diff options
Diffstat (limited to 'src/fec')
| -rw-r--r-- | src/fec/LICENSE | 502 | ||||
| -rw-r--r-- | src/fec/README.md | 12 | ||||
| -rw-r--r-- | src/fec/char.h | 24 | ||||
| -rw-r--r-- | src/fec/decode_rs.h | 298 | ||||
| -rw-r--r-- | src/fec/decode_rs_char.c | 22 | ||||
| -rw-r--r-- | src/fec/encode_rs.h | 58 | ||||
| -rw-r--r-- | src/fec/encode_rs_char.c | 15 | ||||
| -rw-r--r-- | src/fec/fec.h | 30 | ||||
| -rw-r--r-- | src/fec/init_rs.h | 106 | ||||
| -rw-r--r-- | src/fec/init_rs_char.c | 35 | ||||
| -rw-r--r-- | src/fec/rs-common.h | 26 |
11 files changed, 0 insertions, 1128 deletions
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Here is a sample; alter the names: - - Yoyodyne, Inc., hereby disclaims all copyright interest in the - library `Frob' (a library for tweaking knobs) written by James Random Hacker. - - {signature of Ty Coon}, 1 April 1990 - Ty Coon, President of Vice - -That's all there is to it! diff --git a/src/fec/README.md b/src/fec/README.md deleted file mode 100644 index a44d28d..0000000 --- a/src/fec/README.md +++ /dev/null @@ -1,12 +0,0 @@ -FEC routines from KA9Q's libfec -=============================== - -This folder contains part of the libfec library by KA9Q. Only the -char-sized Reed-Solomon encoder and decoder is here. - -The files have been copied from the libfec fork at -https://github.com/Opendigitalradio/ka9q-fec - -Original code is at http://www.ka9q.net/code/fec/ - -All files in this folder are licenced under the LGPL v2.1, please see LICENCE diff --git a/src/fec/char.h b/src/fec/char.h deleted file mode 100644 index 25efd65..0000000 --- a/src/fec/char.h +++ /dev/null @@ -1,24 +0,0 @@ -/* Stuff specific to the 8-bit symbol version of the general purpose RS codecs - * - * Copyright 2003, Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ -typedef unsigned char data_t; - -#define MODNN(x) modnn(rs,x) - -#define MM (rs->mm) -#define NN (rs->nn) -#define ALPHA_TO (rs->alpha_to) -#define INDEX_OF (rs->index_of) -#define GENPOLY (rs->genpoly) -#define NROOTS (rs->nroots) -#define FCR (rs->fcr) -#define PRIM (rs->prim) -#define IPRIM (rs->iprim) -#define PAD (rs->pad) -#define A0 (NN) - - - - diff --git a/src/fec/decode_rs.h b/src/fec/decode_rs.h deleted file mode 100644 index c165cf3..0000000 --- a/src/fec/decode_rs.h +++ /dev/null @@ -1,298 +0,0 @@ -/* The guts of the Reed-Solomon decoder, meant to be #included - * into a function body with the following typedefs, macros and variables supplied - * according to the code parameters: - - * data_t - a typedef for the data symbol - * data_t data[] - array of NN data and parity symbols to be corrected in place - * retval - an integer lvalue into which the decoder's return code is written - * NROOTS - the number of roots in the RS code generator polynomial, - * which is the same as the number of parity symbols in a block. - Integer variable or literal. - * NN - the total number of symbols in a RS block. Integer variable or literal. - * PAD - the number of pad symbols in a block. Integer variable or literal. - * ALPHA_TO - The address of an array of NN elements to convert Galois field - * elements in index (log) form to polynomial form. Read only. - * INDEX_OF - The address of an array of NN elements to convert Galois field - * elements in polynomial form to index (log) form. Read only. - * MODNN - a function to reduce its argument modulo NN. May be inline or a macro. - * FCR - An integer literal or variable specifying the first consecutive root of the - * Reed-Solomon generator polynomial. Integer variable or literal. - * PRIM - The primitive root of the generator poly. Integer variable or literal. - * DEBUG - If set to 1 or more, do various internal consistency checking. Leave this - * undefined for production code - - * The memset(), memmove(), and memcpy() functions are used. The appropriate header - * file declaring these functions (usually <string.h>) must be included by the calling - * program. - */ - - -#if !defined(NROOTS) -#error "NROOTS not defined" -#endif - -#if !defined(NN) -#error "NN not defined" -#endif - -#if !defined(PAD) -#error "PAD not defined" -#endif - -#if !defined(ALPHA_TO) -#error "ALPHA_TO