519 lines
11 KiB
C
519 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Tests for Generic Reed Solomon encoder / decoder library
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*
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* Written by Ferdinand Blomqvist
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* Based on previous work by Phil Karn, KA9Q
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*/
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#include <linux/rslib.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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enum verbosity {
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V_SILENT,
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V_PROGRESS,
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V_CSUMMARY
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};
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enum method {
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CORR_BUFFER,
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CALLER_SYNDROME,
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IN_PLACE
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};
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#define __param(type, name, init, msg) \
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static type name = init; \
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module_param(name, type, 0444); \
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MODULE_PARM_DESC(name, msg)
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__param(int, v, V_PROGRESS, "Verbosity level");
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__param(int, ewsc, 1, "Erasures without symbol corruption");
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__param(int, bc, 1, "Test for correct behaviour beyond error correction capacity");
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struct etab {
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int symsize;
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int genpoly;
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int fcs;
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int prim;
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int nroots;
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int ntrials;
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};
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/* List of codes to test */
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static struct etab Tab[] = {
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{2, 0x7, 1, 1, 1, 100000 },
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{3, 0xb, 1, 1, 2, 100000 },
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{3, 0xb, 1, 1, 3, 100000 },
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{3, 0xb, 2, 1, 4, 100000 },
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{4, 0x13, 1, 1, 4, 10000 },
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{5, 0x25, 1, 1, 6, 1000 },
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{6, 0x43, 3, 1, 8, 1000 },
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{7, 0x89, 1, 1, 14, 500 },
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{8, 0x11d, 1, 1, 30, 100 },
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{8, 0x187, 112, 11, 32, 100 },
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{9, 0x211, 1, 1, 33, 80 },
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{0, 0, 0, 0, 0, 0},
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};
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struct estat {
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int dwrong;
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int irv;
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int wepos;
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int nwords;
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};
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struct bcstat {
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int rfail;
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int rsuccess;
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int noncw;
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int nwords;
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};
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struct wspace {
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uint16_t *c; /* sent codeword */
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uint16_t *r; /* received word */
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uint16_t *s; /* syndrome */
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uint16_t *corr; /* correction buffer */
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int *errlocs;
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int *derrlocs;
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};
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struct pad {
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int mult;
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int shift;
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};
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static struct pad pad_coef[] = {
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{ 0, 0 },
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{ 1, 2 },
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{ 1, 1 },
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{ 3, 2 },
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{ 1, 0 },
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};
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static void free_ws(struct wspace *ws)
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{
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if (!ws)
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return;
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kfree(ws->errlocs);
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kfree(ws->c);
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kfree(ws);
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}
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static struct wspace *alloc_ws(struct rs_codec *rs)
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{
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int nroots = rs->nroots;
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struct wspace *ws;
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int nn = rs->nn;
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ws = kzalloc(sizeof(*ws), GFP_KERNEL);
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if (!ws)
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return NULL;
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ws->c = kmalloc_array(2 * (nn + nroots),
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sizeof(uint16_t), GFP_KERNEL);
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if (!ws->c)
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goto err;
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ws->r = ws->c + nn;
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ws->s = ws->r + nn;
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ws->corr = ws->s + nroots;
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ws->errlocs = kmalloc_array(nn + nroots, sizeof(int), GFP_KERNEL);
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if (!ws->errlocs)
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goto err;
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ws->derrlocs = ws->errlocs + nn;
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return ws;
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err:
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free_ws(ws);
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return NULL;
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}
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/*
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* Generates a random codeword and stores it in c. Generates random errors and
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* erasures, and stores the random word with errors in r. Erasure positions are
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* stored in derrlocs, while errlocs has one of three values in every position:
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*
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* 0 if there is no error in this position;
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* 1 if there is a symbol error in this position;
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* 2 if there is an erasure without symbol corruption.
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*
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* Returns the number of corrupted symbols.
