to have a residual multiply at the end.
// For example, 10^^100 = (((5^^13)^^7) * 5^^9) * 2^^100.
// and 5^^13 still fits into a uint.
evenshiftbits = cast(uint)( (evenbits * y) & BIGDIGITSHIFTMASK);
if (x0 == 1)
{ // Perfect power of 2
result = 1UL;
return result << (evenbits + firstnonzero * 8 * BigDigit.sizeof) * y;
}
int p = highestPowerBelowUintMax(x0);
if (y <= p)
{ // Just do it with pow
result = cast(ulong)intpow(x0, y);
if (evenbits + firstnonzero == 0)
return result;
return result << (evenbits + firstnonzero * 8 * BigDigit.sizeof) * y;
}
y0 = y / p;
finalMultiplier = intpow(x0, y - y0*p);
x0 = intpow(x0, p);
// Result is x0
nonzerolength = 1;
}
// Now if (singledigit), x^^y = finalMultiplier * (x0 ^^ y0) * 2^^(evenbits * y) * 2^^(firstnonzero*y*BigDigitBits))
// Perform a crude check for overflow and allocate result buffer.
// The length required is y * lg2(x) bits.
// which will always fit into y*x.length digits. But this is
// a gross overestimate if x is small (length 1 or 2) and the highest
// digit is nearly empty.
// A better estimate is:
// y * lg2(x[$-1]/BigDigit.max) + y * (x.length - 1) digits,
// and the first term is always between
// y * (bsr(x.data[$-1]) + 1) / BIGDIGITBITS and
// y * (bsr(x.data[$-1]) + 2) / BIGDIGITBITS
// For single digit payloads, we already have
// x^^y = finalMultiplier * (x0 ^^ y0) * 2^^(evenbits * y) * 2^^(firstnonzero*y*BigDigitBits))
// and x0 is almost a full digit, so it's a tight estimate.
// Number of digits is therefore 1 + x0.length*y0 + (evenbits*y)/BIGDIGIT + firstnonzero*y
// Note that the divisions must be rounded up.
// Estimated length in BigDigits
ulong estimatelength = singledigit
? 1 + y0 + ((evenbits*y + BigDigit.sizeof * 8 - 1) / (BigDigit.sizeof *8)) + firstnonzero*y
: x.data.length * y;
// Imprecise check for overflow. Makes the extreme cases easier to debug
// (less extreme overflow will result in an out of memory error).
if (estimatelength > uint.max/(4*BigDigit.sizeof))
assert(0, "Overflow in BigInt.pow");
// The result buffer includes space for all the trailing zeros
BigDigit [] resultBuffer = new BigDigit[cast(size_t)estimatelength];
// Do all the powers of 2!
size_t result_start = cast(size_t)( firstnonzero * y
+ (singledigit ? ((evenbits * y) >> LG2BIGDIGITBITS) : 0));
resultBuffer[0..result_start] = 0;
BigDigit [] t1 = resultBuffer[result_start..$];
BigDigit [] r1;
if (singledigit)
{
r1 = t1[0..1];
r1[0] = x0;
y = y0;
}
else
{
// It's not worth right shifting by evenbits unless we also shrink the length after each
// multiply or squaring operation. That might still be worthwhile for large y.
r1 = t1[0..x.data.length - firstnonzero];
r1[0..$] = x.data[firstnonzero..$];
}
if (y>1)
{ // Set r1 = r1 ^^ y.
// The secondary buffer only needs space for the multiplication results
BigDigit [] secondaryBuffer = new BigDigit[resultBuffer.length - result_start];
BigDigit [] t2 = secondaryBuffer;
BigDigit [] r2;
int shifts = 63; // num bits in a long
while(!(y & 0x8000_0000_0000_0000L))
{
y <<= 1;
--shifts;
}
y <<=1;
while(y!=0)
{
// For each bit of y: Set r1 = r1 * r1
// If the bit is 1, set r1 = r1 * x
// Eg, if y is 0b101, result = ((x^^2)^^2)*x == x^^5.
// Optimization opportunity: if more than 2 bits in y are set,
// it's usually possible to reduce the number of multiplies
// by caching odd powers of x. eg for y = 54,
// (0b110110), set u = x^^3, and result is ((u^^8)*u)^^2
r2 = t2[0 .. r1.length*2];
squareInternal(r2, r1);
if (y & 0x8000_0000_0000_0000L)
{
r1 = t1[0 .. r2.length + nonzerolength];
if (singledigit)
{
r1[$-1] = multibyteMul(r1[0 .. $-1], r2, x0, 0);
}
else
{
mulInternal(r1, r2, x.data[firstnonzero..$]);
}
}
else
{
r1 = t1[0 .. r2.length];
r1[] = r2[];
}
y <<=1;
shifts--;
}
while (shifts>0)
{
r2 = t2[0 .. r1.length * 2];
squareInternal(r2, r1);
r1 = t1[0 .. r2.length];
r1[] = r2[];
--shifts;
}
}
if (finalMultiplier!=1)
{
BigDigit carry = multibyteMul(r1, r1, finalMultiplier, 0);
if (carry)
{
r1 = t1[0 .. r1.length + 1];
r1[$-1] = carry;
}
}
if (evenshiftbits)
{
BigDigit carry = multibyteShl(r1, r1, evenshiftbits);
if (carry!=0)
{
r1 = t1[0 .. r1.length + 1];
r1[$ - 1] = carry;
}
}
while(r1[$ - 1]==0)
{
r1=r1[0 .. $ - 1];
}
return BigUint(trustedAssumeUnique(resultBuffer[0 .. result_start + r1.length]));
}
// Implement toHash so that BigUint works properly as an AA key.
