commit b71f6d6a47af96f5fab5d139e585739b078ea54a Author: Yawning Angel yawning@schwanenlied.me Date: Thu Nov 5 18:21:43 2015 +0000

Fix SipHash-2-4 performance for non multiple of 8 buffers.

Code cribbed from Andrew Moon's Public Domain SipHash-2-4 implementation (which IMO is also cleaner).

Fixes bug 17544. --- changes/bug17544 | 4 ++++ src/ext/csiphash.c | 57 ++++++++++++++++++---------------------------------- 2 files changed, 24 insertions(+), 37 deletions(-)

diff --git a/changes/bug17544 b/changes/bug17544 new file mode 100644 index 0000000..4316d07 --- /dev/null +++ b/changes/bug17544 @@ -0,0 +1,4 @@ + o Minor bugfix (SipHash-2-4 performance): + - Improve performance when hashing non-multiple of 8 sized buffers, + based on Andrew Moon's Public Domain SipHash-2-4 implementation. + Fixes bug 17544; bugfix on 0.2.5.3-alpha. diff --git a/src/ext/csiphash.c b/src/ext/csiphash.c index 27c5358..b60f73a 100644 --- a/src/ext/csiphash.c +++ b/src/ext/csiphash.c @@ -97,65 +97,48 @@ #endif

uint64_t siphash24(const void *src, unsigned long src_sz, const struct sipkey *key) { + const uint8_t *m = src; uint64_t k0 = key->k0; uint64_t k1 = key->k1; - uint64_t b = (uint64_t)src_sz << 56; -#ifdef UNALIGNED_OK - const uint64_t *in = (uint64_t*)src; -#else - /* On platforms where alignment matters, if 'in' is a pointer to a - * datatype that must be aligned, the compiler is allowed to - * generate code that assumes that it is aligned as such. - */ - const uint8_t *in = (uint8_t *)src; -#endif - - uint64_t t; - uint8_t *pt, *m; + uint64_t last7 = (uint64_t)(src_sz & 0xff) << 56; + size_t i, blocks;

uint64_t v0 = k0 ^ 0x736f6d6570736575ULL; uint64_t v1 = k1 ^ 0x646f72616e646f6dULL; uint64_t v2 = k0 ^ 0x6c7967656e657261ULL; uint64_t v3 = k1 ^ 0x7465646279746573ULL;

- while (src_sz >= 8) { + for (i = 0, blocks = (src_sz & ~7); i < blocks; i+= 8) { #ifdef UNALIGNED_OK - uint64_t mi = _le64toh(*in); - in += 1; + uint64_t mi = _le64toh(*(m + i)); #else uint64_t mi; - memcpy(&mi, in, 8); + memcpy(&mi, m + i, 8); mi = _le64toh(mi); - in += 8; #endif - src_sz -= 8; v3 ^= mi; DOUBLE_ROUND(v0,v1,v2,v3); v0 ^= mi; }

- t = 0; pt = (uint8_t*)&t; m = (uint8_t*)in; - switch (src_sz) { - case 7: pt[6] = m[6]; - case 6: pt[5] = m[5]; - case 5: pt[4] = m[4]; -#ifdef UNALIGNED_OK - case 4: *((uint32_t*)&pt[0]) = *((uint32_t*)&m[0]); break; -#else - case 4: pt[3] = m[3]; -#endif - case 3: pt[2] = m[2]; - case 2: pt[1] = m[1]; - case 1: pt[0] = m[0]; + switch (src_sz - blocks) { + case 7: last7 |= (uint64_t)m[i + 6] << 48; + case 6: last7 |= (uint64_t)m[i + 5] << 40; + case 5: last7 |= (uint64_t)m[i + 4] << 32; + case 4: last7 |= (uint64_t)m[i + 3] << 24; + case 3: last7 |= (uint64_t)m[i + 2] << 16; + case 2: last7 |= (uint64_t)m[i + 1] << 8; + case 1: last7 |= (uint64_t)m[i + 0] ; + case 0: + default:; } - b |= _le64toh(t); - - v3 ^= b; + v3 ^= last7; DOUBLE_ROUND(v0,v1,v2,v3); - v0 ^= b; v2 ^= 0xff; + v0 ^= last7; + v2 ^= 0xff; DOUBLE_ROUND(v0,v1,v2,v3); DOUBLE_ROUND(v0,v1,v2,v3); - return (v0 ^ v1) ^ (v2 ^ v3); + return v0 ^ v1 ^ v2 ^ v3; }