Re: Linux 2.4.21-rc4-ac1
From: David Woodhouse (dwmw2@infradead.org)
Date: Wed May 28 2003 - 03:32:54 EST
> o Add CRC32 libraries backport (David Woodhouse, Duncan Sands)
This fixes the 'CONFIG_CRC32=y but nothing references it' case, and also
merges the optimisations made by Joakim Tjernlund in 2.5's version.
diff -uNr linux-2.4.21-rc4-ac1/kernel/ksyms.c linux-2.4.21-rc4-ac1-crc/kernel/ksyms.c
--- linux-2.4.21-rc4-ac1/kernel/ksyms.c Wed May 28 09:19:53 2003
+++ linux-2.4.21-rc4-ac1-crc/kernel/ksyms.c Wed May 28 09:23:34 2003
@@ -49,6 +49,7 @@
#include <linux/completion.h>
#include <linux/seq_file.h>
#include <linux/dnotify.h>
+#include <linux/crc32.h>
#include <asm/checksum.h>
#if defined(CONFIG_PROC_FS)
@@ -575,6 +576,12 @@
EXPORT_SYMBOL(strnicmp);
EXPORT_SYMBOL(strspn);
EXPORT_SYMBOL(strsep);
+
+#ifdef CONFIG_CRC32
+EXPORT_SYMBOL(crc32_le);
+EXPORT_SYMBOL(crc32_be);
+EXPORT_SYMBOL(bitreverse);
+#endif
/* software interrupts */
EXPORT_SYMBOL(tasklet_hi_vec);
diff -uNr linux-2.4.21-rc4-ac1/lib/Makefile linux-2.4.21-rc4-ac1-crc/lib/Makefile
--- linux-2.4.21-rc4-ac1/lib/Makefile Wed May 28 09:19:53 2003
+++ linux-2.4.21-rc4-ac1-crc/lib/Makefile Wed May 28 09:23:34 2003
@@ -8,7 +8,8 @@
L_TARGET := lib.a
-export-objs := cmdline.o dec_and_lock.o rwsem-spinlock.o rwsem.o rbtree.o crc32.o
+export-objs := cmdline.o dec_and_lock.o rwsem-spinlock.o rwsem.o \
+ rbtree.o crc32.o
obj-y := errno.o ctype.o string.o vsprintf.o brlock.o cmdline.o \
bust_spinlocks.o rbtree.o dump_stack.o
diff -uNr linux-2.4.21-rc4-ac1/lib/crc32.c linux-2.4.21-rc4-ac1-crc/lib/crc32.c
--- linux-2.4.21-rc4-ac1/lib/crc32.c Wed May 28 09:19:53 2003
+++ linux-2.4.21-rc4-ac1-crc/lib/crc32.c Wed May 28 09:23:34 2003
@@ -90,32 +90,29 @@
const u32 *tab = crc32table_le;
# ifdef __LITTLE_ENDIAN
-# define DO_CRC crc = (crc>>8) ^ tab[ crc & 255 ]
-# define ENDIAN_SHIFT 0
+# define DO_CRC(x) crc = tab[ (crc ^ (x)) & 255 ] ^ (crc>>8)
# else
-# define DO_CRC crc = (crc<<8) ^ tab[ crc >> 24 ]
-# define ENDIAN_SHIFT 24
+# define DO_CRC(x) crc = tab[ ((crc >> 24) ^ (x)) & 255] ^ (crc<<8)
# endif
crc = __cpu_to_le32(crc);
/* Align it */
- if( ((u32)b)&3 && len){
+ if(unlikely(((long)b)&3 && len)){
do {
- crc ^= *((u8 *)b)++ << ENDIAN_SHIFT;
- DO_CRC;
- } while ((--len) && ((u32)b)&3 );
+ DO_CRC(*((u8 *)b)++);
+ } while ((--len) && ((long)b)&3 );
}
- if(len >= 4){
+ if(likely(len >= 4)){
/* load data 32 bits wide, xor data 32 bits wide. */
size_t save_len = len & 3;
len = len >> 2;
