89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
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#include <stdio.h>
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#define NWK 20
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#define JTRY(j,k,m) ((long)((((double)(k))*((double)(j)))/((double)(m))))
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typedef struct {
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unsigned long *ilob,*iupb,*ncumfq,jdif,nc,minint,nch,ncum,nrad;
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} arithcode;
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void arcode(ich,codep,lcode,lcd,isign,acode)
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arithcode *acode;
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int isign;
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unsigned char **codep;
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unsigned long *ich,*lcd,*lcode;
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{
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char *realloc();
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void arcsum();
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void nrerror();
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int j,k;
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unsigned long ihi,ja,jh,jl,m;
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if (!isign) {
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acode->jdif=acode->nrad-1;
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for (j=NWK;j>=1;j--) {
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acode->iupb[j]=acode->nrad-1;
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acode->ilob[j]=0;
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acode->nc=j;
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if (acode->jdif > acode->minint) return;
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acode->jdif=(acode->jdif+1)*acode->nrad-1;
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}
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nrerror("NWK too small in arcode.");
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} else {
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if (isign > 0) {
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if (*ich > acode->nch) nrerror("bad ich in arcode.");
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}
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else {
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ja=(*codep)[*lcd]-acode->ilob[acode->nc];
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for (j=acode->nc+1;j<=NWK;j++) {
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ja *= acode->nrad;
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ja += ((*codep)[*lcd+j-acode->nc]-acode->ilob[j]);
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}
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ihi=acode->nch+1;
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*ich=0;
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while (ihi-(*ich) > 1) {
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m=(*ich+ihi)>>1;
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if (ja >= JTRY(acode->jdif,acode->ncumfq[m+1],acode->ncum))
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*ich=m;
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else ihi=m;
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}
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if (*ich == acode->nch) return;
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}
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jh=JTRY(acode->jdif,acode->ncumfq[*ich+2],acode->ncum);
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jl=JTRY(acode->jdif,acode->ncumfq[*ich+1],acode->ncum);
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acode->jdif=jh-jl;
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arcsum(acode->ilob,acode->iupb,jh,NWK,acode->nrad,acode->nc);
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arcsum(acode->ilob,acode->ilob,jl,NWK,acode->nrad,acode->nc);
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for (j=acode->nc;j<=NWK;j++) {
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if (*ich != acode->nch && acode->iupb[j] != acode->ilob[j]) break;
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if (*lcd > *lcode) {
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fprintf(stderr,"Reached the end of the 'code' array.\n");
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fprintf(stderr,"Attempting to expand its size.\n");
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*lcode += *lcode/2;
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if ((*codep=(unsigned char *)realloc(*codep,
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(unsigned)(*lcode*sizeof(unsigned char)))) == NULL) {
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nrerror("Size expansion failed");
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}
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}
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if (isign > 0) (*codep)[*lcd]=(unsigned char)acode->ilob[j];
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++(*lcd);
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}
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if (j > NWK) return;
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acode->nc=j;
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for(j=0;acode->jdif<acode->minint;j++)
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acode->jdif *= acode->nrad;
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if (acode->nc-j < 1) nrerror("NWK too small in arcode.");
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if (j) {
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for (k=acode->nc;k<=NWK;k++) {
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acode->iupb[k-j]=acode->iupb[k];
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acode->ilob[k-j]=acode->ilob[k];
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}
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}
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acode->nc -= j;
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for (k=NWK-j+1;k<=NWK;k++) acode->iupb[k]=acode->ilob[k]=0;
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}
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return;
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}
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#undef NWK
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#undef JTRY
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