OpenAL32/Include/alFilter.h

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