--b; /* use pre increment below(*++b) for speed */
do {
crc ^= *++b;
- DO_CRC;
- DO_CRC;
- DO_CRC;
- DO_CRC;
+ DO_CRC(0);
+ DO_CRC(0);
+ DO_CRC(0);
+ DO_CRC(0);
} while (--len);
b++; /* point to next byte(s) */
len = save_len;
@@ -123,8 +120,7 @@
/* And the last few bytes */
if(len){
do {
- crc ^= *((u8 *)b)++ << ENDIAN_SHIFT;
- DO_CRC;
+ DO_CRC(*((u8 *)b)++);
} while (--len);
}
@@ -195,32 +191,29 @@
const u32 *tab = crc32table_be;
# ifdef __LITTLE_ENDIAN
-# define DO_CRC crc = (crc>>8) ^ tab[ crc & 255 ]
-# define ENDIAN_SHIFT 24
+# define DO_CRC(x) crc = tab[ (crc ^ (x)) & 255 ] ^ (crc>>8)
# else
-# define DO_CRC crc = (crc<<8) ^ tab[ crc >> 24 ]
-# define ENDIAN_SHIFT 0
+# define DO_CRC(x) crc = tab[ ((crc >> 24) ^ (x)) & 255] ^ (crc<<8)
# endif
crc = __cpu_to_be32(crc);
/* Align it */
- if( ((u32)b)&3 && len){
+ if(unlikely(((long)b)&3 && len)){
do {
- crc ^= *((u8 *)b)++ << ENDIAN_SHIFT;
- DO_CRC;
- } while ((--len) && ((u32)b)&3 );
+ DO_CRC(*((u8 *)b)++);
+ } while ((--len) && ((long)b)&3 );
}
- if(len >= 4){
+ if(likely(len >= 4)){
/* load data 32 bits wide, xor data 32 bits wide. */
size_t save_len = len & 3;
len = len >> 2;
--b; /* use pre increment below(*++b) for speed */
do {
crc ^= *++b;
- DO_CRC;
- DO_CRC;
- DO_CRC;
- DO_CRC;
+ DO_CRC(0);
+ DO_CRC(0);
+ DO_CRC(0);
+ DO_CRC(0);
} while (--len);
b++; /* point to next byte(s) */
len = save_len;
@@ -228,8 +221,7 @@
/* And the last few bytes */
if(len){
do {
- crc ^= *((u8 *)b)++ << ENDIAN_SHIFT;
- DO_CRC;
+ DO_CRC(*((u8 *)b)++);
} while (--len);
}
return __be32_to_cpu(crc);
@@ -266,9 +258,12 @@
return x;
}
+#ifdef MODULE /* These are exported from kernel/ksyms.c in the non-module
+ case, to ensure that this file is pulled in from lib/lib.a */
EXPORT_SYMBOL(crc32_le);
EXPORT_SYMBOL(crc32_be);
EXPORT_SYMBOL(bitreverse);
+#endif
/*
* A brief CRC tutorial.
diff -uNr linux-2.4.21-rc4-ac1/lib/crc32defs.h linux-2.4.21-rc4-ac1-crc/lib/crc32defs.h
--- linux-2.4.21-rc4-ac1/lib/crc32defs.h Wed May 28 09:19:53 2003
+++ linux-2.4.21-rc4-ac1-crc/lib/crc32defs.h Wed May 28 09:23:34 2003
@@ -8,8 +8,12 @@
/* How many bits at a time to use. Requires a table of 4<<CRC_xx_BITS bytes. */
/* For less performance-sensitive, use 4 */
-#define CRC_LE_BITS 8
-#define CRC_BE_BITS 8
+#ifndef CRC_LE_BITS
+# define CRC_LE_BITS 8
+#endif
+#ifndef CRC_BE_BITS
+# define CRC_BE_BITS 8
+#endif
/*
* Little-endian CRC computation. Used with serial bit streams sent
--
dwmw2
-
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