size_t toHash() const @trusted nothrow
{
return typeid(data).getHash(&data);
}
} // end BigUint
@safe pure nothrow unittest
{
// ulong comparison test
BigUint a = [1];
assert(a == 1);
assert(a < 0x8000_0000_0000_0000UL); // bug 9548
// bug 12234
BigUint z = [0];
assert(z == 0UL);
assert(!(z > 0UL));
assert(!(z < 0UL));
}
// Remove leading zeros from x, to restore the BigUint invariant
inout(BigDigit) [] removeLeadingZeros(inout(BigDigit) [] x) pure nothrow @safe
{
size_t k = x.length;
while(k>1 && x[k - 1]==0) --k;
return x[0 .. k];
}
pure unittest
{
BigUint r = BigUint([5]);
BigUint t = BigUint([7]);
BigUint s = BigUint.mod(r, t);
assert(s==5);
}
@safe pure unittest
{
BigUint r;
r = 5UL;
assert(r.peekUlong(0) == 5UL);
assert(r.peekUint(0) == 5U);
r = 0x1234_5678_9ABC_DEF0UL;
assert(r.peekUlong(0) == 0x1234_5678_9ABC_DEF0UL);
assert(r.peekUint(0) == 0x9ABC_DEF0U);
}
// Pow tests
pure unittest
{
BigUint r, s;
r.fromHexString("80000000_00000001");
s = BigUint.pow(r, 5);
r.fromHexString("08000000_00000000_50000000_00000001_40000000_00000002_80000000"
~ "_00000002_80000000_00000001");
assert(s == r);
s = 10UL;
s = BigUint.pow(s, 39);
r.fromDecimalString("1000000000000000000000000000000000000000");
assert(s == r);
r.fromHexString("1_E1178E81_00000000");
s = BigUint.pow(r, 15); // Regression test: this used to overflow array bounds
r.fromDecimalString("000_000_00");
assert(r == 0);
r.fromDecimalString("0007");
assert(r == 7);
r.fromDecimalString("0");
assert(r == 0);
}
// Radix conversion tests
@safe pure unittest
{
BigUint r;
r.fromHexString("1_E1178E81_00000000");
assert(r.toHexString(0, '_', 0) == "1_E1178E81_00000000");
assert(r.toHexString(0, '_', 20) == "0001_E1178E81_00000000");
assert(r.toHexString(0, '_', 16+8) == "00000001_E1178E81_00000000");
assert(r.toHexString(0, '_', 16+9) == "0_00000001_E1178E81_00000000");
assert(r.toHexString(0, '_', 16+8+8) == "00000000_00000001_E1178E81_00000000");
assert(r.toHexString(0, '_', 16+8+8+1) == "0_00000000_00000001_E1178E81_00000000");
assert(r.toHexString(0, '_', 16+8+8+1, ' ') == " 1_E1178E81_00000000");
assert(r.toHexString(0, 0, 16+8+8+1) == "00000000000000001E1178E8100000000");
r = 0UL;
assert(r.toHexString(0, '_', 0) == "0");
assert(r.toHexString(0, '_', 7) == "0000000");
assert(r.toHexString(0, '_', 7, ' ') == " 0");
assert(r.toHexString(0, '#', 9) == "0#00000000");
assert(r.toHexString(0, 0, 9) == "000000000");
}
private:
void twosComplement(const(BigDigit) [] x, BigDigit[] result)
pure nothrow @safe
{
foreach (i; 0..x.length)
{
result[i] = ~x[i];
}
result[x.length..$] = BigDigit.max;
bool sgn = false;
foreach (i; 0..result.length)
{
if (result[i] == BigDigit.max)
{
result[i] = 0;
}
else
{
result[i] += 1;
break;
}
}
}
// Encode BigInt as BigDigit array (sign and 2's complement)
BigDigit[] includeSign(const(BigDigit) [] x, size_t minSize, bool sign)
pure nothrow @safe
{
size_t length = (x.length > minSize) ? x.length : minSize;
BigDigit [] result = new BigDigit[length];
if (sign)
{
twosComplement(x, result);
}
else
{
result[0..x.length] = x;
}
return result;
}
// works for any type
T intpow(T)(T x, ulong n) pure nothrow @safe
{
T p;
switch (n)
{
case 0:
p = 1;
break;
case 1:
p = x;
break;
case 2:
p = x * x;
break;
default:
p = 1;
while (1){
if (n & 1)
p *= x;
n >>= 1;
if (!n)
break;
x *= x;
}
break;
}
return p;
}
// returns the maximum power of x that will fit in a uint.
int highestPowerBelowUintMax(uint x) pure nothrow @safe
{
assert(x>1);
static immutable ubyte [22] maxpwr = [ 31, 20, 15, 13, 12, 11, 10, 10, 9, 9,
8, 8, 8, 8, 7, 7, 7, 7, 7, 7, 7, 7];
if (x<24) return maxpwr[x-2];
if (x<41) return 6;
if (x<85) return 5;
if (x<256) return 4;
if (x<1626) return 3;
if (x<65536) return 2;
return 1;
}
// returns the maximum power of x that will fit in a ulong.
int highestPowerBelowUlongMax(uint x) pure nothrow @safe
{
assert(x>1);
static immutable ubyte [39] maxpwr = [ 63, 40, 31, 27, 24, 22, 21, 20, 19, 18,
17, 17, 16, 16, 15, 15, 15, 15, 14, 14,
14, 14, 13, 13, 13, 13, 13, 13, 13, 12,
12, 12, 12, 12, 12, 12, 12, 12, 12];
if (x<41) return maxpwr[x-2];
if (x<57) return 11;
if (x<85) return 10;
if (x<139) return 9;
if (x<256) return 8;
if (x<566) return 7;
if (x<1626) return 6;
if (x<7132) return 5;
if (x<65536) return 4;
if (x<2642246) return 3;
return 2;
}
version(unittest)
{
int slowHighestPowerBelowUintMax(uint x) pure nothrow @safe
{
int pwr = 1;
for (ulong q = x;x*q < cast(ulong)uint.max; )
{
q*=x; ++pwr;
}
return pwr;
}
@safe pure unittest
{
assert(highestPowerBelowUintMax(10)==9);
for (int k=82; k<88; ++k)
{
assert(highestPowerBelowUintMax(k)== slowHighestPowerBelowUintMax(k));
}
}
}
/* General unsigned subtraction routine for bigints.
* Sets result = x - y. If the result is negative, negative will be true.
*/
BigDigit [] sub(const BigDigit [] x, const BigDigit [] y, bool *negative)
pure nothrow
{
if (x.length == y.length)
{
// There's a possibility of cancellation, if x and y are almost equal.
ptrdiff_t last = highestDifferentDigit(x, y);
BigDigit [] result = new BigDigit[last+1];
if (x[last] < y[last])
{ // we know result is negative
multibyteSub(result[0..last+1], y[0..last+1], x[0..last+1], 0);
*negative = true;
}
else
{ // positive or zero result
multibyteSub(result[0..last+1], x[0..last+1], y[0..last+1], 0);
*negative = false;
}
while (result.length > 1 && result[$-1] == 0)
{
result = result[0..$-1];
}
// if (result.length >1 && result[$-1]==0) return result[0..$-1];
return result;
}
// Lengths are different
const(BigDigit) [] large, small;
if (x.length < y.length)
{
*negative = true;
large = y; small = x;
}
else
{
*negative = false;
large = x; small = y;
}
// result.length will be equal to larger length, or could decrease by 1.
