diff options
| author | Mike Belopuhov <mikeb@cvs.openbsd.org> | 2014-11-12 17:52:03 +0000 |
|---|---|---|
| committer | Mike Belopuhov <mikeb@cvs.openbsd.org> | 2014-11-12 17:52:03 +0000 |
| commit | cbdc5a2c9424fd375cb84dc28265c5f1468531ff (patch) | |
| tree | 409bcf3e51a30d76ee8c01c935427caacad83253 /sys | |
| parent | a2e2bd90e50b4e7d27dba3eb5a0a50a97f628863 (diff) | |
Improve performance of an internal loop by saving up on branching
Pointed out by John-Mark Gurney <jmg at funkthat ! com>, thanks!
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/crypto/gmac.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/sys/crypto/gmac.c b/sys/crypto/gmac.c index d90f2ceaf4a..eb031546637 100644 --- a/sys/crypto/gmac.c +++ b/sys/crypto/gmac.c @@ -1,4 +1,4 @@ -/* $OpenBSD: gmac.c,v 1.3 2011/01/11 15:44:23 deraadt Exp $ */ +/* $OpenBSD: gmac.c,v 1.4 2014/11/12 17:52:02 mikeb Exp $ */ /* * Copyright (c) 2010 Mike Belopuhov <mike@vantronix.net> @@ -38,7 +38,7 @@ ghash_gfmul(uint32_t *X, uint32_t *Y, uint32_t *product) uint32_t v[4]; uint32_t z[4] = { 0, 0, 0, 0}; uint8_t *x = (uint8_t *)X; - uint32_t mul; + uint32_t mask, mul; int i; v[0] = betoh32(Y[0]); @@ -48,12 +48,12 @@ ghash_gfmul(uint32_t *X, uint32_t *Y, uint32_t *product) for (i = 0; i < GMAC_BLOCK_LEN * 8; i++) { /* update Z */ - if (x[i >> 3] & (1 << (~i & 7))) { - z[0] ^= v[0]; - z[1] ^= v[1]; - z[2] ^= v[2]; - z[3] ^= v[3]; - } /* else: we preserve old values */ + mask = !!(x[i >> 3] & (1 << (~i & 7))); + mask = ~(mask - 1); + z[0] ^= v[0] & mask; + z[1] ^= v[1] & mask; + z[2] ^= v[2] & mask; + z[3] ^= v[3] & mask; /* update V */ mul = v[3] & 1; |