block-sha1: move code around
[git/git.git] / block-sha1 / sha1.c
1 /*
2 * Based on the Mozilla SHA1 (see mozilla-sha1/sha1.c),
3 * optimized to do word accesses rather than byte accesses,
4 * and to avoid unnecessary copies into the context array.
5 */
6
7 #include <string.h>
8 #include <arpa/inet.h>
9
10 #include "sha1.h"
11
12 #if defined(__i386__) || defined(__x86_64__)
13
14 #define SHA_ASM(op, x, n) ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; })
15 #define SHA_ROL(x,n) SHA_ASM("rol", x, n)
16 #define SHA_ROR(x,n) SHA_ASM("ror", x, n)
17 #define SMALL_REGISTER_SET
18
19 #else
20
21 #define SHA_ROT(X,l,r) (((X) << (l)) | ((X) >> (r)))
22 #define SHA_ROL(X,n) SHA_ROT(X,n,32-(n))
23 #define SHA_ROR(X,n) SHA_ROT(X,32-(n),n)
24
25 #endif
26
27 /* This "rolls" over the 512-bit array */
28 #define W(x) (array[(x)&15])
29
30 /*
31 * If you have 32 registers or more, the compiler can (and should)
32 * try to change the array[] accesses into registers. However, on
33 * machines with less than ~25 registers, that won't really work,
34 * and at least gcc will make an unholy mess of it.
35 *
36 * So to avoid that mess which just slows things down, we force
37 * the stores to memory to actually happen (we might be better off
38 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
39 * suggested by Artur Skawina - that will also make gcc unable to
40 * try to do the silly "optimize away loads" part because it won't
41 * see what the value will be).
42 *
43 * Ben Herrenschmidt reports that on PPC, the C version comes close
44 * to the optimized asm with this (ie on PPC you don't want that
45 * 'volatile', since there are lots of registers).
46 */
47 #ifdef SMALL_REGISTER_SET
48 #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
49 #else
50 #define setW(x, val) (W(x) = (val))
51 #endif
52
53 /*
54 * Where do we get the source from? The first 16 iterations get it from
55 * the input data, the next mix it from the 512-bit array.
56 */
57 #define SHA_SRC(t) htonl(data[t])
58 #define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
59
60 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
61 unsigned int TEMP = input(t); setW(t, TEMP); \
62 E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
63 B = SHA_ROR(B, 2); } while (0)
64
65 #define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
66 #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
67 #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
68 #define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
69 #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
70
71 static void blk_SHA1_Block(blk_SHA_CTX *ctx, const unsigned int *data)
72 {
73 unsigned int A,B,C,D,E;
74 unsigned int array[16];
75
76 A = ctx->H[0];
77 B = ctx->H[1];
78 C = ctx->H[2];
79 D = ctx->H[3];
80 E = ctx->H[4];
81
82 /* Round 1 - iterations 0-16 take their input from 'data' */
83 T_0_15( 0, A, B, C, D, E);
84 T_0_15( 1, E, A, B, C, D);
85 T_0_15( 2, D, E, A, B, C);
86 T_0_15( 3, C, D, E, A, B);
87 T_0_15( 4, B, C, D, E, A);
88 T_0_15( 5, A, B, C, D, E);
89 T_0_15( 6, E, A, B, C, D);
90 T_0_15( 7, D, E, A, B, C);
91 T_0_15( 8, C, D, E, A, B);
92 T_0_15( 9, B, C, D, E, A);
93 T_0_15(10, A, B, C, D, E);
94 T_0_15(11, E, A, B, C, D);
95 T_0_15(12, D, E, A, B, C);
96 T_0_15(13, C, D, E, A, B);
97 T_0_15(14, B, C, D, E, A);
98 T_0_15(15, A, B, C, D, E);
99
100 /* Round 1 - tail. Input from 512-bit mixing array */
101 T_16_19(16, E, A, B, C, D);
102 T_16_19(17, D, E, A, B, C);
103 T_16_19(18, C, D, E, A, B);
104 T_16_19(19, B, C, D, E, A);
