/* MAKE-PCHK.C - Make a parity check matrix explicitly. *//* 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 "alloc.h"#include "intio.h"#include "open.h"#include "mod2sparse.h"#include "mod2dense.h"#include "mod2convert.h"#include "rcode.h"void usage(void);/* MAIN PROGRAM. */int main( int argc,  char **argv){  char **bit_specs;  char *file;  FILE *f;  int i, j, k;  char junk;  if (!(file = argv[1])    || !argv[2] || sscanf(argv[2],"%d%c",&M,&junk)!=1 || M<=0   || !argv[3] || sscanf(argv[3],"%d%c",&N,&junk)!=1 || N<=0)  { usage();  }  bit_specs = argv+4;  if (bit_specs[0]==0)   { usage();  }  H = mod2sparse_allocate(M,N);  for (k = 0; bit_specs[k]!=0; k++)  { if (sscanf(bit_specs[k],"%d:%d%c",&i,&j,&junk)!=2 || i<0 || j<0)     { usage();    }    if (i>=M || j>=N)    { fprintf(stderr,"Bit %d:%d is out of range\n",i,j);      exit(1);    }    mod2sparse_insert(H,i,j);  }  f = open_file_std(file,"wb");  if (f==NULL)   { fprintf(stderr,"Can't create parity check file: %s\n",file);    exit(1);  }  intio_write(f,('P'<<8)+0x80);    if (ferror(f) || !mod2sparse_write(f,H) || fclose(f)!=0)  { fprintf(stderr,"Error writing to parity check file %s\n",file);    exit(1);  }  return 0;}/* PRINT USAGE MESSAGE AND EXIT. */void usage(void){ fprintf(stderr,"Usage: make-pchk pchk-file n-checks n-bits row:col ...\n");  exit(1);}