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simple-tone: sin() lookup tables

This commit is contained in:
Kamal Mostafa 2012-08-13 21:09:24 -07:00
parent d273828f80
commit e2225d6098
2 changed files with 85 additions and 9 deletions
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90
src/simple-tone-generator.c
View File

@ -1,7 +1,7 @@
/*
* simple-tone-generator.c
*
* Copyright (C) 2011 Kamal Mostafa <kamal@whence.com>
* Copyright (C) 2011-2012 Kamal Mostafa <kamal@whence.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -26,6 +26,67 @@
#include "simpleaudio.h"
static unsigned int sin_table_len;
static short *sin_table_short;
static float *sin_table_float;
void
simpleaudio_tone_init( unsigned int new_sin_table_len )
{
sin_table_len = new_sin_table_len;
if ( sin_table_len != 0 ) {
sin_table_short = realloc(sin_table_short, sin_table_len * sizeof(short));
sin_table_float = realloc(sin_table_float, sin_table_len * sizeof(float));
if ( !sin_table_short || !sin_table_float ) {
perror("malloc");
assert(0);
}
unsigned int i;
for ( i=0; i<sin_table_len; i++ )
sin_table_short[i] = 32767 * sin(M_PI*2.0*(float)i/sin_table_len);
for ( i=0; i<sin_table_len; i++ )
sin_table_float[i] = sinf(M_PI*2.0*(float)i/sin_table_len);
} else {
if ( sin_table_short ) {
free(sin_table_short);
sin_table_short = NULL;
}
if ( sin_table_float ) {
free(sin_table_float);
sin_table_float = NULL;
}
}
}
/*
* in: turns (0.0 to 1.0) out: (-32767 to +32767)
*/
static inline short
sin_lu_short( float turns )
{
turns = fmodf(turns, 1.0);
int t = (float)sin_table_len * turns;
// assert ( t >= 0 && t < sin_table_len );
return sin_table_short[t];
}
/*
* in: turns (0.0 to 1.0) out: -1.0 to +1.0
*/
static inline float
sin_lu_float( float turns )
{
turns = fmodf(turns, 1.0);
int t = (float)sin_table_len * turns;
// assert ( t >= 0 && t < sin_table_len );
return sin_table_float[t];
}
/* "current" phase state of the tone generator */
static float sa_tone_cphase = 0.0;
@ -48,25 +109,38 @@ simpleaudio_tone(simpleaudio *sa_out, float tone_freq, size_t nsamples_dur)
float wave_nsamples = simpleaudio_get_rate(sa_out) / tone_freq;
size_t i;
#define SINE_PHASE_ANGLE ( M_PI*2.0*(i/wave_nsamples + sa_tone_cphase) )
#define TURNS_TO_RADIANS(t) ( M_PI*2.0 * (t) )
#define SINE_PHASE_TURNS ( (float)i/wave_nsamples + sa_tone_cphase )
#define SINE_PHASE_RADIANS TURNS_TO_RADIANS(SINE_PHASE_TURNS)
switch ( simpleaudio_get_format(sa_out) ) {
case SA_SAMPLE_FORMAT_FLOAT:
{
float *float_buf = buf;
for ( i=0; i<nsamples_dur; i++ )
float_buf[i] = sinf(SINE_PHASE_ANGLE);
if ( sin_table_float ) {
for ( i=0; i<nsamples_dur; i++ )
float_buf[i] = sin_lu_float(SINE_PHASE_TURNS);
} else {
for ( i=0; i<nsamples_dur; i++ )
float_buf[i] = sinf(SINE_PHASE_RADIANS);
}
}
break;
case SA_SAMPLE_FORMAT_S16:
{
short *float_buf = buf;
for ( i=0; i<nsamples_dur; i++ )
float_buf[i] = 32767 * sinf(SINE_PHASE_ANGLE);
short *short_buf = buf;
if ( sin_table_short ) {
for ( i=0; i<nsamples_dur; i++ )
short_buf[i] = sin_lu_short(SINE_PHASE_TURNS);
} else {
for ( i=0; i<nsamples_dur; i++ )
short_buf[i] = 32767 * sinf(SINE_PHASE_RADIANS);
}
break;
}
break;
default:
assert(0);

4
src/simpleaudio.h
View File

@ -1,7 +1,7 @@
/*
* simpleaudio.h
*
* Copyright (C) 2011 Kamal Mostafa <kamal@whence.com>
* Copyright (C) 2011-2012 Kamal Mostafa <kamal@whence.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
@ -95,5 +95,7 @@ simpleaudio_tone_reset();
void
simpleaudio_tone(simpleaudio *sa_out, float tone_freq, size_t nsamples_dur);
void
simpleaudio_tone_init( unsigned int new_sin_table_len );
#endif