crc32-main.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Aug 8, 2011 Bob Pearson with help from Joakim Tjernlund and George Spelvin
  4 * cleaned up code to current version of sparse and added the slicing-by-8
  5 * algorithm to the closely similar existing slicing-by-4 algorithm.
  6 *
  7 * Oct 15, 2000 Matt Domsch <Matt_Domsch@dell.com>
  8 * Nicer crc32 functions/docs submitted by linux@horizon.com.  Thanks!
  9 * Code was from the public domain, copyright abandoned.  Code was
 10 * subsequently included in the kernel, thus was re-licensed under the
 11 * GNU GPL v2.
 12 *
 13 * Oct 12, 2000 Matt Domsch <Matt_Domsch@dell.com>
 14 * Same crc32 function was used in 5 other places in the kernel.
 15 * I made one version, and deleted the others.
 16 * There are various incantations of crc32().  Some use a seed of 0 or ~0.
 17 * Some xor at the end with ~0.  The generic crc32() function takes
 18 * seed as an argument, and doesn't xor at the end.  Then individual
 19 * users can do whatever they need.
 20 *   drivers/net/smc9194.c uses seed ~0, doesn't xor with ~0.
 21 *   fs/jffs2 uses seed 0, doesn't xor with ~0.
 22 *   fs/partitions/efi.c uses seed ~0, xor's with ~0.
 23 */
 24
 25/* see: Documentation/staging/crc32.rst for a description of algorithms */
 26
 27#include <linux/crc32.h>
 28#include <linux/export.h>
 29#include <linux/module.h>
 30#include <linux/types.h>
 31
 32#include "crc32table.h"
 33
 34static inline u32 __maybe_unused
 35crc32_le_base(u32 crc, const u8 *p, size_t len)
 36{
 37	while (len--)
 38		crc = (crc >> 8) ^ crc32table_le[(crc & 255) ^ *p++];
 39	return crc;
 40}
 41
 42static inline u32 __maybe_unused
 43crc32_be_base(u32 crc, const u8 *p, size_t len)
 44{
 45	while (len--)
 46		crc = (crc << 8) ^ crc32table_be[(crc >> 24) ^ *p++];
 47	return crc;
 48}
 49
 50static inline u32 __maybe_unused
 51crc32c_base(u32 crc, const u8 *p, size_t len)
 52{
 53	while (len--)
 54		crc = (crc >> 8) ^ crc32ctable_le[(crc & 255) ^ *p++];
 55	return crc;
 56}
 57
 58#ifdef CONFIG_CRC32_ARCH
 59#include "crc32.h" /* $(SRCARCH)/crc32.h */
 60
 61u32 crc32_optimizations(void)
 62{
 63	return crc32_optimizations_arch();
 64}
 65EXPORT_SYMBOL(crc32_optimizations);
 66#else
 67#define crc32_le_arch crc32_le_base
 68#define crc32_be_arch crc32_be_base
 69#define crc32c_arch crc32c_base
 70#endif
 71
 72u32 crc32_le(u32 crc, const void *p, size_t len)
 73{
 74	return crc32_le_arch(crc, p, len);
 75}
 76EXPORT_SYMBOL(crc32_le);
 77
 78u32 crc32_be(u32 crc, const void *p, size_t len)
 79{
 80	return crc32_be_arch(crc, p, len);
 81}
 82EXPORT_SYMBOL(crc32_be);
 83
 84u32 crc32c(u32 crc, const void *p, size_t len)
 85{
 86	return crc32c_arch(crc, p, len);
 87}
 88EXPORT_SYMBOL(crc32c);
 89
 90#ifdef crc32_mod_init_arch
 91static int __init crc32_mod_init(void)
 92{
 93	crc32_mod_init_arch();
 94	return 0;
 95}
 96subsys_initcall(crc32_mod_init);
 97
 98static void __exit crc32_mod_exit(void)
 99{
100}
101module_exit(crc32_mod_exit);
102#endif
103
104MODULE_DESCRIPTION("CRC32 library functions");
105MODULE_LICENSE("GPL");