mirror of
https://github.com/libretro/RetroArch.git
synced 2024-11-28 18:50:29 +00:00
111 lines
3.0 KiB
C
111 lines
3.0 KiB
C
/* SSNES - A Super Nintendo Entertainment System (SNES) Emulator frontend for libsnes.
|
|
* Copyright (C) 2010-2011 - Hans-Kristian Arntzen
|
|
*
|
|
* Some code herein may be based on code found in BSNES.
|
|
*
|
|
* SSNES is free software: you can redistribute it and/or modify it under the terms
|
|
* of the GNU General Public License as published by the Free Software Found-
|
|
* ation, either version 3 of the License, or (at your option) any later version.
|
|
*
|
|
* SSNES is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
|
|
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
|
|
* PURPOSE. See the GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along with SSNES.
|
|
* If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
// Hermite resampler based on bsnes' audio library.
|
|
|
|
#include "hermite.h"
|
|
#include <stdlib.h>
|
|
|
|
#define MAX_CHANS 8
|
|
|
|
struct hermite_resampler
|
|
{
|
|
float chan_data[MAX_CHANS][4];
|
|
double r_frac;
|
|
unsigned chans;
|
|
};
|
|
|
|
static inline float hermite_kernel(float mu1, float a, float b, float c, float d)
|
|
{
|
|
float mu2, mu3, m0, m1, a0, a1, a2, a3;
|
|
|
|
mu2 = mu1 * mu1;
|
|
mu3 = mu2 * mu1;
|
|
|
|
m0 = (c - a) * 0.5;
|
|
m1 = (d - b) * 0.5;
|
|
|
|
a0 = +2 * mu3 - 3 * mu2 + 1;
|
|
a1 = mu3 - 2 * mu2 + mu1;
|
|
a2 = mu3 - mu2;
|
|
a3 = -2 * mu3 + 3 * mu2;
|
|
|
|
return (a0 * b) + (a1 * m0) + (a2 * m1) + (a3 * c);
|
|
}
|
|
|
|
hermite_resampler_t *hermite_new(unsigned channels)
|
|
{
|
|
if (channels > MAX_CHANS)
|
|
return NULL;
|
|
|
|
hermite_resampler_t *re = calloc(1, sizeof(*re));
|
|
if (!re)
|
|
return NULL;
|
|
re->chans = channels;
|
|
return re;
|
|
}
|
|
|
|
void hermite_process(hermite_resampler_t *re, struct hermite_data *data)
|
|
{
|
|
double r_step = 1.0 / data->src_ratio;
|
|
size_t processed_out = 0;
|
|
size_t processed_in = 0;
|
|
|
|
size_t in_frames = data->input_frames;
|
|
size_t out_frames = data->output_frames;
|
|
const float *in_data = data->data_in;
|
|
float *out_data = data->data_out;
|
|
|
|
while (processed_in < in_frames && processed_out < out_frames)
|
|
{
|
|
while (re->r_frac <= 1.0 && processed_out < out_frames)
|
|
{
|
|
re->r_frac += r_step;
|
|
for (unsigned i = 0; i < re->chans; i++)
|
|
{
|
|
float res = hermite_kernel(re->r_frac,
|
|
re->chan_data[i][0], re->chan_data[i][1], re->chan_data[i][2], re->chan_data[i][3]);
|
|
*out_data++ = res;
|
|
}
|
|
processed_out++;
|
|
}
|
|
|
|
if (re->r_frac >= 1.0)
|
|
{
|
|
re->r_frac -= 1.0;
|
|
|
|
for (unsigned i = 0; i < re->chans; i++)
|
|
{
|
|
re->chan_data[i][0] = re->chan_data[i][1];
|
|
re->chan_data[i][1] = re->chan_data[i][2];
|
|
re->chan_data[i][2] = re->chan_data[i][3];
|
|
re->chan_data[i][3] = *in_data++;
|
|
}
|
|
processed_in++;
|
|
}
|
|
}
|
|
|
|
data->input_frames_used = processed_in;
|
|
data->output_frames_gen = processed_out;
|
|
}
|
|
|
|
void hermite_free(hermite_resampler_t *re)
|
|
{
|
|
free(re);
|
|
}
|
|
|