/usr/include/guacamole/hash.h is in libguac-dev 0.8.3-1+b2.
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
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*
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* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is libguac.
*
* The Initial Developer of the Original Code is
* Michael Jumper.
* Portions created by the Initial Developer are Copyright (C) 2010
* the Initial Developer. All Rights Reserved.
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* Alternatively, the contents of this file may be used under the terms of
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#ifndef _GUAC_HASH_H
#define _GUAC_HASH_H
#include <cairo/cairo.h>
/**
* Provides functions and structures for producing likely-to-be-unique hash
* values for images.
*
* @file hash.h
*/
/**
* Produces a 24-bit hash value from all pixels of the given surface. The
* surface provided must be RGB or ARGB with each pixel stored in 32 bits.
* The hashing algorithm used is a variant of the cyclic polynomial rolling
* hash.
*
* @param surface The Cairo surface to hash.
* @return An arbitrary 24-bit unsigned integer value intended to be well
* distributed across different images.
*/
unsigned int guac_hash_surface(cairo_surface_t* surface);
/**
* Given two Cairo surfaces, returns zero if the data contained within each
* is identical, and a positive or negative value if the value of the first
* is found to be lexically greater or less than the second respectively.
*
* @param a The first Cairo surface to compare.
* @param b The Cairo surface to compare the first surface against.
* @return Zero if the data contained within each is identical, and a positive
* or negative value if the value of the first is found to be lexically
* greater or less than the second respectively.
*/
int guac_surface_cmp(cairo_surface_t* a, cairo_surface_t* b);
#endif
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