BigDigit [] result = new BigDigit[large.length];
BigDigit carry = multibyteSub(result[0..small.length], large[0..small.length], small, 0);
result[small.length..$] = large[small.length..$];
if (carry)
{
multibyteIncrementAssign!('-')(result[small.length..$], carry);
}
while (result.length > 1 && result[$-1] == 0)
{
result = result[0..$-1];
}
return result;
}
// return a + b
BigDigit [] add(const BigDigit [] a, const BigDigit [] b) pure nothrow
{
const(BigDigit) [] x, y;
if (a.length < b.length)
{
x = b; y = a;
}
else
{
x = a; y = b;
}
// now we know x.length > y.length
// create result. add 1 in case it overflows
BigDigit [] result = new BigDigit[x.length + 1];
BigDigit carry = multibyteAdd(result[0..y.length], x[0..y.length], y, 0);
if (x.length != y.length)
{
result[y.length..$-1]= x[y.length..$];
carry = multibyteIncrementAssign!('+')(result[y.length..$-1], carry);
}
if (carry)
{
result[$-1] = carry;
return result;
}
else
return result[0..$-1];
}
/** return x + y
*/
BigDigit [] addInt(const BigDigit[] x, ulong y) pure nothrow
{
uint hi = cast(uint)(y >>> 32);
uint lo = cast(uint)(y& 0xFFFF_FFFF);
auto len = x.length;
if (x.length < 2 && hi!=0) ++len;
BigDigit [] result = new BigDigit[len+1];
result[0..x.length] = x[];
if (x.length < 2 && hi!=0)
{
result[1]=hi;
hi=0;
}
uint carry = multibyteIncrementAssign!('+')(result[0..$-1], lo);
if (hi!=0) carry += multibyteIncrementAssign!('+')(result[1..$-1], hi);
if (carry)
{
result[$-1] = carry;
return result;
}
else
return result[0..$-1];
}
/** Return x - y.
* x must be greater than y.
*/
BigDigit [] subInt(const BigDigit[] x, ulong y) pure nothrow
{
uint hi = cast(uint)(y >>> 32);
uint lo = cast(uint)(y & 0xFFFF_FFFF);
BigDigit [] result = new BigDigit[x.length];
result[] = x[];
multibyteIncrementAssign!('-')(result[], lo);
if (hi)
multibyteIncrementAssign!('-')(result[1..$], hi);
if (result[$-1] == 0)
return result[0..$-1];
else
return result;
}
/** General unsigned multiply routine for bigints.
* Sets result = x * y.
*
* The length of y must not be larger than the length of x.
* Different algorithms are used, depending on the lengths of x and y.
* TODO: "Modern Computer Arithmetic" suggests the OddEvenKaratsuba algorithm for the
* unbalanced case. (But I doubt it would be faster in practice).
*
*/
void mulInternal(BigDigit[] result, const(BigDigit)[] x, const(BigDigit)[] y)
pure nothrow
{
assert( result.length == x.length + y.length );
assert( y.length > 0 );
assert( x.length >= y.length);
if (y.length <= KARATSUBALIMIT)
{
// Small multiplier, we'll just use the asm classic multiply.
if (y.length == 1)
{ // Trivial case, no cache effects to worry about
result[x.length] = multibyteMul(result[0..x.length], x, y[0], 0);
return;
}
if (x.length + y.length < CACHELIMIT)
return mulSimple(result, x, y);
// If x is so big that it won't fit into the cache, we divide it into chunks
// Every chunk must be greater than y.length.
// We make the first chunk shorter, if necessary, to ensure this.
auto chunksize = CACHELIMIT / y.length;
auto residual = x.length % chunksize;
if (residual < y.length)
{
chunksize -= y.length;
}
// Use schoolbook multiply.
mulSimple(result[0 .. chunksize + y.length], x[0..chunksize], y);
auto done = chunksize;
while (done < x.length)
{
// result[done .. done+ylength] already has a value.
chunksize = (done + (CACHELIMIT / y.length) < x.length) ? (CACHELIMIT / y.length) : x.length - done;
BigDigit [KARATSUBALIMIT] partial;
partial[0..y.length] = result[done..done+y.length];
mulSimple(result[done..done+chunksize+y.length], x[done..done+chunksize], y);
addAssignSimple(result[done..done+chunksize + y.length], partial[0..y.length]);
done += chunksize;
}
return;
}
auto half = (x.length >> 1) + (x.length & 1);
if (2*y.length*y.length <= x.length*x.length)
{
// UNBALANCED MULTIPLY
// Use school multiply to cut into quasi-squares of Karatsuba-size
// or larger. The ratio of the two sides of the 'square' must be
// between 1.414:1 and 1:1. Use Karatsuba on each chunk.
//
// For maximum performance, we want the ratio to be as close to
// 1:1 as possible. To achieve this, we can either pad x or y.
// The best choice depends on the modulus x%y.
auto numchunks = x.length / y.length;
auto chunksize = y.length;
auto extra = x.length % y.length;
auto maxchunk = chunksize + extra;
bool paddingY; // true = we're padding Y, false = we're padding X.
if (extra * extra * 2 < y.length*y.length)
{
// The leftover bit is small enough that it should be incorporated
// in the existing chunks.
// Make all the chunks a tiny bit bigger
// (We're padding y with zeros)
chunksize += extra / numchunks;
extra = x.length - chunksize*numchunks;
// there will probably be a few left over.
// Every chunk will either have size chunksize, or chunksize+1.
maxchunk = chunksize + 1;
paddingY = true;
assert(chunksize + extra + chunksize *(numchunks-1) == x.length );
}
else
{
// the extra bit is large enough that it's worth making a new chunk.
// (This means we're padding x with zeros, when doing the first one).
maxchunk = chunksize;
++numchunks;
paddingY = false;
assert(extra + chunksize *(numchunks-1) == x.length );
}
// We make the buffer a bit bigger so we have space for the partial sums.
BigDigit [] scratchbuff = new BigDigit[karatsubaRequiredBuffSize(maxchunk) + y.length];
BigDigit [] partial = scratchbuff[$ - y.length .. $];
size_t done; // how much of X have we done so far?
double residual = 0;
if (paddingY)
{
// If the first chunk is bigger, do it first. We're padding y.
mulKaratsuba(result[0 .. y.length + chunksize + (extra > 0 ? 1 : 0 )],
x[0 .. chunksize + (extra>0?1:0)], y, scratchbuff);
done = chunksize + (extra > 0 ? 1 : 0);
if (extra) --extra;
}
else
{ // We're padding X. Begin with the extra bit.
mulKaratsuba(result[0 .. y.length + extra], y, x[0..extra], scratchbuff);
done = extra;
extra = 0;
}
auto basechunksize = chunksize;
while (done < x.length)
{
chunksize = basechunksize + (extra > 0 ? 1 : 0);
if (extra) --extra;
partial[] = result[done .. done+y.length];
mulKaratsuba(result[done .. done + y.length + chunksize],
x[done .. done+chunksize], y, scratchbuff);
addAssignSimple(result[done .. done + y.length + chunksize], partial);
done += chunksize;
}
delete scratchbuff;
}
else
{
// Balanced. Use Karatsuba directly.
