/* This is a cos() approximation designed to be bit-exact on any platform. Bit exactness
with this approximation is important because it has an impact on the bit allocation */
static opus_int16 bitexact_cos(opus_int16 x)
{
opus_int32 tmp;
opus_int16 x2;
tmp = (4096+((opus_int32)(x)*(x)))>>13;
celt_assert(tmp<=32767);
x2 = tmp;
x2 = (32767-x2) + FRAC_MUL16(x2, (-7651 + FRAC_MUL16(x2, (8277 + FRAC_MUL16(-626, x2)))));
celt_assert(x2<=32766);
return 1+x2;
}
static int bitexact_log2tan(int isin,int icos)
{
int lc;
int ls;
lc=EC_ILOG(icos);
ls=EC_ILOG(isin);
icos<<=15-lc;
isin<<=15-ls;
return (ls-lc)*(1<<11)
+FRAC_MUL16(isin, FRAC_MUL16(isin, -2597) + 7932)
-FRAC_MUL16(icos, FRAC_MUL16(icos, -2597) + 7932);
}
/* This is a cos() approximation designed to be bit-exact on any platform. Bit exactness
with this approximation is important because it has an impact on the bit allocation */
static int16_t bitexact_cos(int16_t x)
{
int32_t tmp;
int16_t x2;
tmp = (4096 + ((int32_t) (x) * (x))) >> 13;
assert(tmp <= 32767);
x2 = tmp;
x2 = (32767 - x2) + FRAC_MUL16(x2,
(-7651 +
FRAC_MUL16(x2,
(8277 +
FRAC_MUL16(-626, x2)))));
assert(x2 <= 32766);
return 1 + x2;
}
