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-rw-r--r--lib/reed_solomon/Makefile7
-rw-r--r--lib/reed_solomon/decode_rs.c326
-rw-r--r--lib/reed_solomon/encode_rs.c47
-rw-r--r--lib/reed_solomon/reed_solomon.c424
-rw-r--r--lib/reed_solomon/test_rslib.c518
5 files changed, 1322 insertions, 0 deletions
diff --git a/lib/reed_solomon/Makefile b/lib/reed_solomon/Makefile
new file mode 100644
index 000000000..5d4fa68f2
--- /dev/null
+++ b/lib/reed_solomon/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# This is a modified version of reed solomon lib,
+#
+
+obj-$(CONFIG_REED_SOLOMON) += reed_solomon.o
+obj-$(CONFIG_REED_SOLOMON_TEST) += test_rslib.o
diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c
new file mode 100644
index 000000000..805de84ae
--- /dev/null
+++ b/lib/reed_solomon/decode_rs.c
@@ -0,0 +1,326 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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@linutronix.de)
+ *
+ * Generic data width independent code which is included by the wrappers.
+ */
+{
+ struct rs_codec *rs = rsc->codec;
+ 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;
+ int count = 0;
+ int num_corrected;
+ uint16_t msk = (uint16_t) rs->nn;
+
+ /*
+ * The decoder buffers are in the rs control struct. They are
+ * arrays sized [nroots + 1]
+ */
+ uint16_t *lambda = rsc->buffers + RS_DECODE_LAMBDA * (nroots + 1);
+ uint16_t *syn = rsc->buffers + RS_DECODE_SYN * (nroots + 1);
+ uint16_t *b = rsc->buffers + RS_DECODE_B * (nroots + 1);
+ uint16_t *t = rsc->buffers + RS_DECODE_T * (nroots + 1);
+ uint16_t *omega = rsc->buffers + RS_DECODE_OMEGA * (nroots + 1);
+ uint16_t *root = rsc->buffers + RS_DECODE_ROOT * (nroots + 1);
+ uint16_t *reg = rsc->buffers + RS_DECODE_REG * (nroots + 1);
+ uint16_t *loc = rsc->buffers + RS_DECODE_LOC * (nroots + 1);
+
+ /* Check length parameter for validity */
+ pad = nn - nroots - len;
+ BUG_ON(pad < 0 || pad >= nn - nroots);
+
+ /* Does the caller provide the syndrome ? */
+ if (s != NULL) {
+ for (i = 0; i < nroots; i++) {
+ /* The syndrome is in index form,
+ * so nn represents zero
+ */
+ if (s[i] != nn)
+ goto decode;
+ }
+
+ /* syndrome is zero, no errors to correct */
+ return 0;
+ }
+
+ /* 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
+ */
+ return 0;
+ }
+
+ 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] + pad)))];
+ for (i = 1; i < no_eras; i++) {
+ u = rs_modnn(rs, prim * (nn - 1 - (eras_pos[i] + pad)));
+ 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;
+ }
+
+ if (deg_lambda == 0) {
+ /*
+ * deg(lambda) is zero even though the syndrome is non-zero
+ * => uncorrectable error detected
+ */
+ return -EBADMSG;
+ }
+
+ /* Find roots of error+erasure locator polynomial by Chien search */
+ memcpy(&reg[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 */
+
+ if (k < pad) {
+ /* Impossible error location. Uncorrectable error. */
+ return -EBADMSG;
+ }
+
+ /* 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
+ */
+ return -EBADMSG;
+ }
+ /*
+ * 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
+ * Note: we reuse the buffer for b to store the correction pattern
+ */
+ num_corrected = 0;
+ 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])];
+ }
+
+ if (num1 == 0) {
+ /* Nothing to correct at this position */
+ b[j] = 0;
+ continue;
+ }
+
+ 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])];
+ }
+ }
+
+ b[j] = alpha_to[rs_modnn(rs, index_of[num1] +
+ index_of[num2] +
+ nn - index_of[den])];
+ num_corrected++;
+ }
+
+ /*
+ * We compute the syndrome of the 'error' and check that it matches
+ * the syndrome of the received word
+ */
+ for (i = 0; i < nroots; i++) {
+ tmp = 0;
+ for (j = 0; j < count; j++) {
+ if (b[j] == 0)
+ continue;
+
+ k = (fcr + i) * prim * (nn-loc[j]-1);
+ tmp ^= alpha_to[rs_modnn(rs, index_of[b[j]] + k)];
+ }
+
+ if (tmp != alpha_to[s[i]])
+ return -EBADMSG;
+ }
+
+ /*
+ * Store the error correction pattern, if a
+ * correction buffer is available
+ */
+ if (corr && eras_pos) {
+ j = 0;
+ for (i = 0; i < count; i++) {
+ if (b[i]) {
+ corr[j] = b[i];
+ eras_pos[j++] = loc[i] - pad;
+ }
+ }
+ } else if (data && par) {
+ /* Apply error to data and parity */
+ for (i = 0; i < count; i++) {
+ if (loc[i] < (nn - nroots))
+ data[loc[i] - pad] ^= b[i];
+ else
+ par[loc[i] - pad - len] ^= b[i];
+ }
+ }
+
+ return num_corrected;
+}
diff --git a/lib/reed_solomon/encode_rs.c b/lib/reed_solomon/encode_rs.c
new file mode 100644
index 000000000..9112d46e8
--- /dev/null
+++ b/lib/reed_solomon/encode_rs.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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@linutronix.de)
+ *
+ * Generic data width independent code which is included by the wrappers.
+ */
+{
+ struct rs_codec *rs = rsc->codec;
+ 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 000000000..bbc01bad3
--- /dev/null
+++ b/lib/reed_solomon/reed_solomon.c
@@ -0,0 +1,424 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic Reed Solomon encoder / decoder library
+ *
+ * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
+ *
+ * Reed Solomon code lifted from reed solomon library written by Phil Karn
+ * Copyright 2002 Phil Karn, KA9Q
+ *
+ * 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. The control struct is unique per instance.
+ * It points to a codec which can be shared by multiple control structures.
+ * If a codec is newly allocated 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/errno.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/rslib.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+
+enum {
+ RS_DECODE_LAMBDA,
+ RS_DECODE_SYN,
+ RS_DECODE_B,
+ RS_DECODE_T,
+ RS_DECODE_OMEGA,
+ RS_DECODE_ROOT,
+ RS_DECODE_REG,
+ RS_DECODE_LOC,
+ RS_DECODE_NUM_BUFFERS
+};
+
+/* This list holds all currently allocated rs codec structures */
+static LIST_HEAD(codec_list);
+/* Protection for the list */
+static DEFINE_MUTEX(rslistlock);
+
+/**
+ * codec_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)
+ * @gfp: GFP_ flags for allocations
+ *
+ * Allocate a codec structure and the polynom arrays for faster
+ * en/decoding. Fill the arrays according to the given parameters.
+ */
+static struct rs_codec *codec_init(int symsize, int gfpoly, int (*gffunc)(int),
+ int fcr, int prim, int nroots, gfp_t gfp)
+{
+ int i, j, sr, root, iprim;
+ struct rs_codec *rs;
+
+ rs = kzalloc(sizeof(*rs), gfp);
+ if (!rs)
+ 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_array(rs->nn + 1, sizeof(uint16_t), gfp);
+ if (rs->alpha_to == NULL)
+ goto err;
+
+ rs->index_of = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
+ if (rs->index_of == NULL)
+ goto err;
+
+ rs->genpoly = kmalloc_array(rs->nroots + 1, sizeof(uint16_t), gfp);
+ if(rs->genpoly == NULL)
+ goto err;
+
+ /* 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 err;
+
+ /* 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]];
+
+ rs->users = 1;
+ list_add(&rs->list, &codec_list);
+ return rs;
+
+err:
+ kfree(rs->genpoly);
+ kfree(rs->index_of);
+ kfree(rs->alpha_to);
+ kfree(rs);
+ return NULL;
+}
+
+
+/**
+ * free_rs - Free the rs control structure
+ * @rs: The control structure which is not longer used by the
+ * caller
+ *
+ * Free the control structure. If @rs is the last user of the associated
+ * codec, free the codec as well.