BigDigit [] scratchbuff = new BigDigit[karatsubaRequiredBuffSize(x.length)];
mulKaratsuba(result, x, y, scratchbuff);
delete scratchbuff;
}
}
/** General unsigned squaring routine for BigInts.
* Sets result = x*x.
* NOTE: If the highest half-digit of x is zero, the highest digit of result will
* also be zero.
*/
void squareInternal(BigDigit[] result, const BigDigit[] x) pure nothrow
{
// Squaring is potentially half a multiply, plus add the squares of
// the diagonal elements.
assert(result.length == 2*x.length);
if (x.length <= KARATSUBASQUARELIMIT)
{
if (x.length==1)
{
result[1] = multibyteMul(result[0..1], x, x[0], 0);
return;
}
return squareSimple(result, x);
}
// The nice thing about squaring is that it always stays balanced
BigDigit [] scratchbuff = new BigDigit[karatsubaRequiredBuffSize(x.length)];
squareKaratsuba(result, x, scratchbuff);
delete scratchbuff;
}
import core.bitop : bsr;
/// if remainder is null, only calculate quotient.
void divModInternal(BigDigit [] quotient, BigDigit[] remainder, const BigDigit [] u,
const BigDigit [] v) pure nothrow
{
assert(quotient.length == u.length - v.length + 1);
assert(remainder == null || remainder.length == v.length);
assert(v.length > 1);
assert(u.length >= v.length);
// Normalize by shifting v left just enough so that
// its high-order bit is on, and shift u left the
// same amount. The highest bit of u will never be set.
BigDigit [] vn = new BigDigit[v.length];
BigDigit [] un = new BigDigit[u.length + 1];
// How much to left shift v, so that its MSB is set.
uint s = BIGDIGITSHIFTMASK - bsr(v[$-1]);
if (s!=0)
{
multibyteShl(vn, v, s);
un[$-1] = multibyteShl(un[0..$-1], u, s);
}
else
{
vn[] = v[];
un[0..$-1] = u[];
un[$-1] = 0;
}
if (quotient.length<FASTDIVLIMIT)
{
schoolbookDivMod(quotient, un, vn);
}
else
{
blockDivMod(quotient, un, vn);
}
// Unnormalize remainder, if required.
if (remainder != null)
{
if (s == 0) remainder[] = un[0..vn.length];
else multibyteShr(remainder, un[0..vn.length+1], s);
}
delete un;
delete vn;
}
pure unittest
{
immutable(uint) [] u = [0, 0xFFFF_FFFE, 0x8000_0000];
immutable(uint) [] v = [0xFFFF_FFFF, 0x8000_0000];
uint [] q = new uint[u.length - v.length + 1];
uint [] r = new uint[2];
divModInternal(q, r, u, v);
assert(q[]==[0xFFFF_FFFFu, 0]);
assert(r[]==[0xFFFF_FFFFu, 0x7FFF_FFFF]);
u = [0, 0xFFFF_FFFE, 0x8000_0001];
v = [0xFFFF_FFFF, 0x8000_0000];
divModInternal(q, r, u, v);
}
private:
// Converts a big uint to a hexadecimal string.
//
// Optionally, a separator character (eg, an underscore) may be added between
// every 8 digits.
// buff.length must be data.length*8 if separator is zero,
// or data.length*9 if separator is non-zero. It will be completely filled.
char [] biguintToHex(char [] buff, const BigDigit [] data, char separator=0)
pure nothrow @safe
{
int x=0;
for (ptrdiff_t i=data.length - 1; i>=0; --i)
{
toHexZeroPadded(buff[x..x+8], data[i]);
x+=8;
if (separator)
{
if (i>0) buff[x] = separator;
++x;
}
}
return buff;
}
/** Convert a big uint into a decimal string.
*
* Params:
* data The biguint to be converted. Will be destroyed.
* buff The destination buffer for the decimal string. Must be
* large enough to store the result, including leading zeros.
* Will be filled backwards, starting from buff[$-1].
*
* buff.length must be >= (data.length*32)/log2(10) = 9.63296 * data.length.
* Returns:
* the lowest index of buff which was used.
*/
size_t biguintToDecimal(char [] buff, BigDigit [] data) pure nothrow
{
ptrdiff_t sofar = buff.length;
// Might be better to divide by (10^38/2^32) since that gives 38 digits for
// the price of 3 divisions and a shr; this version only gives 27 digits
// for 3 divisions.
while(data.length>1)
{
uint rem = multibyteDivAssign(data, 10_0000_0000, 0);
itoaZeroPadded(buff[sofar-9 .. sofar], rem);
sofar -= 9;
if (data[$-1] == 0 && data.length > 1)
{
data.length = data.length - 1;
}
}
itoaZeroPadded(buff[sofar-10 .. sofar], data[0]);
sofar -= 10;
// and strip off the leading zeros
while(sofar!= buff.length-1 && buff[sofar] == '0')
sofar++;
return sofar;
}
/** Convert a decimal string into a big uint.
*
* Params:
* data The biguint to be receive the result. Must be large enough to
* store the result.
* s The decimal string. May contain _ or 0..9
*
* The required length for the destination buffer is slightly less than
* 1 + s.length/log2(10) = 1 + s.length/3.3219.
*
* Returns:
* the highest index of data which was used.
*/
int biguintFromDecimal(BigDigit [] data, const(char)[] s) pure
in
{
assert((data.length >= 2) || (data.length == 1 && s.length == 1));
}
body
{
import std.conv : ConvException;
// Convert to base 1e19 = 10_000_000_000_000_000_000.
// (this is the largest power of 10 that will fit into a long).
// The length will be less than 1 + s.length/log2(10) = 1 + s.length/3.3219.
// 485 bits will only just fit into 146 decimal digits.
// As we convert the string, we record the number of digits we've seen in base 19:
// hi is the number of digits/19, lo is the extra digits (0 to 18).
// TODO: This is inefficient for very large strings (it is O(n^^2)).
