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#include <stdlib.h>
#include <string.h>
static const char base32_lookup[] = "abcdefghijklmnopqrstuvwxyz234567";
int
check_base32(char *subject) {
size_t offset = 0;
if ((offset = strspn(subject, base32_lookup)) != strlen(subject)) {
return offset;
}
return 0;
}
/* Simple and reliable base32 algorithm - "old trusty"
* Note: This is not a general base32 algorithm; it outputs only the
* first 16 base32 symbols of the input buffer, using only the first
* 20 bytes of that buffer.
*/
void
onion_base32(char output[16], unsigned char sum[20]) {
size_t c = 0;
int i = 0;
for (i = 0; i < 10; i+=5) {
output[c++] = base32_lookup[sum[i] >> 3];
output[c++] = base32_lookup[((sum[i] & 0x07) << 2) | (sum[i+1] >> 6)];
output[c++] = base32_lookup[(sum[i+1] >> 1) & 0x1F];
output[c++] = base32_lookup[((sum[i+1] & 1) << 4) | (sum[i+2] >> 4)];
output[c++] = base32_lookup[((sum[i+2] & 0x0F) << 1) | ((sum[i+3] & 0x80) >> 7)];
output[c++] = base32_lookup[(sum[i+3] >> 2) & 0x1F];
output[c++] = base32_lookup[((sum[i+3] & 0x03) << 3) | (sum[i+4] >> 5)];
output[c++] = base32_lookup[sum[i+4] & 0x1F];
}
}
#ifdef AVX_ONION_BASE32
#include <immintrin.h>
/* A slightly-parallel base32 algorithm using AVX
* Note: This is not a general base32 algorithm; it outputs only the
* first 16 base32 symbols of the input buffer, using only the first
* 20 bytes of that buffer.
*
* Somewhat inspired by http://www.alfredklomp.com/programming/sse-base64/
*/
void
onion_base32_avx(char output[16], unsigned char sum[20]) {
__m128i res;
__m128i ssum;
__m128i masklow5;
__m128i lmask, l;
__m128i nmask, n;
ssum = _mm_loadu_si128((__m128i*)sum);
/* FIXME seems a little hacky */
masklow5 = _mm_set1_epi32(0x1F000000);
masklow5 = _mm_slli_epi64(masklow5, 32);
ssum = _mm_shuffle_epi8(ssum,
_mm_setr_epi8(9,9,9,9,8,7,6,5,4,4,4,4,3,2,1,0 ));
/* remember how I said "slightly parallel" ? */
res = _mm_srli_epi64(ssum, 3) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 6) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 9) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 12) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 15) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 18) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 21) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res |= _mm_srli_epi64(ssum, 24) & masklow5;
masklow5 = _mm_srli_epi64(masklow5, 8);
res = _mm_shuffle_epi8(res,
_mm_setr_epi8(15,14,13,12,11,10,9,8,7,6,5,4,3,2,1,0));
lmask = _mm_cmplt_epi8(res, _mm_set1_epi8(26));
nmask = _mm_andnot_si128(lmask, _mm_cmplt_epi8(res, _mm_set1_epi8(32)));
l = lmask & _mm_add_epi8(res, _mm_set1_epi8('a'));
n = nmask & _mm_add_epi8(res, _mm_set1_epi8('2' - 26));
_mm_storeu_si128((__m128i*)output, l|n);
}
#endif /* ifdef AVX_ONION_BASE32 */
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