mirror of https://github.com/encounter/SDL.git
166 lines
3.4 KiB
C
166 lines
3.4 KiB
C
/*
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Simple DirectMedia Layer
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Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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/*
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Used by the test execution component.
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Original source code contributed by A. Schiffler for GSOC project.
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*/
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#include "SDL_config.h"
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#include "SDL_test.h"
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int SDLTest_Crc32Init(SDLTest_Crc32Context *crcContext)
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{
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int i,j;
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CrcUint32 c;
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/* Sanity check context pointer */
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if (crcContext==NULL) {
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return -1;
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}
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/*
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* Build auxiliary table for parallel byte-at-a-time CRC-32
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*/
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#ifdef ORIGINAL_METHOD
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for (i = 0; i < 256; ++i) {
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for (c = i << 24, j = 8; j > 0; --j) {
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c = c & 0x80000000 ? (c << 1) ^ CRC32_POLY : (c << 1);
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}
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crcContext->crc32_table[i] = c;
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}
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#else
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for (i=0; i<256; i++) {
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c = i;
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for (j=8; j>0; j--) {
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if (c & 1) {
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c = (c >> 1) ^ CRC32_POLY;
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} else {
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c >>= 1;
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}
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}
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crcContext->crc32_table[i] = c;
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}
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#endif
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return 0;
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}
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/* Complete CRC32 calculation on a memory block */
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int SDLTest_Crc32Calc(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
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{
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if (SDLTest_Crc32CalcStart(crcContext,crc32)) {
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return -1;
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}
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if (SDLTest_Crc32CalcBuffer(crcContext, inBuf, inLen, crc32)) {
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return -1;
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}
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if (SDLTest_Crc32CalcEnd(crcContext, crc32)) {
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return -1;
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}
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return 0;
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}
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/* Start crc calculation */
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int SDLTest_Crc32CalcStart(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32)
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{
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/* Sanity check pointers */
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if (crcContext==NULL) {
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*crc32=0;
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return -1;
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}
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/*
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* Preload shift register, per CRC-32 spec
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*/
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*crc32 = 0xffffffff;
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return 0;
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}
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/* Finish crc calculation */
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int SDLTest_Crc32CalcEnd(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32)
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{
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/* Sanity check pointers */
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if (crcContext==NULL) {
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*crc32=0;
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return -1;
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}
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/*
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* Return complement, per CRC-32 spec
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*/
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*crc32 = (~(*crc32));
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return 0;
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}
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/* Include memory block in crc */
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int SDLTest_Crc32CalcBuffer(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
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{
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CrcUint8 *p;
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register CrcUint32 crc;
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if (crcContext==NULL) {
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*crc32=0;
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return -1;
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}
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if (inBuf==NULL) {
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return -1;
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}
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/*
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* Calculate CRC from data
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*/
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crc = *crc32;
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for (p = inBuf; inLen > 0; ++p, --inLen) {
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#ifdef ORIGINAL_METHOD
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crc = (crc << 8) ^ crcContext->crc32_table[(crc >> 24) ^ *p];
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#else
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crc = ((crc >> 8) & 0x00FFFFFF) ^ crcContext->crc32_table[ (crc ^ *p) & 0xFF ];
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#endif
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}
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*crc32 = crc;
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return 0;
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}
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int SDLTest_Crc32Done(SDLTest_Crc32Context * crcContext)
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{
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if (crcContext==NULL) {
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return -1;
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}
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return 0;
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}
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