81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
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/* Driver for routines arcmak and arcode */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define NRANSI
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#include "nr.h"
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#include "nrutil.h"
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#define MC 512
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#define NWK 20
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#define MAXLINE 256
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int main(void)
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{
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int k;
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unsigned long i,j,lc,lcode=MAXLINE,n,nch,nrad,nt,nfreq[257],tmp,zero=0;
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unsigned char *code,mess[MAXLINE],ness[MAXLINE];
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arithcode acode;
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FILE *fp;
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code=cvector(0,MAXLINE);
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acode.ilob=lvector(1,NWK);
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acode.iupb=lvector(1,NWK);
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acode.ncumfq=lvector(1,MC+2);
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if ((fp = fopen("text.dat","r")) == NULL)
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nrerror("Input file text.dat not found.\n");
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for (j=1;j<=256;j++) nfreq[j]=0;
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while ((k=getc(fp)) != EOF) {
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if ((k -= 31) >= 1) nfreq[k]++;
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}
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fclose(fp);
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nch=96;
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nrad=256;
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/* here is the initialization that constructs the code */
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arcmak(nfreq,(int)nch,(int)nrad,&acode);
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/* now ready to prompt for lines to encode */
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for (;;) {
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printf("Enter a line:\n");
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if (gets((char *)&mess[1]) == NULL) break;
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n=strlen((char *)&mess[1]);
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/* shift from 256 character alphabet to 96 printing characters */
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for (j=1;j<=n;j++) mess[j] -= 32;
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/* message initialization */
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lc=1;
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arcode(&zero,&code,&lcode,&lc,0,&acode);
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/* here we arithmetically encode mess(1:n) */
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for (j=1;j<=n;j++) {
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tmp=mess[j];
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arcode(&tmp,&code,&lcode,&lc,1,&acode);
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}
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/* message termination */
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arcode(&nch,&code,&lcode,&lc,1,&acode);
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printf("Length of line input, coded= %lu %lu\n",n,lc-1);
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/* here we decode the message, hopefully to get the original back */
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lc=1;
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arcode(&zero,&code,&lcode,&lc,0,&acode);
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for (j=1;j<=lcode;j++) {
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arcode(&i,&code,&lcode,&lc,-1,&acode);
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if (i == nch) break;
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else ness[j]=(unsigned char)i;
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}
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if (j > lcode) nrerror("Arith. coding: Never get here");
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nt=j-1;
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printf("Decoded output:\n");
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for (j=1;j<=nt;j++) printf("%c",(char)(ness[j]+32));
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printf("\n");
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if (nt != n) printf("Error ! j decoded != n input.\n");
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}
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free_cvector(code,0,MAXLINE);
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free_lvector(acode.ncumfq,1,MC+2);
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free_lvector(acode.iupb,1,NWK);
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free_lvector(acode.ilob,1,NWK);
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printf("Normal completion\n");
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return 0;
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}
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#undef NRANSI
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