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linux-next/lib/xz/xz_crc32.c
Joel Stanley 242cdad873 lib/xz: Put CRC32_POLY_LE in xz_private.h
This fixes a regression introduced by faa16bc404 ("lib: Use
existing define with polynomial").

The cleanup added a dependency on include/linux, which broke the PowerPC
boot wrapper/decompresser when KERNEL_XZ is enabled:

  BOOTCC  arch/powerpc/boot/decompress.o
 In file included from arch/powerpc/boot/../../../lib/decompress_unxz.c:233,
                 from arch/powerpc/boot/decompress.c:42:
 arch/powerpc/boot/../../../lib/xz/xz_crc32.c:18:10: fatal error:
 linux/crc32poly.h: No such file or directory
  #include <linux/crc32poly.h>
           ^~~~~~~~~~~~~~~~~~~

The powerpc decompresser is a hairy corner of the kernel. Even while building
a 64-bit kernel it needs to build a 32-bit binary and therefore avoid including
files from include/linux.

This allows users of the xz library to avoid including headers from
'include/linux/' while still achieving the cleanup of the magic number.

Fixes: faa16bc404 ("lib: Use existing define with polynomial")
Reported-by: Meelis Roos <mroos@linux.ee>
Reported-by: kbuild test robot <lkp@intel.com>
Suggested-by: Christophe LEROY <christophe.leroy@c-s.fr>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Tested-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-10-02 08:44:59 +10:00

60 lines
1.2 KiB
C

/*
* CRC32 using the polynomial from IEEE-802.3
*
* Authors: Lasse Collin <lasse.collin@tukaani.org>
* Igor Pavlov <http://7-zip.org/>
*
* This file has been put into the public domain.
* You can do whatever you want with this file.
*/
/*
* This is not the fastest implementation, but it is pretty compact.
* The fastest versions of xz_crc32() on modern CPUs without hardware
* accelerated CRC instruction are 3-5 times as fast as this version,
* but they are bigger and use more memory for the lookup table.
*/
#include "xz_private.h"
/*
* STATIC_RW_DATA is used in the pre-boot environment on some architectures.
* See <linux/decompress/mm.h> for details.
*/
#ifndef STATIC_RW_DATA
# define STATIC_RW_DATA static
#endif
STATIC_RW_DATA uint32_t xz_crc32_table[256];
XZ_EXTERN void xz_crc32_init(void)
{
const uint32_t poly = CRC32_POLY_LE;
uint32_t i;
uint32_t j;
uint32_t r;
for (i = 0; i < 256; ++i) {
r = i;
for (j = 0; j < 8; ++j)
r = (r >> 1) ^ (poly & ~((r & 1) - 1));
xz_crc32_table[i] = r;
}
return;
}
XZ_EXTERN uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
{
crc = ~crc;
while (size != 0) {
crc = xz_crc32_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
--size;
}
return ~crc;
}