From d10839ab23b4ac4dea5ba183c451b650dd07331a Mon Sep 17 00:00:00 2001 From: "Matthias P. Braendli" Date: Fri, 9 Feb 2018 10:06:34 +0100 Subject: Move external code to lib and stop using SUBDIRS --- lib/fec/LICENSE | 502 +++++++++++++++++++++++++++++++++++++++++++++++ lib/fec/README.md | 12 ++ lib/fec/char.h | 24 +++ lib/fec/decode_rs.h | 298 ++++++++++++++++++++++++++++ lib/fec/decode_rs_char.c | 22 +++ lib/fec/encode_rs.h | 58 ++++++ lib/fec/encode_rs_char.c | 15 ++ lib/fec/fec.h | 30 +++ lib/fec/init_rs.h | 106 ++++++++++ lib/fec/init_rs_char.c | 35 ++++ lib/fec/rs-common.h | 26 +++ 11 files changed, 1128 insertions(+) create mode 100644 lib/fec/LICENSE create mode 100644 lib/fec/README.md create mode 100644 lib/fec/char.h create mode 100644 lib/fec/decode_rs.h create mode 100644 lib/fec/decode_rs_char.c create mode 100644 lib/fec/encode_rs.h create mode 100644 lib/fec/encode_rs_char.c create mode 100644 lib/fec/fec.h create mode 100644 lib/fec/init_rs.h create mode 100644 lib/fec/init_rs_char.c create mode 100644 lib/fec/rs-common.h (limited to 'lib/fec') diff --git a/lib/fec/LICENSE b/lib/fec/LICENSE new file mode 100644 index 0000000..5a883d3 --- /dev/null +++ b/lib/fec/LICENSE @@ -0,0 +1,502 @@ +GNU LESSER GENERAL PUBLIC LICENSE + Version 2.1, February 1999 + + Copyright (C) 1991, 1999 Free Software Foundation, Inc. + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + +(This is the first released version of the Lesser GPL. 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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/lib/fec/README.md b/lib/fec/README.md new file mode 100644 index 0000000..a44d28d --- /dev/null +++ b/lib/fec/README.md @@ -0,0 +1,12 @@ +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/lib/fec/char.h b/lib/fec/char.h new file mode 100644 index 0000000..25efd65 --- /dev/null +++ b/lib/fec/char.h @@ -0,0 +1,24 @@ +/* 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/lib/fec/decode_rs.h b/lib/fec/decode_rs.h new file mode 100644 index 0000000..c165cf3 --- /dev/null +++ b/lib/fec/decode_rs.h @@ -0,0 +1,298 @@ +/* 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 ) 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 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 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 +#endif + +#include + +#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/lib/fec/encode_rs.h b/lib/fec/encode_rs.h new file mode 100644 index 0000000..2c157f9 --- /dev/null +++ b/lib/fec/encode_rs.h @@ -0,0 +1,58 @@ +/* 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 ) 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 + +#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/lib/fec/fec.h b/lib/fec/fec.h new file mode 100644 index 0000000..0d1bae1 --- /dev/null +++ b/lib/fec/fec.h @@ -0,0 +1,30 @@ +/* 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 + +#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/lib/fec/init_rs.h b/lib/fec/init_rs.h new file mode 100644 index 0000000..2b2ae98 --- /dev/null +++ b/lib/fec/init_rs.h @@ -0,0 +1,106 @@ +/* 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<= (1<= (1<= ((1<mm = symsize; + rs->nn = (1<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;inn;i++){ + rs->index_of[sr] = i; + rs->alpha_to[i] = sr; + sr <<= 1; + if(sr & (1<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/lib/fec/init_rs_char.c b/lib/fec/init_rs_char.c new file mode 100644 index 0000000..a51099a --- /dev/null +++ b/lib/fec/init_rs_char.c @@ -0,0 +1,35 @@ +/* Initialize a RS codec + * + * Copyright 2002 Phil Karn, KA9Q + * May be used under the terms of the GNU Lesser General Public License (LGPL) + */ +#include + +#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/lib/fec/rs-common.h b/lib/fec/rs-common.h new file mode 100644 index 0000000..e64eb39 --- /dev/null +++ b/lib/fec/rs-common.h @@ -0,0 +1,26 @@ +/* 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<= rs->nn) { + x -= rs->nn; + x = (x >> rs->mm) + (x & rs->nn); + } + return x; +} -- cgit v1.2.3