// We should take advantage of fast multiplication once the numbers exceed
// Karatsuba size.
uint lo = 0; // number of powers of digits, 0..18
uint x = 0;
ulong y = 0;
uint hi = 0; // number of base 1e19 digits
data[0] = 0; // initially number is 0.
if (data.length > 1)
data[1] = 0;
for (int i= (s[0]=='-' || s[0]=='+')? 1 : 0; i<s.length; ++i)
{
if (s[i] == '_')
continue;
if (s[i] < '0' || s[i] > '9')
throw new ConvException("invalid digit");
x *= 10;
x += s[i] - '0';
++lo;
if (lo == 9)
{
y = x;
x = 0;
}
if (lo == 18)
{
y *= 10_0000_0000;
y += x;
x = 0;
}
if (lo == 19)
{
y *= 10;
y += x;
x = 0;
// Multiply existing number by 10^19, then add y1.
if (hi>0)
{
data[hi] = multibyteMul(data[0..hi], data[0..hi], 1220703125*2u, 0); // 5^13*2 = 0x9184_E72A
++hi;
data[hi] = multibyteMul(data[0..hi], data[0..hi], 15625*262144u, 0); // 5^6*2^18 = 0xF424_0000
++hi;
}
else
hi = 2;
uint c = multibyteIncrementAssign!('+')(data[0..hi], cast(uint)(y&0xFFFF_FFFF));
c += multibyteIncrementAssign!('+')(data[1..hi], cast(uint)(y>>32));
if (c!=0)
{
data[hi]=c;
++hi;
}
y = 0;
lo = 0;
}
}
// Now set y = all remaining digits.
if (lo>=18)
{
}
else if (lo>=9)
{
for (int k=9; k<lo; ++k) y*=10;
y+=x;
}
else
{
for (int k=0; k<lo; ++k) y*=10;
y+=x;
}
if (lo != 0)
{
if (hi == 0)
{
data[0] = cast(uint)y;
if (data.length == 1)
{
hi = 1;
}
else
{
data[1] = cast(uint)(y >>> 32);
hi=2;
}
}
else
{
while (lo>0)
{
uint c = multibyteMul(data[0..hi], data[0..hi], 10, 0);
if (c!=0)
{
data[hi]=c;
++hi;
}
--lo;
}
uint c = multibyteIncrementAssign!('+')(data[0..hi], cast(uint)(y&0xFFFF_FFFF));
if (y > 0xFFFF_FFFFL)
{
c += multibyteIncrementAssign!('+')(data[1..hi], cast(uint)(y>>32));
}
if (c!=0)
{
data[hi]=c;
++hi;
}
}
}
while (hi>1 && data[hi-1]==0)
--hi;
return hi;
}
private:
// ------------------------
// These in-place functions are only for internal use; they are incompatible
// with COW.
// Classic 'schoolbook' multiplication.
void mulSimple(BigDigit[] result, const(BigDigit) [] left,
const(BigDigit)[] right) pure nothrow
in
{
assert(result.length == left.length + right.length);
assert(right.length>1);
}
body
{
result[left.length] = multibyteMul(result[0..left.length], left, right[0], 0);
multibyteMultiplyAccumulate(result[1..$], left, right[1..$]);
}
// Classic 'schoolbook' squaring
void squareSimple(BigDigit[] result, const(BigDigit) [] x) pure nothrow
in
{
assert(result.length == 2*x.length);
assert(x.length>1);
}
body
{
multibyteSquare(result, x);
}
// add two uints of possibly different lengths. Result must be as long
// as the larger length.
// Returns carry (0 or 1).
uint addSimple(BigDigit[] result, const BigDigit [] left, const BigDigit [] right)
pure nothrow
in
{
assert(result.length == left.length);
assert(left.length >= right.length);
assert(right.length>0);
}
body
{
uint carry = multibyteAdd(result[0..right.length],
left[0..right.length], right, 0);
if (right.length < left.length)
{
result[right.length..left.length] = left[right.length .. $];
carry = multibyteIncrementAssign!('+')(result[right.length..$], carry);
}
return carry;
}
// result = left - right
// returns carry (0 or 1)
BigDigit subSimple(BigDigit [] result,const(BigDigit) [] left,
const(BigDigit) [] right) pure nothrow
in
{
assert(result.length == left.length);
assert(left.length >= right.length);
assert(right.length>0);
}
body
{
BigDigit carry = multibyteSub(result[0..right.length],
left[0..right.length], right, 0);
if (right.length < left.length)
{
result[right.length..left.length] = left[right.length .. $];
carry = multibyteIncrementAssign!('-')(result[right.length..$], carry);
} //else if (result.length==left.length+1) { result[$-1] = carry; carry=0; }
return carry;
}
/* result = result - right
* Returns carry = 1 if result was less than right.
*/
BigDigit subAssignSimple(BigDigit [] result, const(BigDigit) [] right)
pure nothrow
{
assert(result.length >= right.length);
uint c = multibyteSub(result[0..right.length], result[0..right.length], right, 0);
if (c && result.length > right.length)
c = multibyteIncrementAssign!('-')(result[right.length .. $], c);
return c;
}
/* result = result + right
*/
BigDigit addAssignSimple(BigDigit [] result, const(BigDigit) [] right)
pure nothrow
{
assert(result.length >= right.length);
uint c = multibyteAdd(result[0..right.length], result[0..right.length], right, 0);
if (c && result.length > right.length)
c = multibyteIncrementAssign!('+')(result[right.length .. $], c);
return c;
}
/* performs result += wantSub? - right : right;
*/
BigDigit addOrSubAssignSimple(BigDigit [] result, const(BigDigit) [] right,
bool wantSub) pure nothrow
{
if (wantSub)
return subAssignSimple(result, right);
else
return addAssignSimple(result, right);
}
// return true if x<y, considering leading zeros
bool less(const(BigDigit)[] x, const(BigDigit)[] y) pure nothrow
{
assert(x.length >= y.length);
auto k = x.length-1;
while(x[k]==0 && k>=y.length)
--k;
if (k>=y.length)
return false;
while (k>0 && x[k]==y[k])
--k;
return x[k] < y[k];
}
// Set result = abs(x-y), return true if result is negative(x<y), false if x<=y.
bool inplaceSub(BigDigit[] result, const(BigDigit)[] x, const(BigDigit)[] y)
pure nothrow
{
assert(result.length == (x.length >= y.length) ? x.length : y.length);
size_t minlen;
bool negative;
if (x.length >= y.length)
{
minlen = y.length;
negative = less(x, y);
}
else
{
minlen = x.length;
negative = !less(y, x);
}
const (BigDigit)[] large, small;
if (negative)
{
large = y; small = x;
}
else
{
large = x; small = y;
}
BigDigit carry = multibyteSub(result[0..minlen], large[0..minlen], small[0..minlen], 0);
if (x.length != y.length)
{
result[minlen..large.length]= large[minlen..$];
result[large.length..$] = 0;
if (carry)
multibyteIncrementAssign!('-')(result[minlen..$], carry);
}
return negative;
}
/* Determine how much space is required for the temporaries
* when performing a Karatsuba multiplication.
