eden-emu/opus
19
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

optimisation: simplified the "full gain" case of alg_quant() to remove some

Browse source 
32-bit muls.
This commit is contained in:
Jean-Marc Valin 2008-04-15 18:04:33 +10:00
parent ed317c94c3
commit d568303134
2 changed files with 34 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

17
libcelt/mathops.h
View file

@ -85,6 +85,7 @@ static inline int find_max32(celt_word32_t *x, int len)
#ifndef FIXED_POINT
#define celt_sqrt(x) ((float)sqrt(x))
#define celt_psqrt(x) ((float)sqrt(x))
#define celt_rsqrt(x) (1.f/celt_sqrt(x))
#define celt_acos acos
#define celt_exp exp
@ -153,6 +154,22 @@ static inline celt_word32_t celt_sqrt(celt_word32_t x)
return rt;
}
/** Sqrt approximation (QX input, QX/2 output) that assumes that the input is
strictly positive */
static inline celt_word32_t celt_psqrt(celt_word32_t x)
{
int k;
celt_word16_t n;
celt_word32_t rt;
const celt_word16_t C[5] = {23174, 11584, -3011, 1570, -557};
k = (celt_ilog2(x)>>1)-7;
x = VSHR32(x, (k<<1));
n = x-32768;
rt = ADD16(C[0], MULT16_16_Q15(n, ADD16(C[1], MULT16_16_Q15(n, ADD16(C[2],
MULT16_16_Q15(n, ADD16(C[3], MULT16_16_Q15(n, (C[4])))))))));
rt = VSHR32(rt,7-k);
return rt;
}
#define L1 32767
#define L2 -7651