1 files changed, 343 insertions, 0 deletions
diff --git a/lib/crc32.c b/lib/crc32.c
new file mode 100644
index 000000000..1a5d08470
--- /dev/null
+++ b/lib/crc32.c
@@ -0,0 +1,343 @@
+/*
+ * Aug 8, 2011 Bob Pearson with help from Joakim Tjernlund and George Spelvin
+ * cleaned up code to current version of sparse and added the slicing-by-8
+ * algorithm to the closely similar existing slicing-by-4 algorithm.
+ *
+ * Oct 15, 2000 Matt Domsch <Matt_Domsch@dell.com>
+ * Nicer crc32 functions/docs submitted by linux@horizon.com.  Thanks!
+ * Code was from the public domain, copyright abandoned.  Code was
+ * subsequently included in the kernel, thus was re-licensed under the
+ * GNU GPL v2.
+ *
+ * Oct 12, 2000 Matt Domsch <Matt_Domsch@dell.com>
+ * Same crc32 function was used in 5 other places in the kernel.
+ * I made one version, and deleted the others.
+ * There are various incantations of crc32().  Some use a seed of 0 or ~0.
+ * Some xor at the end with ~0.  The generic crc32() function takes
+ * seed as an argument, and doesn't xor at the end.  Then individual
+ * users can do whatever they need.
+ *   drivers/net/smc9194.c uses seed ~0, doesn't xor with ~0.
+ *   fs/jffs2 uses seed 0, doesn't xor with ~0.
+ *   fs/partitions/efi.c uses seed ~0, xor's with ~0.
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+/* see: Documentation/crc32.txt for a description of algorithms */
+
+#include <linux/crc32.h>
+#include <linux/crc32poly.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include "crc32defs.h"
+
+#if CRC_LE_BITS > 8
+# define tole(x) ((__force u32) cpu_to_le32(x))
+#else
+# define tole(x) (x)
+#endif
+
+#if CRC_BE_BITS > 8
+# define tobe(x) ((__force u32) cpu_to_be32(x))
+#else
+# define tobe(x) (x)
+#endif
+
+#include "crc32table.h"
+
+MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
+MODULE_DESCRIPTION("Various CRC32 calculations");
+MODULE_LICENSE("GPL");
+
+#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
+
+/* implements slicing-by-4 or slicing-by-8 algorithm */
+static inline u32 __pure
+crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
+{
+# ifdef __LITTLE_ENDIAN
+#  define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8)
+#  define DO_CRC4 (t3[(q) & 255] ^ t2[(q >> 8) & 255] ^ \
+		   t1[(q >> 16) & 255] ^ t0[(q >> 24) & 255])
+#  define DO_CRC8 (t7[(q) & 255] ^ t6[(q >> 8) & 255] ^ \
+		   t5[(q >> 16) & 255] ^ t4[(q >> 24) & 255])
+# else
+#  define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
+#  define DO_CRC4 (t0[(q) & 255] ^ t1[(q >> 8) & 255] ^ \
+		   t2[(q >> 16) & 255] ^ t3[(q >> 24) & 255])
+#  define DO_CRC8 (t4[(q) & 255] ^ t5[(q >> 8) & 255] ^ \
+		   t6[(q >> 16) & 255] ^ t7[(q >> 24) & 255])
+# endif
+	const u32 *b;
+	size_t    rem_len;
+# ifdef CONFIG_X86
+	size_t i;
+# endif
+	const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3];
+# if CRC_LE_BITS != 32
+	const u32 *t4 = tab[4], *t5 = tab[5], *t6 = tab[6], *t7 = tab[7];
+# endif
+	u32 q;
+
