[PATCH 5/9] lib: Import reed solomon code from kernel
Markus Pargmann
mpa at pengutronix.de
Wed Dec 2 05:48:47 PST 2015
reed solomon code is used by RAMOOPS to check and fix data stored in
volatile memory.
Signed-off-by: Markus Pargmann <mpa at pengutronix.de>
---
include/linux/rslib.h | 109 ++++++++++++
lib/Kconfig | 15 ++
lib/Makefile | 1 +
lib/reed_solomon/Makefile | 6 +
lib/reed_solomon/decode_rs.c | 271 +++++++++++++++++++++++++++++
lib/reed_solomon/encode_rs.c | 54 ++++++
lib/reed_solomon/reed_solomon.c | 377 ++++++++++++++++++++++++++++++++++++++++
7 files changed, 833 insertions(+)
create mode 100644 include/linux/rslib.h
create mode 100644 lib/reed_solomon/Makefile
create mode 100644 lib/reed_solomon/decode_rs.c
create mode 100644 lib/reed_solomon/encode_rs.c
create mode 100644 lib/reed_solomon/reed_solomon.c
diff --git a/include/linux/rslib.h b/include/linux/rslib.h
new file mode 100644
index 000000000000..746580c1939c
--- /dev/null
+++ b/include/linux/rslib.h
@@ -0,0 +1,109 @@
+/*
+ * include/linux/rslib.h
+ *
+ * Overview:
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright (C) 2004 Thomas Gleixner (tglx at linutronix.de)
+ *
+ * RS code lifted from reed solomon library written by Phil Karn
+ * Copyright 2002 Phil Karn, KA9Q
+ *
+ * $Id: rslib.h,v 1.4 2005/11/07 11:14:52 gleixner Exp $
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _RSLIB_H_
+#define _RSLIB_H_
+
+#include <linux/list.h>
+
+/**
+ * struct rs_control - rs control structure
+ *
+ * @mm: Bits per symbol
+ * @nn: Symbols per block (= (1<<mm)-1)
+ * @alpha_to: log lookup table
+ * @index_of: Antilog lookup table
+ * @genpoly: Generator polynomial
+ * @nroots: Number of generator roots = number of parity symbols
+ * @fcr: First consecutive root, index form
+ * @prim: Primitive element, index form
+ * @iprim: prim-th root of 1, index form
+ * @gfpoly: The primitive generator polynominal
+ * @gffunc: Function to generate the field, if non-canonical representation
+ * @users: Users of this structure
+ * @list: List entry for the rs control list
+*/
+struct rs_control {
+ int mm;
+ int nn;
+ uint16_t *alpha_to;
+ uint16_t *index_of;
+ uint16_t *genpoly;
+ int nroots;
+ int fcr;
+ int prim;
+ int iprim;
+ int gfpoly;
+ int (*gffunc)(int);
+ int users;
+ struct list_head list;
+};
+
+/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */
+#ifdef CONFIG_REED_SOLOMON_ENC8
+int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
+ uint16_t invmsk);
+#endif
+#ifdef CONFIG_REED_SOLOMON_DEC8
+int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len,
+ uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+ uint16_t *corr);
+#endif
+
+/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */
+#ifdef CONFIG_REED_SOLOMON_ENC16
+int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
+ uint16_t invmsk);
+#endif
+#ifdef CONFIG_REED_SOLOMON_DEC16
+int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
+ uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+ uint16_t *corr);
+#endif
+
+/* Create or get a matching rs control structure */
+struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
+ int nroots);
+struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int),
+ int fcr, int prim, int nroots);
+
+/* Release a rs control structure */
+void free_rs(struct rs_control *rs);
+
+/** modulo replacement for galois field arithmetics
+ *
+ * @rs: the rs control structure
+ * @x: the value to reduce
+ *
+ * where
+ * rs->mm = number of bits per symbol
+ * rs->nn = (2^rs->mm) - 1
+ *
+ * Simple arithmetic modulo would return a wrong result for values
+ * >= 3 * rs->nn
+*/
+static inline int rs_modnn(struct rs_control *rs, int x)
+{
+ while (x >= rs->nn) {
+ x -= rs->nn;
+ x = (x >> rs->mm) + (x & rs->nn);
+ }
+ return x;
+}
+
+#endif
diff --git a/lib/Kconfig b/lib/Kconfig
index fbf9f0f34849..f2f3b5775ace 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -22,6 +22,21 @@ config XZ_DECOMPRESS
bool "include xz uncompression support"
select UNCOMPRESS
+config REED_SOLOMON
+ bool
+
+config REED_SOLOMON_ENC8
+ bool
+
+config REED_SOLOMON_DEC8
+ bool
+
+config REED_SOLOMON_ENC16
+ bool
+
+config REED_SOLOMON_DEC16
+ bool
+
config GENERIC_FIND_NEXT_BIT
def_bool n
diff --git a/lib/Makefile b/lib/Makefile
index abb34cfbdbeb..6ffa3e010434 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -56,3 +56,4 @@ obj-y += gcd.o
obj-y += hexdump.o
obj-$(CONFIG_FONTS) += fonts/
obj-$(CONFIG_BAREBOX_LOGO) += logo/
+obj-y += reed_solomon/
diff --git a/lib/reed_solomon/Makefile b/lib/reed_solomon/Makefile
new file mode 100644
index 000000000000..c3d7136827ed
--- /dev/null
+++ b/lib/reed_solomon/Makefile
@@ -0,0 +1,6 @@
+#
+# This is a modified version of reed solomon lib,
+#
+
+obj-$(CONFIG_REED_SOLOMON) += reed_solomon.o
+
diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
new file mode 100644
index 000000000000..0ec3f257ffdf
--- /dev/null
+++ b/lib/reed_solomon/decode_rs.c
@@ -0,0 +1,271 @@
+/*
+ * lib/reed_solomon/decode_rs.c
+ *
+ * Overview:
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright 2002, Phil Karn, KA9Q
+ * May be used under the terms of the GNU General Public License (GPL)
+ *
+ * Adaption to the kernel by Thomas Gleixner (tglx at linutronix.de)
+ *
+ * $Id: decode_rs.c,v 1.7 2005/11/07 11:14:59 gleixner Exp $
+ *
+ */
+
+/* Generic data width independent code which is included by the
+ * wrappers.
+ */
+{
+ int deg_lambda, el, deg_omega;
+ int i, j, r, k, pad;
+ int nn = rs->nn;
+ int nroots = rs->nroots;
+ int fcr = rs->fcr;
+ int prim = rs->prim;
+ int iprim = rs->iprim;
+ uint16_t *alpha_to = rs->alpha_to;
+ uint16_t *index_of = rs->index_of;
+ uint16_t u, q, tmp, num1, num2, den, discr_r, syn_error;
+ /* Err+Eras Locator poly and syndrome poly The maximum value
+ * of nroots is 8. So the necessary stack size will be about
+ * 220 bytes max.
