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block-sha1: factor out get_be and put_be wrappers
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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 <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>
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peff authored and gitster committed Jan 23, 2014
1 parent 1a6d8b9 commit 802b123
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Showing 2 changed files with 32 additions and 32 deletions.
32 changes: 0 additions & 32 deletions block-sha1/sha1.c
Original file line number Diff line number Diff line change
Expand Up @@ -62,38 +62,6 @@
#define setW(x, val) (W(x) = (val))
#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

/* This "rolls" over the 512-bit array */
#define W(x) (array[(x)&15])

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32 changes: 32 additions & 0 deletions compat/bswap.h
Original file line number Diff line number Diff line change
Expand Up @@ -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

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