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/**
* OpenAL cross platform audio library
* Copyright (C) 2011 by Chris Robinson
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include "AL/al.h"
#include "AL/alc.h"
#include "alMain.h"
#include "alSource.h"
#define HRIR_COUNT 828
static const ALubyte evCount = 19;
static const ALushort evOffset[19] = { 0, 1, 13, 37, 73, 118, 174, 234, 306, 378, 450, 522, 594, 654, 710, 755, 791, 815, 827 };
static const ALubyte azCount[19] = { 1, 12, 24, 36, 45, 56, 60, 72, 72, 72, 72, 72, 60, 56, 45, 36, 24, 12, 1 };
static struct HRTF {
ALshort coeffs[HRIR_COUNT][HRIR_LENGTH];
ALubyte delays[HRIR_COUNT];
} Hrtf;
static ALuint CalcEvIndex(ALdouble ev)
{
ev = (M_PI/2.0 + ev) * (evCount-1) / M_PI;
return (ALuint)(ev+0.5);
}
static ALuint CalcAzIndex(ALint evidx, ALdouble az)
{
az = (M_PI*2.0 + az) * azCount[evidx] / (M_PI*2.0);
return (ALuint)(az+0.5) % azCount[evidx];
}
void GetHrtfCoeffs(ALfloat elevation, ALfloat angle, const ALshort **left, const ALshort **right, ALuint *ldelay, ALuint *rdelay)
{
ALuint lidx, ridx;
ALuint evidx, azidx;
evidx = CalcEvIndex(elevation);
azidx = CalcAzIndex(evidx, angle);
lidx = evOffset[evidx] + azidx;
ridx = evOffset[evidx] + ((azCount[evidx]-azidx) % azCount[evidx]);
*ldelay = Hrtf.delays[lidx];
*rdelay = Hrtf.delays[ridx];
*left = Hrtf.coeffs[lidx];
*right = Hrtf.coeffs[ridx];
}
void InitHrtf(void)
{
const char *str;
FILE *f = NULL;
str = GetConfigValue(NULL, "hrtf_tables", "");
if(str[0] != '\0')
f = fopen(str, "rb");
if(f != NULL)
{
const ALubyte maxDelay = SRC_HISTORY_LENGTH - HRIR_LENGTH;
struct HRTF newdata;
size_t i, j;
union {
ALfloat f;
ALubyte ub[4];
} val;
for(i = 0;i < HRIR_COUNT;i++)
{
for(j = 0;j < HRIR_LENGTH;j++)
{
val.ub[0] = fgetc(f);
val.ub[1] = fgetc(f);
val.ub[2] = fgetc(f);
val.ub[3] = fgetc(f);
if(val.f > 1.0f) newdata.coeffs[i][j] = 32767;
else if(val.f < -1.0f) newdata.coeffs[i][j] = -32768;
else newdata.coeffs[i][j] = (ALshort)(val.f*32767.0f);
}
}
val.ub[0] = fgetc(f);
val.ub[1] = fgetc(f);
val.ub[2] = fgetc(f);
val.ub[3] = fgetc(f);
/* skip maxHrtd */
for(i = 0;i < HRIR_COUNT;i++)
{
val.ub[0] = fgetc(f);
val.ub[1] = fgetc(f);
val.ub[2] = fgetc(f);
val.ub[3] = fgetc(f);
val.f *= 44100.0f;
if(val.f >= maxDelay) newdata.delays[i] = maxDelay;
else newdata.delays[i] = (ALubyte)val.f;
}
if(!feof(f))
Hrtf = newdata;
fclose(f);
f = NULL;
}
}
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