+ */
+ uint16_t lambda[nroots + 1], syn[nroots];
+ uint16_t b[nroots + 1], t[nroots + 1], omega[nroots + 1];
+ uint16_t root[nroots], reg[nroots + 1], loc[nroots];
+ int count = 0;
+ uint16_t msk = (uint16_t) rs->nn;
+
+ /* Check length parameter for validity */
+ pad = nn - nroots - len;
+ BUG_ON(pad < 0 || pad >= nn);
+
+ /* Does the caller provide the syndrome ? */
+ if (s != NULL)
+ goto decode;
+
+ /* form the syndromes; i.e., evaluate data(x) at roots of
+ * g(x) */
+ for (i = 0; i < nroots; i++)
+ syn[i] = (((uint16_t) data[0]) ^ invmsk) & msk;
+
+ for (j = 1; j < len; j++) {
+ for (i = 0; i < nroots; i++) {
+ if (syn[i] == 0) {
+ syn[i] = (((uint16_t) data[j]) ^
+ invmsk) & msk;
+ } else {
+ syn[i] = ((((uint16_t) data[j]) ^
+ invmsk) & msk) ^
+ alpha_to[rs_modnn(rs, index_of[syn[i]] +
+ (fcr + i) * prim)];
+ }
+ }
+ }
+
+ for (j = 0; j < nroots; j++) {
+ for (i = 0; i < nroots; i++) {
+ if (syn[i] == 0) {
+ syn[i] = ((uint16_t) par[j]) & msk;
+ } else {
+ syn[i] = (((uint16_t) par[j]) & msk) ^
+ alpha_to[rs_modnn(rs, index_of[syn[i]] +
+ (fcr+i)*prim)];
+ }
+ }
+ }
+ s = syn;
+
+ /* Convert syndromes to index form, checking for nonzero condition */
+ syn_error = 0;
+ for (i = 0; i < nroots; i++) {
+ syn_error |= s[i];
+ s[i] = index_of[s[i]];
+ }
+
+ if (!syn_error) {
+ /* if syndrome is zero, data[] is a codeword and there are no
+ * errors to correct. So return data[] unmodified
+ */
+ count = 0;
+ goto finish;
+ }
+
+ decode:
+ memset(&lambda[1], 0, nroots * sizeof(lambda[0]));
+ lambda[0] = 1;
+
+ if (no_eras > 0) {
+ /* Init lambda to be the erasure locator polynomial */
+ lambda[1] = alpha_to[rs_modnn(rs,
+ prim * (nn - 1 - eras_pos[0]))];
+ for (i = 1; i < no_eras; i++) {
+ u = rs_modnn(rs, prim * (nn - 1 - eras_pos[i]));
+ for (j = i + 1; j > 0; j--) {
+ tmp = index_of[lambda[j - 1]];
+ if (tmp != nn) {
+ lambda[j] ^=
+ alpha_to[rs_modnn(rs, u + tmp)];
+ }
+ }
+ }
+ }
+
+ for (i = 0; i < nroots + 1; i++)
+ b[i] = index_of[lambda[i]];
+
+ /*
+ * Begin Berlekamp-Massey algorithm to determine error+erasure
+ * locator polynomial
+ */
+ r = no_eras;
+ el = no_eras;
+ while (++r <= nroots) { /* r is the step number */
+ /* Compute discrepancy at the r-th step in poly-form */
+ discr_r = 0;
+ for (i = 0; i < r; i++) {
+ if ((lambda[i] != 0) && (s[r - i - 1] != nn)) {
+ discr_r ^=
+ alpha_to[rs_modnn(rs,
+ index_of[lambda[i]] +
+ s[r - i - 1])];
+ }
+ }
+ discr_r = index_of[discr_r]; /* Index form */
+ if (discr_r == nn) {
+ /* 2 lines below: B(x) <-- x*B(x) */
+ memmove (&b[1], b, nroots * sizeof (b[0]));
+ b[0] = nn;
+ } else {
+ /* 7 lines below: T(x) <-- lambda(x)-discr_r*x*b(x) */
+ t[0] = lambda[0];
+ for (i = 0; i < nroots; i++) {
+ if (b[i] != nn) {
+ t[i + 1] = lambda[i + 1] ^
+ alpha_to[rs_modnn(rs, discr_r +
+ b[i])];
+ } else
+ t[i + 1] = lambda[i + 1];
+ }
+ if (2 * el <= r + no_eras - 1) {
+ el = r + no_eras - el;
+ /*
+ * 2 lines below: B(x) <-- inv(discr_r) *
+ * lambda(x)
+ */
+ for (i = 0; i <= nroots; i++) {
+ b[i] = (lambda[i] == 0) ? nn :
+ rs_modnn(rs, index_of[lambda[i]]
+ - discr_r + nn);
+ }
+ } else {
+ /* 2 lines below: B(x) <-- x*B(x) */
+ memmove(&b[1], b, nroots * sizeof(b[0]));
+ b[0] = nn;
+ }
+ memcpy(lambda, t, (nroots + 1) * sizeof(t[0]));
+ }
+ }
+
