#include "bch.h"
#include "dev.h"
#include "log.h"
#include "stdlib.h"
typedef unsigned int __u32;
#define GF_M(_p) ((_p)->m)
#define GF_T(_p) ((_p)->t)
#define GF_N(_p) ((_p)->n)
#define cpu_to_be32(x) ((__u32)( \
(((__u32)(x) & (__u32)0x000000ffUL) << 24) | \
(((__u32)(x) & (__u32)0x0000ff00UL) << 8) | \
(((__u32)(x) & (__u32)0x00ff0000UL) >> 8) | \
(((__u32)(x) & (__u32)0xff000000UL) >> 24)))
#define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
#define BCH_ECC_WORDS(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 32)
#define BCH_ECC_BYTES(_p) DIV_ROUND_UP(GF_M(_p)*GF_T(_p), 8)
#ifndef dbg
#define dbg(_fmt, args...) do {} while (0)
#endif
/**
* memset - Fill a region of memory with the given value
* @s: Pointer to the start of the area.
* @c: The byte to fill the area with
* @count: The size of the area.
*
* Do not use memset() to access IO space, use memset_io() instead.
*/
#if 0
void *memset(void *s,int c,size_t count)
{
unsigned long *sl = (unsigned long *) s;
unsigned long cl = 0;
char *s8;
int i;
/* do it one word at a time (32 bits or 64 bits) while possible */
if (((ulong)s & (sizeof(*sl) - 1)) == 0) {
for (i = 0; i < sizeof(*sl); i++) {
cl <<= 8;
cl |= c & 0xff;
}
while (count >= sizeof(*sl)) {
*sl++ = cl;
count -= sizeof(*sl);
}
}
/* fill 8 bits at a time */
s8 = (char *)sl;
while (count--)
*s8++ = c;
return s;
}
/**
* memcpy - Copy one area of memory to another
* @dest: Where to copy to
* @src: Where to copy from
* @count: The size of the area.
*
* You should not use this function to access IO space, use memcpy_toio()
* or memcpy_fromio() instead.
*/
void * memcpy(void *dest, const void *src, size_t count)
{
unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
char *d8, *s8;
if (src == dest)
return dest;
/* while all data is aligned (common case), copy a word at a time */
if ( (((uint64_t)dest | (uint64_t)src) & (sizeof(*dl) - 1)) == 0) {
while (count >= sizeof(*dl)) {
*dl++ = *sl++;
count -= sizeof(*dl);
}
}
/* copy the reset one byte at a time */
d8 = (char *)dl;
s8 = (char *)sl;
while (count--)
*d8++ = *s8++;
return dest;
}
#endif
#if 0
/*
* represent a polynomial over GF(2^m)
*/
struct gf_poly {
unsigned int deg; /* polynomial degree */
unsigned int c[0]; /* polynomial terms */
};
#endif
/* given its degree, compute a polynomial size in bytes */
#define GF_POLY_SZ(_d) (sizeof(struct gf_poly)+((_d)+1)*sizeof(unsigned int))
/* polynomial of degree 1 */
struct gf_poly_deg1 {
struct gf_poly poly;
unsigned int c[2];
};
/*
* same as encode_bch(), but process input data one byte at a time
*/
static void encode_bch_unaligned(struct bch_control *bch,
const unsigned char *data, unsigned int len,
uint32_t *ecc)
{
LOG_ECC("********* encode_bch_unaligned **********\n");
int i;
const uint32_t *p;
const int l = BCH_ECC_WORDS(bch)-1;
while (len--) {
p = bch->mod8_tab + (l+1)*(((ecc[0] >> 24)^(*data++)) & 0xff);
for (i = 0; i < l; i++)
ecc[i] = ((ecc[i] << 8)|(ecc[i+1] >> 24))^(*p++);
ecc[l] = (ecc[l] << 8)^(*p);
}
}
/*
* convert ecc bytes to aligned, zero-padded 32-bit ecc words
*/
static void load_ecc8(struct bch_control *bch, uint32_t *dst,
const uint8_t *src)
{
uint8_t pad[4] = {0, 0, 0, 0};
unsigned int i, nwords = BCH_ECC_WORDS(bch)-1;
for (i = 0; i < nwords; i++, src += 4)
dst[i] = (src[0] << 24)|(src[1] << 16)|(src[2] << 8)|src[3];
memcpy(pad, src, BCH_ECC_BYTES(bch)-4*nwords); // 处理剩余可能不满4位的数据
dst[nwords] = (pad[0] << 24)|(pad[1] << 16)|(pad[2] << 8)|pad[3]; //最后
}
/*
* convert 32-bit ecc words to ecc bytes
*/
static void store_ecc8(struct bch_control *bch, uint8_t *dst,
const uint32_t *src)
{
uint8_t pad[4];
unsigned int i, nwords = BCH_ECC_WORDS(bch)-1;
for (i = 0; i < nwords; i++) {
*dst++ = (src[i] >> 24);
*dst++ = (src[i] >> 16) & 0xff;
*dst++ = (src[i] >> 8) & 0xff;
*dst++ = (src[i] >> 0) & 0xff;
}
pad[0] = (src[nwords] >> 24);
pad[1] = (src[nwords] >> 16) & 0xff;
pad[2] = (src[nwords] >> 8) & 0xff;
pad[3] = (src[nwords] >> 0) & 0xff;
memcpy(dst, pad, BCH_ECC_BYTES(bch)-4*nwords);
}
/**
* encode_bch - calculate BCH ecc parity of data
* @bch: BCH control structure
* @data: data to encode
* @len: data length in bytes
* @ecc: ecc parity data, must be initialized by caller
*
* The @ecc parity array is used both as input and output parameter, in order to
* allow incremental computations. It should be of the size indicated by member
* @ecc_bytes of @bch, and should be initialized to 0 before the first call.
