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Issue #3: implementation as proposed (hopefully) 

The full test suite runs fine and the performance numbers are:

Before:
real	1m7,040s
user	1m6,319s
sys	0m0,716s

After:
real	1m6,707s
user	1m6,035s
sys	0m0,672s

Not bad. But mostly, it saves stack. Nice. :-)
This commit is contained in:
Alain Mosnier 2019-08-03 23:10:25 +02:00
parent ff76937294
commit db722a7329
No known key found for this signature in database
GPG Key ID: 331DCAAEDE209451
1 changed files with 46 additions and 37 deletions
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81
sha-256.c
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@ -137,7 +137,7 @@ void calc_sha_256(uint8_t hash[32], const void * input, size_t len)
* (first 32 bits of the fractional parts of the square roots of the first 8 primes 2..19):
*/
uint32_t h[] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
int i, j;
unsigned i, j;
/* 512-bit chunks is what we will operate on. */
uint8_t chunk[64];
@ -149,49 +149,58 @@ void calc_sha_256(uint8_t hash[32], const void * input, size_t len)
while (calc_chunk(chunk, &state)) {
uint32_t ah[8];
/*
* create a 64-entry message schedule array w[0..63] of 32-bit words
* (The initial values in w[0..63] don't matter, so many implementations zero them here)
* copy chunk into first 16 words w[0..15] of the message schedule array
*/
uint32_t w[64];
const uint8_t *p = chunk;
memset(w, 0x00, sizeof w);
for (i = 0; i < 16; i++) {
w[i] = (uint32_t) p[0] << 24 | (uint32_t) p[1] << 16 |
(uint32_t) p[2] << 8 | (uint32_t) p[3];
p += 4;
}
/* Extend the first 16 words into the remaining 48 words w[16..63] of the message schedule array: */
for (i = 16; i < 64; i++) {
const uint32_t s0 = right_rot(w[i - 15], 7) ^ right_rot(w[i - 15], 18) ^ (w[i - 15] >> 3);
const uint32_t s1 = right_rot(w[i - 2], 17) ^ right_rot(w[i - 2], 19) ^ (w[i - 2] >> 10);
w[i] = w[i - 16] + s0 + w[i - 7] + s1;
}
/* Initialize working variables to current hash value: */
for (i = 0; i < 8; i++)
ah[i] = h[i];
/* Compression function main loop: */
for (i = 0; i < 64; i++) {
const uint32_t s1 = right_rot(ah[4], 6) ^ right_rot(ah[4], 11) ^ right_rot(ah[4], 25);
const uint32_t ch = (ah[4] & ah[5]) ^ (~ah[4] & ah[6]);
const uint32_t temp1 = ah[7] + s1 + ch + k[i] + w[i];
const uint32_t s0 = right_rot(ah[0], 2) ^ right_rot(ah[0], 13) ^ right_rot(ah[0], 22);
const uint32_t maj = (ah[0] & ah[1]) ^ (ah[0] & ah[2]) ^ (ah[1] & ah[2]);
const uint32_t temp2 = s0 + maj;
for (i = 0; i < 4; i++) {
/*
* The w-array is really w[64], but since we only need
* 16 of them at a time, we save stack by calculating
* 16 at a time.
*
* This optimization was not there initially and the
* rest of the comments about w[64] are kept in their
* initial state.
*/
ah[7] = ah[6];
ah[6] = ah[5];
ah[5] = ah[4];
ah[4] = ah[3] + temp1;
ah[3] = ah[2];
ah[2] = ah[1];
ah[1] = ah[0];
ah[0] = temp1 + temp2;
/*
* create a 64-entry message schedule array w[0..63] of 32-bit words
* (The initial values in w[0..63] don't matter, so many implementations zero them here)
* copy chunk into first 16 words w[0..15] of the message schedule array
*/
uint32_t w[16];
for (j = 0; j < 16; j++) {
if (i == 0) {
w[j] = (uint32_t) p[0] << 24 | (uint32_t) p[1] << 16 |
(uint32_t) p[2] << 8 | (uint32_t) p[3];
p += 4;
} else {
/* Extend the first 16 words into the remaining 48 words w[16..63] of the message schedule array: */
const uint32_t s0 = right_rot(w[(j + 1) & 0xf], 7) ^ right_rot(w[(j + 1) & 0xf], 18) ^ (w[(j + 1) & 0xf] >> 3);
const uint32_t s1 = right_rot(w[(j + 14) & 0xf], 17) ^ right_rot(w[(j + 14) & 0xf], 19) ^ (w[(j + 14) & 0xf] >> 10);
w[j] = w[j] + s0 + w[(j + 9) & 0xf] + s1;
}
const uint32_t s1 = right_rot(ah[4], 6) ^ right_rot(ah[4], 11) ^ right_rot(ah[4], 25);
const uint32_t ch = (ah[4] & ah[5]) ^ (~ah[4] & ah[6]);
const uint32_t temp1 = ah[7] + s1 + ch + k[i * 16 + j] + w[j];
const uint32_t s0 = right_rot(ah[0], 2) ^ right_rot(ah[0], 13) ^ right_rot(ah[0], 22);
const uint32_t maj = (ah[0] & ah[1]) ^ (ah[0] & ah[2]) ^ (ah[1] & ah[2]);
const uint32_t temp2 = s0 + maj;
ah[7] = ah[6];
ah[6] = ah[5];
ah[5] = ah[4];
ah[4] = ah[3] + temp1;
ah[3] = ah[2];
ah[2] = ah[1];
ah[1] = ah[0];
ah[0] = temp1 + temp2;
}
}
/* Add the compressed chunk to the current hash value: */