+ /* Convert lambda to index form and compute deg(lambda(x)) */
+ deg_lambda = 0;
+ for (i = 0; i < nroots + 1; i++) {
+ lambda[i] = index_of[lambda[i]];
+ if (lambda[i] != nn)
+ deg_lambda = i;
+ }
+ /* Find roots of error+erasure locator polynomial by Chien search */
+ memcpy(®[1], &lambda[1], nroots * sizeof(reg[0]));
+ count = 0; /* Number of roots of lambda(x) */
+ for (i = 1, k = iprim - 1; i <= nn; i++, k = rs_modnn(rs, k + iprim)) {
+ q = 1; /* lambda[0] is always 0 */
+ for (j = deg_lambda; j > 0; j--) {
+ if (reg[j] != nn) {
+ reg[j] = rs_modnn(rs, reg[j] + j);
+ q ^= alpha_to[reg[j]];
+ }
+ }
+ if (q != 0)
+ continue; /* Not a root */
+ /* store root (index-form) and error location number */
+ root[count] = i;
+ loc[count] = k;
+ /* If we've already found max possible roots,
+ * abort the search to save time
+ */
+ if (++count == deg_lambda)
+ break;
+ }
+ if (deg_lambda != count) {
+ /*
+ * deg(lambda) unequal to number of roots => uncorrectable
+ * error detected
+ */
+ count = -EBADMSG;
+ goto finish;
+ }
+ /*
+ * Compute err+eras evaluator poly omega(x) = s(x)*lambda(x) (modulo
+ * x**nroots). in index form. Also find deg(omega).
+ */
+ deg_omega = deg_lambda - 1;
+ for (i = 0; i <= deg_omega; i++) {
+ tmp = 0;
+ for (j = i; j >= 0; j--) {
+ if ((s[i - j] != nn) && (lambda[j] != nn))
+ tmp ^=
+ alpha_to[rs_modnn(rs, s[i - j] + lambda[j])];
+ }
+ omega[i] = index_of[tmp];
+ }
+
+ /*
+ * Compute error values in poly-form. num1 = omega(inv(X(l))), num2 =
+ * inv(X(l))**(fcr-1) and den = lambda_pr(inv(X(l))) all in poly-form
+ */
+ for (j = count - 1; j >= 0; j--) {
+ num1 = 0;
+ for (i = deg_omega; i >= 0; i--) {
+ if (omega[i] != nn)
+ num1 ^= alpha_to[rs_modnn(rs, omega[i] +
+ i * root[j])];
+ }
+ num2 = alpha_to[rs_modnn(rs, root[j] * (fcr - 1) + nn)];
+ den = 0;
+
+ /* lambda[i+1] for i even is the formal derivative
+ * lambda_pr of lambda[i] */
+ for (i = min(deg_lambda, nroots - 1) & ~1; i >= 0; i -= 2) {
+ if (lambda[i + 1] != nn) {
+ den ^= alpha_to[rs_modnn(rs, lambda[i + 1] +
+ i * root[j])];
+ }
+ }
+ /* Apply error to data */
+ if (num1 != 0 && loc[j] >= pad) {
+ uint16_t cor = alpha_to[rs_modnn(rs,index_of[num1] +
+ index_of[num2] +
+ nn - index_of[den])];
+ /* Store the error correction pattern, if a
+ * correction buffer is available */
+ if (corr) {
+ corr[j] = cor;
+ } else {
+ /* If a data buffer is given and the
+ * error is inside the message,
+ * correct it */
+ if (data && (loc[j] < (nn - nroots)))
+ data[loc[j] - pad] ^= cor;
+ }
+ }
+ }
+
+finish:
+ if (eras_pos != NULL) {
+ for (i = 0; i < count; i++)
+ eras_pos[i] = loc[i] - pad;
+ }
+ return count;
+
+}
diff --git a/lib/reed_solomon/encode_rs.c b/lib/reed_solomon/encode_rs.c
new file mode 100644
index 000000000000..0b5b1a6728ec
--- /dev/null
+++ b/lib/reed_solomon/encode_rs.c
@@ -0,0 +1,54 @@
+/*
+ * lib/reed_solomon/encode_rs.c
+ *
+ * Overview:
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright 2002, Phil Karn, KA9Q
+ * May be used under the terms of the GNU General Public License (GPL)
+ *
+ * Adaption to the kernel by Thomas Gleixner (tglx at linutronix.de)
+ *
+ * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $
+ *
+ */
+
+/* Generic data width independent code which is included by the
+ * wrappers.
+ * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par)
+ */
+{
+ int i, j, pad;
+ int nn = rs->nn;
+ int nroots = rs->nroots;
+ uint16_t *alpha_to = rs->alpha_to;
+ uint16_t *index_of = rs->index_of;
+ uint16_t *genpoly = rs->genpoly;
+ uint16_t fb;
+ uint16_t msk = (uint16_t) rs->nn;
+
+ /* Check length parameter for validity */
+ pad = nn - nroots - len;
+ if (pad < 0 || pad >= nn)
+ return -ERANGE;
+
+ for (i = 0; i < len; i++) {
+ fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]];
+ /* feedback term is non-zero */
+ if (fb != nn) {
+ for (j = 1; j < nroots; j++) {
+ par[j] ^= alpha_to[rs_modnn(rs, fb +
+ genpoly[nroots - j])];
+ }
+ }
+ /* Shift */
+ memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1));
+ if (fb != nn) {
+ par[nroots - 1] = alpha_to[rs_modnn(rs,
+ fb + genpoly[0])];
+ } else {
+ par[nroots - 1] = 0;
+ }
+ }
+ return 0;
+}
diff --git a/lib/reed_solomon/reed_solomon.c b/lib/reed_solomon/reed_solomon.c
new file mode 100644
index 000000000000..f9ea907bfef9
--- /dev/null
+++ b/lib/reed_solomon/reed_solomon.c
@@ -0,0 +1,377 @@
+/*
+ * lib/reed_solomon/reed_solomon.c
+ *
+ * Overview:
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright (C) 2004 Thomas Gleixner (tglx at linutronix.de)
+ *
+ * Reed Solomon code lifted from reed solomon library written by Phil Karn
+ * Copyright 2002 Phil Karn, KA9Q
+ *
+ * $Id: rslib.c,v 1.7 2005/11/07 11:14:59 gleixner Exp $
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Description:
+ *
+ * The generic Reed Solomon library provides runtime configurable
+ * encoding / decoding of RS codes.
+ * Each user must call init_rs to get a pointer to a rs_control
+ * structure for the given rs parameters. This structure is either
+ * generated or a already available matching control structure is used.
+ * If a structure is generated then the polynomial arrays for
+ * fast encoding / decoding are built. This can take some time so
+ * make sure not to call this function from a time critical path.
+ * Usually a module / driver should initialize the necessary
+ * rs_control structure on module / driver init and release it
+ * on exit.
+ * The encoding puts the calculated syndrome into a given syndrome
+ * buffer.
+ * The decoding is a two step process. The first step calculates
+ * the syndrome over the received (data + syndrome) and calls the
+ * second stage, which does the decoding / error correction itself.