*
* The exact number of computed ecc parity bits is given by member @ecc_bits of
* @bch; it may be less than m*t for large values of t.
*/
void encode_bch(struct bch_control *bch, const uint8_t *data,
unsigned int len, uint8_t *ecc)
{
const unsigned int l = BCH_ECC_WORDS(bch)-1;
unsigned int i, mlen;
unsigned long m;
//LOG_ECC("encode_bch: l = %d, bch->m = %d, bcm->t = %d \n",l, bch->m, bch->t);
uint32_t w, r[l+1];
const uint32_t * const tab0 = bch->mod8_tab;
const uint32_t * const tab1 = tab0 + 256*(l+1);
const uint32_t * const tab2 = tab1 + 256*(l+1);
const uint32_t * const tab3 = tab2 + 256*(l+1);
const uint32_t *pdata, *p0, *p1, *p2, *p3;
if (ecc) {
/* load ecc parity bytes into internal 32-bit buffer */
load_ecc8(bch, bch->ecc_buf, ecc);
} else {
memset(bch->ecc_buf, 0, sizeof(r));
}
/* process first unaligned data bytes */
m = ((unsigned long)data) & 3;
if (m) {
mlen = (len < (4-m)) ? len : 4-m;
encode_bch_unaligned(bch, data, mlen, bch->ecc_buf);
data += mlen;
len -= mlen;
}
/* process 32-bit aligned data words */
pdata = (uint32_t *)data;
mlen = len/4;
data += 4*mlen;
len -= 4*mlen;
memcpy(r, bch->ecc_buf, sizeof(r));
/*
* split each 32-bit word into 4 polynomials of weight 8 as follows:
*
* 31 ...24 23 ...16 15 ... 8 7 ... 0
* xxxxxxxx yyyyyyyy zzzzzzzz tttttttt
* tttttttt mod g = r0 (precomputed)
* zzzzzzzz 00000000 mod g = r1 (precomputed)
* yyyyyyyy 00000000 00000000 mod g = r2 (precomputed)
* xxxxxxxx 00000000 00000000 00000000 mod g = r3 (precomputed)
* xxxxxxxx yyyyyyyy zzzzzzzz tttttttt mod g = r0^r1^r2^r3
*/
while (mlen--) {
/* input data is read in big-endian format */
//w = r[0]^cpu_to_be32(*pdata++);
w = r[0]^(*pdata++);
p0 = tab0 + (l+1)*((w >> 0) & 0xff);
p1 = tab1 + (l+1)*((w >> 8) & 0xff);
p2 = tab2 + (l+1)*((w >> 16) & 0xff);
p3 = tab3 + (l+1)*((w >> 24) & 0xff);
for (i = 0; i < l; i++)
r[i] = r[i+1]^p0[i]^p1[i]^p2[i]^p3[i];
r[l] = p0[l]^p1[l]^p2[l]^p3[l];
}
memcpy(bch->ecc_buf, r, sizeof(r));
/* process last unaligned bytes */
if (len)
encode_bch_unaligned(bch, data, len, bch->ecc_buf);
/* store ecc parity bytes into original parity buffer */
if (ecc)
store_ecc8(bch, ecc, bch->ecc_buf);
}
static inline int modulo(struct bch_control *bch, unsigned int v)
{
const unsigned int n = GF_N(bch);
while (v >= n) {
v -= n;
v = (v & n) + (v >> GF_M(bch));
}
return v;
}
/*
* shorter and faster modulo function, only works when v < 2N.
*/
static inline int mod_s(struct bch_control *bch, unsigned int v)
{
const unsigned int n = GF_N(bch);
return (v < n) ? v : v-n;
}
static inline int deg(unsigned int poly)
{
/* polynomial degree is the most-significant bit index */
return fls(poly)-1;
}
static inline int parity(unsigned int x)
{
/*
* public domain code snippet, lifted from
* http://www-graphics.stanford.edu/~seander/bithacks.html
*/
x ^= x >> 1;
x ^= x >> 2;
x = (x & 0x11111111U) * 0x11111111U;
return (x >> 28) & 1;
}
/* Galois field basic operations: multiply, divide, inverse, etc. */
static inline unsigned int gf_mul(struct bch_control *bch, unsigned int a,
unsigned int b)
{
return (a && b) ? bch->a_pow