105
106 /* Round 2 */
107 T_20_39(20, A, B, C, D, E);
108 T_20_39(21, E, A, B, C, D);
109 T_20_39(22, D, E, A, B, C);
110 T_20_39(23, C, D, E, A, B);
111 T_20_39(24, B, C, D, E, A);
112 T_20_39(25, A, B, C, D, E);
113 T_20_39(26, E, A, B, C, D);
114 T_20_39(27, D, E, A, B, C);
115 T_20_39(28, C, D, E, A, B);
116 T_20_39(29, B, C, D, E, A);
117 T_20_39(30, A, B, C, D, E);
118 T_20_39(31, E, A, B, C, D);
119 T_20_39(32, D, E, A, B, C);
120 T_20_39(33, C, D, E, A, B);
121 T_20_39(34, B, C, D, E, A);
122 T_20_39(35, A, B, C, D, E);
123 T_20_39(36, E, A, B, C, D);
124 T_20_39(37, D, E, A, B, C);
125 T_20_39(38, C, D, E, A, B);
126 T_20_39(39, B, C, D, E, A);
127
128 /* Round 3 */
129 T_40_59(40, A, B, C, D, E);
130 T_40_59(41, E, A, B, C, D);
131 T_40_59(42, D, E, A, B, C);
132 T_40_59(43, C, D, E, A, B);
133 T_40_59(44, B, C, D, E, A);
134 T_40_59(45, A, B, C, D, E);
135 T_40_59(46, E, A, B, C, D);
136 T_40_59(47, D, E, A, B, C);
137 T_40_59(48, C, D, E, A, B);
138 T_40_59(49, B, C, D, E, A);
139 T_40_59(50, A, B, C, D, E);
140 T_40_59(51, E, A, B, C, D);
141 T_40_59(52, D, E, A, B, C);
142 T_40_59(53, C, D, E, A, B);
143 T_40_59(54, B, C, D, E, A);
144 T_40_59(55, A, B, C, D, E);
145 T_40_59(56, E, A, B, C, D);
146 T_40_59(57, D, E, A, B, C);
147 T_40_59(58, C, D, E, A, B);
148 T_40_59(59, B, C, D, E, A);
149
150 /* Round 4 */
151 T_60_79(60, A, B, C, D, E);
152 T_60_79(61, E, A, B, C, D);
153 T_60_79(62, D, E, A, B, C);
154 T_60_79(63, C, D, E, A, B);
155 T_60_79(64, B, C, D, E, A);
156 T_60_79(65, A, B, C, D, E);
157 T_60_79(66, E, A, B, C, D);
158 T_60_79(67, D, E, A, B, C);
159 T_60_79(68, C, D, E, A, B);
160 T_60_79(69, B, C, D, E, A);
161 T_60_79(70, A, B, C, D, E);
162 T_60_79(71, E, A, B, C, D);
163 T_60_79(72, D, E, A, B, C);
164 T_60_79(73, C, D, E, A, B);
165 T_60_79(74, B, C, D, E, A);
166 T_60_79(75, A, B, C, D, E);
167 T_60_79(76, E, A, B, C, D);
168 T_60_79(77, D, E, A, B, C);
169 T_60_79(78, C, D, E, A, B);
170 T_60_79(79, B, C, D, E, A);
171
172 ctx->H[0] += A;
173 ctx->H[1] += B;
174 ctx->H[2] += C;
175 ctx->H[3] += D;
176 ctx->H[4] += E;
177 }
178
179 void blk_SHA1_Init(blk_SHA_CTX *ctx)
180 {
181 ctx->size = 0;
182
183 /* Initialize H with the magic constants (see FIPS180 for constants) */
184 ctx->H[0] = 0x67452301;
185 ctx->H[1] = 0xefcdab89;
186 ctx->H[2] = 0x98badcfe;
187 ctx->H[3] = 0x10325476;
188 ctx->H[4] = 0xc3d2e1f0;
189 }
190
191 void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
192 {
193 int lenW = ctx->size & 63;
194
195 ctx->size += len;
196
197 /* Read the data into W and process blocks as they get full */
198 if (lenW) {
199 int left = 64 - lenW;
200 if (len < left)
201 left = len;
202 memcpy(lenW + (char *)ctx->W, data, left);
203 lenW = (lenW + left) & 63;
204 len -= left;
205 data += left;
206 if (lenW)
207 return;
208 blk_SHA1_Block(ctx, ctx->W);
209 }
210 while (len >= 64) {
211 blk_SHA1_Block(ctx, data);
212 data += 64;
213 len -= 64;
214 }
215 if (len)
216 memcpy(ctx->W, data, len);
217 }
218
219 void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
220 {
221 static const unsigned char pad[64] = { 0x80 };
222 unsigned int padlen[2];
223 int i;
224
225 /* Pad with a binary 1 (ie 0x80), then zeroes, then length */
226 padlen[0] = htonl(ctx->size >> 29);
227 padlen[1] = htonl(ctx->size << 3);
228
229 i = ctx->size & 63;
230 blk_SHA1_Update(ctx, pad, 1+ (63 & (55 - i)));
231 blk_SHA1_Update(ctx, padlen, 8);
232
233 /* Output hash */
234 for (i = 0; i < 5; i++)
235 ((unsigned int *)hashout)[i] = htonl(ctx->H[i]);
236 }