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*/
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static int get_rcw_we(struct rs_control *rs, struct wspace *ws,
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int len, int errs, int eras)
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{
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int nroots = rs->codec->nroots;
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int *derrlocs = ws->derrlocs;
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int *errlocs = ws->errlocs;
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int dlen = len - nroots;
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int nn = rs->codec->nn;
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uint16_t *c = ws->c;
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uint16_t *r = ws->r;
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int errval;
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int errloc;
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int i;
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/* Load c with random data and encode */
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for (i = 0; i < dlen; i++)
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c[i] = prandom_u32() & nn;
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memset(c + dlen, 0, nroots * sizeof(*c));
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encode_rs16(rs, c, dlen, c + dlen, 0);
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/* Make copyand add errors and erasures */
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memcpy(r, c, len * sizeof(*r));
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memset(errlocs, 0, len * sizeof(*errlocs));
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memset(derrlocs, 0, nroots * sizeof(*derrlocs));
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/* Generating random errors */
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for (i = 0; i < errs; i++) {
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do {
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/* Error value must be nonzero */
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errval = prandom_u32() & nn;
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} while (errval == 0);
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do {
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/* Must not choose the same location twice */
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errloc = prandom_u32() % len;
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} while (errlocs[errloc] != 0);
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errlocs[errloc] = 1;
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r[errloc] ^= errval;
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}
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/* Generating random erasures */
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for (i = 0; i < eras; i++) {
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do {
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/* Must not choose the same location twice */
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errloc = prandom_u32() % len;
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} while (errlocs[errloc] != 0);
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derrlocs[i] = errloc;
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if (ewsc && (prandom_u32() & 1)) {
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/* Erasure with the symbol intact */
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errlocs[errloc] = 2;
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} else {
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/* Erasure with corrupted symbol */
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do {
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/* Error value must be nonzero */
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errval = prandom_u32() & nn;
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} while (errval == 0);
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errlocs[errloc] = 1;
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r[errloc] ^= errval;
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errs++;
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}
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}
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return errs;
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}
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static void fix_err(uint16_t *data, int nerrs, uint16_t *corr, int *errlocs)
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{
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int i;
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for (i = 0; i < nerrs; i++)
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data[errlocs[i]] ^= corr[i];
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}
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static void compute_syndrome(struct rs_control *rsc, uint16_t *data,
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int len, uint16_t *syn)
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{
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struct rs_codec *rs = rsc->codec;
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uint16_t *alpha_to = rs->alpha_to;
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uint16_t *index_of = rs->index_of;
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int nroots = rs->nroots;
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int prim = rs->prim;
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int fcr = rs->fcr;
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int i, j;
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/* Calculating syndrome */
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for (i = 0; i < nroots; i++) {
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syn[i] = data[0];
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for (j = 1; j < len; j++) {
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if (syn[i] == 0) {
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syn[i] = data[j];
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} else {
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syn[i] = data[j] ^
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alpha_to[rs_modnn(rs, index_of[syn[i]]
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+ (fcr + i) * prim)];
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}
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}
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}
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/* Convert to index form */
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for (i = 0; i < nroots; i++)
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syn[i] = rs->index_of[syn[i]];
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}
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/* Test up to error correction capacity */
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static void test_uc(struct rs_control *rs, int len, int errs,
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int eras, int trials, struct estat *stat,
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struct wspace *ws, int method)
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{
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int dlen = len - rs->codec->nroots;
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int *derrlocs = ws->derrlocs;
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int *errlocs = ws->errlocs;
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uint16_t *corr = ws->corr;
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uint16_t *c = ws->c;
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uint16_t *r = ws->r;
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uint16_t *s = ws->s;
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int derrs, nerrs;
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int i, j;
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for (j = 0; j < trials; j++) {
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nerrs = get_rcw_we(rs, ws, len, errs, eras);
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switch (method) {
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case CORR_BUFFER:
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derrs = decode_rs16(rs, r, r + dlen, dlen,
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NULL, eras, derrlocs, 0, corr);
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fix_err(r, derrs, corr, derrlocs);
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break;
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case CALLER_SYNDROME:
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compute_syndrome(rs, r, len, s);
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derrs = decode_rs16(rs, NULL, NULL, dlen,
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s, eras, derrlocs, 0, corr);
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fix_err(r, derrs, corr, derrlocs);
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break;
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case IN_PLACE:
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derrs = decode_rs16(rs, r, r + dlen, dlen,
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NULL, eras, derrlocs, 0, NULL);
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break;
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default:
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continue;
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}
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if (derrs != nerrs)
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stat->irv++;
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if (method != IN_PLACE) {
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for (i = 0; i < derrs; i++) {
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if (errlocs[derrlocs[i]] != 1)
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stat->wepos++;
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}
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}
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if (memcmp(r, c, len * sizeof(*r)))
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stat->dwrong++;
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}
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stat->nwords += trials;
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}
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static int ex_rs_helper(struct rs_control *rs, struct wspace *ws,
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int len, int trials, int method)
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{
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static const char * const desc[] = {
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"Testing correction buffer interface...",
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"Testing with caller provided syndrome...",
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"Testing in-place interface..."
