Commit 0d28aa99 authored by Jean-Marc Valin's avatar Jean-Marc Valin
Browse files

Now no divisions required in the cwrs code

parent bf17da60
......@@ -30,6 +30,42 @@
#include <stdlib.h>
#include "cwrs.h"
/* Knowing ncwrs() for a fixed number of pulses m and for all vector sizes n,
compute ncwrs() for m+1, for all n. Could also be used when m and n are
swapped just by changing nc */
static celt_uint32_t next_ncwrs32(celt_uint32_t *nc, int len, int nc0)
{
int i;
celt_uint32_t mem;
mem = nc[0];
nc[0] = nc0;
for (i=1;i<len;i++)
{
celt_uint32_t tmp = nc[i]+nc[i-1]+mem;
mem = nc[i];
nc[i] = tmp;
}
}
/* Knowing ncwrs() for a fixed number of pulses m and for all vector sizes n,
compute ncwrs() for m-1, for all n. Could also be used when m and n are
swapped just by changing nc */
static celt_uint32_t prev_ncwrs32(celt_uint32_t *nc, int len, int nc0)
{
int i;
celt_uint32_t mem;
mem = nc[0];
nc[0] = nc0;
for (i=1;i<len;i++)
{
celt_uint32_t tmp = nc[i]-nc[i-1]-mem;
mem = nc[i];
nc[i] = tmp;
}
}
static celt_uint64_t next_ncwrs64(celt_uint64_t *nc, int len, int nc0)
{
int i;
......@@ -60,83 +96,34 @@ static celt_uint64_t prev_ncwrs64(celt_uint64_t *nc, int len, int nc0)
}
}
/* Optional implementation of ncwrs64 using update_ncwrs64(). It's slightly
slower than the standard ncwrs64(), but it could still be useful.
celt_uint64_t ncwrs64_opt(int _n,int _m)
/*Returns the numer of ways of choosing _m elements from a set of size _n with
replacement when a sign bit is needed for each unique element.*/
celt_uint32_t ncwrs(int _n,int _m)
{
int i;
celt_uint64_t ret;
celt_uint64_t nc[_n+1];
celt_uint32_t ret;
celt_uint32_t nc[_n+1];
for (i=0;i<_n+1;i++)
nc[i] = 1;
for (i=0;i<_m;i++)
update_ncwrs64(nc, _n+1, 0);
next_ncwrs32(nc, _n+1, 0);
return nc[_n];
}*/
}
/*Returns the numer of ways of choosing _m elements from a set of size _n with
replacement when a sign bit is needed for each unique element.*/
#if 0
static celt_uint32_t ncwrs(int _n,int _m){
static celt_uint32_t c[32][32];
if(_n<0||_m<0)return 0;
if(!c[_n][_m]){
if(_m<=0)c[_n][_m]=1;
else if(_n>0)c[_n][_m]=ncwrs(_n-1,_m)+ncwrs(_n,_m-1)+ncwrs(_n-1,_m-1);
}
return c[_n][_m];
}
#else
celt_uint32_t ncwrs(int _n,int _m){
celt_uint32_t ret;
celt_uint32_t f;
celt_uint32_t d;
int i;
if(_n<0||_m<0)return 0;
if(_m==0)return 1;
if(_n==0)return 0;
ret=0;
f=_n;
d=1;
for(i=1;i<=_m;i++){
ret+=f*d<<i;
f=(f*(_n-i))/(i+1);
d=(d*(_m-i))/i;
}
return ret;
celt_uint64_t ncwrs64(int _n,int _m)
{
int i;
celt_uint64_t ret;
celt_uint64_t nc[_n+1];
for (i=0;i<_n+1;i++)
nc[i] = 1;
for (i=0;i<_m;i++)
next_ncwrs64(nc, _n+1, 0);
return nc[_n];
}
#endif
#if 0
celt_uint64_t ncwrs64(int _n,int _m){
static celt_uint64_t c[101][101];
if(_n<0||_m<0)return 0;
if(!c[_n][_m]){
if(_m<=0)c[_n][_m]=1;
else if(_n>0)c[_n][_m]=ncwrs64(_n-1,_m)+ncwrs64(_n,_m-1)+ncwrs64(_n-1,_m-1);
}
return c[_n][_m];
}
#else
celt_uint64_t ncwrs64(int _n,int _m){
celt_uint64_t ret;
celt_uint64_t f;
celt_uint64_t d;
int i;
if(_n<0||_m<0)return 0;
if(_m==0)return 1;
if(_n==0)return 0;
ret=0;
f=_n;
d=1;
for(i=1;i<=_m;i++){
ret+=f*d<<i;
f=(f*(_n-i))/(i+1);
d=(d*(_m-i))/i;
}
return ret;
}
#endif
/*Returns the _i'th combination of _m elements chosen from a set of size _n
with associated sign bits.
