/usr/src/lttng-modules-2.5.1/lib/bitfield.h is in lttng-modules-dkms 2.5.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#define _BABELTRACE_BITFIELD_H
/*
* BabelTrace
*
* Bitfields read/write functions.
*
* Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "../lttng-endian.h"
#ifndef CHAR_BIT
#define CHAR_BIT 8
#endif
/* We can't shift a int from 32 bit, >> 32 and << 32 on int is undefined */
#define _bt_piecewise_rshift(_v, _shift) \
({ \
typeof(_v) ___v = (_v); \
typeof(_shift) ___shift = (_shift); \
unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \
unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
\
for (; sb; sb--) \
___v >>= sizeof(___v) * CHAR_BIT - 1; \
___v >>= final; \
})
#define _bt_piecewise_lshift(_v, _shift) \
({ \
typeof(_v) ___v = (_v); \
typeof(_shift) ___shift = (_shift); \
unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \
unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \
\
for (; sb; sb--) \
___v <<= sizeof(___v) * CHAR_BIT - 1; \
___v <<= final; \
})
#define _bt_is_signed_type(type) (((type)(-1)) < 0)
#define _bt_unsigned_cast(type, v) \
({ \
(sizeof(v) < sizeof(type)) ? \
((type) (v)) & (~(~(type) 0 << (sizeof(v) * CHAR_BIT))) : \
(type) (v); \
})
/*
* bt_bitfield_write - write integer to a bitfield in native endianness
*
* Save integer to the bitfield, which starts at the "start" bit, has "len"
* bits.
* The inside of a bitfield is from high bits to low bits.
* Uses native endianness.
* For unsigned "v", pad MSB with 0 if bitfield is larger than v.
* For signed "v", sign-extend v if bitfield is larger than v.
*
* On little endian, bytes are placed from the less significant to the most
* significant. Also, consecutive bitfields are placed from lower bits to higher
* bits.
*
* On big endian, bytes are places from most significant to less significant.
* Also, consecutive bitfields are placed from higher to lower bits.
*/
#define _bt_bitfield_write_le(_ptr, type, _start, _length, _v) \
do { \
typeof(_v) __v = (_v); \
type *__ptr = (void *) (_ptr); \
unsigned long __start = (_start), __length = (_length); \
type mask, cmask; \
unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
unsigned long start_unit, end_unit, this_unit; \
unsigned long end, cshift; /* cshift is "complement shift" */ \
\
if (!__length) \
break; \
\
end = __start + __length; \
start_unit = __start / ts; \
end_unit = (end + (ts - 1)) / ts; \
\
/* Trim v high bits */ \
if (__length < sizeof(__v) * CHAR_BIT) \
__v &= ~((~(typeof(__v)) 0) << __length); \
\
/* We can now append v with a simple "or", shift it piece-wise */ \
this_unit = start_unit; \
if (start_unit == end_unit - 1) { \
mask = ~((~(type) 0) << (__start % ts)); \
if (end % ts) \
mask |= (~(type) 0) << (end % ts); \
cmask = (type) __v << (__start % ts); \
cmask &= ~mask; \
__ptr[this_unit] &= mask; \
__ptr[this_unit] |= cmask; \
break; \
} \
if (__start % ts) { \
cshift = __start % ts; \
mask = ~((~(type) 0) << cshift); \
cmask = (type) __v << cshift; \
cmask &= ~mask; \
__ptr[this_unit] &= mask; \
__ptr[this_unit] |= cmask; \
__v = _bt_piecewise_rshift(__v, ts - cshift); \
__start += ts - cshift; \
this_unit++; \
} \
for (; this_unit < end_unit - 1; this_unit++) { \
__ptr[this_unit] = (type) __v; \
__v = _bt_piecewise_rshift(__v, ts); \
__start += ts; \
} \
if (end % ts) { \
mask = (~(type) 0) << (end % ts); \
cmask = (type) __v; \
cmask &= ~mask; \
__ptr[this_unit] &= mask; \
__ptr[this_unit] |= cmask; \
} else \
__ptr[this_unit] = (type) __v; \
} while (0)
#define _bt_bitfield_write_be(_ptr, type, _start, _length, _v) \
do { \
typeof(_v) __v = (_v); \
type *__ptr = (void *) (_ptr); \
unsigned long __start = (_start), __length = (_length); \
type mask, cmask; \
unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
unsigned long start_unit, end_unit, this_unit; \
unsigned long end, cshift; /* cshift is "complement shift" */ \
\
if (!__length) \
break; \
\
end = __start + __length; \
start_unit = __start / ts; \
end_unit = (end + (ts - 1)) / ts; \
\
/* Trim v high bits */ \
if (__length < sizeof(__v) * CHAR_BIT) \
__v &= ~((~(typeof(__v)) 0) << __length); \
\
/* We can now append v with a simple "or", shift it piece-wise */ \
this_unit = end_unit - 1; \
if (start_unit == end_unit - 1) { \
mask = ~((~(type) 0) << ((ts - (end % ts)) % ts)); \
if (__start % ts) \
mask |= (~((type) 0)) << (ts - (__start % ts)); \
cmask = (type) __v << ((ts - (end % ts)) % ts); \
cmask &= ~mask; \
__ptr[this_unit] &= mask; \
__ptr[this_unit] |= cmask; \
break; \
} \
if (end % ts) { \
cshift = end % ts; \
mask = ~((~(type) 0) << (ts - cshift)); \
cmask = (type) __v << (ts - cshift); \
cmask &= ~mask; \
__ptr[this_unit] &= mask; \
__ptr[this_unit] |= cmask; \
__v = _bt_piecewise_rshift(__v, cshift); \
end -= cshift; \
this_unit--; \
} \
for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
__ptr[this_unit] = (type) __v; \
__v = _bt_piecewise_rshift(__v, ts); \
end -= ts; \
} \
if (__start % ts) { \
mask = (~(type) 0) << (ts - (__start % ts)); \
cmask = (type) __v; \
cmask &= ~mask; \
__ptr[this_unit] &= mask; \
__ptr[this_unit] |= cmask; \
} else \
__ptr[this_unit] = (type) __v; \
} while (0)
/*
* bt_bitfield_write - write integer to a bitfield in native endianness
* bt_bitfield_write_le - write integer to a bitfield in little endian
* bt_bitfield_write_be - write integer to a bitfield in big endian
*/
#if (__BYTE_ORDER == __LITTLE_ENDIAN)
#define bt_bitfield_write(ptr, type, _start, _length, _v) \
_bt_bitfield_write_le(ptr, type, _start, _length, _v)
#define bt_bitfield_write_le(ptr, type, _start, _length, _v) \
_bt_bitfield_write_le(ptr, type, _start, _length, _v)
#define bt_bitfield_write_be(ptr, type, _start, _length, _v) \
_bt_bitfield_write_be(ptr, unsigned char, _start, _length, _v)
#elif (__BYTE_ORDER == __BIG_ENDIAN)
#define bt_bitfield_write(ptr, type, _start, _length, _v) \
_bt_bitfield_write_be(ptr, type, _start, _length, _v)
#define bt_bitfield_write_le(ptr, type, _start, _length, _v) \
_bt_bitfield_write_le(ptr, unsigned char, _start, _length, _v)
#define bt_bitfield_write_be(ptr, type, _start, _length, _v) \
_bt_bitfield_write_be(ptr, type, _start, _length, _v)
#else /* (BYTE_ORDER == PDP_ENDIAN) */
#error "Byte order not supported"
#endif
#define _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
do { \
typeof(*(_vptr)) *__vptr = (_vptr); \
typeof(*__vptr) __v; \
type *__ptr = (void *) (_ptr); \
unsigned long __start = (_start), __length = (_length); \
type mask, cmask; \
unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
unsigned long start_unit, end_unit, this_unit; \
unsigned long end, cshift; /* cshift is "complement shift" */ \
\
if (!__length) { \
*__vptr = 0; \
break; \
} \
\
end = __start + __length; \
start_unit = __start / ts; \
end_unit = (end + (ts - 1)) / ts; \
\
this_unit = end_unit - 1; \
if (_bt_is_signed_type(typeof(__v)) \
&& (__ptr[this_unit] & ((type) 1 << ((end % ts ? : ts) - 1)))) \
__v = ~(typeof(__v)) 0; \
else \
__v = 0; \
if (start_unit == end_unit - 1) { \
cmask = __ptr[this_unit]; \
cmask >>= (__start % ts); \
if ((end - __start) % ts) { \
mask = ~((~(type) 0) << (end - __start)); \
cmask &= mask; \
} \
__v = _bt_piecewise_lshift(__v, end - __start); \
__v |= _bt_unsigned_cast(typeof(__v), cmask); \
*__vptr = __v; \
break; \
} \
if (end % ts) { \
cshift = end % ts; \
mask = ~((~(type) 0) << cshift); \
cmask = __ptr[this_unit]; \
cmask &= mask; \