*/
size_t karatsubaRequiredBuffSize(size_t xlen) pure nothrow @safe
{
return xlen <= KARATSUBALIMIT ? 0 : 2*xlen; // - KARATSUBALIMIT+2;
}
/* Sets result = x*y, using Karatsuba multiplication.
* x must be longer or equal to y.
* Valid only for balanced multiplies, where x is not shorter than y.
* It is superior to schoolbook multiplication if and only if
* sqrt(2)*y.length > x.length > y.length.
* Karatsuba multiplication is O(n^1.59), whereas schoolbook is O(n^2)
* The maximum allowable length of x and y is uint.max; but better algorithms
* should be used far before that length is reached.
* Params:
* scratchbuff An array long enough to store all the temporaries. Will be destroyed.
*/
void mulKaratsuba(BigDigit [] result, const(BigDigit) [] x,
const(BigDigit)[] y, BigDigit [] scratchbuff) pure nothrow
{
assert(x.length >= y.length);
assert(result.length < uint.max, "Operands too large");
assert(result.length == x.length + y.length);
if (x.length <= KARATSUBALIMIT)
{
return mulSimple(result, x, y);
}
// Must be almost square (otherwise, a schoolbook iteration is better)
assert(2L * y.length * y.length > (x.length-1) * (x.length-1),
"Bigint Internal Error: Asymmetric Karatsuba");
// The subtractive version of Karatsuba multiply uses the following result:
// (Nx1 + x0)*(Ny1 + y0) = (N*N)*x1y1 + x0y0 + N * (x0y0 + x1y1 - mid)
// where mid = (x0-x1)*(y0-y1)
// requiring 3 multiplies of length N, instead of 4.
// The advantage of the subtractive over the additive version is that
// the mid multiply cannot exceed length N. But there are subtleties:
// (x0-x1),(y0-y1) may be negative or zero. To keep it simple, we
// retain all of the leading zeros in the subtractions
// half length, round up.
auto half = (x.length >> 1) + (x.length & 1);
const(BigDigit) [] x0 = x[0 .. half];
const(BigDigit) [] x1 = x[half .. $];
const(BigDigit) [] y0 = y[0 .. half];
const(BigDigit) [] y1 = y[half .. $];
BigDigit [] mid = scratchbuff[0 .. half*2];
BigDigit [] newscratchbuff = scratchbuff[half*2 .. $];
BigDigit [] resultLow = result[0 .. 2*half];
BigDigit [] resultHigh = result[2*half .. $];
// initially use result to store temporaries
BigDigit [] xdiff= result[0 .. half];
BigDigit [] ydiff = result[half .. half*2];
// First, we calculate mid, and sign of mid
bool midNegative = inplaceSub(xdiff, x0, x1)
^ inplaceSub(ydiff, y0, y1);
mulKaratsuba(mid, xdiff, ydiff, newscratchbuff);
// Low half of result gets x0 * y0. High half gets x1 * y1
mulKaratsuba(resultLow, x0, y0, newscratchbuff);
if (2L * y1.length * y1.length < x1.length * x1.length)
{
// an asymmetric situation has been created.
// Worst case is if x:y = 1.414 : 1, then x1:y1 = 2.41 : 1.
// Applying one schoolbook multiply gives us two pieces each 1.2:1
if (y1.length <= KARATSUBALIMIT)
mulSimple(resultHigh, x1, y1);
else
{
// divide x1 in two, then use schoolbook multiply on the two pieces.
auto quarter = (x1.length >> 1) + (x1.length & 1);
bool ysmaller = (quarter >= y1.length);
mulKaratsuba(resultHigh[0..quarter+y1.length], ysmaller ? x1[0..quarter] : y1,
ysmaller ? y1 : x1[0..quarter], newscratchbuff);
// Save the part which will be overwritten.
bool ysmaller2 = ((x1.length - quarter) >= y1.length);
newscratchbuff[0..y1.length] = resultHigh[quarter..quarter + y1.length];
mulKaratsuba(resultHigh[quarter..$], ysmaller2 ? x1[quarter..$] : y1,
ysmaller2 ? y1 : x1[quarter..$], newscratchbuff[y1.length..$]);
resultHigh[quarter..$].addAssignSimple(newscratchbuff[0..y1.length]);
}
}
else
mulKaratsuba(resultHigh, x1, y1, newscratchbuff);
/* We now have result = x0y0 + (N*N)*x1y1
Before adding or subtracting mid, we must calculate
result += N * (x0y0 + x1y1)
We can do this with three half-length additions. With a = x0y0, b = x1y1:
aHI aLO
+ aHI aLO
+ bHI bLO
+ bHI bLO
= R3 R2 R1 R0
R1 = aHI + bLO + aLO
R2 = aHI + bLO + aHI + carry_from_R1
R3 = bHi + carry_from_R2
It might actually be quicker to do it in two full-length additions:
newscratchbuff[2*half] = addSimple(newscratchbuff[0..2*half], result[0..2*half], result[2*half..$]);
addAssignSimple(result[half..$], newscratchbuff[0..2*half+1]);
*/
BigDigit[] R1 = result[half..half*2];
BigDigit[] R2 = result[half*2..half*3];
BigDigit[] R3 = result[half*3..$];
BigDigit c1 = multibyteAdd(R2, R2, R1, 0); // c1:R2 = R2 + R1
BigDigit c2 = multibyteAdd(R1, R2, result[0..half], 0); // c2:R1 = R2 + R1 + R0
BigDigit c3 = addAssignSimple(R2, R3); // R2 = R2 + R1 + R3
if (c1+c2)
multibyteIncrementAssign!('+')(result[half*2..$], c1+c2);
if (c1+c3)
multibyteIncrementAssign!('+')(R3, c1+c3);
// And finally we subtract mid
addOrSubAssignSimple(result[half..$], mid, !midNegative);
}
void squareKaratsuba(BigDigit [] result, const BigDigit [] x,
BigDigit [] scratchbuff) pure nothrow
{
// See mulKaratsuba for implementation comments.
