1 /*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2020 Sam Lantinga <slouken@libsdl.org>
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
29 #include "SDL_config.h"
30
31 #include "SDL_test.h"
32
33
SDLTest_Crc32Init(SDLTest_Crc32Context * crcContext)34 int SDLTest_Crc32Init(SDLTest_Crc32Context *crcContext)
35 {
36 int i,j;
37 CrcUint32 c;
38
39 /* Sanity check context pointer */
40 if (crcContext==NULL) {
41 return -1;
42 }
43
44 /*
45 * Build auxiliary table for parallel byte-at-a-time CRC-32
46 */
47 #ifdef ORIGINAL_METHOD
48 for (i = 0; i < 256; ++i) {
49 for (c = i << 24, j = 8; j > 0; --j) {
50 c = c & 0x80000000 ? (c << 1) ^ CRC32_POLY : (c << 1);
51 }
52 crcContext->crc32_table[i] = c;
53 }
54 #else
55 for (i=0; i<256; i++) {
56 c = i;
57 for (j=8; j>0; j--) {
58 if (c & 1) {
59 c = (c >> 1) ^ CRC32_POLY;
60 } else {
61 c >>= 1;
62 }
63 }
64 crcContext->crc32_table[i] = c;
65 }
66 #endif
67
68 return 0;
69 }
70
71 /* Complete CRC32 calculation on a memory block */
SDLTest_Crc32Calc(SDLTest_Crc32Context * crcContext,CrcUint8 * inBuf,CrcUint32 inLen,CrcUint32 * crc32)72 int SDLTest_Crc32Calc(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
73 {
74 if (SDLTest_Crc32CalcStart(crcContext,crc32)) {
75 return -1;
76 }
77
78 if (SDLTest_Crc32CalcBuffer(crcContext, inBuf, inLen, crc32)) {
79 return -1;
80 }
81
82 if (SDLTest_Crc32CalcEnd(crcContext, crc32)) {
83 return -1;
84 }
85
86 return 0;
87 }
88
89 /* Start crc calculation */
90
SDLTest_Crc32CalcStart(SDLTest_Crc32Context * crcContext,CrcUint32 * crc32)91 int SDLTest_Crc32CalcStart(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32)
92 {
93 /* Sanity check pointers */
94 if (crcContext==NULL) {
95 *crc32=0;
96 return -1;
97 }
98
99 /*
100 * Preload shift register, per CRC-32 spec
101 */
102 *crc32 = 0xffffffff;
103
104 return 0;
105 }
106
107 /* Finish crc calculation */
108
SDLTest_Crc32CalcEnd(SDLTest_Crc32Context * crcContext,CrcUint32 * crc32)109 int SDLTest_Crc32CalcEnd(SDLTest_Crc32Context * crcContext, CrcUint32 *crc32)
110 {
111 /* Sanity check pointers */
112 if (crcContext==NULL) {
113 *crc32=0;
114 return -1;
115 }
116
117 /*
118 * Return complement, per CRC-32 spec
119 */
120 *crc32 = (~(*crc32));
121
122 return 0;
123 }
124
125 /* Include memory block in crc */
126
SDLTest_Crc32CalcBuffer(SDLTest_Crc32Context * crcContext,CrcUint8 * inBuf,CrcUint32 inLen,CrcUint32 * crc32)127 int SDLTest_Crc32CalcBuffer(SDLTest_Crc32Context * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
128 {
129 CrcUint8 *p;
130 register CrcUint32 crc;
131
132 if (crcContext==NULL) {
133 *crc32=0;
134 return -1;
135 }
136
137 if (inBuf==NULL) {
138 return -1;
139 }
140
141 /*
142 * Calculate CRC from data
143 */
144 crc = *crc32;
145 for (p = inBuf; inLen > 0; ++p, --inLen) {
146 #ifdef ORIGINAL_METHOD
147 crc = (crc << 8) ^ crcContext->crc32_table[(crc >> 24) ^ *p];
148 #else
149 crc = ((crc >> 8) & 0x00FFFFFF) ^ crcContext->crc32_table[ (crc ^ *p) & 0xFF ];
150 #endif
151 }
152 *crc32 = crc;
153
154 return 0;
155 }
156
SDLTest_Crc32Done(SDLTest_Crc32Context * crcContext)157 int SDLTest_Crc32Done(SDLTest_Crc32Context * crcContext)
158 {
159 if (crcContext==NULL) {
160 return -1;
161 }
162
163 return 0;
164 }
165
166 /* vi: set ts=4 sw=4 expandtab: */
167