crc32: minor optimizations and cleanup
Move common crc body to new function crc32_body() cleaup and micro
optimize crc32_body for speed and less size.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/crc32.c b/lib/crc32.c
index 49d1c9e..02e3b31 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -42,6 +42,48 @@
MODULE_DESCRIPTION("Ethernet CRC32 calculations");
MODULE_LICENSE("GPL");
+#if CRC_LE_BITS == 8 || CRC_BE_BITS == 8
+
+static inline u32
+crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 *tab)
+{
+# ifdef __LITTLE_ENDIAN
+# define DO_CRC(x) crc = tab[(crc ^ (x)) & 255 ] ^ (crc >> 8)
+# else
+# define DO_CRC(x) crc = tab[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
+# endif
+ const u32 *b = (const u32 *)buf;
+ size_t rem_len;
+
+ /* Align it */
+ if (unlikely((long)b & 3 && len)) {
+ u8 *p = (u8 *)b;
+ do {
+ DO_CRC(*p++);
+ } while ((--len) && ((long)p)&3);
+ b = (u32 *)p;
+ }
+ rem_len = len & 3;
+ /* load data 32 bits wide, xor data 32 bits wide. */
+ len = len >> 2;
+ for (--b; len; --len) {
+ crc ^= *++b; /* use pre increment for speed */
+ DO_CRC(0);
+ DO_CRC(0);
+ DO_CRC(0);
+ DO_CRC(0);
+ }
+ len = rem_len;
+ /* And the last few bytes */
+ if (len) {
+ u8 *p = (u8 *)(b + 1) - 1;
+ do {
+ DO_CRC(*++p); /* use pre increment for speed */
+ } while (--len);
+ }
+ return crc;
+}
+#endif
/**
* crc32_le() - Calculate bitwise little-endian Ethernet AUTODIN II CRC32
* @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for
@@ -72,48 +114,10 @@
u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
{
# if CRC_LE_BITS == 8
- const u32 *b =(u32 *)p;
const u32 *tab = crc32table_le;
-# ifdef __LITTLE_ENDIAN
-# define DO_CRC(x) crc = tab[ (crc ^ (x)) & 255 ] ^ (crc>>8)
-# else
-# define DO_CRC(x) crc = tab[ ((crc >> 24) ^ (x)) & 255] ^ (crc<<8)
-# endif
-
crc = __cpu_to_le32(crc);
- /* Align it */
- if(unlikely(((long)b)&3 && len)){
- do {
- u8 *p = (u8 *)b;
- DO_CRC(*p++);
- b = (void *)p;
- } while ((--len) && ((long)b)&3 );
- }
- 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(0);
- DO_CRC(0);
- DO_CRC(0);
- DO_CRC(0);
- } while (--len);
- b++; /* point to next byte(s) */
- len = save_len;
- }
- /* And the last few bytes */
- if(len){
- do {
- u8 *p = (u8 *)b;
- DO_CRC(*p++);
- b = (void *)p;
- } while (--len);
- }
-
+ crc = crc32_body(crc, p, len, tab);
return __le32_to_cpu(crc);
#undef ENDIAN_SHIFT
#undef DO_CRC
@@ -170,47 +174,10 @@
u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
{
# if CRC_BE_BITS == 8
- const u32 *b =(u32 *)p;
const u32 *tab = crc32table_be;
-# ifdef __LITTLE_ENDIAN
-# define DO_CRC(x) crc = tab[ (crc ^ (x)) & 255 ] ^ (crc>>8)
-# else
-# define DO_CRC(x) crc = tab[ ((crc >> 24) ^ (x)) & 255] ^ (crc<<8)
-# endif
-
crc = __cpu_to_be32(crc);
- /* Align it */
- if(unlikely(((long)b)&3 && len)){
- do {
- u8 *p = (u8 *)b;
- DO_CRC(*p++);
- b = (u32 *)p;
- } while ((--len) && ((long)b)&3 );
- }
- 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(0);
- DO_CRC(0);
- DO_CRC(0);
- DO_CRC(0);
- } while (--len);
- b++; /* point to next byte(s) */
- len = save_len;
- }
- /* And the last few bytes */
- if(len){
- do {
- u8 *p = (u8 *)b;
- DO_CRC(*p++);
- b = (void *)p;
- } while (--len);
- }
+ crc = crc32_body(crc, p, len, tab);
return __be32_to_cpu(crc);
#undef ENDIAN_SHIFT
#undef DO_CRC