70 lines
1.9 KiB
C
70 lines
1.9 KiB
C
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#define NRANSI
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#include "nrutil.h"
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typedef struct {
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unsigned long *icod,*ncod,*left,*right,nch,nodemax;
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} huffcode;
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void hufmak(unsigned long nfreq[], unsigned long nchin, unsigned long *ilong,
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unsigned long *nlong, huffcode *hcode)
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{
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void hufapp(unsigned long index[], unsigned long nprob[], unsigned long n,
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unsigned long i);
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int ibit;
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long node,*up;
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unsigned long j,k,*index,n,nused,*nprob;
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static unsigned long setbit[32]={0x1L,0x2L,0x4L,0x8L,0x10L,0x20L,
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0x40L,0x80L,0x100L,0x200L,0x400L,0x800L,0x1000L,0x2000L,
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0x4000L,0x8000L,0x10000L,0x20000L,0x40000L,0x80000L,0x100000L,
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0x200000L,0x400000L,0x800000L,0x1000000L,0x2000000L,0x4000000L,
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0x8000000L,0x10000000L,0x20000000L,0x40000000L,0x80000000L};
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hcode->nch=nchin;
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index=lvector(1,(long)(2*hcode->nch-1));
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up=(long *)lvector(1,(long)(2*hcode->nch-1));
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nprob=lvector(1,(long)(2*hcode->nch-1));
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for (nused=0,j=1;j<=hcode->nch;j++) {
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nprob[j]=nfreq[j];
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hcode->icod[j]=hcode->ncod[j]=0;
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if (nfreq[j]) index[++nused]=j;
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}
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for (j=nused;j>=1;j--) hufapp(index,nprob,nused,j);
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k=hcode->nch;
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while (nused > 1) {
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node=index[1];
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index[1]=index[nused--];
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hufapp(index,nprob,nused,1);
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nprob[++k]=nprob[index[1]]+nprob[node];
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hcode->left[k]=node;
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hcode->right[k]=index[1];
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up[index[1]] = -(long)k;
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up[node]=index[1]=k;
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hufapp(index,nprob,nused,1);
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}
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up[hcode->nodemax=k]=0;
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for (j=1;j<=hcode->nch;j++) {
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if (nprob[j]) {
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for (n=0,ibit=0,node=up[j];node;node=up[node],ibit++) {
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if (node < 0) {
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n |= setbit[ibit];
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node = -node;
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}
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}
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hcode->icod[j]=n;
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hcode->ncod[j]=ibit;
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}
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}
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*nlong=0;
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for (j=1;j<=hcode->nch;j++) {
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if (hcode->ncod[j] > *nlong) {
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*nlong=hcode->ncod[j];
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*ilong=j-1;
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}
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}
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free_lvector(nprob,1,(long)(2*hcode->nch-1));
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free_lvector((unsigned long *)up,1,(long)(2*hcode->nch-1));
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free_lvector(index,1,(long)(2*hcode->nch-1));
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}
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#undef NRANSI
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