+ */
+void free_rs(struct rs_control *rs)
+{
+ struct rs_codec *cd;
+
+ if (!rs)
+ return;
+
+ cd = rs->codec;
+ mutex_lock(&rslistlock);
+ cd->users--;
+ if(!cd->users) {
+ list_del(&cd->list);
+ kfree(cd->alpha_to);
+ kfree(cd->index_of);
+ kfree(cd->genpoly);
+ kfree(cd);
+ }
+ mutex_unlock(&rslistlock);
+ kfree(rs);
+}
+EXPORT_SYMBOL_GPL(free_rs);
+
+/**
+ * init_rs_internal - Allocate rs control, find a matching codec or allocate a new one
+ * @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)
+ * @gfp: GFP_ flags for allocations
+ */
+static struct rs_control *init_rs_internal(int symsize, int gfpoly,
+ int (*gffunc)(int), int fcr,
+ int prim, int nroots, gfp_t gfp)
+{
+ struct list_head *tmp;
+ struct rs_control *rs;
+ unsigned int bsize;
+
+ /* 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;
+
+ /*
+ * The decoder needs buffers in each control struct instance to
+ * avoid variable size or large fixed size allocations on
+ * stack. Size the buffers to arrays of [nroots + 1].
+ */
+ bsize = sizeof(uint16_t) * RS_DECODE_NUM_BUFFERS * (nroots + 1);
+ rs = kzalloc(sizeof(*rs) + bsize, gfp);
+ if (!rs)
+ return NULL;
+
+ mutex_lock(&rslistlock);
+
+ /* Walk through the list and look for a matching entry */
+ list_for_each(tmp, &codec_list) {
+ struct rs_codec *cd = list_entry(tmp, struct rs_codec, list);
+
+ if (symsize != cd->mm)
+ continue;
+ if (gfpoly != cd->gfpoly)
+ continue;
+ if (gffunc != cd->gffunc)
+ continue;
+ if (fcr != cd->fcr)
+ continue;
+ if (prim != cd->prim)
+ continue;
+ if (nroots != cd->nroots)
+ continue;
+ /* We have a matching one already */
+ cd->users++;
+ rs->codec = cd;
+ goto out;
+ }
+
+ /* Create a new one */
+ rs->codec = codec_init(symsize, gfpoly, gffunc, fcr, prim, nroots, gfp);
+ if (!rs->codec) {
+ kfree(rs);
+ rs = NULL;
+ }
+out:
+ mutex_unlock(&rslistlock);
+ return rs;
+}
+
+/**
+ * init_rs_gfp - Create a RS control struct and initialize it
+ * @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)
+ * @gfp: Memory allocation flags.
+ */
+struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
+ int nroots, gfp_t gfp)
+{
+ return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots, gfp);
+}
+EXPORT_SYMBOL_GPL(init_rs_gfp);
+
+/**
+ * init_rs_non_canonical - Allocate rs control struct 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,
+ GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(init_rs_non_canonical);
+
+#ifdef CONFIG_REED_SOLOMON_ENC8
+/**
+ * encode_rs8 - Calculate the parity for data values (8bit data width)
+ * @rsc: 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 *rsc, 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)
+ * @rsc: the rs control structure
+ * @data: data field of a given type
+ * @par: received parity data field
+ * @len: data length
+ * @s: syndrome data field, must be in index form
+ * (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.
+ *
+ * Note: The rs_control struct @rsc contains buffers which are used for
+ * decoding, so the caller has to ensure that decoder invocations are
+ * serialized.
+ *
+ * Returns the number of corrected symbols or -EBADMSG for uncorrectable
+ * errors. The count includes errors in the parity.
+ */
+int decode_rs8(struct rs_control *rsc, 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)
+ * @rsc: 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 *rsc, 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)
+ * @rsc: the rs control structure
+ * @data: data field of a given type
+ * @par: received parity data field
+ * @len: data length
+ * @s: syndrome data field, must be in index form
+ * (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.
+ *
+ * Note: The rc_control struct @rsc contains buffers which are used for
+ * decoding, so the caller has to ensure that decoder invocations are
+ * serialized.