+ * Many hw encoders provide a syndrome calculation over the received
+ * data + syndrome and can call the second stage directly.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/rslib.h>
+#include <malloc.h>
+#include <module.h>
+#include <linux/string.h>
+#include <stdio.h>
+#include <asm-generic/errno.h>
+
+/* This list holds all currently allocated rs control structures */
+static LIST_HEAD (rslist);
+
+/**
+ * rs_init - Initialize a Reed-Solomon codec
+ * @symsize: symbol size, bits (1-8)
+ * @gfpoly: Field generator polynomial coefficients
+ * @gffunc: Field generator function
+ * @fcr: first root of RS code generator polynomial, index form
+ * @prim: primitive element to generate polynomial roots
+ * @nroots: RS code generator polynomial degree (number of roots)
+ *
+ * Allocate a control structure and the polynom arrays for faster
+ * en/decoding. Fill the arrays according to the given parameters.
+ */
+static struct rs_control *rs_init(int symsize, int gfpoly, int (*gffunc)(int),
+ int fcr, int prim, int nroots)
+{
+ struct rs_control *rs;
+ int i, j, sr, root, iprim;
+
+ /* Allocate the control structure */
+ rs = kmalloc(sizeof (struct rs_control), GFP_KERNEL);
+ if (rs == NULL)
+ return NULL;
+
+ INIT_LIST_HEAD(&rs->list);
+
+ rs->mm = symsize;
+ rs->nn = (1 << symsize) - 1;
+ rs->fcr = fcr;
+ rs->prim = prim;
+ rs->nroots = nroots;
+ rs->gfpoly = gfpoly;
+ rs->gffunc = gffunc;
+
+ /* Allocate the arrays */
+ rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
+ if (rs->alpha_to == NULL)
+ goto errrs;
+
+ rs->index_of = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
+ if (rs->index_of == NULL)
+ goto erralp;
+
+ rs->genpoly = kmalloc(sizeof(uint16_t) * (rs->nroots + 1), GFP_KERNEL);
+ if(rs->genpoly == NULL)
+ goto erridx;
+
+ /* Generate Galois field lookup tables */
+ rs->index_of[0] = rs->nn; /* log(zero) = -inf */
+ rs->alpha_to[rs->nn] = 0; /* alpha**-inf = 0 */
+ if (gfpoly) {
+ sr = 1;
+ for (i = 0; i < rs->nn; i++) {
+ rs->index_of[sr] = i;
+ rs->alpha_to[i] = sr;
+ sr <<= 1;
+ if (sr & (1 << symsize))
+ sr ^= gfpoly;
+ sr &= rs->nn;
+ }
+ } else {
+ sr = gffunc(0);
+ for (i = 0; i < rs->nn; i++) {
+ rs->index_of[sr] = i;
+ rs->alpha_to[i] = sr;
+ sr = gffunc(sr);
+ }
+ }
+ /* If it's not primitive, exit */
+ if(sr != rs->alpha_to[0])
+ goto errpol;
+
+ /* Find prim-th root of 1, used in decoding */
+ for(iprim = 1; (iprim % prim) != 0; iprim += rs->nn);
+ /* prim-th root of 1, index form */
+ rs->iprim = iprim / prim;
+
+ /* Form RS code generator polynomial from its roots */
+ rs->genpoly[0] = 1;
+ for (i = 0, root = fcr * prim; i < nroots; i++, root += prim) {
+ rs->genpoly[i + 1] = 1;
+ /* Multiply rs->genpoly[] by @**(root + x) */
+ for (j = i; j > 0; j--) {
+ if (rs->genpoly[j] != 0) {
+ rs->genpoly[j] = rs->genpoly[j -1] ^
+ rs->alpha_to[rs_modnn(rs,
+ rs->index_of[rs->genpoly[j]] + root)];
+ } else
+ rs->genpoly[j] = rs->genpoly[j - 1];
+ }
+ /* rs->genpoly[0] can never be zero */
+ rs->genpoly[0] =
+ rs->alpha_to[rs_modnn(rs,
+ rs->index_of[rs->genpoly[0]] + root)];
+ }
+ /* convert rs->genpoly[] to index form for quicker encoding */
+ for (i = 0; i <= nroots; i++)
+ rs->genpoly[i] = rs->index_of[rs->genpoly[i]];
+ return rs;
+
+ /* Error exit */
+errpol:
+ kfree(rs->genpoly);
+erridx:
+ kfree(rs->index_of);
+erralp:
+ kfree(rs->alpha_to);
+errrs:
+ kfree(rs);
+ return NULL;
+}
+
+
+/**
+ * free_rs - Free the rs control structure, if it is no longer used
+ * @rs: the control structure which is not longer used by the
+ * caller
+ */
+void free_rs(struct rs_control *rs)
+{
+ rs->users--;
+ if(!rs->users) {
+ list_del(&rs->list);
+ kfree(rs->alpha_to);
