Atlas - SDL_test_crc32.c
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1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2025 Sam Lantinga <[email protected]>
4
5  This software is provided 'as-is', without any express or implied
6  warranty.  In no event will the authors be held liable for any damages
7  arising from the use of this software.
8
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12
13  1. The origin of this software must not be misrepresented; you must not
14     claim that you wrote the original software. If you use this software
15     in a product, an acknowledgment in the product documentation would be
16     appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18     misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20*/
21
22/*
23
24 Used by the test execution component.
25 Original source code contributed by A. Schiffler for GSOC project.
26
27*/
28#include <SDL3/SDL_test.h>
29
30bool SDLTest_Crc32Init(SDLTest_Crc32Context *crcContext)
31{
32    int i, j;
33    CrcUint32 c;
34
35    /* Sanity check context pointer */
36    if (!crcContext) {
37        return SDL_InvalidParamError("crcContext");
38    }
39
40    /*
41     * Build auxiliary table for parallel byte-at-a-time CRC-32
42     */
43#ifdef ORIGINAL_METHOD
44    for (i = 0; i < 256; ++i) {
45        for (c = i << 24, j = 8; j > 0; --j) {
46            c = c & 0x80000000 ? (c << 1) ^ CRC32_POLY : (c << 1);
47        }
48        crcContext->crc32_table[i] = c;
49    }
50#else
51    for (i = 0; i < 256; i++) {
52        c = i;
53        for (j = 8; j > 0; j--) {
54            if (c & 1) {
55                c = (c >> 1) ^ CRC32_POLY;
56            } else {
57                c >>= 1;
58            }
59        }
60        crcContext->crc32_table[i] = c;
61    }
62#endif
63
64    return true;
65}
66
67/* Complete CRC32 calculation on a memory block */
68bool SDLTest_Crc32Calc(SDLTest_Crc32Context *crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
69{
70    if (!SDLTest_Crc32CalcStart(crcContext, crc32)) {
71        return false;
72    }
73
74    if (!SDLTest_Crc32CalcBuffer(crcContext, inBuf, inLen, crc32)) {
75        return false;
76    }
77
78    if (!SDLTest_Crc32CalcEnd(crcContext, crc32)) {
79        return false;
80    }
81
82    return true;
83}
84
85/* Start crc calculation */
86
87bool SDLTest_Crc32CalcStart(SDLTest_Crc32Context *crcContext, CrcUint32 *crc32)
88{
89    /* Sanity check pointers */
90    if (!crcContext) {
91        *crc32 = 0;
92        return SDL_InvalidParamError("crcContext");
93    }
94
95    /*
96     * Preload shift register, per CRC-32 spec
97     */
98    *crc32 = 0xffffffff;
99
100    return true;
101}
102
103/* Finish crc calculation */
104
105bool SDLTest_Crc32CalcEnd(SDLTest_Crc32Context *crcContext, CrcUint32 *crc32)
106{
107    /* Sanity check pointers */
108    if (!crcContext) {
109        *crc32 = 0;
110        return SDL_InvalidParamError("crcContext");
111    }
112
113    /*
114     * Return complement, per CRC-32 spec
115     */
116    *crc32 = (~(*crc32));
117
118    return true;
119}
120
121/* Include memory block in crc */
122
123bool SDLTest_Crc32CalcBuffer(SDLTest_Crc32Context *crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
124{
125    CrcUint8 *p;
126    register CrcUint32 crc;
127
128    if (!crcContext) {
129        *crc32 = 0;
130        return SDL_InvalidParamError("crcContext");
131    }
132
133    if (!inBuf) {
134        return SDL_InvalidParamError("inBuf");
135    }
136
137    /*
138     * Calculate CRC from data
139     */
140    crc = *crc32;
141    for (p = inBuf; inLen > 0; ++p, --inLen) {
142#ifdef ORIGINAL_METHOD
143        crc = (crc << 8) ^ crcContext->crc32_table[(crc >> 24) ^ *p];
144#else
145        crc = ((crc >> 8) & 0x00FFFFFF) ^ crcContext->crc32_table[(crc ^ *p) & 0xFF];
146#endif
147    }
148    *crc32 = crc;
149
150    return true;
151}
152
153bool SDLTest_Crc32Done(SDLTest_Crc32Context *crcContext)
154{
155    if (!crcContext) {
156        return SDL_InvalidParamError("crcContext");
157    }
158
159    return true;
160}
161
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