+ *
+ * Returns the number of corrected symbols or -EBADMSG for uncorrectable
+ * errors. The count includes errors in the parity.
+ */
+int decode_rs16(struct rs_control *rsc, 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
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
+MODULE_AUTHOR("Phil Karn, Thomas Gleixner");
+
diff --git a/lib/reed_solomon/test_rslib.c b/lib/reed_solomon/test_rslib.c
new file mode 100644
index 000000000..4eb29f365
--- /dev/null
+++ b/lib/reed_solomon/test_rslib.c
@@ -0,0 +1,518 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests for Generic Reed Solomon encoder / decoder library
+ *
+ * Written by Ferdinand Blomqvist
+ * Based on previous work by Phil Karn, KA9Q
+ */
+#include <linux/rslib.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+
+enum verbosity {
+ V_SILENT,
+ V_PROGRESS,
+ V_CSUMMARY
+};
+
+enum method {
+ CORR_BUFFER,
+ CALLER_SYNDROME,
+ IN_PLACE
+};
+
+#define __param(type, name, init, msg) \
+ static type name = init; \
+ module_param(name, type, 0444); \
+ MODULE_PARM_DESC(name, msg)
+
+__param(int, v, V_PROGRESS, "Verbosity level");
+__param(int, ewsc, 1, "Erasures without symbol corruption");
+__param(int, bc, 1, "Test for correct behaviour beyond error correction capacity");
+
+struct etab {
+ int symsize;
+ int genpoly;
+ int fcs;
+ int prim;
+ int nroots;
+ int ntrials;
+};
+
+/* List of codes to test */
+static struct etab Tab[] = {
+ {2, 0x7, 1, 1, 1, 100000 },
+ {3, 0xb, 1, 1, 2, 100000 },
+ {3, 0xb, 1, 1, 3, 100000 },
+ {3, 0xb, 2, 1, 4, 100000 },
+ {4, 0x13, 1, 1, 4, 10000 },
+ {5, 0x25, 1, 1, 6, 1000 },
+ {6, 0x43, 3, 1, 8, 1000 },
+ {7, 0x89, 1, 1, 14, 500 },
+ {8, 0x11d, 1, 1, 30, 100 },
+ {8, 0x187, 112, 11, 32, 100 },
+ {9, 0x211, 1, 1, 33, 80 },
+ {0, 0, 0, 0, 0, 0},
+};
+
+
+struct estat {
+ int dwrong;
+ int irv;
+ int wepos;
+ int nwords;
+};
+
+struct bcstat {
+ int rfail;
+ int rsuccess;
+ int noncw;
+ int nwords;
+};
+
+struct wspace {
+ uint16_t *c; /* sent codeword */
+ uint16_t *r; /* received word */
+ uint16_t *s; /* syndrome */
+ uint16_t *corr; /* correction buffer */
+ int *errlocs;
+ int *derrlocs;
+};
+
+struct pad {
+ int mult;
+ int shift;
+};
+
+static struct pad pad_coef[] = {
+ { 0, 0 },
+ { 1, 2 },
+ { 1, 1 },
+ { 3, 2 },
+ { 1, 0 },
+};
+
+static void free_ws(struct wspace *ws)
+{
+ if (!ws)
+ return;
+
+ kfree(ws->errlocs);
+ kfree(ws->c);
+ kfree(ws);
+}
+
+static struct wspace *alloc_ws(struct rs_codec *rs)
+{
+ int nroots = rs->nroots;
+ struct wspace *ws;
+ int nn = rs->nn;
+
+ ws = kzalloc(sizeof(*ws), GFP_KERNEL);
+ if (!ws)
+ return NULL;
+
+ ws->c = kmalloc_array(2 * (nn + nroots),
+ sizeof(uint16_t), GFP_KERNEL);
+ if (!ws->c)
+ goto err;
+
+ ws->r = ws->c + nn;
+ ws->s = ws->r + nn;
+ ws->corr = ws->s + nroots;
+
+ ws->errlocs = kmalloc_array(nn + nroots, sizeof(int), GFP_KERNEL);
+ if (!ws->errlocs)
+ goto err;
+
+ ws->derrlocs = ws->errlocs + nn;
+ return ws;
+
+err:
+ free_ws(ws);
+ return NULL;
+}
+
+
+/*
+ * Generates a random codeword and stores it in c. Generates random errors and
+ * erasures, and stores the random word with errors in r. Erasure positions are
+ * stored in derrlocs, while errlocs has one of three values in every position:
+ *
+ * 0 if there is no error in this position;
+ * 1 if there is a symbol error in this position;
+ * 2 if there is an erasure without symbol corruption.
