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Optimize hermite resampler slightly. The vtable lookup on read probably still hurts fine-granularity sound systems like OSS.

This commit is contained in:
Brandon Wright 2011-12-14 02:47:44 -06:00
parent 1b0c82ed3b
commit 2337ab3ed0
1 changed files with 13 additions and 33 deletions
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46
apu/hermite_resampler.h
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@ -14,25 +14,20 @@ class HermiteResampler : public Resampler
{
protected:
double r_step;
double r_frac;
int r_left[4], r_right[4];
float r_step;
float r_frac;
int r_left[4], r_right[4];
double
hermite (double mu1, double a, double b, double c, double d)
static inline float
hermite (float mu1, float a, float b, float c, float d)
{
const double tension = 0.0; //-1 = low, 0 = normal, 1 = high
const double bias = 0.0; //-1 = left, 0 = even, 1 = right
double mu2, mu3, m0, m1, a0, a1, a2, a3;
float mu2, mu3, m0, m1, a0, a1, a2, a3;
mu2 = mu1 * mu1;
mu3 = mu2 * mu1;
m0 = (b - a) * (1 + bias) * (1 - tension) / 2;
m0 += (c - b) * (1 - bias) * (1 - tension) / 2;
m1 = (c - b) * (1 + bias) * (1 - tension) / 2;
m1 += (d - c) * (1 - bias) * (1 - tension) / 2;
m0 = (c - a) * 0.5;
m1 = (d - b) * 0.5;
a0 = +2 * mu3 - 3 * mu2 + 1;
a1 = mu3 - 2 * mu2 + mu1;
@ -72,6 +67,7 @@ class HermiteResampler : public Resampler
read (short *data, int num_samples)
{
int i_position = start >> 1;
int max_samples = buffer_size >> 1;
short *internal_buffer = (short *) buffer;
int o_position = 0;
int consumed = 0;
@ -80,22 +76,6 @@ class HermiteResampler : public Resampler
{
int s_left = internal_buffer[i_position];
int s_right = internal_buffer[i_position + 1];
int max_samples = buffer_size >> 1;
const double margin_of_error = 1.0e-10;
if (fabs(r_step - 1.0) < margin_of_error)
{
data[o_position] = (short) s_left;
data[o_position + 1] = (short) s_right;
o_position += 2;
i_position += 2;
if (i_position >= max_samples)
i_position -= max_samples;
consumed += 2;
continue;
}
while (r_frac <= 1.0 && o_position < num_samples)
{
@ -113,14 +93,14 @@ class HermiteResampler : public Resampler
r_left [1] = r_left [2];
r_left [2] = r_left [3];
r_left [3] = s_left;
r_right[0] = r_right[1];
r_right[1] = r_right[2];
r_right[2] = r_right[3];
r_right[3] = s_right;
r_right[3] = s_right;
r_frac -= 1.0;
i_position += 2;
if (i_position >= max_samples)
i_position -= max_samples;