add numerical recipes library

lib/nr/cpp/recipes/arcode.cpp

@@ -0,0 +1,72 @@
+#include "nr.h"
+
+namespace {
+	inline unsigned long JTRY(const unsigned long j, const unsigned long k,
+		const unsigned long m)
+	{
+		return (unsigned long) (DP(j)*DP(k)/DP (m));
+	}
+}
+
+void NR::arcode(unsigned long &ich, string &code, unsigned long &lcd,
+	const int isign, arithcode &acode)
+{
+	int j,k;
+	unsigned long ihi,ja,jh,jl,m;
+
+	int NWK=acode.ilob.size();
+	if (isign == 0) {
+		acode.jdif=acode.nrad-1;
+		for (j=NWK-1;j>=0;j--) {
+			acode.iupb[j]=acode.nrad-1;
+			acode.ilob[j]=0;
+			acode.nc=j;
+			if (acode.jdif > acode.minint) return;
+			acode.jdif=(acode.jdif+1)*acode.nrad-1;
+		}
+		nrerror("NWK too small in arcode.");
+	} else {
+		if (isign > 0) {
+			if (ich > acode.nch) nrerror("bad ich in arcode.");
+		} else {
+			ja=(unsigned char) code[lcd]-acode.ilob[acode.nc];
+			for (j=acode.nc+1;j<NWK;j++) {
+				ja *= acode.nrad;
+				ja += ((unsigned char) code[lcd+j-acode.nc]-acode.ilob[j]);
+			}
+			ihi=acode.nch+1;
+			ich=0;
+			while (ihi-ich > 1) {
+				m=(ich+ihi)>>1;
+				if (ja >= JTRY(acode.jdif,acode.ncumfq[m],acode.ncum))
+					ich=m;
+				else ihi=m;
+			}
+			if (ich == acode.nch) return;
+		}
+		jh=JTRY(acode.jdif,acode.ncumfq[ich+1],acode.ncum);
+		jl=JTRY(acode.jdif,acode.ncumfq[ich],acode.ncum);
+		acode.jdif=jh-jl;
+		arcsum(acode.ilob,acode.iupb,jh,NWK,acode.nrad,acode.nc);
+		arcsum(acode.ilob,acode.ilob,jl,NWK,acode.nrad,acode.nc);
+		for (j=acode.nc;j<NWK;j++) {
+			if (ich != acode.nch && acode.iupb[j] != acode.ilob[j]) break;
+			if (isign > 0) code += (unsigned char)acode.ilob[j];
+			lcd++;
+		}
+		if (j+1 > NWK) return;
+		acode.nc=j;
+		for(j=0;acode.jdif<acode.minint;j++)
+			acode.jdif *= acode.nrad;
+		if (j > acode.nc) nrerror("NWK too small in arcode.");
+		if (j != 0) {
+			for (k=acode.nc;k<NWK;k++) {
+				acode.iupb[k-j]=acode.iupb[k];
+				acode.ilob[k-j]=acode.ilob[k];
+			}
+		}
+		acode.nc -= j;
+		for (k=NWK-j;k<NWK;k++) acode.iupb[k]=acode.ilob[k]=0;
+	}
+	return;
+}