+ *
+ * Returns the number of corrupted symbols.
+ */
+static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
+ int len, int errs, int eras)
+{
+ int nroots = rs->codec->nroots;
+ int *derrlocs = ws->derrlocs;
+ int *errlocs = ws->errlocs;
+ int dlen = len - nroots;
+ int nn = rs->codec->nn;
+ uint16_t *c = ws->c;
+ uint16_t *r = ws->r;
+ int errval;
+ int errloc;
+ int i;
+
+ /* Load c with random data and encode */
+ for (i = 0; i < dlen; i++)
+ c[i] = prandom_u32() & nn;
+
+ memset(c + dlen, 0, nroots * sizeof(*c));
+ encode_rs16(rs, c, dlen, c + dlen, 0);
+
+ /* Make copyand add errors and erasures */
+ memcpy(r, c, len * sizeof(*r));
+ memset(errlocs, 0, len * sizeof(*errlocs));
+ memset(derrlocs, 0, nroots * sizeof(*derrlocs));
+
+ /* Generating random errors */
+ for (i = 0; i < errs; i++) {
+ do {
+ /* Error value must be nonzero */
+ errval = prandom_u32() & nn;
+ } while (errval == 0);
+
+ do {
+ /* Must not choose the same location twice */
+ errloc = prandom_u32() % len;
+ } while (errlocs[errloc] != 0);
+
+ errlocs[errloc] = 1;
+ r[errloc] ^= errval;
+ }
+
+ /* Generating random erasures */
+ for (i = 0; i < eras; i++) {
+ do {
+ /* Must not choose the same location twice */
+ errloc = prandom_u32() % len;
+ } while (errlocs[errloc] != 0);
+
+ derrlocs[i] = errloc;
+
+ if (ewsc && (prandom_u32() & 1)) {
+ /* Erasure with the symbol intact */
+ errlocs[errloc] = 2;
+ } else {
+ /* Erasure with corrupted symbol */
+ do {
+ /* Error value must be nonzero */
+ errval = prandom_u32() & nn;
+ } while (errval == 0);
+
+ errlocs[errloc] = 1;
+ r[errloc] ^= errval;
+ errs++;
+ }
+ }
+
+ return errs;
+}
+
+static void fix_err(uint16_t *data, int nerrs, uint16_t *corr, int *errlocs)
+{
+ int i;
+
+ for (i = 0; i < nerrs; i++)
+ data[errlocs[i]] ^= corr[i];
+}
+
+static void compute_syndrome(struct rs_control *rsc, uint16_t *data,
+ int len, uint16_t *syn)
+{
+ struct rs_codec *rs = rsc->codec;
+ uint16_t *alpha_to = rs->alpha_to;
+ uint16_t *index_of = rs->index_of;
+ int nroots = rs->nroots;
+ int prim = rs->prim;
+ int fcr = rs->fcr;
+ int i, j;
+
+ /* Calculating syndrome */
+ for (i = 0; i < nroots; i++) {
+ syn[i] = data[0];
+ for (j = 1; j < len; j++) {
+ if (syn[i] == 0) {
+ syn[i] = data[j];
+ } else {
+ syn[i] = data[j] ^
+ alpha_to[rs_modnn(rs, index_of[syn[i]]
+ + (fcr + i) * prim)];
+ }
+ }
+ }
+
+ /* Convert to index form */
+ for (i = 0; i < nroots; i++)
+ syn[i] = rs->index_of[syn[i]];
+}
+
+/* Test up to error correction capacity */
+static void test_uc(struct rs_control *rs, int len, int errs,
+ int eras, int trials, struct estat *stat,
+ struct wspace *ws, int method)
+{
+ int dlen = len - rs->codec->nroots;
+ int *derrlocs = ws->derrlocs;
+ int *errlocs = ws->errlocs;
+ uint16_t *corr = ws->corr;
+ uint16_t *c = ws->c;
+ uint16_t *r = ws->r;
+ uint16_t *s = ws->s;
+ int derrs, nerrs;
+ int i, j;
+
+ for (j = 0; j < trials; j++) {
+ nerrs = get_rcw_we(rs, ws, len, errs, eras);
+