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};
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struct estat stat = {0, 0, 0, 0};
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int nroots = rs->codec->nroots;
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int errs, eras, retval;
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if (v >= V_PROGRESS)
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pr_info(" %s\n", desc[method]);
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for (errs = 0; errs <= nroots / 2; errs++)
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for (eras = 0; eras <= nroots - 2 * errs; eras++)
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test_uc(rs, len, errs, eras, trials, &stat, ws, method);
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if (v >= V_CSUMMARY) {
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pr_info(" Decodes wrong: %d / %d\n",
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stat.dwrong, stat.nwords);
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pr_info(" Wrong return value: %d / %d\n",
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stat.irv, stat.nwords);
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if (method != IN_PLACE)
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pr_info(" Wrong error position: %d\n", stat.wepos);
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}
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retval = stat.dwrong + stat.wepos + stat.irv;
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if (retval && v >= V_PROGRESS)
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pr_warn(" FAIL: %d decoding failures!\n", retval);
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return retval;
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}
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static int exercise_rs(struct rs_control *rs, struct wspace *ws,
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int len, int trials)
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{
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int retval = 0;
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int i;
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if (v >= V_PROGRESS)
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pr_info("Testing up to error correction capacity...\n");
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for (i = 0; i <= IN_PLACE; i++)
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retval |= ex_rs_helper(rs, ws, len, trials, i);
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return retval;
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}
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/* Tests for correct behaviour beyond error correction capacity */
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static void test_bc(struct rs_control *rs, int len, int errs,
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int eras, int trials, struct bcstat *stat,
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struct wspace *ws)
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{
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int nroots = rs->codec->nroots;
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int dlen = len - nroots;
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int *derrlocs = ws->derrlocs;
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uint16_t *corr = ws->corr;
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uint16_t *r = ws->r;
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int derrs, j;
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for (j = 0; j < trials; j++) {
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get_rcw_we(rs, ws, len, errs, eras);
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derrs = decode_rs16(rs, r, r + dlen, dlen,
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NULL, eras, derrlocs, 0, corr);
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fix_err(r, derrs, corr, derrlocs);
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if (derrs >= 0) {
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stat->rsuccess++;
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/*
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* We check that the returned word is actually a
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* codeword. The obious way to do this would be to
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* compute the syndrome, but we don't want to replicate
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* that code here. However, all the codes are in
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* systematic form, and therefore we can encode the
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* returned word, and see whether the parity changes or
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* not.
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*/
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memset(corr, 0, nroots * sizeof(*corr));
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encode_rs16(rs, r, dlen, corr, 0);
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if (memcmp(r + dlen, corr, nroots * sizeof(*corr)))
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stat->noncw++;
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} else {
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stat->rfail++;
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}
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}
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stat->nwords += trials;
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}
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static int exercise_rs_bc(struct rs_control *rs, struct wspace *ws,
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int len, int trials)
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{
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struct bcstat stat = {0, 0, 0, 0};
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int nroots = rs->codec->nroots;
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int errs, eras, cutoff;
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if (v >= V_PROGRESS)
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pr_info("Testing beyond error correction capacity...\n");
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for (errs = 1; errs <= nroots; errs++) {
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eras = nroots - 2 * errs + 1;
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if (eras < 0)
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eras = 0;
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cutoff = nroots <= len - errs ? nroots : len - errs;
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for (; eras <= cutoff; eras++)
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test_bc(rs, len, errs, eras, trials, &stat, ws);
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}
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if (v >= V_CSUMMARY) {
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pr_info(" decoder gives up: %d / %d\n",
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stat.rfail, stat.nwords);
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pr_info(" decoder returns success: %d / %d\n",
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stat.rsuccess, stat.nwords);
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pr_info(" not a codeword: %d / %d\n",
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stat.noncw, stat.rsuccess);
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}
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if (stat.noncw && v >= V_PROGRESS)
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pr_warn(" FAIL: %d silent failures!\n", stat.noncw);
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return stat.noncw;
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}
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static int run_exercise(struct etab *e)
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{
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int nn = (1 << e->symsize) - 1;
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int kk = nn - e->nroots;
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struct rs_control *rsc;
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int retval = -ENOMEM;
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int max_pad = kk - 1;
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int prev_pad = -1;
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struct wspace *ws;
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int i;
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rsc = init_rs(e->symsize, e->genpoly, e->fcs, e->prim, e->nroots);
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if (!rsc)
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return retval;
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ws = alloc_ws(rsc->codec);
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if (!ws)
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goto err;
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retval = 0;
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for (i = 0; i < ARRAY_SIZE(pad_coef); i++) {
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int pad = (pad_coef[i].mult * max_pad) >> pad_coef[i].shift;
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int len = nn - pad;
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if (pad == prev_pad)
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continue;
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prev_pad = pad;
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if (v >= V_PROGRESS) {
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pr_info("Testing (%d,%d)_%d code...\n",
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len, kk - pad, nn + 1);
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}
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retval |= exercise_rs(rsc, ws, len, e->ntrials);
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if (bc)
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retval |= exercise_rs_bc(rsc, ws, len, e->ntrials);
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}
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free_ws(ws);
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err:
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free_rs(rsc);
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return retval;
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}
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static int __init test_rslib_init(void)
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{
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int i, fail = 0;
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for (i = 0; Tab[i].symsize != 0 ; i++) {
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int retval;
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retval = run_exercise(Tab + i);
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if (retval < 0)
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return -ENOMEM;
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fail |= retval;
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}
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if (fail)
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pr_warn("rslib: test failed\n");
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else
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pr_info("rslib: test ok\n");
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return -EAGAIN; /* Fail will directly unload the module */
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}
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static void __exit test_rslib_exit(void)
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{
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}
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module_init(test_rslib_init)
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module_exit(test_rslib_exit)
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Ferdinand Blomqvist");
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MODULE_DESCRIPTION("Reed-Solomon library test");
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