add numerical recipes library

lib/nr/ansi/examples/xarcode.c

@@ -0,0 +1,80 @@
+
+/* Driver for routines arcmak and arcode */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define MC 512
+
+#define NWK 20
+
+#define MAXLINE 256
+
+int main(void)
+{
+	int k;
+	unsigned long i,j,lc,lcode=MAXLINE,n,nch,nrad,nt,nfreq[257],tmp,zero=0;
+	unsigned char *code,mess[MAXLINE],ness[MAXLINE];
+	arithcode acode;
+	FILE *fp;
+
+	code=cvector(0,MAXLINE);
+	acode.ilob=lvector(1,NWK);
+	acode.iupb=lvector(1,NWK);
+	acode.ncumfq=lvector(1,MC+2);
+	if ((fp = fopen("text.dat","r")) == NULL)
+		nrerror("Input file text.dat not found.\n");
+	for (j=1;j<=256;j++) nfreq[j]=0;
+	while ((k=getc(fp)) != EOF) {
+		if ((k -= 31) >= 1) nfreq[k]++;
+	}
+	fclose(fp);
+	nch=96;
+	nrad=256;
+	/* here is the initialization that constructs the code */
+	arcmak(nfreq,(int)nch,(int)nrad,&acode);
+	/* now ready to prompt for lines to encode */
+	for (;;) {
+		printf("Enter a line:\n");
+		if (gets((char *)&mess[1]) == NULL) break;
+		n=strlen((char *)&mess[1]);
+		/* shift from 256 character alphabet to 96 printing characters */
+		for (j=1;j<=n;j++) mess[j] -= 32;
+		/* message initialization */
+		lc=1;
+		arcode(&zero,&code,&lcode,&lc,0,&acode);
+		/* here we arithmetically encode mess(1:n) */
+		for (j=1;j<=n;j++) {
+			tmp=mess[j];
+			arcode(&tmp,&code,&lcode,&lc,1,&acode);
+		}
+		/* message termination */
+		arcode(&nch,&code,&lcode,&lc,1,&acode);
+		printf("Length of line input, coded= %lu %lu\n",n,lc-1);
+		/* here we decode the message, hopefully to get the original back */
+		lc=1;
+		arcode(&zero,&code,&lcode,&lc,0,&acode);
+		for (j=1;j<=lcode;j++) {
+			arcode(&i,&code,&lcode,&lc,-1,&acode);
+			if (i == nch) break;
+			else ness[j]=(unsigned char)i;
+		}
+		if (j > lcode) nrerror("Arith. coding: Never get here");
+		nt=j-1;
+		printf("Decoded output:\n");
+		for (j=1;j<=nt;j++) printf("%c",(char)(ness[j]+32));
+		printf("\n");
+		if (nt != n) printf("Error ! j decoded != n input.\n");
+	}
+	free_cvector(code,0,MAXLINE);
+	free_lvector(acode.ncumfq,1,MC+2);
+	free_lvector(acode.iupb,1,NWK);
+	free_lvector(acode.ilob,1,NWK);
+	printf("Normal completion\n");
+	return 0;
+}
+#undef NRANSI