mirror of
https://github.com/ekeeke/Genesis-Plus-GX.git
synced 2024-12-29 04:31:49 +01:00
345 lines
6.9 KiB
C
345 lines
6.9 KiB
C
/* Game_Music_Emu 0.5.2. http://www.slack.net/~ant/ */
|
|
/* Copyright (C) 2004-2006 Shay Green. */
|
|
/* C Conversion by Eke-Eke for use in Genesis Plus (2009). */
|
|
|
|
#include "Fir_Resampler.h"
|
|
|
|
//#include <assert.h>
|
|
#include <string.h>
|
|
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <math.h>
|
|
|
|
/* sound buffer */
|
|
static sample_t *buffer = NULL;
|
|
static int buffer_size = 0;
|
|
|
|
static sample_t impulses[MAX_RES][WIDTH];
|
|
static sample_t* write_pos = NULL;
|
|
static int res = 1;
|
|
static int imp_phase = 0;
|
|
static unsigned long skip_bits = 0;
|
|
static int step = STEREO;
|
|
static int input_per_cycle;
|
|
static double ratio = 1.0;
|
|
|
|
static void gen_sinc(double rolloff, int width, double offset, double spacing, double scale, int count, sample_t *out )
|
|
{
|
|
double w, rolloff_cos_a, num, den, sinc;
|
|
double const maxh = 256;
|
|
double const fstep = M_PI / maxh * spacing;
|
|
double const to_w = maxh * 2 / width;
|
|
double const pow_a_n = pow( rolloff, maxh );
|
|
scale /= maxh * 2;
|
|
|
|
double angle = (count / 2 - 1 + offset) * -fstep;
|
|
|
|
while ( count-- )
|
|
{
|
|
*out++ = 0;
|
|
w = angle * to_w;
|
|
if ( fabs( w ) < M_PI )
|
|
{
|
|
rolloff_cos_a = rolloff * cos( angle );
|
|
num = 1 - rolloff_cos_a -
|
|
pow_a_n * cos( maxh * angle ) +
|
|
pow_a_n * rolloff * cos( (maxh - 1) * angle );
|
|
den = 1 - rolloff_cos_a - rolloff_cos_a + rolloff * rolloff;
|
|
sinc = scale * num / den - scale;
|
|
|
|
out [-1] = (short) (cos( w ) * sinc + sinc);
|
|
}
|
|
angle += fstep;
|
|
}
|
|
}
|
|
|
|
/*static int available( long input_count )
|
|
{
|
|
int cycle_count = input_count / input_per_cycle;
|
|
int output_count = cycle_count * res * STEREO;
|
|
input_count -= cycle_count * input_per_cycle;
|
|
|
|
unsigned long skip = skip_bits >> imp_phase;
|
|
int remain = res - imp_phase;
|
|
while ( input_count >= 0 )
|
|
{
|
|
input_count -= step + (skip & 1) * STEREO;
|
|
skip >>= 1;
|
|
if ( !--remain )
|
|
{
|
|
skip = skip_bits;
|
|
remain = res;
|
|
}
|
|
output_count += 2;
|
|
}
|
|
return output_count;
|
|
}
|
|
*/
|
|
int Fir_Resampler_avail()
|
|
{
|
|
long count = 0;
|
|
sample_t* in = buffer;
|
|
sample_t* end_pos = write_pos;
|
|
unsigned long skip = skip_bits >> imp_phase;
|
|
int remain = res - imp_phase;
|
|
if ( end_pos - in >= WIDTH * STEREO )
|
|
{
|
|
end_pos -= WIDTH * STEREO;
|
|
do
|
|
{
|
|
count++;
|
|
remain--;
|
|
in += (skip * STEREO) & STEREO;
|
|
skip >>= 1;
|
|
in += step;
|
|
|
|
if ( !remain )
|
|
{
|
|
skip = skip_bits;
|
|
remain = res;
|
|
}
|
|
}
|
|
while ( in <= end_pos );
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
int Fir_Resampler_initialize( int new_size )
|
|
{
|
|
res = 1;
|
|
skip_bits = 0;
|
|
imp_phase = 0;
|
|
step = STEREO;
|
|
ratio = 1.0;
|
|
buffer = (sample_t *) realloc( buffer, (new_size + WRITE_OFFSET) * sizeof (sample_t) );
|
|
write_pos = 0;
|
|
if ( !buffer ) return 0;
|
|
buffer_size = new_size + WRITE_OFFSET;
|
|
Fir_Resampler_clear();
|
|
return 1;
|
|
}
|
|
|
|
void Fir_Resampler_shutdown( void )
|
|
{
|
|
if (buffer) free(buffer);
|
|
buffer = 0;
|
|
buffer_size = 0;
|
|
write_pos = 0;
|
|
}
|
|
|
|
void Fir_Resampler_clear()
|
|
{
|
|
imp_phase = 0;
|
|
if ( buffer_size )
|
|
{
|
|
write_pos = &buffer [WRITE_OFFSET];
|
|
memset( buffer, 0, buffer_size * sizeof (sample_t) );
|
|
}
|
|
}
|
|
|
|
double Fir_Resampler_time_ratio( double new_factor, double rolloff )
|
|
{
|
|
ratio = new_factor;
|
|
|
|
int i, r;
|
|
double nearest, error;
|
|
double fstep = 0.0;
|
|
double least_error = 2;
|
|
double pos = 0.0;
|
|
res = -1;
|
|
|
|
for ( r = 1; r <= MAX_RES; r++ )
|
|
{
|
|
pos += ratio;
|
|
nearest = floor( pos + 0.5 );
|
|
