From 7a3153cbfb72f603ae31269bdc11c9275dbd2319 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Thu, 28 Sep 2023 11:20:55 +1000 Subject: [PATCH] siphash: Add siphash_feed() helper We have macros or inlines for a number of common operations in the siphash functions. However, in a number of places we still open code feeding another 64-bits of data into the hash function: an xor, followed by 2 rounds of shuffling, followed by another xor. Implement an inline function for this, which results in somewhat shortened code. Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- siphash.c | 52 +++++++++++++++++++++------------------------------- 1 file changed, 21 insertions(+), 31 deletions(-) diff --git a/siphash.c b/siphash.c index e1fcf18..716ab62 100644 --- a/siphash.c +++ b/siphash.c @@ -91,11 +91,21 @@ static inline void sipround(uint64_t *v, int n) } } +/** + * siphash_feed() - Fold 64-bits of data into the hash state + * @v: siphash state (4 x 64-bit integers) + * @in: New value to fold into hash + */ +static inline void siphash_feed(uint64_t *v, uint64_t in) +{ + v[3] ^= in; + sipround(v, 2); + v[0] ^= in; +} + #define POSTAMBLE \ do { \ - v[3] ^= b; \ - sipround(v, 2); \ - v[0] ^= b; \ + siphash_feed(v, b); \ v[2] ^= 0xff; \ sipround(v, 4); \ b = (v[0] ^ v[1]) ^ (v[2] ^ v[3]); \ @@ -123,9 +133,7 @@ __attribute__((optimize("-fno-strict-aliasing"))) uint64_t siphash_8b(const uint8_t *in, const uint64_t *k) { PREAMBLE(8); - v[3] ^= *(uint64_t *)in; - sipround(v, 2); - v[0] ^= *(uint64_t *)in; + siphash_feed(v, *(uint64_t *)in); POSTAMBLE; return b; @@ -144,14 +152,9 @@ __attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */ uint64_t siphash_12b(const uint8_t *in, const uint64_t *k) { uint32_t *in32 = (uint32_t *)in; - uint64_t combined; - - combined = (uint64_t)(*(in32 + 1)) << 32 | *in32; PREAMBLE(12); - v[3] ^= combined; - sipround(v, 2); - v[0] ^= combined; + siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32); b |= *(in32 + 2); POSTAMBLE; @@ -174,13 +177,8 @@ uint64_t siphash_20b(const uint8_t *in, const uint64_t *k) PREAMBLE(20); - for (i = 0; i < 2; i++, in32 += 2) { - uint64_t combined = (uint64_t)(*(in32 + 1)) << 32 | *in32; - - v[3] ^= combined; - sipround(v, 2); - v[0] ^= combined; - } + for (i = 0; i < 2; i++, in32 += 2) + siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32); b |= *in32; POSTAMBLE; @@ -205,11 +203,8 @@ uint64_t siphash_32b(const uint8_t *in, const uint64_t *k) PREAMBLE(32); - for (i = 0; i < 4; i++, in64++) { - v[3] ^= *in64; - sipround(v, 2); - v[0] ^= *in64; - } + for (i = 0; i < 4; i++, in64++) + siphash_feed(v, *in64); POSTAMBLE; @@ -232,13 +227,8 @@ uint64_t siphash_36b(const uint8_t *in, const uint64_t *k) PREAMBLE(36); - for (i = 0; i < 4; i++, in32 += 2) { - uint64_t combined = (uint64_t)(*(in32 + 1)) << 32 | *in32; - - v[3] ^= combined; - sipround(v, 2); - v[0] ^= combined; - } + for (i = 0; i < 4; i++, in32 += 2) + siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32); b |= *in32; POSTAMBLE;