// Squaring is simpler, since it never gets asymmetric.
assert(result.length < uint.max, "Operands too large");
assert(result.length == 2*x.length);
if (x.length <= KARATSUBASQUARELIMIT)
{
return squareSimple(result, x);
}
// half length, round up.
auto half = (x.length >> 1) + (x.length & 1);
const(BigDigit)[] x0 = x[0 .. half];
const(BigDigit)[] x1 = x[half .. $];
BigDigit [] mid = scratchbuff[0 .. half*2];
BigDigit [] newscratchbuff = scratchbuff[half*2 .. $];
// initially use result to store temporaries
BigDigit [] xdiff= result[0 .. half];
BigDigit [] ydiff = result[half .. half*2];
// First, we calculate mid. We don't need its sign
inplaceSub(xdiff, x0, x1);
squareKaratsuba(mid, xdiff, newscratchbuff);
// Set result = x0x0 + (N*N)*x1x1
squareKaratsuba(result[0 .. 2*half], x0, newscratchbuff);
squareKaratsuba(result[2*half .. $], x1, newscratchbuff);
/* result += N * (x0x0 + x1x1)
Do this with three half-length additions. With a = x0x0, b = x1x1:
R1 = aHI + bLO + aLO
R2 = aHI + bLO + aHI + carry_from_R1
R3 = bHi + carry_from_R2
*/
BigDigit[] R1 = result[half..half*2];
BigDigit[] R2 = result[half*2..half*3];
BigDigit[] R3 = result[half*3..$];
BigDigit c1 = multibyteAdd(R2, R2, R1, 0); // c1:R2 = R2 + R1
BigDigit c2 = multibyteAdd(R1, R2, result[0..half], 0); // c2:R1 = R2 + R1 + R0
BigDigit c3 = addAssignSimple(R2, R3); // R2 = R2 + R1 + R3
if (c1+c2) multibyteIncrementAssign!('+')(result[half*2..$], c1+c2);
if (c1+c3) multibyteIncrementAssign!('+')(R3, c1+c3);
// And finally we subtract mid, which is always positive
subAssignSimple(result[half..$], mid);
}
/* Knuth's Algorithm D, as presented in
* H.S. Warren, "Hacker's Delight", Addison-Wesley Professional (2002).
* Also described in "Modern Computer Arithmetic" 0.2, Exercise 1.8.18.
* Given u and v, calculates quotient = u / v, u = u % v.
* v must be normalized (ie, the MSB of v must be 1).
* The most significant words of quotient and u may be zero.
* u[0..v.length] holds the remainder.
*/
void schoolbookDivMod(BigDigit [] quotient, BigDigit [] u, in BigDigit [] v)
pure nothrow
{
assert(quotient.length == u.length - v.length);
assert(v.length > 1);
assert(u.length >= v.length);
assert((v[$-1]&0x8000_0000)!=0);
assert(u[$-1] < v[$-1]);
// BUG: This code only works if BigDigit is uint.
uint vhi = v[$-1];
uint vlo = v[$-2];
for (ptrdiff_t j = u.length - v.length - 1; j >= 0; j--)
{
// Compute estimate of quotient[j],
// qhat = (three most significant words of u)/(two most sig words of v).
uint qhat;
if (u[j + v.length] == vhi)
{
// uu/vhi could exceed uint.max (it will be 0x8000_0000 or 0x8000_0001)
qhat = uint.max;
}
else
{
uint ulo = u[j + v.length - 2];
version(D_InlineAsm_X86)
{
// Note: On DMD, this is only ~10% faster than the non-asm code.
uint *p = &u[j + v.length - 1];
asm pure nothrow
{
mov EAX, p;
mov EDX, [EAX+4];
mov EAX, [EAX];
div dword ptr [vhi];
mov qhat, EAX;
mov ECX, EDX;
div3by2correction:
mul dword ptr [vlo]; // EDX:EAX = qhat * vlo
sub EAX, ulo;
sbb EDX, ECX;
jbe div3by2done;
mov EAX, qhat;
dec EAX;
mov qhat, EAX;
add ECX, dword ptr [vhi];
jnc div3by2correction;
div3by2done: ;
}
}
else
{ // version(InlineAsm)
ulong uu = (cast(ulong)(u[j + v.length]) << 32) | u[j + v.length - 1];
ulong bigqhat = uu / vhi;
ulong rhat = uu - bigqhat * vhi;
qhat = cast(uint)bigqhat;
again:
if (cast(ulong)qhat * vlo > ((rhat << 32) + ulo))
{
--qhat;
rhat += vhi;
if (!(rhat & 0xFFFF_FFFF_0000_0000L))
goto again;
}
} // version(InlineAsm)
}
// Multiply and subtract.
uint carry = multibyteMulAdd!('-')(u[j..j + v.length], v, qhat, 0);
if (u[j+v.length] < carry)
{
// If we subtracted too much, add back
--qhat;
carry -= multibyteAdd(u[j..j + v.length],u[j..j + v.length], v, 0);
}
quotient[j] = qhat;
u[j + v.length] = u[j + v.length] - carry;
}
}
private:
// TODO: Replace with a library call
void itoaZeroPadded(char[] output, uint value, int radix = 10)
pure nothrow @safe
{
ptrdiff_t x = output.length - 1;
for( ; x >= 0; --x)
{
output[x]= cast(char)(value % radix + '0');
value /= radix;
}
}
void toHexZeroPadded(char[] output, uint value) pure nothrow @safe
{
ptrdiff_t x = output.length - 1;
static immutable string hexDigits = "0123456789ABCDEF";
for( ; x>=0; --x)
{
output[x] = hexDigits[value & 0xF];
value >>= 4;
}
}
private:
// Returns the highest value of i for which left[i]!=right[i],
// or 0 if left[] == right[]
size_t highestDifferentDigit(const BigDigit [] left, const BigDigit [] right)
pure nothrow @nogc @safe
{
assert(left.length == right.length);
for (ptrdiff_t i = left.length - 1; i>0; --i)
{
if (left[i] != right[i])
return i;
}
return 0;
}
// Returns the lowest value of i for which x[i]!=0.
int firstNonZeroDigit(const BigDigit [] x) pure nothrow @nogc @safe
{
int k = 0;
while (x[k]==0)
{
++k;
assert(k<x.length);
}
return k;
}
import core.stdc.stdio;
/*
Calculate quotient and remainder of u / v using fast recursive division.
v must be normalised, and must be at least half as long as u.
Given u and v, v normalised, calculates quotient = u/v, u = u%v.
scratch is temporary storage space, length must be >= quotient + 1.
Returns:
u[0..v.length] is the remainder. u[v.length..$] is corrupted.
Implements algorithm 1.8 from MCA.
This algorithm has an annoying special case. After the first recursion, the
highest bit of the quotient may be set. This means that in the second
recursive call, the 'in' contract would be violated. (This happens only
when the top quarter of u is equal to the top half of v. A base 10
equivalent example of this situation is 5517/56; the first step gives
55/5 = 11). To maintain the in contract, we pad a zero to the top of both
u and the quotient. 'mayOverflow' indicates that that the special case
has occurred.
