#include <assert.h>
#include "dmtx.h"
#include "dmtxstatic.h"

Macros
#define	NN 255

#define	MAX_ERROR_WORD_COUNT 68

#define	DMTX_CHECK_BOUNDS(l, i)

#define	GfAdd(a, b)

#define	GfMult(a, b)

#define	GfMultAntilog(a, b)

#define	CHKPASS

#define	CHKPASS

#define	CHKPASS

#define	CHKPASS

#define	CHKPASS

#define	CHKPASS

#define	CHKPASS

Functions
static DmtxPassFail	rsEncode (DmtxMessage *message, int sizeIdx)
	Encode xyz.

static DmtxPassFail	rsDecode (unsigned char *code, int sizeIdx, int fix)
	Decode xyz.

static DmtxPassFail	rsGenPoly (DmtxByteList *gen, int errorWordCount)
	Populate generator polynomial.

static DmtxBoolean	rsComputeSyndromes (DmtxByteList syn, const DmtxByteList rec, int blockErrorWords)
	Populate generator polynomial.

static DmtxBoolean	rsFindErrorLocatorPoly (DmtxByteList elpOut, const DmtxByteList syn, int errorWordCount, int maxCorrectable)
	Find the error location polynomial using Berlekamp-Massey.

static DmtxBoolean	rsFindErrorLocations (DmtxByteList loc, const DmtxByteList elp)
	Find roots of the error locator polynomial (Chien Search).

static DmtxPassFail	rsRepairErrors (DmtxByteList rec, const DmtxByteList loc, const DmtxByteList elp, const DmtxByteList syn)
	Find the error values and repair.

Variables
static DmtxByte	log301 []

static DmtxByte	antilog301 []

Detailed Description

See LICENSE file in the main project directory for full terms of use and distribution.

Portions of this file were derived from the Reed-Solomon

encoder/decoder released by Simon Rockliff in June 1991.

Contact: Vadim A. Misbakh-Soloviov dmtx@.nosp@m.mva..nosp@m.name Mike Laughton mike@.nosp@m.drag.nosp@m.onfly.nosp@m.logi.nosp@m.c.com

Definition in file dmtxreedsol.c.

Macro Definition Documentation

◆ CHKPASS [1/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxFail;      \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ CHKPASS [2/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxFail;      \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ CHKPASS [3/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxFail;      \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ CHKPASS [4/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxTrue;      \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ CHKPASS [5/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxFalse;     \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ CHKPASS [6/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxFalse;     \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ CHKPASS [7/7]

#define CHKPASS

Value:

    {                             \
        if (passFail == DmtxFail) \
            return DmtxFail;      \
    }

Definition at line 71 of file dmtxreedsol.c.

◆ DMTX_CHECK_BOUNDS

#define DMTX_CHECK_BOUNDS	(		l,
			i )

Value:

DmtxAssert((i) >= 0 && (i) < (l)->length && (l)->length <= (l)->capacity)

l

static struct @0 l

DmtxAssert

#define DmtxAssert(expr)

Definition dmtxstatic.h:96

Definition at line 29 of file dmtxreedsol.c.

◆ GfAdd

#define GfAdd	(		a,
			b )

Value:

((a) ^ (b))

Definition at line 32 of file dmtxreedsol.c.

◆ GfMult

#define GfMult	(		a,
			b )

Value:

(((a) == 0 || (b) == 0) ? 0 : antilog301[(log301[(a)] + log301[(b)]) % NN])

NN

#define NN

Definition dmtxreedsol.c:26

antilog301

static DmtxByte antilog301[]

Definition dmtxreedsol.c:56

log301

static DmtxByte log301[]

Definition dmtxreedsol.c:41

Definition at line 35 of file dmtxreedsol.c.

◆ GfMultAntilog

#define GfMultAntilog	(		a,
			b )

Value:

(((a) == 0) ? 0 : antilog301[(log301[(a)] + (b)) % NN])

Definition at line 38 of file dmtxreedsol.c.

◆ MAX_ERROR_WORD_COUNT

#define MAX_ERROR_WORD_COUNT 68

Definition at line 27 of file dmtxreedsol.c.

◆ NN

#define NN 255

Definition at line 26 of file dmtxreedsol.c.

