diff options
| author | David Benjamin <davidben@google.com> | 2016-04-25 20:22:22 +0300 |
|---|---|---|
| committer | Adam Langley <agl@google.com> | 2016-04-26 02:05:20 +0300 |
| commit | f13444a5ad92974005df38c4344c922af2449ca3 (patch) | |
| tree | 113c6e88fdcea31de1d0aea32bb76cea2d187871 /crypto/ec | |
| parent | 1fc7564ba7dd985f311d5fccd1de4b01ee368b43 (diff) | |
Use different bit tricks to extend the LSB.
C gets grumpy when you shift into a sign bit. Replace it with a different bit
trick.
BUG=chromium:603502
Change-Id: Ia4cc2e2d68675528b7c0155882ff4d6230df482b
Reviewed-on: https://boringssl-review.googlesource.com/7740
Reviewed-by: Adam Langley <agl@google.com>
Diffstat (limited to 'crypto/ec')
| -rw-r--r-- | crypto/ec/p256-64.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/crypto/ec/p256-64.c b/crypto/ec/p256-64.c index 84b65979..c4259b62 100644 --- a/crypto/ec/p256-64.c +++ b/crypto/ec/p256-64.c @@ -328,8 +328,7 @@ static void felem_shrink(smallfelem out, const felem in) { * conditionally subtract kPrime if tmp[3] is large enough. */ high = tmp[3] >> 64; /* As tmp[3] < 2^65, high is either 1 or 0 */ - high <<= 63; - high >>= 63; + high = ~(high - 1); /* high is: * all ones if the high word of tmp[3] is 1 * all zeros if the high word of tmp[3] if 0 */ |