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| author | Jeff King <peff@peff.net> | 2014-01-23 21:23:09 (GMT) |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2014-01-23 22:03:21 (GMT) |
| commit | 802b123366b5b3b6e18ee9e25a240815d1c97aae (patch) | |
| tree | e0f885c82a00ed16d40987cca97bddac9b02881a /compat | |
| parent | 1a6d8b91489ad4a7b7d267b46a3e838b004157f1 (diff) | |
| download | git-802b123366b5b3b6e18ee9e25a240815d1c97aae.zip git-802b123366b5b3b6e18ee9e25a240815d1c97aae.tar.gz git-802b123366b5b3b6e18ee9e25a240815d1c97aae.tar.bz2 | |
block-sha1: factor out get_be and put_be wrappers
The BLK_SHA1 code has optimized wrappers for doing endian
conversions on memory that may not be aligned. Let's pull
them out so that we can use them elsewhere, especially the
time-tested list of platforms that prefer each strategy.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'compat')
| -rw-r--r-- | compat/bswap.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/compat/bswap.h b/compat/bswap.h index c18a78e..7d17953 100644 --- a/compat/bswap.h +++ b/compat/bswap.h @@ -122,3 +122,35 @@ static inline uint64_t git_bswap64(uint64_t x) #endif #endif + +/* + * Performance might be improved if the CPU architecture is OK with + * unaligned 32-bit loads and a fast ntohl() is available. + * Otherwise fall back to byte loads and shifts which is portable, + * and is faster on architectures with memory alignment issues. + */ + +#if defined(__i386__) || defined(__x86_64__) || \ + defined(_M_IX86) || defined(_M_X64) || \ + defined(__ppc__) || defined(__ppc64__) || \ + defined(__powerpc__) || defined(__powerpc64__) || \ + defined(__s390__) || defined(__s390x__) + +#define get_be32(p) ntohl(*(unsigned int *)(p)) +#define put_be32(p, v) do { *(unsigned int *)(p) = htonl(v); } while (0) + +#else + +#define get_be32(p) ( \ + (*((unsigned char *)(p) + 0) << 24) | \ + (*((unsigned char *)(p) + 1) << 16) | \ + (*((unsigned char *)(p) + 2) << 8) | \ + (*((unsigned char *)(p) + 3) << 0) ) +#define put_be32(p, v) do { \ + unsigned int __v = (v); \ + *((unsigned char *)(p) + 0) = __v >> 24; \ + *((unsigned char *)(p) + 1) = __v >> 16; \ + *((unsigned char *)(p) + 2) = __v >> 8; \ + *((unsigned char *)(p) + 3) = __v >> 0; } while (0) + +#endif |