ref: 55f7d6f8841f97d21f630a5e97b774ac35b4bd05
dir: /src/effects_i.c/
/* Implements a libSoX internal interface for implementing effects.
* All public functions & data are prefixed with lsx_ .
*
* (c) 2005-8 Chris Bagwell and SoX contributors
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at
* your option) any later version.
*
* This library 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 Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "sox_i.h"
#include <string.h>
#undef sox_fail
#define sox_fail sox_globals.subsystem=effp->handler.name,sox_fail
int lsx_usage(sox_effect_t * effp)
{
if (effp->handler.usage)
sox_fail("usage: %s", effp->handler.usage);
else
sox_fail("this effect takes no parameters");
return SOX_EOF;
}
/* here for linear interp. might be useful for other things */
sox_sample_t lsx_gcd(sox_sample_t a, sox_sample_t b)
{
if (b == 0)
return a;
else
return lsx_gcd(b, a % b);
}
sox_sample_t lsx_lcm(sox_sample_t a, sox_sample_t b)
{
/* parenthesize this way to avoid sox_sample_t overflow in product term */
return a * (b / lsx_gcd(a, b));
}
enum_item const lsx_wave_enum[] = {
ENUM_ITEM(SOX_WAVE_,SINE)
ENUM_ITEM(SOX_WAVE_,TRIANGLE)
{0, 0}};
void lsx_generate_wave_table(
lsx_wave_t wave_type,
sox_data_t data_type,
void *table,
uint32_t table_size,
double min,
double max,
double phase)
{
uint32_t t;
uint32_t phase_offset = phase / M_PI / 2 * table_size + 0.5;
for (t = 0; t < table_size; t++)
{
uint32_t point = (t + phase_offset) % table_size;
double d;
switch (wave_type)
{
case SOX_WAVE_SINE:
d = (sin((double)point / table_size * 2 * M_PI) + 1) / 2;
break;
case SOX_WAVE_TRIANGLE:
d = (double)point * 2 / table_size;
switch (4 * point / table_size)
{
case 0: d = d + 0.5; break;
case 1: case 2: d = 1.5 - d; break;
case 3: d = d - 1.5; break;
}
break;
default: /* Oops! FIXME */
d = 0.0; /* Make sure we have a value */
break;
}
d = d * (max - min) + min;
switch (data_type)
{
case SOX_FLOAT:
{
float *fp = (float *)table;
*fp++ = (float)d;
table = fp;
continue;
}
case SOX_DOUBLE:
{
double *dp = (double *)table;
*dp++ = d;
table = dp;
continue;
}
default: break;
}
d += d < 0? -0.5 : +0.5;
switch (data_type)
{
case SOX_SHORT:
{
short *sp = table;
*sp++ = (short)d;
table = sp;
continue;
}
case SOX_INT:
{
int *ip = table;
*ip++ = (int)d;
table = ip;
continue;
}
default: break;
}
}
}
/*
* lsx_parsesamples
*
* Parse a string for # of samples. If string ends with a 's'
* then the string is interpreted as a user calculated # of samples.
* If string contains ':' or '.' or if it ends with a 't' then its
* treated as an amount of time. This is converted into seconds and
* fraction of seconds and then use the sample rate to calculate
* # of samples.
* Returns NULL on error, pointer to next char to parse otherwise.
*/
char const * lsx_parsesamples(sox_rate_t rate, const char *str, sox_size_t *samples, int def)
{
int found_samples = 0, found_time = 0;
int time = 0;
long long_samples;
float frac = 0;
char const * end;
char const * pos;
sox_bool found_colon, found_dot;
for (end = str; *end && strchr("0123456789:.ts", *end); ++end);
if (end == str)
return NULL;
pos = strchr(str, ':');
found_colon = pos && pos < end;
pos = strchr(str, '.');
found_dot = pos && pos < end;
if (found_colon || found_dot || *(end-1) == 't')
found_time = 1;
else if (*(end-1) == 's')
found_samples = 1;
if (found_time || (def == 't' && !found_samples))
{
*samples = 0;
while(1)
{
if (str[0] != '.' && sscanf(str, "%d", &time) != 1)
return NULL;
*samples += time;
while (*str != ':' && *str != '.' && *str != 0)
str++;
if (*str == '.' || *str == 0)
break;
/* Skip past ':' */
str++;
*samples *= 60;
}
if (*str == '.')
{
if (sscanf(str, "%f", &frac) != 1)
return NULL;
}
*samples *= rate;
*samples += (rate * frac) + 0.5;
return end;
}
if (found_samples || (def == 's' && !found_time))
{
if (sscanf(str, "%ld", &long_samples) != 1)
return NULL;
*samples = long_samples;
return end;
}
return NULL;
}
/* a note is given as an int,
* 0 => 440 Hz = A
* >0 => number of half notes 'up',
* <0 => number of half notes down,
* example 12 => A of next octave, 880Hz
*
* calculated by freq = 440Hz * 2**(note/12)
*/
static double calc_note_freq(double note)
{
return 440.0 * pow(2.0, note / 12.0);
}
/* Read string 'text' and convert to frequency.
* 'text' can be a positive number which is the frequency in Hz.
* If 'text' starts with a hash '%' and a following number the corresponding
* note is calculated.
* Return -1 on error.
*/
double lsx_parse_frequency(char const * text, char * * end_ptr)
{
double result;
if (*text == '%') {
result = strtod(text + 1, end_ptr);
if (*end_ptr == text + 1)
return -1;
return calc_note_freq(result);
}
result = strtod(text, end_ptr);
if (end_ptr) {
if (*end_ptr == text)
return -1;
if (**end_ptr == 'k') {
result *= 1000;
++*end_ptr;
}
}
return result < 0 ? -1 : result;
}
double bessel_I_0(double x)
{
double term = 1, sum = 1, last_sum, x2 = x / 2;
int i = 1;
do {
double y = x2 / i++;
last_sum = sum, sum += term *= y * y;
} while (sum != last_sum);
return sum;
}