[PATCH] lib/libcrc32c implementation

[Clay Haapala <chaapala@cisco.com>]

This patch agains 2.6.4 kernel code implements the CRC32C algorithm.
The routines are based on the same design as the existing CRC32 code.
Licensing is intended to be identical (GPL).

The immediate customer of this code is the wrapper code in
crypto/crc32c, available in another patch.

And the immediate customer of the crypto code is the linux-iscsi
driver module, currently in review.  See the linux-iscsi project on
SourceForge for details.
-- 
Clay Haapala (chaapala@cisco.com) Cisco Systems SRBU +1 763-398-1056
   6450 Wedgwood Rd, Suite 130 Maple Grove MN 55311 PGP: C89240AD
     Of course the drugs advertised in all those emails are safe.
		      Show me the dead spammers!
			      (Please!)

diff -urN linux-2.6.4.orig/include/linux/crc32c.h linux/include/linux/crc32c.h
--- linux-2.6.4.orig/include/linux/crc32c.h	1969-12-31 18:00:00.000000000 -0600
+++ linux/include/linux/crc32c.h	2004-03-18 15:34:18.000000000 -0600
@@ -0,0 +1,11 @@
+#ifndef _LINUX_CRC32C_H
+#define _LINUX_CRC32C_H
+
+#include <linux/types.h>
+
+extern u32 crc32c_le(u32 crc, unsigned char const *address, size_t length);
+extern u32 crc32c_be(u32 crc, unsigned char const *address, size_t length);
+
+#define crc32c(seed, data, length)  crc32c_le(seed, (unsigned char const *)data, length)
+
+#endif	/* _LINUX_CRC32C_H */
diff -urN linux-2.6.4.orig/lib/Kconfig linux/lib/Kconfig
--- linux-2.6.4.orig/lib/Kconfig	2004-03-10 20:55:33.000000000 -0600
+++ linux/lib/Kconfig	2004-03-18 16:28:42.000000000 -0600
@@ -12,6 +12,15 @@
 	  kernel tree does. Such modules that use library CRC32 functions
 	  require M here.
 
