1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/OpenAL32/Include/alFilter.h	Tue Oct 25 13:02:31 2011 -0700
     1.3 @@ -0,0 +1,92 @@
     1.4 +#ifndef _AL_FILTER_H_
     1.5 +#define _AL_FILTER_H_
     1.6 +
     1.7 +#include "AL/al.h"
     1.8 +#include "alu.h"
     1.9 +
    1.10 +#ifdef __cplusplus
    1.11 +extern "C" {
    1.12 +#endif
    1.13 +
    1.14 +typedef struct {
    1.15 +    ALfloat coeff;
    1.16 +#ifndef _MSC_VER
    1.17 +    ALfloat history[0];
    1.18 +#else
    1.19 +    ALfloat history[1];
    1.20 +#endif
    1.21 +} FILTER;
    1.22 +
    1.23 +static __inline ALfloat lpFilter2P(FILTER *iir, ALuint offset, ALfloat input)
    1.24 +{
    1.25 +    ALfloat *history = &iir->history[offset*2];
    1.26 +    ALfloat a = iir->coeff;
    1.27 +    ALfloat output = input;
    1.28 +
    1.29 +    output = output + (history[0]-output)*a;
    1.30 +    history[0] = output;
    1.31 +    output = output + (history[1]-output)*a;
    1.32 +    history[1] = output;
    1.33 +
    1.34 +    return output;
    1.35 +}
    1.36 +static __inline ALfloat lpFilter1P(FILTER *iir, ALuint offset, ALfloat input)
    1.37 +{
    1.38 +    ALfloat *history = &iir->history[offset];
    1.39 +    ALfloat a = iir->coeff;
    1.40 +    ALfloat output = input;
    1.41 +
    1.42 +    output = output + (history[0]-output)*a;
    1.43 +    history[0] = output;
    1.44 +
    1.45 +    return output;
    1.46 +}
    1.47 +
    1.48 +static __inline ALfloat lpFilter2PC(const FILTER *iir, ALuint offset, ALfloat input)
    1.49 +{
    1.50 +    const ALfloat *history = &iir->history[offset*2];
    1.51 +    ALfloat a = iir->coeff;
    1.52 +    ALfloat output = input;
    1.53 +
    1.54 +    output = output + (history[0]-output)*a;
    1.55 +    output = output + (history[1]-output)*a;
    1.56 +
    1.57 +    return output;
    1.58 +}
    1.59 +static __inline ALfloat lpFilter1PC(FILTER *iir, ALuint offset, ALfloat input)
    1.60 +{
    1.61 +    const ALfloat *history = &iir->history[offset];
    1.62 +    ALfloat a = iir->coeff;
    1.63 +    ALfloat output = input;
    1.64 +
    1.65 +    output = output + (history[0]-output)*a;
    1.66 +
    1.67 +    return output;
    1.68 +}
    1.69 +
    1.70 +/* Calculates the low-pass filter coefficient given the pre-scaled gain and
    1.71 + * cos(w) value. Note that g should be pre-scaled (sqr(gain) for one-pole,
    1.72 + * sqrt(gain) for four-pole, etc) */
    1.73 +ALfloat lpCoeffCalc(ALfloat g, ALfloat cw);
    1.74 +
    1.75 +
    1.76 +typedef struct ALfilter
    1.77 +{
    1.78 +    // Filter type (AL_FILTER_NULL, ...)
    1.79 +    ALenum type;
    1.80 +
    1.81 +    ALfloat Gain;
    1.82 +    ALfloat GainHF;
    1.83 +
    1.84 +    // Index to itself
    1.85 +    ALuint filter;
    1.86 +} ALfilter;
    1.87 +
    1.88 +
    1.89 +ALvoid ReleaseALFilters(ALCdevice *device);
    1.90 +
    1.91 +#ifdef __cplusplus
    1.92 +}
    1.93 +#endif
    1.94 +
    1.95 +#endif