Function Documentation

◆ rsComputeSyndromes()

static DmtxBoolean rsComputeSyndromes	(	DmtxByteList *	syn,
		const DmtxByteList *	rec,
		int	blockErrorWords )

static

Populate generator polynomial.

Assume we have received bits grouped into mm-bit symbols in rec[i], i=0..(nn-1), and rec[i] is index form (ie as powers of alpha). We first compute the 2*tt syndromes by substituting alpha**i into rec(X) and evaluating, storing the syndromes in syn[i], i=1..2tt (leave syn[0] zero).

Parameters

syn
rec
blockErrorWords

Returns: Are error(s) present? (DmtxPass|DmtxFail)

Definition at line 298 of file dmtxreedsol.c.

◆ rsDecode()

static DmtxPassFail rsDecode	(	unsigned char *	code,
		int	sizeIdx,
		int	fix )

static

Decode xyz.

More detailed description.

Parameters

code
sizeIdx
fix

Returns: Function success (DmtxPass|DmtxFail)

Definition at line 148 of file dmtxreedsol.c.

◆ rsEncode()

static DmtxPassFail rsEncode	(	DmtxMessage *	message,
		int	sizeIdx )

static

Encode xyz.

More detailed description.

Parameters

message
sizeIdx

Returns: Function success (DmtxPass|DmtxFail)

Definition at line 83 of file dmtxreedsol.c.

◆ rsFindErrorLocations()

static DmtxBoolean rsFindErrorLocations	(	DmtxByteList *	loc,
		const DmtxByteList *	elp )

static

Find roots of the error locator polynomial (Chien Search).

If the degree of elp is <= tt, we substitute alpha**i, i=1..n into the elp to get the roots, hence the inverse roots, the error location numbers. If the number of errors located does not equal the degree of the elp, we have more than tt errors and cannot correct them.

Parameters

loc
elp

Returns: Is block repairable? (DmtxTrue|DmtxFalse)

Definition at line 437 of file dmtxreedsol.c.

◆ rsFindErrorLocatorPoly()

static DmtxBoolean rsFindErrorLocatorPoly	(	DmtxByteList *	elpOut,
		const DmtxByteList *	syn,
		int	errorWordCount,
		int	maxCorrectable )

static

Find the error location polynomial using Berlekamp-Massey.

More detailed description.

Parameters

elpOut
syn
errorWordCount
maxCorrectable

Returns: Is block repairable? (DmtxTrue|DmtxFalse)

Definition at line 339 of file dmtxreedsol.c.

◆ rsGenPoly()

static DmtxPassFail rsGenPoly	(	DmtxByteList *	gen,
		int	errorWordCount )

static

Populate generator polynomial.

More detailed description.

Parameters

gen
errorWordCount

Returns: Function success (DmtxPass|DmtxFail)

Definition at line 258 of file dmtxreedsol.c.

◆ rsRepairErrors()

static DmtxPassFail rsRepairErrors	(	DmtxByteList *	rec,
		const DmtxByteList *	loc,
		const DmtxByteList *	elp,
		const DmtxByteList *	syn )

static

Find the error values and repair.

Solve for the error value at the error location and correct the error. The procedure is that found in Lin and Costello. For the cases where the number of errors is known to be too large to correct, the information symbols as received are output (the advantage of systematic encoding is that hopefully some of the information symbols will be okay and that if we are in luck, the errors are in the parity part of the transmitted codeword).

Parameters

rec
loc
elp
syn

Definition at line 485 of file dmtxreedsol.c.

Variable Documentation

◆ antilog301

DmtxByte antilog301[]

static

Initial value:

= {
    1,   2,   4,   8,   16,  32,  64,  128, 45,  90,  180, 69,  138, 57,  114, 228, 229, 231, 227, 235, 251, 219,
    155, 27,  54,  108, 216, 157, 23,  46,  92,  184, 93,  186, 89,  178, 73,  146, 9,   18,  36,  72,  144, 13,
    26,  52,  104, 208, 141, 55,  110, 220, 149, 7,   14,  28,  56,  112, 224, 237, 247, 195, 171, 123, 246, 193,
    175, 115, 230, 225, 239, 243, 203, 187, 91,  182, 65,  130, 41,  82,  164, 101, 202, 185, 95,  190, 81,  162,
    105, 210, 137, 63,  126, 252, 213, 135, 35,  70,  140, 53,  106, 212, 133, 39,  78,  156, 21,  42,  84,  168,
    125, 250, 217, 159, 19,  38,  76,  152, 29,  58,  116, 232, 253, 215, 131, 43,  86,  172, 117, 234, 249, 223,
    147, 11,  22,  44,  88,  176, 77,  154, 25,  50,  100, 200, 189, 87,  174, 113, 226, 233, 255, 211, 139, 59,
    118, 236, 245, 199, 163, 107, 214, 129, 47,  94,  188, 85,  170, 121, 242, 201, 191, 83,  166, 97,  194, 169,
    127, 254, 209, 143, 51,  102, 204, 181, 71,  142, 49,  98,  196, 165, 103, 206, 177, 79,  158, 17,  34,  68,
    136, 61,  122, 244, 197, 167, 99,  198, 161, 111, 222, 145, 15,  30,  60,  120, 240, 205, 183, 67,  134, 33,
    66,  132, 37,  74,  148, 5,   10,  20,  40,  80,  160, 109, 218, 153, 31,  62,  124, 248, 221, 151, 3,   6,
    12,  24,  48,  96,  192, 173, 119, 238, 241, 207, 179, 75,  150, 0}

Definition at line 56 of file dmtxreedsol.c.

◆ log301

DmtxByte log301[]

static

Initial value:

= {
    255, 0,   1,   240, 2,   225, 241, 53,  3,   38,  226, 133, 242, 43,  54,  210, 4,   195, 39,  114, 227, 106,
    134, 28,  243, 140, 44,  23,  55,  118, 211, 234, 5,   219, 196, 96,  40,  222, 115, 103, 228, 78,  107, 125,
    135, 8,   29,  162, 244, 186, 141, 180, 45,  99,  24,  49,  56,  13,  119, 153, 212, 199, 235, 91,  6,   76,
    220, 217, 197, 11,  97,  184, 41,  36,  223, 253, 116, 138, 104, 193, 229, 86,  79,  171, 108, 165, 126, 145,
    136, 34,  9,   74,  30,  32,  163, 84,  245, 173, 187, 204, 142, 81,  181, 190, 46,  88,  100, 159, 25,  231,
    50,  207, 57,  147, 14,  67,  120, 128, 154, 248, 213, 167, 200, 63,  236, 110, 92,  176, 7,   161, 77,  124,
    221, 102, 218, 95,  198, 90,  12,  152, 98,  48,  185, 179, 42,  209, 37,  132, 224, 52,  254, 239, 117, 233,
    139, 22,  105, 27,  194, 113, 230, 206, 87,  158, 80,  189, 172, 203, 109, 175, 166, 62,  127, 247, 146, 66,
    137, 192, 35,  252, 10,  183, 75,  216, 31,  83,  33,  73,  164, 144, 85,  170, 246, 65,  174, 61,  188, 202,
    205, 157, 143, 169, 82,  72,  182, 215, 191, 251, 47,  178, 89,  151, 101, 94,  160, 123, 26,  112, 232, 21,
    51,  238, 208, 131, 58,  69,  148, 18,  15,  16,  68,  17,  121, 149, 129, 19,  155, 59,  249, 70,  214, 250,
    168, 71,  201, 156, 64,  60,  237, 130, 111, 20,  93,  122, 177, 150}

Definition at line 41 of file dmtxreedsol.c.

Macros

Functions

Variables

Detailed Description

encoder/decoder released by Simon Rockliff in June 1991.

Macro Definition Documentation

◆ CHKPASS [1/7]

◆ CHKPASS [2/7]

◆ CHKPASS [3/7]

◆ CHKPASS [4/7]

◆ CHKPASS [5/7]

◆ CHKPASS [6/7]

◆ CHKPASS [7/7]

◆ DMTX_CHECK_BOUNDS

◆ GfAdd

◆ GfMult

◆ GfMultAntilog

◆ MAX_ERROR_WORD_COUNT

◆ NN

Function Documentation

◆ rsComputeSyndromes()

◆ rsDecode()

◆ rsEncode()

◆ rsFindErrorLocations()

◆ rsFindErrorLocatorPoly()

◆ rsGenPoly()

◆ rsRepairErrors()

Variable Documentation

◆ antilog301

◆ log301