+config LIBCRC32C
+	tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
+	help
+	  This option is provided for the case where no in-kernel-tree
+	  modules require CRC32c functions, but a module built outside the
+	  kernel tree does. Such modules that use library CRC32c functions
+	  require M here.  See Castagnoli93.
+	  Module will be libcrc32c.
+
 #
 # compression support is select'ed if needed
 #
diff -urN linux-2.6.4.orig/lib/libcrc32c.c linux/lib/libcrc32c.c
--- linux-2.6.4.orig/lib/libcrc32c.c	1969-12-31 18:00:00.000000000 -0600
+++ linux/lib/libcrc32c.c	2004-03-18 16:27:54.000000000 -0600
@@ -0,0 +1,205 @@
+/* 
+ * CRC32C
+ *@Article{castagnoli-crc,
+ * author =       { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
+ * title =        {{Optimization of Cyclic Redundancy-Check Codes with 24
+ *                 and 32 Parity Bits}},
+ * journal =      IEEE Transactions on Communication,
+ * year =         {1993},
+ * volume =       {41},
+ * number =       {6},
+ * pages =        {},
+ * month =        {June},
+ *}
+ * Used by the iSCSI driver, possibly others, and derived from the
+ * the iscsi-crc.c module of the linux-iscsi driver at
+ * http://linux-iscsi.sourceforge.net.
+ *
+ * Following the example of lib/crc32, this function is intended to be
+ * flexible and useful for all users.  Modules that currently have their
+ * own crc32c, but hopefully may be able to use this one are:
+ *  net/sctp (please add all your doco to here if you change to
+ *            use this one!)
+ *  <endoflist>
+ *
+ * Copyright (c) 2003 Cisco Systems, Inc.
+ * 
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option) 
+ * any later version.
+ *
+ */
+#include <linux/crc32c.h>
+#include <linux/module.h>
+#include <asm/byteorder.h>
+
+MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
+MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
+MODULE_LICENSE("GPL");
+
+#if __GNUC__ >= 3	/* 2.x has "attribute", but only 3.0 has "pure */
+#define attribute(x) __attribute__(x)
+#else
+#define attribute(x)
+#endif
+
+#define CRC32C_POLY_BE 0x1EDC6F41
+#define CRC32C_POLY_LE 0x82F63B78
+
+#ifndef CRC_LE_BITS 
+# define CRC_LE_BITS 8
+#endif
+
+
+/*
+ * Haven't generated a big-endian table yet, but the bit-wise version
+ * should at least work.
+ */
+#if defined CRC_BE_BITS && CRC_BE_BITS != 1
+#undef CRC_BE_BITS
+#endif
+#ifndef CRC_BE_BITS
+# define CRC_BE_BITS 1
+#endif
+
+EXPORT_SYMBOL(crc32c_le);
+
+#if CRC_LE_BITS == 1
+/*
+ * Compute things bit-wise, as done in crc32.c.  We could share the tight 
+ * loop below with crc32 and vary the POLY if we don't find value in terms
+ * of space and maintainability in keeping the two modules separate.
+ */
+u32 attribute((pure))
+crc32c_le(u32 crc, unsigned char const *p, size_t len)
+{
+	int i;
+	while (len--) {
+		crc ^= *p++;
+		for (i = 0; i < 8; i++)
+			crc = (crc >> 1) ^ ((crc & 1) ? CRC32C_POLY_LE : 0);
+	}
+	return crc;
+}
+#else
+
+/*
+ * This is the CRC-32C table
+ * Generated with:
+ * width = 32 bits
+ * poly = 0x1EDC6F41
+ * reflect input bytes = true
+ * reflect output bytes = true
+ */
+
+static u32 crc32c_table[256] = {
+	0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
+	0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
+	0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
+	0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
+	0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
+	0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
+	0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
+	0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
+	0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
+	0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
+	0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
+	0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
+	0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
+	0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
+	0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
+	0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
+	0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
+	0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
+	0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
+	0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
+	0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
+	0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
+	0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
+	0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
+	0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
+	0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
+	0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
+	0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
+	0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
+	0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
+	0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
+	0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
+	0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
+	0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
+	0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
+	0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
+	0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
+	0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
+	0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
+	0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
+	0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
+	0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
+	0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
+	0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
+	0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
+	0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
+	0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
+	0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
+	0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
+	0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
+	0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
+	0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
+	0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
+	0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
+	0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
+	0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
+	0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
+	0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
+	0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
+	0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
+	0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
+	0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
+	0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
+	0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
+};
+
+/*
+ * Steps through buffer one byte at at time, calculates reflected 
+ * crc using table.
+ */
+
+u32 attribute((pure))
+crc32c_le(u32 seed, unsigned char const *data, size_t length)
+{
+	u32 crc = __cpu_to_le32(seed);
+	
+	while (length--)
+		crc =
+		    crc32c_table[(crc ^ *data++) & 0xFFL] ^ (crc >> 8);
+
+	return __le32_to_cpu(crc);
+}
+
+#endif	/* CRC_LE_BITS == 8 */
+
+/*EXPORT_SYMBOL(crc32c_be);*/
+
+#if CRC_BE_BITS == 1
+u32 attribute((pure))
+crc32_be(u32 crc, unsigned char const *p, size_t len)
+{
+	int i;
+	while (len--) {
+		crc ^= *p++ << 24;
+		for (i = 0; i < 8; i++)
+			crc =
+			    (crc << 1) ^ ((crc & 0x80000000) ? CRC32C_POLY_BE :
+					  0);
+	}
+	return crc;
+}
+#endif
+
+/*
+ * Unit test
+ *
+ * A small unit test suite is implemented as part of the crypto suite.
+ * Select CRYPTO_CRC32C and use the tcrypt module to run the tests.
+ */
diff -urN linux-2.6.4.orig/lib/Makefile linux/lib/Makefile
--- linux-2.6.4.orig/lib/Makefile	2004-03-10 20:55:21.000000000 -0600
+++ linux/lib/Makefile	2004-03-18 15:59:55.000000000 -0600
@@ -16,6 +16,7 @@
 endif
 
 obj-$(CONFIG_CRC32)	+= crc32.o
+obj-$(CONFIG_LIBCRC32C)	+= libcrc32c.o
 
 obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate/
 obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate/