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Reduce the number of branches around ncwrs* and ucwrs* calls with k==0.

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This slightly reduces the executable size and might improve
performance on platforms without good branch prediction.
This commit is contained in:
Benjamin M. Schwartz 2011-08-16 21:18:32 -04:00 • committed by Jean-Marc Valin
parent 222494f3ea
commit 711eade6d5
1 changed files with 20 additions and 12 deletions
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32
libcelt/cwrs.c
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@ -253,33 +253,39 @@ static inline opus_uint32 imusdiv32even(opus_uint32 _a,opus_uint32 _b,
/*Compute U(2,_k). /*Compute U(2,_k).
Note that this may be called with _k=32768 (maxK[2]+1).*/ Note that this may be called with _k=32768 (maxK[2]+1).*/
static inline unsigned ucwrs2(unsigned _k){ static inline unsigned ucwrs2(unsigned _k){
return _k?_k+(_k-1):0; celt_assert(_k>0);
return _k+(_k-1);
} }
/*Compute V(2,_k).*/ /*Compute V(2,_k).*/
static inline opus_uint32 ncwrs2(int _k){ static inline opus_uint32 ncwrs2(int _k){
return _k?4*(opus_uint32)_k:1; celt_assert(_k>0);
return 4*(opus_uint32)_k;
} }
/*Compute U(3,_k). /*Compute U(3,_k).
Note that this may be called with _k=32768 (maxK[3]+1).*/ Note that this may be called with _k=32768 (maxK[3]+1).*/
static inline opus_uint32 ucwrs3(unsigned _k){ static inline opus_uint32 ucwrs3(unsigned _k){
return _k?(2*(opus_uint32)_k-2)*_k+1:0; celt_assert(_k>0);
return (2*(opus_uint32)_k-2)*_k+1;
} }
/*Compute V(3,_k).*/ /*Compute V(3,_k).*/
static inline opus_uint32 ncwrs3(int _k){ static inline opus_uint32 ncwrs3(int _k){
return _k?2*(2*(unsigned)_k*(opus_uint32)_k+1):1; celt_assert(_k>0);
return 2*(2*(unsigned)_k*(opus_uint32)_k+1);
} }
/*Compute U(4,_k).*/ /*Compute U(4,_k).*/
static inline opus_uint32 ucwrs4(int _k){ static inline opus_uint32 ucwrs4(int _k){
return _k?imusdiv32odd(2*_k,(2*_k-3)*(opus_uint32)_k+4,3,1):0; celt_assert(_k>0);
return imusdiv32odd(2*_k,(2*_k-3)*(opus_uint32)_k+4,3,1);
} }
/*Compute V(4,_k).*/ /*Compute V(4,_k).*/
static inline opus_uint32 ncwrs4(int _k){ static inline opus_uint32 ncwrs4(int _k){
return _k?((_k*(opus_uint32)_k+2)*_k)/3<<3:1; celt_assert(_k>0);
return ((_k*(opus_uint32)_k+2)*_k)/3<<3;
} }
#endif /* SMALL_FOOTPRINT */ #endif /* SMALL_FOOTPRINT */
@ -382,7 +388,7 @@ static inline void cwrsi2(int _k,opus_uint32 _i,int *_y){
_i-=p&s; _i-=p&s;
yj=_k; yj=_k;
_k=_i+1>>1; _k=_i+1>>1;
p=ucwrs2(_k); p=_k?ucwrs2(_k):0;
_i-=p; _i-=p;
yj-=_k; yj-=_k;
_y[0]=yj+s^s; _y[0]=yj+s^s;
@ -403,7 +409,7 @@ static void cwrsi3(int _k,opus_uint32 _i,int *_y){
/*Finds the maximum _k such that ucwrs3(_k)<=_i (tested for all /*Finds the maximum _k such that ucwrs3(_k)<=_i (tested for all
_i<2147418113=U(3,32768)).*/ _i<2147418113=U(3,32768)).*/
_k=_i>0?isqrt32(2*_i-1)+1>>1:0; _k=_i>0?isqrt32(2*_i-1)+1>>1:0;
p=ucwrs3(_k); p=_k?ucwrs3(_k):0;
_i-=p; _i-=p;
yj-=_k; yj-=_k;
_y[0]=yj+s^s; _y[0]=yj+s^s;
@ -430,7 +436,7 @@ static void cwrsi4(int _k,opus_uint32 _i,int *_y){
kr=_k; kr=_k;
for(;;){ for(;;){
_k=kl+kr>>1; _k=kl+kr>>1;
p=ucwrs4(_k); p=_k?ucwrs4(_k):0;
if(p<_i){ if(p<_i){
if(_k>=kr)break; if(_k>=kr)break;
kl=_k+1; kl=_k+1;
@ -492,7 +498,7 @@ static inline opus_uint32 icwrs2(const int *_y,int *_k){
opus_uint32 i; opus_uint32 i;
int k; int k;
i=icwrs1(_y+1,&k); i=icwrs1(_y+1,&k);
i+=ucwrs2(k); i+=k?ucwrs2(k):0;
k+=abs(_y[0]); k+=abs(_y[0]);
if(_y[0]<0)i+=ucwrs2(k+1U); if(_y[0]<0)i+=ucwrs2(k+1U);
*_k=k; *_k=k;
@ -507,7 +513,7 @@ static inline opus_uint32 icwrs3(const int *_y,int *_k){
opus_uint32 i; opus_uint32 i;
int k; int k;
i=icwrs2(_y+1,&k); i=icwrs2(_y+1,&k);
i+=ucwrs3(k); i+=k?ucwrs3(k):0;
k+=abs(_y[0]); k+=abs(_y[0]);
if(_y[0]<0)i+=ucwrs3(k+1U); if(_y[0]<0)i+=ucwrs3(k+1U);
*_k=k; *_k=k;
@ -522,7 +528,7 @@ static inline opus_uint32 icwrs4(const int *_y,int *_k){
opus_uint32 i; opus_uint32 i;
int k; int k;
i=icwrs3(_y+1,&k); i=icwrs3(_y+1,&k);
i+=ucwrs4(k); i+=k?ucwrs4(k):0;
k+=abs(_y[0]); k+=abs(_y[0]);
if(_y[0]<0)i+=ucwrs4(k+1); if(_y[0]<0)i+=ucwrs4(k+1);
*_k=k; *_k=k;
@ -584,6 +590,7 @@ void get_required_bits(opus_int16 *_bits,int _n,int _maxk,int _frac){
void encode_pulses(const int *_y,int _n,int _k,ec_enc *_enc){ void encode_pulses(const int *_y,int _n,int _k,ec_enc *_enc){
opus_uint32 i; opus_uint32 i;
celt_assert(_k>0);
#ifndef SMALL_FOOTPRINT #ifndef SMALL_FOOTPRINT
switch(_n){ switch(_n){
case 2:{ case 2:{
@ -616,6 +623,7 @@ void encode_pulses(const int *_y,int _n,int _k,ec_enc *_enc){
void decode_pulses(int *_y,int _n,int _k,ec_dec *_dec) void decode_pulses(int *_y,int _n,int _k,ec_dec *_dec)
{ {
celt_assert(_k>0);
#ifndef SMALL_FOOTPRINT #ifndef SMALL_FOOTPRINT
switch(_n){ switch(_n){
case 2:cwrsi2(_k,ec_dec_uint(_dec,ncwrs2(_k)),_y);break; case 2:cwrsi2(_k,ec_dec_uint(_dec,ncwrs2(_k)),_y);break;