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     ALfloat history[0];
  14 } FILTER;
  15
  16 static __inline ALfloat lpFilter4P(FILTER *iir, ALuint offset, ALfloat input)
  17 {
  18     ALfloat *history = &iir->history[offset];
  19     ALfloat a = iir->coeff;
  20     ALfloat output = input;
  21
  22     output = output + (history[0]-output)*a;
  23     history[0] = output;
  24     output = output + (history[1]-output)*a;
  25     history[1] = output;
  26     output = output + (history[2]-output)*a;
  27     history[2] = output;
  28     output = output + (history[3]-output)*a;
  29     history[3] = output;
  30
  31     return output;
  32 }
  33
  34 static __inline ALfloat lpFilter2P(FILTER *iir, ALuint offset, ALfloat input)
  35 {
  36     ALfloat *history = &iir->history[offset];
  37     ALfloat a = iir->coeff;
  38     ALfloat output = input;
  39
  40     output = output + (history[0]-output)*a;
  41     history[0] = output;
  42     output = output + (history[1]-output)*a;
  43     history[1] = output;
  44
  45     return output;
  46 }
  47
  48
  49 #define AL_FILTER_TYPE                                     0x8001
  50
  51 #define AL_FILTER_NULL                                     0x0000
  52 #define AL_FILTER_LOWPASS                                  0x0001
  53 #define AL_FILTER_HIGHPASS                                 0x0002
  54 #define AL_FILTER_BANDPASS                                 0x0003
  55
  56 #define AL_LOWPASS_GAIN                                    0x0001
  57 #define AL_LOWPASS_GAINHF                                  0x0002
  58
  59
  60 typedef struct ALfilter_struct
  61 {
  62     // Filter type (AL_FILTER_NULL, ...)
  63     ALenum type;
  64
  65     ALfloat Gain;
  66     ALfloat GainHF;
  67
  68     // Index to itself
  69     ALuint filter;
  70
  71     struct ALfilter_struct *next;
  72 } ALfilter;
  73
  74 ALvoid AL_APIENTRY alGenFilters(ALsizei n, ALuint *filters);
  75 ALvoid AL_APIENTRY alDeleteFilters(ALsizei n, ALuint *filters);
  76 ALboolean AL_APIENTRY alIsFilter(ALuint filter);
  77
  78 ALvoid AL_APIENTRY alFilteri(ALuint filter, ALenum param, ALint iValue);
  79 ALvoid AL_APIENTRY alFilteriv(ALuint filter, ALenum param, ALint *piValues);
  80 ALvoid AL_APIENTRY alFilterf(ALuint filter, ALenum param, ALfloat flValue);
  81 ALvoid AL_APIENTRY alFilterfv(ALuint filter, ALenum param, ALfloat *pflValues);
  82
  83 ALvoid AL_APIENTRY alGetFilteri(ALuint filter, ALenum param, ALint *piValue);
  84 ALvoid AL_APIENTRY alGetFilteriv(ALuint filter, ALenum param, ALint *piValues);
  85 ALvoid AL_APIENTRY alGetFilterf(ALuint filter, ALenum param, ALfloat *pflValue);
  86 ALvoid AL_APIENTRY alGetFilterfv(ALuint filter, ALenum param, ALfloat *pflValues);
  87
  88 ALvoid ReleaseALFilters(ALvoid);
  89
  90 #ifdef __cplusplus
  91 }
  92 #endif
  93
  94 #endif