d352ac6814
This improves the comments at the top of many functions. It didn't dive into the guts of functions because I was trying to avoid merging problems with the new allocator and back reference work. extent-tree.c and volumes.c were both skipped, and there is definitely more work todo in cleaning and commenting the code. Signed-off-by: Chris Mason <chris.mason@oracle.com>
120 lines
3 KiB
C
120 lines
3 KiB
C
/*
|
|
* Copyright (C) 2008 Oracle. All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public
|
|
* License v2 as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public
|
|
* License along with this program; if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
* Boston, MA 021110-1307, USA.
|
|
*/
|
|
|
|
#ifndef __BTRFS_CRC32C__
|
|
#define __BTRFS_CRC32C__
|
|
#include <asm/byteorder.h>
|
|
#include <linux/crc32c.h>
|
|
#include <linux/version.h>
|
|
|
|
/* #define CONFIG_BTRFS_HW_SUM 1 */
|
|
|
|
#ifdef CONFIG_BTRFS_HW_SUM
|
|
#ifdef CONFIG_X86
|
|
/*
|
|
* Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
|
|
* CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
|
|
* CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
|
|
* http://www.intel.com/products/processor/manuals/
|
|
* Intel(R) 64 and IA-32 Architectures Software Developer's Manual
|
|
* Volume 2A: Instruction Set Reference, A-M
|
|
*/
|
|
|
|
#include <asm/cpufeature.h>
|
|
#include <asm/processor.h>
|
|
|
|
#define X86_FEATURE_XMM4_2 (4*32+20) /* Streaming SIMD Extensions-4.2 */
|
|
#define cpu_has_xmm4_2 boot_cpu_has(X86_FEATURE_XMM4_2)
|
|
|
|
#ifdef CONFIG_X86_64
|
|
#define REX_PRE "0x48, "
|
|
#define SCALE_F 8
|
|
#else
|
|
#define REX_PRE
|
|
#define SCALE_F 4
|
|
#endif
|
|
|
|
static inline u32 btrfs_crc32c_le_hw_byte(u32 crc, unsigned char const *data,
|
|
size_t length)
|
|
{
|
|
while (length--) {
|
|
__asm__ __volatile__(
|
|
".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
|
|
:"=S"(crc)
|
|
:"0"(crc), "c"(*data)
|
|
);
|
|
data++;
|
|
}
|
|
|
|
return crc;
|
|
}
|
|
|
|
static inline u32 __pure btrfs_crc32c_le_hw(u32 crc, unsigned char const *p,
|
|
size_t len)
|
|
{
|
|
unsigned int iquotient = len / SCALE_F;
|
|
unsigned int iremainder = len % SCALE_F;
|
|
#ifdef CONFIG_X86_64
|
|
u64 *ptmp = (u64 *)p;
|
|
#else
|
|
u32 *ptmp = (u32 *)p;
|
|
#endif
|
|
|
|
while (iquotient--) {
|
|
__asm__ __volatile__(
|
|
".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
|
|
:"=S"(crc)
|
|
:"0"(crc), "c"(*ptmp)
|
|
);
|
|
ptmp++;
|
|
}
|
|
|
|
if (iremainder)
|
|
crc = btrfs_crc32c_le_hw_byte(crc, (unsigned char *)ptmp,
|
|
iremainder);
|
|
|
|
return crc;
|
|
}
|
|
#endif /* CONFIG_BTRFS_HW_SUM */
|
|
|
|
static inline u32 __btrfs_crc32c(u32 crc, unsigned char const *address,
|
|
size_t len)
|
|
{
|
|
#ifdef CONFIG_BTRFS_HW_SUM
|
|
if (cpu_has_xmm4_2)
|
|
return btrfs_crc32c_le_hw(crc, address, len);
|
|
#endif
|
|
return crc32c_le(crc, address, len);
|
|
}
|
|
|
|
#else
|
|
|
|
#define __btrfs_crc32c(seed, data, length) crc32c(seed, data, length)
|
|
|
|
#endif /* CONFIG_X86 */
|
|
|
|
/**
|
|
* implementation of crc32c_le() changed in linux-2.6.23,
|
|
* has of v0.13 btrfs-progs is using the latest version.
|
|
* We must workaround older implementations of crc32c_le()
|
|
* found on older kernel versions.
|
|
*/
|
|
#define btrfs_crc32c(seed, data, length) \
|
|
__btrfs_crc32c(seed, (unsigned char const *)data, length)
|
|
#endif
|
|
|