error = fabs( pos - nearest );
|
|
if ( error < least_error )
|
|
{
|
|
res = r;
|
|
fstep = nearest / res;
|
|
least_error = error;
|
|
}
|
|
}
|
|
|
|
skip_bits = 0;
|
|
|
|
step = STEREO * (int) floor( fstep );
|
|
|
|
ratio = fstep;
|
|
fstep = fmod( fstep, 1.0 );
|
|
|
|
double filter = (ratio < 1.0) ? 1.0 : 1.0 / ratio;
|
|
pos = 0.0;
|
|
input_per_cycle = 0;
|
|
|
|
memset(impulses, 0, MAX_RES*WIDTH*sizeof(sample_t));
|
|
|
|
for ( i = 0; i < res; i++ )
|
|
{
|
|
gen_sinc( rolloff, (int) (WIDTH * filter + 1) & ~1, pos, filter,
|
|
(double) (0x7FFF * GAIN * filter),
|
|
(int) WIDTH, impulses[i] );
|
|
|
|
pos += fstep;
|
|
input_per_cycle += step;
|
|
if ( pos >= 0.9999999 )
|
|
{
|
|
pos -= 1.0;
|
|
skip_bits |= 1 << i;
|
|
input_per_cycle++;
|
|
}
|
|
}
|
|
|
|
Fir_Resampler_clear();
|
|
|
|
return ratio;
|
|
}
|
|
|
|
/* Current ratio */
|
|
double Fir_Resampler_ratio( void )
|
|
{
|
|
return ratio;
|
|
}
|
|
|
|
/* Number of input samples that can be written */
|
|
int Fir_Resampler_max_write( void )
|
|
{
|
|
return buffer + buffer_size - write_pos;
|
|
}
|
|
|
|
/* Pointer to place to write input samples */
|
|
sample_t* Fir_Resampler_buffer( void )
|
|
{
|
|
return write_pos;
|
|
}
|
|
|
|
/* Number of input samples in buffer */
|
|
int Fir_Resampler_written( void )
|
|
{
|
|
return write_pos - &buffer [WRITE_OFFSET];
|
|
}
|
|
|
|
/* Number of output samples available */
|
|
/*int Fir_Resampler_avail( void )
|
|
{
|
|
return available( write_pos - &buffer [WIDTH * STEREO] );
|
|
}*/
|
|
|
|
void Fir_Resampler_write( long count )
|
|
{
|
|
write_pos += count;
|
|
// assert( write_pos <= ( buffer + buffer_size ) );
|
|
}
|
|
|
|
int Fir_Resampler_read( sample_t* out, long count )
|
|
{
|
|
sample_t* out_ = out;
|
|
sample_t* in = buffer;
|
|
sample_t* end_pos = write_pos;
|
|
unsigned long skip = skip_bits >> imp_phase;
|
|
sample_t const* imp = impulses [imp_phase];
|
|
int remain = res - imp_phase;
|
|
int n;
|
|
int pt0,pt1;
|
|
sample_t* i;
|
|
long l,r;
|
|
|
|
if ( end_pos - in >= WIDTH * STEREO )
|
|
{
|
|
end_pos -= WIDTH * STEREO;
|
|
do
|
|
{
|
|
count--;
|
|
|
|
if ( count < 0 )
|
|
break;
|
|
|
|
/* accumulate in extended precision */
|
|
l = 0;
|
|
r = 0;
|
|
|
|
i = in;
|
|
|
|
for ( n = WIDTH / 2; n; --n )
|
|
{
|
|
pt0 = imp [0];
|
|
l += pt0 * i [0];
|
|
r += pt0 * i [1];
|
|
pt1 = imp [1];
|
|
imp += 2;
|
|
l += pt1 * i [2];
|
|
r += pt1 * i [3];
|
|
i += 4;
|
|
}
|
|
|
|
remain--;
|
|
|
|
l >>= 15;
|
|
r >>= 15;
|
|
|
|
in += (skip * STEREO) & STEREO;
|
|
skip >>= 1;
|
|
in += step;
|
|
|
|
if ( !remain )
|
|
{
|
|
imp = impulses [0];
|
|
skip = skip_bits;
|
|
remain = res;
|
|
}
|
|
|
|
*out++ = (sample_t) l;
|
|
*out++ = (sample_t) r;
|
|
}
|
|
while ( in <= end_pos );
|
|
}
|
|
|
|
imp_phase = res - remain;
|
|
|
|
int left = write_pos - in;
|
|
write_pos = &buffer [left];
|
|
memmove( buffer, in, left * sizeof *in );
|
|
|
|
return out - out_;
|
|
}
|
|
|
|
/* fixed (Eke_Eke) */
|
|
int Fir_Resampler_input_needed( long output_count )
|
|
{
|
|
long input_count = 0;
|
|
|
|
unsigned long skip = skip_bits >> imp_phase;
|
|
int remain = res - imp_phase;
|
|
while ( (output_count) > 0 )
|
|
{
|
|
input_count += step + (skip & 1) * STEREO;
|
|
skip >>= 1;
|
|
if ( !--remain )
|
|
{
|
|
skip = skip_bits;
|
|
remain = res;
|
|
}
|
|
output_count --;
|
|
}
|
|
|
|
long input_extra = input_count - (write_pos - &buffer [WRITE_OFFSET]);
|
|
if ( input_extra < 0 )
|
|
input_extra = 0;
|
|
return (input_extra >> 1);
|
|
}
|
|
|
|
int Fir_Resampler_skip_input( long count )
|
|
{
|
|
int remain = write_pos - buffer;
|
|
int max_count = remain - WIDTH * STEREO;
|
|
if ( count > max_count )
|
|
count = max_count;
|
|
|
|
remain -= count;
|
|
write_pos = &buffer [remain];
|
|
memmove( buffer, &buffer [count], remain * sizeof buffer [0] );
|
|
|
|
return count;
|
|
}
|