(In MCA, a different strategy is used: the in contract is weakened, and
schoolbookDivMod is more general: it allows the high bit of u to be set).
See also:
- C. Burkinel and J. Ziegler, "Fast Recursive Division", MPI-I-98-1-022,
Max-Planck Institute fuer Informatik, (Oct 1998).
*/
void recursiveDivMod(BigDigit[] quotient, BigDigit[] u, const(BigDigit)[] v,
BigDigit[] scratch, bool mayOverflow = false)
pure nothrow
in
{
// v must be normalized
assert(v.length > 1);
assert((v[$ - 1] & 0x8000_0000) != 0);
assert(!(u[$ - 1] & 0x8000_0000));
assert(quotient.length == u.length - v.length);
if (mayOverflow)
{
assert(u[$-1] == 0);
assert(u[$-2] & 0x8000_0000);
}
// Must be symmetric. Use block schoolbook division if not.
assert((mayOverflow ? u.length-1 : u.length) <= 2 * v.length);
assert((mayOverflow ? u.length-1 : u.length) >= v.length);
assert(scratch.length >= quotient.length + (mayOverflow ? 0 : 1));
}
body
{
if (quotient.length < FASTDIVLIMIT)
{
return schoolbookDivMod(quotient, u, v);
}
// Split quotient into two halves, but keep padding in the top half
auto k = (mayOverflow ? quotient.length - 1 : quotient.length) >> 1;
// RECURSION 1: Calculate the high half of the quotient
// Note that if u and quotient were padded, they remain padded during
// this call, so in contract is satisfied.
recursiveDivMod(quotient[k .. $], u[2 * k .. $], v[k .. $],
scratch, mayOverflow);
// quotient[k..$] is our guess at the high quotient.
// u[2*k.. 2.*k + v.length - k = k + v.length] is the high part of the
// first remainder. u[0..2*k] is the low part.
// Calculate the full first remainder to be
// remainder - highQuotient * lowDivisor
// reducing highQuotient until the remainder is positive.
// The low part of the remainder, u[0..k], cannot be altered by this.
adjustRemainder(quotient[k .. $], u[k .. k + v.length], v, k,
scratch[0 .. quotient.length], mayOverflow);
// RECURSION 2: Calculate the low half of the quotient
// The full first remainder is now in u[0..k + v.length].
if (u[k + v.length - 1] & 0x8000_0000)
{
// Special case. The high quotient is 0x1_00...000 or 0x1_00...001.
// This means we need an extra quotient word for the next recursion.
// We need to restore the invariant for the recursive calls.
// We do this by padding both u and quotient. Extending u is trivial,
// because the higher words will not be used again. But for the
// quotient, we're clobbering the low word of the high quotient,
// so we need save it, and add it back in after the recursive call.
auto clobberedQuotient = quotient[k];
u[k+v.length] = 0;
recursiveDivMod(quotient[0 .. k+1], u[k .. k + v.length+1],
v[k .. $], scratch, true);
adjustRemainder(quotient[0 .. k+1], u[0 .. v.length], v, k,
scratch[0 .. 2 * k+1], true);
// Now add the quotient word that got clobbered earlier.
multibyteIncrementAssign!('+')(quotient[k..$], clobberedQuotient);
}
else
{
// The special case has NOT happened.
recursiveDivMod(quotient[0 .. k], u[k .. k + v.length], v[k .. $],
scratch, false);
// high remainder is in u[k..k+(v.length-k)] == u[k .. v.length]
adjustRemainder(quotient[0 .. k], u[0 .. v.length], v, k,
scratch[0 .. 2 * k]);
}
}
// rem -= quot * v[0..k].
// If would make rem negative, decrease quot until rem is >=0.
// Needs (quot.length * k) scratch space to store the result of the multiply.
void adjustRemainder(BigDigit[] quot, BigDigit[] rem, const(BigDigit)[] v,
ptrdiff_t k,
BigDigit[] scratch, bool mayOverflow = false) pure nothrow
{
assert(rem.length == v.length);
mulInternal(scratch, quot, v[0 .. k]);
uint carry = 0;
if (mayOverflow)
carry = scratch[$-1] + subAssignSimple(rem, scratch[0..$-1]);
else
carry = subAssignSimple(rem, scratch);
while(carry)
{
multibyteIncrementAssign!('-')(quot, 1); // quot--
carry -= multibyteAdd(rem, rem, v, 0);
}
}
// Cope with unbalanced division by performing block schoolbook division.
void blockDivMod(BigDigit [] quotient, BigDigit [] u, in BigDigit [] v)
pure nothrow
{
assert(quotient.length == u.length - v.length);
assert(v.length > 1);
assert(u.length >= v.length);
assert((v[$-1] & 0x8000_0000)!=0);
assert((u[$-1] & 0x8000_0000)==0);
BigDigit [] scratch = new BigDigit[v.length + 1];
// Perform block schoolbook division, with 'v.length' blocks.
auto m = u.length - v.length;
while (m > v.length)
{
bool mayOverflow = (u[m + v.length -1 ] & 0x8000_0000)!=0;
BigDigit saveq;
if (mayOverflow)
{
u[m + v.length] = 0;
saveq = quotient[m];
}
recursiveDivMod(quotient[m-v.length..m + (mayOverflow? 1: 0)],
u[m - v.length..m + v.length + (mayOverflow? 1: 0)], v, scratch, mayOverflow);
if (mayOverflow)
{
assert(quotient[m] == 0);
quotient[m] = saveq;
}
m -= v.length;
}
recursiveDivMod(quotient[0..m], u[0..m + v.length], v, scratch);
delete scratch;
}
version(unittest)
{
import core.stdc.stdio;
}
unittest
{
void printBiguint(const uint [] data)
{
char [] buff = biguintToHex(new char[data.length*9], data, '_');
printf("%.*s\n", buff.length, buff.ptr);
}
void printDecimalBigUint(BigUint data)
{
auto str = data.toDecimalString(0);
printf("%.*s\n", str.length, str.ptr);
}
uint [] a, b;
a = new uint[43];
b = new uint[179];
for (int i=0; i<a.length; ++i) a[i] = 0x1234_B6E9 + i;
for (int i=0; i<b.length; ++i) b[i] = 0x1BCD_8763 - i*546;
a[$-1] |= 0x8000_0000;
uint [] r = new uint[a.length];
uint [] q = new uint[b.length-a.length+1];
divModInternal(q, r, b, a);
q = q[0..$-1];
uint [] r1 = r.dup;
uint [] q1 = q.dup;
blockDivMod(q, b, a);
r = b[0..a.length];
assert(r[] == r1[]);
assert(q[] == q1[]);
}
|