encode.c

LDPC 编码 解码仿真程序 包括编码解码 矩阵生成

/* ENCODE.C - Encode message blocks. */

/* Copyright (c) 2000, 2001 by Radford M. Neal 
 *
 * Permission is granted for anyone to copy, use, or modify this program 
 * for purposes of research or education, provided this copyright notice 
 * is retained, and note is made of any changes that have been made. 
 *
 * This program is distributed without any warranty, express or implied.
 * As this program was written for research purposes only, it has not been
 * tested to the degree that would be advisable in any important application.
 * All use of this program is entirely at the user's own risk.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "rand.h"
#include "alloc.h"
#include "blockio.h"
#include "open.h"
#include "mod2sparse.h"
#include "mod2dense.h"
#include "mod2convert.h"
#include "rcode.h"
#include "enc.h"

void usage(void);


/* MAIN PROGRAM. */

int main( int argc, char **argv)
{
  char *source_file, *encoded_file;
  char *pchk_file, *gen_file;
  mod2dense *u, *v;

  FILE *srcf, *encf;
  char *sblk, *cblk, *chks;//sourceblock???codeblock???
  int i, n;

  /* Look at arguments. */

  if (!(pchk_file = argv[1]) || !(gen_file = argv[2]) || !(source_file = argv[3])|| !(encoded_file = argv[4])|| argv[5])
  { 
	  usage();
  }

  if ((strcmp(pchk_file,"-")==0) + (strcmp(gen_file,"-")==0) + (strcmp(source_file,"-")==0) > 1)
  { 
	fprintf(stderr,"Can't read more than one stream from standard input\n");
    exit(1);
  }

  /* Read parity check file */

  read_pchk(pchk_file);

  if (N<=M)
  { 
	  fprintf(stderr, "Can't encode if number of bits (%d) not greater than number of checks (%d)\n", N,M);
      exit(1);
  }

  /* Read generator matrix file. */

  read_gen(gen_file,0,0);

  /* Allocate needed space. */

  if (type=='d')
  { 
	u = mod2dense_allocate(N-M,1);
    v = mod2dense_allocate(M,1);
  }

  if (type=='m')
  {
	u = mod2dense_allocate(M,1);
    v = mod2dense_allocate(M,1);
  }
  /* Open source file. */
  srcf = open_file_std(source_file,"r");
  if (srcf==NULL)
  { 
	fprintf(stderr,"Can't open source file: %s\n",source_file);
    exit(1);
  }
  /* Create encoded output file. */
  encf = open_file_std(encoded_file,"w");
  if (encf==NULL)
  { 
    fprintf(stderr,"Can't create file for encoded data: %s\n",encoded_file);
    exit(1);
  }
  sblk = chk_alloc (N-M, sizeof *sblk);//
  cblk = chk_alloc (N, sizeof *cblk);
  chks = chk_alloc (M, sizeof *chks);
  /* Encode successive blocks. */
  for (n = 0; ; n++)
  { 
		/* Read block from source file. */
		if (blockio_read(srcf,sblk,N-M)==EOF) 
		{ 
			break;
		}
		/* Compute encoded block. */
		switch (type)
		{ 
		  case 's':
		  { 
			sparse_encode (sblk, cblk);
			break;
		  }
		  case 'd':
		  { 
			dense_encode (sblk, cblk, u, v);
			break;
		  }
		  case 'm':
		  { 
			mixed_encode (sblk, cblk, u, v);
			break;
		  }
		}

		/* Check that encoded block is a code word. */
		mod2sparse_mulvec (H, cblk, chks);
		for (i = 0; i<M; i++) 
		{ 
		  if (chks[i]==1)
		  { 
			fprintf(stderr,"Output block %d is not a code word!  (Fails check %d)\n",n,i);
			abort(); 
		  }
		}
		/* Write encoded block to encoded output file. */
		blockio_write(encf,cblk,N);
  }

  fprintf(stderr, "Encoded %d blocks, source block size %d, encoded block size %d\n",n,N-M,N);

  if (ferror(encf) || fclose(encf)!=0)
  { 
	fprintf(stderr,"Error writing encoded blocks to %s\n",encoded_file);
    exit(1);
  }
  return 0;
}


/* PRINT USAGE MESSAGE AND EXIT. */

void usage(void)
{ 
  fprintf(stderr, "Usage:  encode pchk-file gen-file source-file encoded-file\n");
  exit(1);
}