__v = _bt_piecewise_lshift(__v, cshift); \
__v |= _bt_unsigned_cast(typeof(__v), cmask); \
end -= cshift; \
this_unit--; \
} \
for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \
__v = _bt_piecewise_lshift(__v, ts); \
__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
end -= ts; \
} \
if (__start % ts) { \
mask = ~((~(type) 0) << (ts - (__start % ts))); \
cmask = __ptr[this_unit]; \
cmask >>= (__start % ts); \
cmask &= mask; \
__v = _bt_piecewise_lshift(__v, ts - (__start % ts)); \
__v |= _bt_unsigned_cast(typeof(__v), cmask); \
} else { \
__v = _bt_piecewise_lshift(__v, ts); \
__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
} \
*__vptr = __v; \
} while (0)
#define _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
do { \
typeof(*(_vptr)) *__vptr = (_vptr); \
typeof(*__vptr) __v; \
type *__ptr = (void *) (_ptr); \
unsigned long __start = (_start), __length = (_length); \
type mask, cmask; \
unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \
unsigned long start_unit, end_unit, this_unit; \
unsigned long end, cshift; /* cshift is "complement shift" */ \
\
if (!__length) { \
*__vptr = 0; \
break; \
} \
\
end = __start + __length; \
start_unit = __start / ts; \
end_unit = (end + (ts - 1)) / ts; \
\
this_unit = start_unit; \
if (_bt_is_signed_type(typeof(__v)) \
&& (__ptr[this_unit] & ((type) 1 << (ts - (__start % ts) - 1)))) \
__v = ~(typeof(__v)) 0; \
else \
__v = 0; \
if (start_unit == end_unit - 1) { \
cmask = __ptr[this_unit]; \
cmask >>= (ts - (end % ts)) % ts; \
if ((end - __start) % ts) { \
mask = ~((~(type) 0) << (end - __start)); \
cmask &= mask; \
} \
__v = _bt_piecewise_lshift(__v, end - __start); \
__v |= _bt_unsigned_cast(typeof(__v), cmask); \
*__vptr = __v; \
break; \
} \
if (__start % ts) { \
cshift = __start % ts; \
mask = ~((~(type) 0) << (ts - cshift)); \
cmask = __ptr[this_unit]; \
cmask &= mask; \
__v = _bt_piecewise_lshift(__v, ts - cshift); \
__v |= _bt_unsigned_cast(typeof(__v), cmask); \
__start += ts - cshift; \
this_unit++; \
} \
for (; this_unit < end_unit - 1; this_unit++) { \
__v = _bt_piecewise_lshift(__v, ts); \
__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
__start += ts; \
} \
if (end % ts) { \
mask = ~((~(type) 0) << (end % ts)); \
cmask = __ptr[this_unit]; \
cmask >>= ts - (end % ts); \
cmask &= mask; \
__v = _bt_piecewise_lshift(__v, end % ts); \
__v |= _bt_unsigned_cast(typeof(__v), cmask); \
} else { \
__v = _bt_piecewise_lshift(__v, ts); \
__v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\
} \
*__vptr = __v; \
} while (0)
/*
* bt_bitfield_read - read integer from a bitfield in native endianness
* bt_bitfield_read_le - read integer from a bitfield in little endian
* bt_bitfield_read_be - read integer from a bitfield in big endian
*/
#if (__BYTE_ORDER == __LITTLE_ENDIAN)
#define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \
_bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
#define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
_bt_bitfield_read_le(_ptr, type, _start, _length, _vptr)
#define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
_bt_bitfield_read_be(_ptr, unsigned char, _start, _length, _vptr)
#elif (__BYTE_ORDER == __BIG_ENDIAN)
#define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \
_bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
#define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \
_bt_bitfield_read_le(_ptr, unsigned char, _start, _length, _vptr)
#define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \
_bt_bitfield_read_be(_ptr, type, _start, _length, _vptr)
#else /* (__BYTE_ORDER == __PDP_ENDIAN) */
#error "Byte order not supported"
#endif
#endif /* _BABELTRACE_BITFIELD_H */
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