rlm@0: #ifndef _AL_FILTER_H_
rlm@0: #define _AL_FILTER_H_
rlm@0: 
rlm@0: #include "AL/al.h"
rlm@0: #include "alu.h"
rlm@0: 
rlm@0: #ifdef __cplusplus
rlm@0: extern "C" {
rlm@0: #endif
rlm@0: 
rlm@0: typedef struct {
rlm@0:     ALfloat coeff;
rlm@0: #ifndef _MSC_VER
rlm@0:     ALfloat history[0];
rlm@0: #else
rlm@0:     ALfloat history[1];
rlm@0: #endif
rlm@0: } FILTER;
rlm@0: 
rlm@0: static __inline ALfloat lpFilter2P(FILTER *iir, ALuint offset, ALfloat input)
rlm@0: {
rlm@0:     ALfloat *history = &iir->history[offset*2];
rlm@0:     ALfloat a = iir->coeff;
rlm@0:     ALfloat output = input;
rlm@0: 
rlm@0:     output = output + (history[0]-output)*a;
rlm@0:     history[0] = output;
rlm@0:     output = output + (history[1]-output)*a;
rlm@0:     history[1] = output;
rlm@0: 
rlm@0:     return output;
rlm@0: }
rlm@0: static __inline ALfloat lpFilter1P(FILTER *iir, ALuint offset, ALfloat input)
rlm@0: {
rlm@0:     ALfloat *history = &iir->history[offset];
rlm@0:     ALfloat a = iir->coeff;
rlm@0:     ALfloat output = input;
rlm@0: 
rlm@0:     output = output + (history[0]-output)*a;
rlm@0:     history[0] = output;
rlm@0: 
rlm@0:     return output;
rlm@0: }
rlm@0: 
rlm@0: static __inline ALfloat lpFilter2PC(const FILTER *iir, ALuint offset, ALfloat input)
rlm@0: {
rlm@0:     const ALfloat *history = &iir->history[offset*2];
rlm@0:     ALfloat a = iir->coeff;
rlm@0:     ALfloat output = input;
rlm@0: 
rlm@0:     output = output + (history[0]-output)*a;
rlm@0:     output = output + (history[1]-output)*a;
rlm@0: 
rlm@0:     return output;
rlm@0: }
rlm@0: static __inline ALfloat lpFilter1PC(FILTER *iir, ALuint offset, ALfloat input)
rlm@0: {
rlm@0:     const ALfloat *history = &iir->history[offset];
rlm@0:     ALfloat a = iir->coeff;
rlm@0:     ALfloat output = input;
rlm@0: 
rlm@0:     output = output + (history[0]-output)*a;
rlm@0: 
rlm@0:     return output;
rlm@0: }
rlm@0: 
rlm@0: /* Calculates the low-pass filter coefficient given the pre-scaled gain and
rlm@0:  * cos(w) value. Note that g should be pre-scaled (sqr(gain) for one-pole,
rlm@0:  * sqrt(gain) for four-pole, etc) */
rlm@0: ALfloat lpCoeffCalc(ALfloat g, ALfloat cw);
rlm@0: 
rlm@0: 
rlm@0: typedef struct ALfilter
rlm@0: {
rlm@0:     // Filter type (AL_FILTER_NULL, ...)
rlm@0:     ALenum type;
rlm@0: 
rlm@0:     ALfloat Gain;
rlm@0:     ALfloat GainHF;
rlm@0: 
rlm@0:     // Index to itself
rlm@0:     ALuint filter;
rlm@0: } ALfilter;
rlm@0: 
rlm@0: 
rlm@0: ALvoid ReleaseALFilters(ALCdevice *device);
rlm@0: 
rlm@0: #ifdef __cplusplus
rlm@0: }
rlm@0: #endif
rlm@0: 
rlm@0: #endif