+ switch (method) {
+ case CORR_BUFFER:
+ derrs = decode_rs16(rs, r, r + dlen, dlen,
+ NULL, eras, derrlocs, 0, corr);
+ fix_err(r, derrs, corr, derrlocs);
+ break;
+ case CALLER_SYNDROME:
+ compute_syndrome(rs, r, len, s);
+ derrs = decode_rs16(rs, NULL, NULL, dlen,
+ s, eras, derrlocs, 0, corr);
+ fix_err(r, derrs, corr, derrlocs);
+ break;
+ case IN_PLACE:
+ derrs = decode_rs16(rs, r, r + dlen, dlen,
+ NULL, eras, derrlocs, 0, NULL);
+ break;
+ default:
+ continue;
+ }
+
+ if (derrs != nerrs)
+ stat->irv++;
+
+ if (method != IN_PLACE) {
+ for (i = 0; i < derrs; i++) {
+ if (errlocs[derrlocs[i]] != 1)
+ stat->wepos++;
+ }
+ }
+
+ if (memcmp(r, c, len * sizeof(*r)))
+ stat->dwrong++;
+ }
+ stat->nwords += trials;
+}
+
+static int ex_rs_helper(struct rs_control *rs, struct wspace *ws,
+ int len, int trials, int method)
+{
+ static const char * const desc[] = {
+ "Testing correction buffer interface...",
+ "Testing with caller provided syndrome...",
+ "Testing in-place interface..."
+ };
+
+ struct estat stat = {0, 0, 0, 0};
+ int nroots = rs->codec->nroots;
+ int errs, eras, retval;
+
+ if (v >= V_PROGRESS)
+ pr_info(" %s\n", desc[method]);
+
+ for (errs = 0; errs <= nroots / 2; errs++)
+ for (eras = 0; eras <= nroots - 2 * errs; eras++)
+ test_uc(rs, len, errs, eras, trials, &stat, ws, method);
+
+ if (v >= V_CSUMMARY) {
+ pr_info(" Decodes wrong: %d / %d\n",
+ stat.dwrong, stat.nwords);
+ pr_info(" Wrong return value: %d / %d\n",
+ stat.irv, stat.nwords);
+ if (method != IN_PLACE)
+ pr_info(" Wrong error position: %d\n", stat.wepos);
+ }
+
+ retval = stat.dwrong + stat.wepos + stat.irv;
+ if (retval && v >= V_PROGRESS)
+ pr_warn(" FAIL: %d decoding failures!\n", retval);
+
+ return retval;
+}
+
+static int exercise_rs(struct rs_control *rs, struct wspace *ws,
+ int len, int trials)
+{
+
+ int retval = 0;
+ int i;
+
+ if (v >= V_PROGRESS)
+ pr_info("Testing up to error correction capacity...\n");
+
+ for (i = 0; i <= IN_PLACE; i++)
+ retval |= ex_rs_helper(rs, ws, len, trials, i);
+
+ return retval;
+}
+
+/* Tests for correct behaviour beyond error correction capacity */
+static void test_bc(struct rs_control *rs, int len, int errs,
+ int eras, int trials, struct bcstat *stat,
+ struct wspace *ws)
+{
+ int nroots = rs->codec->nroots;
+ int dlen = len - nroots;
+ int *derrlocs = ws->derrlocs;
+ uint16_t *corr = ws->corr;
+ uint16_t *r = ws->r;
+ int derrs, j;
+
+ for (j = 0; j < trials; j++) {
+ get_rcw_we(rs, ws, len, errs, eras);
+ derrs = decode_rs16(rs, r, r + dlen, dlen,
+ NULL, eras, derrlocs, 0, corr);
+ fix_err(r, derrs, corr, derrlocs);
+
+ if (derrs >= 0) {
+ stat->rsuccess++;
+
+ /*
+ * We check that the returned word is actually a
+ * codeword. The obious way to do this would be to
+ * compute the syndrome, but we don't want to replicate
+ * that code here. However, all the codes are in
+ * systematic form, and therefore we can encode the
+ * returned word, and see whether the parity changes or
+ * not.
