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#ifndef _AL_FILTER_H_
#define _AL_FILTER_H_
#include "alMain.h"
#ifdef __cplusplus
extern "C" {
#endif
#define LOWPASSFREQREF (5000)
typedef struct {
ALfloat coeff;
#ifndef _MSC_VER
ALfloat history[0];
#else
ALfloat history[1];
#endif
} FILTER;
static __inline ALfloat lpFilter2P(FILTER *iir, ALuint offset, ALfloat input)
{
ALfloat *history = &iir->history[offset*2];
ALfloat a = iir->coeff;
ALfloat output = input;
output = output + (history[0]-output)*a;
history[0] = output;
output = output + (history[1]-output)*a;
history[1] = output;
return output;
}
static __inline ALfloat lpFilter2PC(const FILTER *iir, ALuint offset, ALfloat input)
{
const ALfloat *history = &iir->history[offset*2];
ALfloat a = iir->coeff;
ALfloat output = input;
output = output + (history[0]-output)*a;
output = output + (history[1]-output)*a;
return output;
}
/* Calculates the low-pass filter coefficient given the pre-scaled gain and
* cos(w) value. Note that g should be pre-scaled (sqr(gain) for one-pole,
* sqrt(gain) for four-pole, etc) */
ALfloat lpCoeffCalc(ALfloat g, ALfloat cw);
typedef struct ALfilter {
// Filter type (AL_FILTER_NULL, ...)
ALenum type;
ALfloat Gain;
ALfloat GainHF;
void (*SetParami)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint val);
void (*SetParamiv)(struct ALfilter *filter, ALCcontext *context, ALenum param, const ALint *vals);
void (*SetParamf)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val);
void (*SetParamfv)(struct ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals);
void (*GetParami)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint *val);
void (*GetParamiv)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint *vals);
void (*GetParamf)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val);
void (*GetParamfv)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals);
/* Self ID */
ALuint id;
} ALfilter;
#define ALfilter_SetParami(x, c, p, v) ((x)->SetParami((x),(c),(p),(v)))
#define ALfilter_SetParamiv(x, c, p, v) ((x)->SetParamiv((x),(c),(p),(v)))
#define ALfilter_SetParamf(x, c, p, v) ((x)->SetParamf((x),(c),(p),(v)))
#define ALfilter_SetParamfv(x, c, p, v) ((x)->SetParamfv((x),(c),(p),(v)))
#define ALfilter_GetParami(x, c, p, v) ((x)->GetParami((x),(c),(p),(v)))
#define ALfilter_GetParamiv(x, c, p, v) ((x)->GetParamiv((x),(c),(p),(v)))
#define ALfilter_GetParamf(x, c, p, v) ((x)->GetParamf((x),(c),(p),(v)))
#define ALfilter_GetParamfv(x, c, p, v) ((x)->GetParamfv((x),(c),(p),(v)))
ALvoid ReleaseALFilters(ALCdevice *device);
#ifdef __cplusplus
}
#endif
#endif
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