lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[PATCH] crc32: replace bitreverse by bitrev32

Browse Source 
This patch replaces bitreverse() by bitrev32.  The only users of bitreverse()
are crc32 itself and via-velocity.

Cc: Jeff Garzik <jgarzik@pobox.com>
Cc: Matt Domsch <Matt_Domsch@dell.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Akinobu Mita
2006-12-08 02:36:25 -08:00
committed by Linus Torvalds
parent a5cfc1ec58
commit 906d66df18
4 changed files with 9 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
lib/crc32.c
View File

@ -235,23 +235,8 @@ u32 __attribute_pure__ crc32_be(u32 crc, unsigned char const *p, size_t len)
}
#endif
/**
* bitreverse - reverse the order of bits in a u32 value
* @x: value to be bit-reversed
*/
u32 bitreverse(u32 x)
{
x = (x >> 16) | (x << 16);
x = (x >> 8 & 0x00ff00ff) | (x << 8 & 0xff00ff00);
x = (x >> 4 & 0x0f0f0f0f) | (x << 4 & 0xf0f0f0f0);
x = (x >> 2 & 0x33333333) | (x << 2 & 0xcccccccc);
x = (x >> 1 & 0x55555555) | (x << 1 & 0xaaaaaaaa);
return x;
}
EXPORT_SYMBOL(crc32_le);
EXPORT_SYMBOL(crc32_be);
EXPORT_SYMBOL(bitreverse);
/*
* A brief CRC tutorial.
@ -400,10 +385,7 @@ buf_dump(char const *prefix, unsigned char const *buf, size_t len)
static void bytereverse(unsigned char *buf, size_t len)
{
while (len--) {
unsigned char x = *buf;
x = (x >> 4) | (x << 4);
x = (x >> 2 & 0x33) | (x << 2 & 0xcc);
x = (x >> 1 & 0x55) | (x << 1 & 0xaa);
unsigned char x = bitrev8(*buf);
*buf++ = x;
}
}
@ -460,11 +442,11 @@ static u32 test_step(u32 init, unsigned char *buf, size_t len)
/* Now swap it around for the other test */
bytereverse(buf, len + 4);
init = bitreverse(init);
crc2 = bitreverse(crc1);
if (crc1 != bitreverse(crc2))
init = bitrev32(init);
crc2 = bitrev32(crc1);
if (crc1 != bitrev32(crc2))
printf("\nBit reversal fail: 0x%08x -> 0x%08x -> 0x%08x\n",
crc1, crc2, bitreverse(crc2));
crc1, crc2, bitrev32(crc2));
crc1 = crc32_le(init, buf, len);
if (crc1 != crc2)
printf("\nCRC endianness fail: 0x%08x != 0x%08x\n", crc1,