+ */
+ memset(corr, 0, nroots * sizeof(*corr));
+ encode_rs16(rs, r, dlen, corr, 0);
+
+ if (memcmp(r + dlen, corr, nroots * sizeof(*corr)))
+ stat->noncw++;
+ } else {
+ stat->rfail++;
+ }
+ }
+ stat->nwords += trials;
+}
+
+static int exercise_rs_bc(struct rs_control *rs, struct wspace *ws,
+ int len, int trials)
+{
+ struct bcstat stat = {0, 0, 0, 0};
+ int nroots = rs->codec->nroots;
+ int errs, eras, cutoff;
+
+ if (v >= V_PROGRESS)
+ pr_info("Testing beyond error correction capacity...\n");
+
+ for (errs = 1; errs <= nroots; errs++) {
+ eras = nroots - 2 * errs + 1;
+ if (eras < 0)
+ eras = 0;
+
+ cutoff = nroots <= len - errs ? nroots : len - errs;
+ for (; eras <= cutoff; eras++)
+ test_bc(rs, len, errs, eras, trials, &stat, ws);
+ }
+
+ if (v >= V_CSUMMARY) {
+ pr_info(" decoder gives up: %d / %d\n",
+ stat.rfail, stat.nwords);
+ pr_info(" decoder returns success: %d / %d\n",
+ stat.rsuccess, stat.nwords);
+ pr_info(" not a codeword: %d / %d\n",
+ stat.noncw, stat.rsuccess);
+ }
+
+ if (stat.noncw && v >= V_PROGRESS)
+ pr_warn(" FAIL: %d silent failures!\n", stat.noncw);
+
+ return stat.noncw;
+}
+
+static int run_exercise(struct etab *e)
+{
+ int nn = (1 << e->symsize) - 1;
+ int kk = nn - e->nroots;
+ struct rs_control *rsc;
+ int retval = -ENOMEM;
+ int max_pad = kk - 1;
+ int prev_pad = -1;
+ struct wspace *ws;
+ int i;
+
+ rsc = init_rs(e->symsize, e->genpoly, e->fcs, e->prim, e->nroots);
+ if (!rsc)
+ return retval;
+
+ ws = alloc_ws(rsc->codec);
+ if (!ws)
+ goto err;
+
+ retval = 0;
+ for (i = 0; i < ARRAY_SIZE(pad_coef); i++) {
+ int pad = (pad_coef[i].mult * max_pad) >> pad_coef[i].shift;
+ int len = nn - pad;
+
+ if (pad == prev_pad)
+ continue;
+
+ prev_pad = pad;
+ if (v >= V_PROGRESS) {
+ pr_info("Testing (%d,%d)_%d code...\n",
+ len, kk - pad, nn + 1);
+ }
+
+ retval |= exercise_rs(rsc, ws, len, e->ntrials);
+ if (bc)
+ retval |= exercise_rs_bc(rsc, ws, len, e->ntrials);
+ }
+
+ free_ws(ws);
+
+err:
+ free_rs(rsc);
+ return retval;
+}
+
+static int __init test_rslib_init(void)
+{
+ int i, fail = 0;
+
+ for (i = 0; Tab[i].symsize != 0 ; i++) {
+ int retval;
+
+ retval = run_exercise(Tab + i);
+ if (retval < 0)
+ return -ENOMEM;
+
+ fail |= retval;
+ }
+
+ if (fail)
+ pr_warn("rslib: test failed\n");
+ else
+ pr_info("rslib: test ok\n");
+
+ return -EAGAIN; /* Fail will directly unload the module */
+}
+
+static void __exit test_rslib_exit(void)
+{
+}
+
+module_init(test_rslib_init)
+module_exit(test_rslib_exit)
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ferdinand Blomqvist");
+MODULE_DESCRIPTION("Reed-Solomon library test");
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 08:08:30 +0000