From 9813b147580d9f42e2484d27ecaa3ab244841ee8 Mon Sep 17 00:00:00 2001 From: David Phillips Date: Sun, 14 May 2017 19:52:19 +1200 Subject: Add experimental AVX base32 algo, modularise base32 out --- onion_base32.c | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 onion_base32.c (limited to 'onion_base32.c') diff --git a/onion_base32.c b/onion_base32.c new file mode 100644 index 0000000..d70facf --- /dev/null +++ b/onion_base32.c @@ -0,0 +1,102 @@ +#include +#include + +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 + +/* 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 */ -- cgit v1.1