+ kfree(rs->index_of);
+ kfree(rs->genpoly);
+ kfree(rs);
+ }
+}
+
+/**
+ * init_rs_internal - Find a matching or allocate a new rs control structure
+ * @symsize: the symbol size (number of bits)
+ * @gfpoly: the extended Galois field generator polynomial coefficients,
+ * with the 0th coefficient in the low order bit. The polynomial
+ * must be primitive;
+ * @gffunc: pointer to function to generate the next field element,
+ * or the multiplicative identity element if given 0. Used
+ * instead of gfpoly if gfpoly is 0
+ * @fcr: the first consecutive root of the rs code generator polynomial
+ * in index form
+ * @prim: primitive element to generate polynomial roots
+ * @nroots: RS code generator polynomial degree (number of roots)
+ */
+static struct rs_control *init_rs_internal(int symsize, int gfpoly,
+ int (*gffunc)(int), int fcr,
+ int prim, int nroots)
+{
+ struct list_head *tmp;
+ struct rs_control *rs;
+
+ /* Sanity checks */
+ if (symsize < 1)
+ return NULL;
+ if (fcr < 0 || fcr >= (1<<symsize))
+ return NULL;
+ if (prim <= 0 || prim >= (1<<symsize))
+ return NULL;
+ if (nroots < 0 || nroots >= (1<<symsize))
+ return NULL;
+
+ /* Walk through the list and look for a matching entry */
+ list_for_each(tmp, &rslist) {
+ rs = list_entry(tmp, struct rs_control, list);
+ if (symsize != rs->mm)
+ continue;
+ if (gfpoly != rs->gfpoly)
+ continue;
+ if (gffunc != rs->gffunc)
+ continue;
+ if (fcr != rs->fcr)
+ continue;
+ if (prim != rs->prim)
+ continue;
+ if (nroots != rs->nroots)
+ continue;
+ /* We have a matching one already */
+ rs->users++;
+ goto out;
+ }
+
+ /* Create a new one */
+ rs = rs_init(symsize, gfpoly, gffunc, fcr, prim, nroots);
+ if (rs) {
+ rs->users = 1;
+ list_add(&rs->list, &rslist);
+ }
+out:
+ return rs;
+}
+
+/**
+ * init_rs - Find a matching or allocate a new rs control structure
+ * @symsize: the symbol size (number of bits)
+ * @gfpoly: the extended Galois field generator polynomial coefficients,
+ * with the 0th coefficient in the low order bit. The polynomial
+ * must be primitive;
+ * @fcr: the first consecutive root of the rs code generator polynomial
+ * in index form
+ * @prim: primitive element to generate polynomial roots
+ * @nroots: RS code generator polynomial degree (number of roots)
+ */
+struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
+ int nroots)
+{
+ return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots);
+}
+
+/**
+ * init_rs_non_canonical - Find a matching or allocate a new rs control
+ * structure, for fields with non-canonical
+ * representation
+ * @symsize: the symbol size (number of bits)
+ * @gffunc: pointer to function to generate the next field element,
+ * or the multiplicative identity element if given 0. Used
+ * instead of gfpoly if gfpoly is 0
+ * @fcr: the first consecutive root of the rs code generator polynomial
+ * in index form
+ * @prim: primitive element to generate polynomial roots
+ * @nroots: RS code generator polynomial degree (number of roots)
+ */
+struct rs_control *init_rs_non_canonical(int symsize, int (*gffunc)(int),
+ int fcr, int prim, int nroots)
+{
+ return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots);
+}
+
+#ifdef CONFIG_REED_SOLOMON_ENC8
+/**
+ * encode_rs8 - Calculate the parity for data values (8bit data width)
+ * @rs: the rs control structure
+ * @data: data field of a given type
+ * @len: data length
+ * @par: parity data, must be initialized by caller (usually all 0)
+ * @invmsk: invert data mask (will be xored on data)
+ *
+ * The parity uses a uint16_t data type to enable
+ * symbol size > 8. The calling code must take care of encoding of the
+ * syndrome result for storage itself.