......@@ -145,12 +132,17 @@ celt_uint64_t ncwrs64(int _n,int _m){
void cwrsi(int _n,int _m,celt_uint32_t _i,int *_x,int *_s){
int j;
int k;
celt_uint32_t nc[_n+1];
for (j=0;j<_n+1;j++)
nc[j] = 1;
for (k=0;k<_m-1;k++)
next_ncwrs32(nc, _n+1, 0);
for(k=j=0;k<_m;k++){
celt_uint32_t pn;
celt_uint32_t p;
celt_uint32_t t;
p=ncwrs(_n-j,_m-k-1);
pn=ncwrs(_n-j-1,_m-k-1);
celt_uint32_t pn, p, t;
/*p=ncwrs(_n-j,_m-k-1);
pn=ncwrs(_n-j-1,_m-k-1);*/
p=nc[_n-j];
pn=nc[_n-j-1];
p+=pn;
if(k>0){
t=p>>1;
......@@ -160,13 +152,18 @@ void cwrsi(int _n,int _m,celt_uint32_t _i,int *_x,int *_s){
_i-=p;
j++;
p=pn;
pn=ncwrs(_n-j-1,_m-k-1);
/*pn=ncwrs(_n-j-1,_m-k-1);*/
pn=nc[_n-j-1];
p+=pn;
}
t=p>>1;
_s[k]=_i>=t;
_x[k]=j;
if(_s[k])_i-=t;
if (k<_m-2)
prev_ncwrs32(nc, _n+1, 0);
else
prev_ncwrs32(nc, _n+1, 1);
}
}
......@@ -174,23 +171,37 @@ void cwrsi(int _n,int _m,celt_uint32_t _i,int *_x,int *_s){
of size _n with associated sign bits.
_x: The combination with elements sorted in ascending order.
_s: The associated sign bits.*/
celt_uint32_t icwrs(int _n,int _m,const int *_x,const int *_s){
celt_uint32_t icwrs(int _n,int _m,const int *_x,const int *_s, celt_uint32_t *bound){
celt_uint32_t i;
int j;
int k;
celt_uint32_t nc[_n+1];
for (j=0;j<_n+1;j++)
nc[j] = 1;
for (k=0;k<_m;k++)
next_ncwrs32(nc, _n+1, 0);
if (bound)
*bound = nc[_n];
i=0;
for(k=j=0;k<_m;k++){
celt_uint32_t pn;
celt_uint32_t p;
p=ncwrs(_n-j,_m-k-1);
pn=ncwrs(_n-j-1,_m-k-1);
if (k<_m-1)
prev_ncwrs32(nc, _n+1, 0);
else
prev_ncwrs32(nc, _n+1, 1);
/*p=ncwrs(_n-j,_m-k-1);
pn=ncwrs(_n-j-1,_m-k-1);*/
p=nc[_n-j];
pn=nc[_n-j-1];
p+=pn;
if(k>0)p>>=1;
while(j<_x[k]){
i+=p;
j++;
p=pn;
pn=ncwrs(_n-j-1,_m-k-1);
/*pn=ncwrs(_n-j-1,_m-k-1);*/
pn=nc[_n-j-1];
p+=pn;
}
if((k==0||_x[k]!=_x[k-1])&&_s[k])i+=p>>1;
......@@ -211,9 +222,7 @@ void cwrsi64(int _n,int _m,celt_uint64_t _i,int *_x,int *_s){
for (k=0;k<_m-1;k++)
next_ncwrs64(nc, _n+1, 0);
for(k=j=0;k<_m;k++){
celt_uint64_t pn;
celt_uint64_t p;
celt_uint64_t t;
celt_uint64_t pn, p, t;
/*p=ncwrs64(_n-j,_m-k-1);
pn=ncwrs64(_n-j-1,_m-k-1);*/
p=nc[_n-j];
......@@ -328,16 +337,30 @@ void encode_pulses(int *_y, int N, int K, ec_enc *enc)
int comb[K];
int signs[K];
pulse2comb(N, K, comb, signs, _y);
celt_uint64_t bound, id;
id = icwrs64(N, K, comb, signs, &bound);
ec_enc_uint64(enc,id,bound);
/* Go with 32-bit path if we're sure we can */
if (N<=13 && K<=13)
{
celt_uint32_t bound, id;
id = icwrs(N, K, comb, signs, &bound);
ec_enc_uint(enc,id,bound);
} else {
celt_uint64_t bound, id;
id = icwrs64(N, K, comb, signs, &bound);
ec_enc_uint64(enc,id,bound);
}
}
void decode_pulses(int *_y, int N, int K, ec_dec *dec)
{
int comb[K];
int signs[K];
cwrsi64(N, K, ec_dec_uint64(dec, ncwrs64(N, K)), comb, signs);
comb2pulse(N, K, _y, comb, signs);
if (N<=13 && K<=13)
{
cwrsi(N, K, ec_dec_uint(dec, ncwrs(N, K)), comb, signs);
comb2pulse(N, K, _y, comb, signs);
} else {
cwrsi64(N, K, ec_dec_uint64(dec, ncwrs64(N, K)), comb, signs);
comb2pulse(N, K, _y, comb, signs);
}
}
......@@ -40,7 +40,7 @@ celt_uint32_t ncwrs(int _n,int _m);
void cwrsi(int _n,int _m,celt_uint32_t _i,int *_x,int *_s);
celt_uint32_t icwrs(int _n,int _m,const int *_x,const int *_s);
celt_uint32_t icwrs(int _n,int _m,const int *_x,const int *_s, celt_uint32_t *bound);
void comb2pulse(int _n,int _m,int *_y,const int *_x,const int *_s);
......
......@@ -30,7 +30,7 @@ int main(int _argc,char **_argv){
printf(" %c%i",k>0&&x[k]==x[k-1]?' ':s[k]?'-':'+',x[k]);
}
printf(" ->");*/
if(icwrs(n,m,x,s)!=i){
if(icwrs(n,m,x,s, NULL)!=i){
fprintf(stderr,"Combination-index mismatch.\n");
return 1;
}
......
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