/* table generator */
static av_cold void init_pow2table(void)
{
+ /* fast way of computing 2^i and 2^(0.5*i) for -63 <= i < 64 */
int i;
+ static const float exp2_tab[2] = {1, M_SQRT2};
+ float exp2_val = powf(2, -63);
+ float root_val = powf(2, -32);
for (i = -63; i < 64; i++) {
- pow2tab[63 + i] = pow(2, i);
- rootpow2tab[63 + i] = sqrt(pow(2, i));
+ if (!(i & 1))
+ root_val *= 2;
+ pow2tab[63 + i] = exp2_val;
+ rootpow2tab[63 + i] = root_val * exp2_tab[i & 1];
+ exp2_val *= 2;
}
}