+ */
+int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
+ uint16_t invmsk)
+{
+#include "encode_rs.c"
+}
+EXPORT_SYMBOL_GPL(encode_rs8);
+#endif
+
+#ifdef CONFIG_REED_SOLOMON_DEC8
+/**
+ * decode_rs8 - Decode codeword (8bit data width)
+ * @rs: the rs control structure
+ * @data: data field of a given type
+ * @par: received parity data field
+ * @len: data length
+ * @s: syndrome data field (if NULL, syndrome is calculated)
+ * @no_eras: number of erasures
+ * @eras_pos: position of erasures, can be NULL
+ * @invmsk: invert data mask (will be xored on data, not on parity!)
+ * @corr: buffer to store correction bitmask on eras_pos
+ *
+ * The syndrome and parity uses a uint16_t data type to enable
+ * symbol size > 8. The calling code must take care of decoding of the
+ * syndrome result and the received parity before calling this code.
+ * Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
+ */
+int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len,
+ uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+ uint16_t *corr)
+{
+#include "decode_rs.c"
+}
+EXPORT_SYMBOL_GPL(decode_rs8);
+#endif
+
+#ifdef CONFIG_REED_SOLOMON_ENC16
+/**
+ * encode_rs16 - Calculate the parity for data values (16bit data width)
+ * @rs: the rs control structure
+ * @data: data field of a given type
+ * @len: data length
+ * @par: parity data, must be initialized by caller (usually all 0)
+ * @invmsk: invert data mask (will be xored on data, not on parity!)
+ *
+ * Each field in the data array contains up to symbol size bits of valid data.
+ */
+int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
+ uint16_t invmsk)
+{
+#include "encode_rs.c"
+}
+EXPORT_SYMBOL_GPL(encode_rs16);
+#endif
+
+#ifdef CONFIG_REED_SOLOMON_DEC16
+/**
+ * decode_rs16 - Decode codeword (16bit data width)
+ * @rs: the rs control structure
+ * @data: data field of a given type
+ * @par: received parity data field
+ * @len: data length
+ * @s: syndrome data field (if NULL, syndrome is calculated)
+ * @no_eras: number of erasures
+ * @eras_pos: position of erasures, can be NULL
+ * @invmsk: invert data mask (will be xored on data, not on parity!)
+ * @corr: buffer to store correction bitmask on eras_pos
+ *
+ * Each field in the data array contains up to symbol size bits of valid data.
+ * Returns the number of corrected bits or -EBADMSG for uncorrectable errors.
+ */
+int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len,
+ uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk,
+ uint16_t *corr)
+{
+#include "decode_rs.c"
+}
+EXPORT_SYMBOL_GPL(decode_rs16);
+#endif
+
+EXPORT_SYMBOL_GPL(init_rs);
+EXPORT_SYMBOL_GPL(init_rs_non_canonical);
+EXPORT_SYMBOL_GPL(free_rs);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
+MODULE_AUTHOR("Phil Karn, Thomas Gleixner");
+
--
2.6.2
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