not defined" -#endif - -#if !defined(INDEX_OF) -#error "INDEX_OF not defined" -#endif - -#if !defined(MODNN) -#error "MODNN not defined" -#endif - -#if !defined(FCR) -#error "FCR not defined" -#endif - -#if !defined(PRIM) -#error "PRIM not defined" -#endif - -#if !defined(NULL) -#define NULL ((void *)0) -#endif - -#undef MIN -#define MIN(a,b) ((a) < (b) ? (a) : (b)) -#undef A0 -#define A0 (NN) - -{ - int deg_lambda, el, deg_omega; - int i, j, r,k; - data_t u,q,tmp,num1,num2,den,discr_r; - data_t lambda[NROOTS+1], s[NROOTS]; /* Err+Eras Locator poly - * and syndrome poly */ - data_t b[NROOTS+1], t[NROOTS+1], omega[NROOTS+1]; - data_t root[NROOTS], reg[NROOTS+1], loc[NROOTS]; - int syn_error, count; - - /* form the syndromes; i.e., evaluate data(x) at roots of g(x) */ - for(i=0;i<NROOTS;i++) - s[i] = data[0]; - - for(j=1;j<NN-PAD;j++){ - for(i=0;i<NROOTS;i++){ - if(s[i] == 0){ - s[i] = data[j]; - } else { - s[i] = data[j] ^ ALPHA_TO[MODNN(INDEX_OF[s[i]] + (FCR+i)*PRIM)]; - } - } - } - - /* 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; - } - 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[MODNN(PRIM*(NN-1-eras_pos[0]))]; - for (i = 1; i < no_eras; i++) { - u = MODNN(PRIM*(NN-1-eras_pos[i])); - for (j = i+1; j > 0; j--) { - tmp = INDEX_OF[lambda[j - 1]]; - if(tmp != A0) - lambda[j] ^= ALPHA_TO[MODNN(u + tmp)]; - } - } - -#if DEBUG >= 1 - /* Test code that verifies the erasure locator polynomial just constructed - Needed only for decoder debugging. */ - - /* find roots of the erasure location polynomial */ - for(i=1;i<=no_eras;i++) - reg[i] = INDEX_OF[lambda[i]]; - - count = 0; - for (i = 1,k=IPRIM-1; i <= NN; i++,k = MODNN(k+IPRIM)) { - q = 1; - for (j = 1; j <= no_eras; j++) - if (reg[j] != A0) { - reg[j] = MODNN(reg[j] + j); - q ^= ALPHA_TO[reg[j]]; - } - if (q != 0) - continue; - /* store root and error location number indices */ - root[count] = i; - loc[count] = k; - count++; - } - if (count != no_eras) { - printf("count = %d no_eras = %d\n lambda(x) is WRONG\n",count,no_eras); - count = -1; - goto finish; - } -#if DEBUG >= 2 - printf("\n Erasure positions as determined by roots of Eras Loc Poly:\n"); - for (i = 0; i < count; i++) - printf("%d ", loc[i]); - printf("\n"); -#endif -#endif - } - 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] != A0)) { - discr_r ^= ALPHA_TO[MODNN(INDEX_OF[lambda[i]] + s[r-i-1])]; - } - } - discr_r = INDEX_OF[discr_r]; /* Index form */ - if (discr_r == A0) { - /* 2 lines below: B(x) <-- x*B(x) */ - memmove(&b[1],b,NROOTS*sizeof(b[0])); - b[0] = A0; - } 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] != A0) - t[i+1] = lambda[i+1] ^ ALPHA_TO[MODNN(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) ? A0 : MODNN(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] = A0; - } - 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] != A0) - deg_lambda = i; - } - /* Find roots of the 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 = MODNN(k+IPRIM)) { - q = 1; /* lambda[0] is always 0 */ - for (j = deg_lambda; j > 0; j--){ - if (reg[j] != A0) { - reg[j] = MODNN(reg[j] + j); - q ^= ALPHA_TO[reg[j]]; - } - } - if (q != 0) - continue; /* Not a root */ - /* store root (index-form) and error location number */ -#if DEBUG>=2 - printf("count %d root %d loc %d\n",count,i,k); -#endif - 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 = -1; - 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] != A0) && (lambda[j] != A0)) - tmp ^= ALPHA_TO[MODNN(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] != A0) - num1 ^= ALPHA_TO[MODNN(omega[i] + i * root[j])]; - } - num2 = ALPHA_TO[MODNN(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] != A0) - den ^= ALPHA_TO[MODNN(lambda[i+1] + i * root[j])]; - } -#if DEBUG >= 1 - if (den == 0) { - printf("\n ERROR: denominator = 0\n"); - count = -1; - goto finish; - } -#endif - /* Apply error to data */ - if (num1 != 0 && loc[j] >= PAD) { - data[loc[j]-PAD] ^= ALPHA_TO[MODNN(INDEX_OF[num1] + INDEX_OF[num2] + NN - INDEX_OF[den])]; - } - } - finish: - if(eras_pos != NULL){ - for(i=0;i<count;i++) - eras_pos[i] = loc[i]; - } - retval = count; -} diff --git a/src/fec/decode_rs_char.c b/src/fec/decode_rs_char.c