From ddcaccbc17d7d15d0f050519cfeb0e45acbd9b15 Mon Sep 17 00:00:00 2001 From: Joakim Tjernlund Date: Mon, 14 Dec 2009 18:01:33 -0800 Subject: [PATCH] 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/crc32.c | 121 +++++++++++++++++++--------------------------------- 1 file changed, 44 insertions(+), 77 deletions(-) diff --git a/lib/crc32.c b/lib/crc32.c index 49d1c9e3ce38..02e3b31b3a79 100644 --- a/lib/crc32.c +++ b/lib/crc32.c @@ -42,6 +42,48 @@ MODULE_AUTHOR("Matt Domsch "); 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) 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) 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 -- 2.20.1