mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
346 lines
9.3 KiB
346 lines
9.3 KiB
/* |
|
* 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 <[email protected]> |
|
* Nicer crc32 functions/docs submitted by [email protected]. 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 <[email protected]> |
|
* 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/staging/crc32.rst 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 <[email protected]>"); |
|
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 __weak crc32_le(u32 crc, unsigned char const *p, size_t len) |
|
{ |
|
return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE); |
|
} |
|
u32 __pure __weak __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 __weak 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 __weak __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); |
|
|
|
u32 __pure crc32_le_base(u32, unsigned char const *, size_t) __alias(crc32_le); |
|
u32 __pure __crc32c_le_base(u32, unsigned char const *, size_t) __alias(__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);
|
|
|