+	/* Align it */
+	if (unlikely((long)buf & 3 && len)) {
+		do {
+			DO_CRC(*buf++);
+		} while ((--len) && ((long)buf)&3);
+	}
+
+# if CRC_LE_BITS == 32
+	rem_len = len & 3;
+	len = len >> 2;
+# else
+	rem_len = len & 7;
+	len = len >> 3;
+# endif
+
+	b = (const u32 *)buf;
+# ifdef CONFIG_X86
+	--b;
+	for (i = 0; i < len; i++) {
+# else
+	for (--b; len; --len) {
+# endif
+		q = crc ^ *++b; /* use pre increment for speed */
+# if CRC_LE_BITS == 32
+		crc = DO_CRC4;
+# else
+		crc = DO_CRC8;
+		q = *++b;
+		crc ^= DO_CRC4;
+# endif
+	}
+	len = rem_len;
+	/* And the last few bytes */
+	if (len) {
+		u8 *p = (u8 *)(b + 1) - 1;
+# ifdef CONFIG_X86
+		for (i = 0; i < len; i++)
+			DO_CRC(*++p); /* use pre increment for speed */
+# else
+		do {
+			DO_CRC(*++p); /* use pre increment for speed */
+		} while (--len);
+# endif
+	}
+	return crc;
+#undef DO_CRC
+#undef DO_CRC4
+#undef DO_CRC8
+}
+#endif
+
+
+/**
+ * crc32_le_generic() - Calculate bitwise little-endian Ethernet AUTODIN II
+ *			CRC32/CRC32C
+ * @crc: seed value for computation.  ~0 for Ethernet, sometimes 0 for other
+ *	 uses, or the previous crc32/crc32c value if computing incrementally.
+ * @p: pointer to buffer over which CRC32/CRC32C is run
+ * @len: length of buffer @p
+ * @tab: little-endian Ethernet table
+ * @polynomial: CRC32/CRC32c LE polynomial
+ */
+static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
+					  size_t len, const u32 (*tab)[256],
+					  u32 polynomial)
+{
+#if CRC_LE_BITS == 1
+	int i;
+	while (len--) {
+		crc ^= *p++;
+		for (i = 0; i < 8; i++)
+			crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
+	}
+# elif CRC_LE_BITS == 2
+	while (len--) {
+		crc ^= *p++;
+		crc = (crc >> 2) ^ tab[0][crc & 3];
+		crc = (crc >> 2) ^ tab[0][crc & 3];
+		crc = (crc >> 2) ^ tab[0][crc & 3];
+		crc = (crc >> 2) ^ tab[0][crc & 3];
+	}
+# elif CRC_LE_BITS == 4
+	while (len--) {
+		crc ^= *p++;
+		crc = (crc >> 4) ^ tab[0][crc & 15];
+		crc = (crc >> 4) ^ tab[0][crc & 15];
+	}
+# elif CRC_LE_BITS == 8
+	/* aka Sarwate algorithm */
+	while (len--) {
+		crc ^= *p++;
+		crc = (crc >> 8) ^ tab[0][crc & 255];
+	}
+# else
+	crc = (__force u32) __cpu_to_le32(crc);
+	crc = crc32_body(crc, p, len, tab);
+	crc = __le32_to_cpu((__force __le32)crc);
+#endif
+	return crc;
+}
+
+#if CRC_LE_BITS == 1
+u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE);
+}
+u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
+}
+#else
+u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_le_generic(crc, p, len,
+			(const u32 (*)[256])crc32table_le, CRC32_POLY_LE);
+}
+u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_le_generic(crc, p, len,
+			(const u32 (*)[256])crc32ctable_le, CRC32C_POLY_LE);
+}
+#endif
+EXPORT_SYMBOL(crc32_le);
+EXPORT_SYMBOL(__crc32c_le);
+
+/*
+ * This multiplies the polynomials x and y modulo the given modulus.
+ * This follows the "little-endian" CRC convention that the lsbit
+ * represents the highest power of x, and the msbit represents x^0.
+ */
+static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)
+{
+	u32 product = x & 1 ? y : 0;
+	int i;
+
+	for (i = 0; i < 31; i++) {
+		product = (product >> 1) ^ (product & 1 ? modulus : 0);
+		x >>= 1;
+		product ^= x & 1 ? y : 0;
+	}
+
+	return product;
+}
+
+/**
+ * crc32_generic_shift - Append @len 0 bytes to crc, in logarithmic time
+ * @crc: The original little-endian CRC (i.e. lsbit is x^31 coefficient)
+ * @len: The number of bytes. @crc is multiplied by x^(8*@len)
+ * @polynomial: The modulus used to reduce the result to 32 bits.
+ *
+ * It's possible to parallelize CRC computations by computing a CRC
+ * over separate ranges of a buffer, then summing them.
+ * This shifts the given CRC by 8*len bits (i.e. produces the same effect
+ * as appending len bytes of zero to the data), in time proportional
+ * to log(len).
+ */
+static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,
+						   u32 polynomial)
+{
+	u32 power = polynomial;	/* CRC of x^32 */
+	int i;
+
+	/* Shift up to 32 bits in the simple linear way */
+	for (i = 0; i < 8 * (int)(len & 3); i++)
+		crc = (crc >> 1) ^ (crc & 1 ? polynomial : 0);
+
+	len >>= 2;
+	if (!len)
+		return crc;
+
+	for (;;) {
+		/* "power" is x^(2^i), modulo the polynomial */
+		if (len & 1)
+			crc = gf2_multiply(crc, power, polynomial);
+
+		len >>= 1;
+		if (!len)
+			break;
+
+		/* Square power, advancing to x^(2^(i+1)) */
+		power = gf2_multiply(power, power, polynomial);
+	}
+
+	return crc;
+}
+
+u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len)
+{
+	return crc32_generic_shift(crc, len, CRC32_POLY_LE);
+}
+
+u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)
+{
+	return crc32_generic_shift(crc, len, CRC32C_POLY_LE);
+}
+EXPORT_SYMBOL(crc32_le_shift);
+EXPORT_SYMBOL(__crc32c_le_shift);
+
+/**
+ * crc32_be_generic() - 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 CRC32 is run
+ * @len: length of buffer @p
+ * @tab: big-endian Ethernet table
+ * @polynomial: CRC32 BE polynomial
+ */
+static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
+					  size_t len, const u32 (*tab)[256],
+					  u32 polynomial)
+{
+#if CRC_BE_BITS == 1
+	int i;
+	while (len--) {
+		crc ^= *p++ << 24;
+		for (i = 0; i < 8; i++)
+			crc =
+			    (crc << 1) ^ ((crc & 0x80000000) ? polynomial :
+					  0);
+	}
+# elif CRC_BE_BITS == 2
+	while (len--) {
+		crc ^= *p++ << 24;
+		crc = (crc << 2) ^ tab[0][crc >> 30];
+		crc = (crc << 2) ^ tab[0][crc >> 30];
+		crc = (crc << 2) ^ tab[0][crc >> 30];
+		crc = (crc << 2) ^ tab[0][crc >> 30];
+	}
+# elif CRC_BE_BITS == 4
+	while (len--) {
+		crc ^= *p++ << 24;
+		crc = (crc << 4) ^ tab[0][crc >> 28];
+		crc = (crc << 4) ^ tab[0][crc >> 28];
+	}
+# elif CRC_BE_BITS == 8
+	while (len--) {
+		crc ^= *p++ << 24;
+		crc = (crc << 8) ^ tab[0][crc >> 24];
+	}
+# else
+	crc = (__force u32) __cpu_to_be32(crc);
+	crc = crc32_body(crc, p, len, tab);
+	crc = __be32_to_cpu((__force __be32)crc);
+# endif
+	return crc;
+}
+
+#if CRC_BE_BITS == 1
+u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_be_generic(crc, p, len, NULL, CRC32_POLY_BE);
+}
+#else
+u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
+{
+	return crc32_be_generic(crc, p, len,
+			(const u32 (*)[256])crc32table_be, CRC32_POLY_BE);
+}
+#endif
+EXPORT_SYMBOL(crc32_be);