deleted file mode 100644 index 7105233..0000000 --- a/src/fec/decode_rs_char.c +++ /dev/null @@ -1,22 +0,0 @@ -/* General purpose Reed-Solomon decoder for 8-bit symbols or less - * Copyright 2003 Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ - -#ifdef DEBUG -#include <stdio.h> -#endif - -#include <string.h> - -#include "char.h" -#include "rs-common.h" - -int decode_rs_char(void *p, data_t *data, int *eras_pos, int no_eras){ - int retval; - struct rs *rs = (struct rs *)p; - -#include "decode_rs.h" - - return retval; -} diff --git a/src/fec/encode_rs.h b/src/fec/encode_rs.h deleted file mode 100644 index 2c157f9..0000000 --- a/src/fec/encode_rs.h +++ /dev/null @@ -1,58 +0,0 @@ -/* The guts of the Reed-Solomon encoder, meant to be #included - * into a function body with the following typedefs, macros and variables supplied - * according to the code parameters: - - * data_t - a typedef for the data symbol - * data_t data[] - array of NN-NROOTS-PAD and type data_t to be encoded - * data_t parity[] - an array of NROOTS and type data_t to be written with parity symbols - * NROOTS - the number of roots in the RS code generator polynomial, - * which is the same as the number of parity symbols in a block. - Integer variable or literal. - * - * NN - the total number of symbols in a RS block. Integer variable or literal. - * PAD - the number of pad symbols in a block. Integer variable or literal. - * ALPHA_TO - The address of an array of NN elements to convert Galois field - * elements in index (log) form to polynomial form. Read only. - * INDEX_OF - The address of an array of NN elements to convert Galois field - * elements in polynomial form to index (log) form. Read only. - * MODNN - a function to reduce its argument modulo NN. May be inline or a macro. - * GENPOLY - an array of NROOTS+1 elements containing the generator polynomial in index form - - * The memset() and memmove() functions are used. The appropriate header - * file declaring these functions (usually <string.h>) must be included by the calling - * program. - - * Copyright 2004, Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ - - -#undef A0 -#define A0 (NN) /* Special reserved value encoding zero in index form */ - -{ - int i, j; - data_t feedback; - - memset(parity,0,NROOTS*sizeof(data_t)); - - for(i=0;i<NN-NROOTS-PAD;i++){ - feedback = INDEX_OF[data[i] ^ parity[0]]; - if(feedback != A0){ /* feedback term is non-zero */ -#ifdef UNNORMALIZED - /* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must - * always be for the polynomials constructed by init_rs() - */ - feedback = MODNN(NN - GENPOLY[NROOTS] + feedback); -#endif - for(j=1;j<NROOTS;j++) - parity[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])]; - } - /* Shift */ - memmove(&parity[0],&parity[1],sizeof(data_t)*(NROOTS-1)); - if(feedback != A0) - parity[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])]; - else - parity[NROOTS-1] = 0; - } -} diff --git a/src/fec/encode_rs_char.c b/src/fec/encode_rs_char.c deleted file mode 100644 index a9bf2b8..0000000 --- a/src/fec/encode_rs_char.c +++ /dev/null @@ -1,15 +0,0 @@ -/* Reed-Solomon encoder - * Copyright 2002, Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ -#include <string.h> - -#include "char.h" -#include "rs-common.h" - -void encode_rs_char(void *p,data_t *data, data_t *parity){ - struct rs *rs = (struct rs *)p; - -#include "encode_rs.h" - -} diff --git a/src/fec/fec.h b/src/fec/fec.h deleted file mode 100644 index 0d1bae1..0000000 --- a/src/fec/fec.h +++ /dev/null @@ -1,30 +0,0 @@ -/* Main header for reduced libfec. - * - * The FEC code in this folder is - * Copyright 2003 Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ - -#pragma once - -#include <stdlib.h> - -#include "char.h" -#include "rs-common.h" - -/* Initialize a Reed-Solomon codec - * symsize = symbol size, bits - * gfpoly = Field generator polynomial coefficients - * 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) - * pad = padding bytes at front of shortened block - */ -void *init_rs_char(int symsize,int gfpoly,int fcr,int prim,int nroots,int pad); - -int decode_rs_char(void *p, data_t *data, int *eras_pos, int no_eras); - -void