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#ifndef _AL_FILTER_H_
#define _AL_FILTER_H_
#include "alMain.h"
#ifdef __cplusplus
extern "C" {
#endif
#define LOWPASSFREQREF (5000)
/* Filters implementation is based on the "Cookbook formulae for audio *
* EQ biquad filter coefficients" by Robert Bristow-Johnson *
* http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt */
typedef enum ALfilterType {
ALfilterType_HighShelf,
ALfilterType_LowShelf,
ALfilterType_Peaking,
ALfilterType_LowPass,
ALfilterType_HighPass,
ALfilterType_BandPass,
} ALfilterType;
typedef struct ALfilterState {
ALfloat x[2]; /* History of two last input samples */
ALfloat y[2]; /* History of two last output samples */
ALfloat a[3]; /* Transfer function coefficients "a" */
ALfloat b[3]; /* Transfer function coefficients "b" */
} ALfilterState;
void ALfilterState_clear(ALfilterState *filter);
void ALfilterState_setParams(ALfilterState *filter, ALfilterType type, ALfloat gain, ALfloat freq_scale, ALfloat bandwidth);
inline ALfloat ALfilterState_processSingle(ALfilterState *filter, ALfloat sample)
{
ALfloat outsmp;
outsmp = filter->b[0] * sample +
filter->b[1] * filter->x[0] +
filter->b[2] * filter->x[1] -
filter->a[1] * filter->y[0] -
filter->a[2] * filter->y[1];
filter->x[1] = filter->x[0];
filter->x[0] = sample;
filter->y[1] = filter->y[0];
filter->y[0] = outsmp;
return outsmp;
}
inline ALfloat ALfilterState_processSingleC(const ALfilterState *filter, ALfloat sample)
{
return filter->b[0] * sample +
filter->b[1] * filter->x[0] +
filter->b[2] * filter->x[1] -
filter->a[1] * filter->y[0] -
filter->a[2] * filter->y[1];
}
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)))
inline struct ALfilter *LookupFilter(ALCdevice *device, ALuint id)
{ return (struct ALfilter*)LookupUIntMapKey(&device->FilterMap, id); }
inline struct ALfilter *RemoveFilter(ALCdevice *device, ALuint id)
{ return (struct ALfilter*)RemoveUIntMapKey(&device->FilterMap, id); }
ALvoid ReleaseALFilters(ALCdevice *device);
#ifdef __cplusplus
}
#endif
#endif
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