OpenAL32/Include/alFilter.h

   1 #ifndef _AL_FILTER_H_
   2 #define _AL_FILTER_H_
   3
   4 #include "alMain.h"
   5
   6 #ifdef __cplusplus
   7 extern "C" {
   8 #endif
   9
  10 #define LOWPASSFREQREF  (5000)
  11
  12 typedef struct {
  13     ALfloat coeff;
  14 #ifndef _MSC_VER
  15     ALfloat history[0];
  16 #else
  17     ALfloat history[1];
  18 #endif
  19 } FILTER;
  20
  21 static __inline ALfloat lpFilter2P(FILTER *iir, ALuint offset, ALfloat input)
  22 {
  23     ALfloat *history = &iir->history[offset*2];
  24     ALfloat a = iir->coeff;
  25     ALfloat output = input;
  26
  27     output = output + (history[0]-output)*a;
  28     history[0] = output;
  29     output = output + (history[1]-output)*a;
  30     history[1] = output;
  31
  32     return output;
  33 }
  34
  35 static __inline ALfloat lpFilter2PC(const FILTER *iir, ALuint offset, ALfloat input)
  36 {
  37     const ALfloat *history = &iir->history[offset*2];
  38     ALfloat a = iir->coeff;
  39     ALfloat output = input;
  40
  41     output = output + (history[0]-output)*a;
  42     output = output + (history[1]-output)*a;
  43
  44     return output;
  45 }
  46
  47 /* Calculates the low-pass filter coefficient given the pre-scaled gain and
  48  * cos(w) value. Note that g should be pre-scaled (sqr(gain) for one-pole,
  49  * sqrt(gain) for four-pole, etc) */
  50 ALfloat lpCoeffCalc(ALfloat g, ALfloat cw);
  51
  52
  53 typedef struct ALfilter {
  54     // Filter type (AL_FILTER_NULL, ...)
  55     ALenum type;
  56
  57     ALfloat Gain;
  58     ALfloat GainHF;
  59
  60     void (*SetParami)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint val);
  61     void (*SetParamiv)(struct ALfilter *filter, ALCcontext *context, ALenum param, const ALint *vals);
  62     void (*SetParamf)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val);
  63     void (*SetParamfv)(struct ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals);
  64
  65     void (*GetParami)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint *val);
  66     void (*GetParamiv)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint *vals);
  67     void (*GetParamf)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val);
  68     void (*GetParamfv)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals);
  69
  70     /* Self ID */
  71     ALuint id;
  72 } ALfilter;
  73
  74 #define ALfilter_SetParami(x, c, p, v)  ((x)->SetParami((x),(c),(p),(v)))
  75 #define ALfilter_SetParamiv(x, c, p, v) ((x)->SetParamiv((x),(c),(p),(v)))
  76 #define ALfilter_SetParamf(x, c, p, v)  ((x)->SetParamf((x),(c),(p),(v)))
  77 #define ALfilter_SetParamfv(x, c, p, v) ((x)->SetParamfv((x),(c),(p),(v)))
  78
  79 #define ALfilter_GetParami(x, c, p, v)  ((x)->GetParami((x),(c),(p),(v)))
  80 #define ALfilter_GetParamiv(x, c, p, v) ((x)->GetParamiv((x),(c),(p),(v)))
  81 #define ALfilter_GetParamf(x, c, p, v)  ((x)->GetParamf((x),(c),(p),(v)))
  82 #define ALfilter_GetParamfv(x, c, p, v) ((x)->GetParamfv((x),(c),(p),(v)))
  83
  84 ALvoid ReleaseALFilters(ALCdevice *device);
  85
  86 #ifdef __cplusplus
  87 }
  88 #endif
  89
  90 #endif