encode_rs_char(void *p,data_t *data, data_t *parity); - -void free_rs_char(void *p); - diff --git a/src/fec/init_rs.h b/src/fec/init_rs.h deleted file mode 100644 index 2b2ae98..0000000 --- a/src/fec/init_rs.h +++ /dev/null @@ -1,106 +0,0 @@ -/* Common code for intializing a Reed-Solomon control block (char or int symbols) - * Copyright 2004 Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ -#undef NULL -#define NULL ((void *)0) - -{ - int i, j, sr,root,iprim; - - rs = NULL; - /* Check parameter ranges */ - if(symsize < 0 || symsize > 8*sizeof(data_t)){ - goto done; - } - - if(fcr < 0 || fcr >= (1<<symsize)) - goto done; - if(prim <= 0 || prim >= (1<<symsize)) - goto done; - if(nroots < 0 || nroots >= (1<<symsize)) - goto done; /* Can't have more roots than symbol values! */ - if(pad < 0 || pad >= ((1<<symsize) -1 - nroots)) - goto done; /* Too much padding */ - - rs = (struct rs *)calloc(1,sizeof(struct rs)); - if(rs == NULL) - goto done; - - rs->mm = symsize; - rs->nn = (1<<symsize)-1; - rs->pad = pad; - - rs->alpha_to = (data_t *)malloc(sizeof(data_t)*(rs->nn+1)); - if(rs->alpha_to == NULL){ - free(rs); - rs = NULL; - goto done; - } - rs->index_of = (data_t *)malloc(sizeof(data_t)*(rs->nn+1)); - if(rs->index_of == NULL){ - free(rs->alpha_to); - free(rs); - rs = NULL; - goto done; - } - - /* Generate Galois field lookup tables */ - rs->index_of[0] = A0; /* log(zero) = -inf */ - rs->alpha_to[A0] = 0; /* alpha**-inf = 0 */ - 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; - } - if(sr != 1){ - /* field generator polynomial is not primitive! */ - free(rs->alpha_to); - free(rs->index_of); - free(rs); - rs = NULL; - goto done; - } - - /* Form RS code generator polynomial from its roots */ - rs->genpoly = (data_t *)malloc(sizeof(data_t)*(nroots+1)); - if(rs->genpoly == NULL){ - free(rs->alpha_to); - free(rs->index_of); - free(rs); - rs = NULL; - goto done; - } - rs->fcr = fcr; - rs->prim = prim; - rs->nroots = nroots; - - /* Find prim-th root of 1, used in decoding */ - for(iprim=1;(iprim % prim) != 0;iprim += rs->nn) - ; - rs->iprim = iprim / prim; - - 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[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[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]]; - done:; - -} diff --git a/src/fec/init_rs_char.c b/src/fec/init_rs_char.c deleted file mode 100644 index a51099a..0000000 --- a/src/fec/init_rs_char.c +++ /dev/null @@ -1,35 +0,0 @@ -/* Initialize a RS codec - * - * Copyright 2002 Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ -#include <stdlib.h> - -#include "char.h" -#include "rs-common.h" - -void free_rs_char(void *p){ - struct rs *rs = (struct rs *)p; - - free(rs->alpha_to); - free(rs->index_of); - free(rs->genpoly); - free(rs); -} - -/* Initialize a Reed-Solomon codec - * symsize = symbol size, bits - * gfpoly = Field generator polynomial coefficients - * 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) - * pad = padding bytes at front of shortened block - */ -void *init_rs_char(int symsize,int gfpoly,int fcr,int prim, - int nroots,int pad){ - struct rs *rs; - -#include "init_rs.h" - - return rs; -} diff --git a/src/fec/rs-common.h b/src/fec/rs-common.h deleted file mode 100644 index e64eb39..0000000 --- a/src/fec/rs-common.h +++ /dev/null @@ -1,26 +0,0 @@ -/* Stuff common to all the general-purpose Reed-Solomon codecs - * Copyright 2004 Phil Karn, KA9Q - * May be used under the terms of the GNU Lesser General Public License (LGPL) - */ - -/* Reed-Solomon codec control block */ -struct rs { - int mm; /* Bits per symbol */ - int nn; /* Symbols per block (= (1<<mm)-1) */ - data_t *alpha_to; /* log lookup table */ - data_t *index_of; /* Antilog lookup table */ - data_t *genpoly; /* Generator polynomial */ - int nroots; /* Number of generator roots = number of parity symbols */ - int fcr; /* First consecutive root, index form */ - int prim; /* Primitive element, index form */ - int iprim; /* prim-th root of 1, index form */ - int pad; /* Padding bytes in shortened block */ -}; - -static inline int modnn(struct rs *rs,int x){ - while (x >= rs->nn) { - x -= rs->nn; - x = (x >> rs->mm) + (x & rs->nn); - } - return x; -} |