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
+ * other uses, or the previous crc32 value if computing incrementally.
+ * @p: pointer to buffer over which CRC is run
+ * @len: length of buffer @p
+ */
+u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len);
+
#if CRC_LE_BITS == 1
/*
* In fact, the table-based code will work in this case, but it can be
* simplified by inlining the table in ?: form.
*/
-/**
- * crc32_le() - Calculate bitwise little-endian Ethernet AUTODIN II CRC32
- * @crc - seed value for computation. ~0 for Ethernet, sometimes 0 for
- * other uses, or the previous crc32 value if computing incrementally.
- * @p - pointer to buffer over which CRC is run
- * @len - length of buffer @p
- *
- */
-u32 __attribute_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)
{
int i;
while (len--) {
}
#else /* Table-based approach */
-/**
- * crc32_le() - Calculate bitwise little-endian Ethernet AUTODIN II CRC32
- * @crc - seed value for computation. ~0 for Ethernet, sometimes 0 for
- * other uses, or the previous crc32 value if computing incrementally.
- * @p - pointer to buffer over which CRC is run
- * @len - length of buffer @p
- *
- */
-u32 __attribute_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
}
#endif
+/**
+ * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
+ * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for
+ * other uses, or the previous crc32 value if computing incrementally.
+ * @p: pointer to buffer over which CRC is run
+ * @len: length of buffer @p
+ */
+u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len);
+
#if CRC_BE_BITS == 1
/*
* In fact, the table-based code will work in this case, but it can be
* simplified by inlining the table in ?: form.
*/
-/**
- * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
- * @crc - seed value for computation. ~0 for Ethernet, sometimes 0 for
- * other uses, or the previous crc32 value if computing incrementally.
- * @p - pointer to buffer over which CRC is run
- * @len - length of buffer @p
- *
- */
-u32 __attribute_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)
{
int i;
while (len--) {
}
#else /* Table-based approach */
-/**
- * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
- * @crc - seed value for computation. ~0 for Ethernet, sometimes 0 for
- * other uses, or the previous crc32 value if computing incrementally.
- * @p - pointer to buffer over which CRC is run
- * @len - length of buffer @p
- *
- */
-u32 __attribute_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
}
#endif
-u32 bitreverse(u32 x)
-{
- x = (x >> 16) | (x << 16);
- x = (x >> 8 & 0x00ff00ff) | (x << 8 & 0xff00ff00);
- x = (x >> 4 & 0x0f0f0f0f) | (x << 4 & 0xf0f0f0f0);
- x = (x >> 2 & 0x33333333) | (x << 2 & 0xcccccccc);
- x = (x >> 1 & 0x55555555) | (x << 1 & 0xaaaaaaaa);
- return x;
-}
-
EXPORT_SYMBOL(crc32_le);
EXPORT_SYMBOL(crc32_be);
-EXPORT_SYMBOL(bitreverse);
/*
* A brief CRC tutorial.
* but again the multiple of the polynomial to subtract depends only on
* the high bits, the high 8 bits in this case.
*
- * The multile we need in that case is the low 32 bits of a 40-bit
+ * The multiple we need in that case is the low 32 bits of a 40-bit
* value whose high 8 bits are given, and which is a multiple of the
* generator polynomial. This is simply the CRC-32 of the given
* one-byte message.
static void bytereverse(unsigned char *buf, size_t len)
{
while (len--) {
- unsigned char x = *buf;
- x = (x >> 4) | (x << 4);
- x = (x >> 2 & 0x33) | (x << 2 & 0xcc);
- x = (x >> 1 & 0x55) | (x << 1 & 0xaa);
+ unsigned char x = bitrev8(*buf);
*buf++ = x;
}
}
/* Now swap it around for the other test */
bytereverse(buf, len + 4);
- init = bitreverse(init);
- crc2 = bitreverse(crc1);
- if (crc1 != bitreverse(crc2))
- printf("\nBit reversal fail: 0x%08x -> %0x08x -> 0x%08x\n",
- crc1, crc2, bitreverse(crc2));
+ init = bitrev32(init);
+ crc2 = bitrev32(crc1);
+ if (crc1 != bitrev32(crc2))
+ printf("\nBit reversal fail: 0x%08x -> 0x%08x -> 0x%08x\n",
+ crc1, crc2, bitrev32(crc2));
crc1 = crc32_le(init, buf, len);
if (crc1 != crc2)
printf("\nCRC endianness fail: 0x%08x != 0x%08x\n", crc1,
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff