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 lpFilter4P(FILTER *iir, ALuint offset, ALfloat input)
  21 {
  22     ALfloat *history = &iir->history[offset];
  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     output = output + (history[2]-output)*a;
  31     history[2] = output;
  32     output = output + (history[3]-output)*a;
  33     history[3] = output;
  34
  35     return output;
  36 }
  37
  38 static __inline ALfloat lpFilter2P(FILTER *iir, ALuint offset, ALfloat input)
  39 {
  40     ALfloat *history = &iir->history[offset];
  41     ALfloat a = iir->coeff;
  42     ALfloat output = input;
  43
  44     output = output + (history[0]-output)*a;
  45     history[0] = output;
  46     output = output + (history[1]-output)*a;
  47     history[1] = output;
  48
  49     return output;
  50 }
  51
  52
  53 #define AL_FILTER_TYPE                                     0x8001
  54
  55 #define AL_FILTER_NULL                                     0x0000
  56 #define AL_FILTER_LOWPASS                                  0x0001
  57 #define AL_FILTER_HIGHPASS                                 0x0002
  58 #define AL_FILTER_BANDPASS                                 0x0003
  59
  60 #define AL_LOWPASS_GAIN                                    0x0001
  61 #define AL_LOWPASS_GAINHF                                  0x0002
  62
  63
  64 typedef struct ALfilter_struct
  65 {
  66     // Filter type (AL_FILTER_NULL, ...)
  67     ALenum type;
  68
  69     ALfloat Gain;
  70     ALfloat GainHF;
  71
  72     // Index to itself
  73     ALuint filter;
  74
  75     struct ALfilter_struct *next;
  76 } ALfilter;
  77
  78 ALvoid AL_APIENTRY alGenFilters(ALsizei n, ALuint *filters);
  79 ALvoid AL_APIENTRY alDeleteFilters(ALsizei n, ALuint *filters);
  80 ALboolean AL_APIENTRY alIsFilter(ALuint filter);
  81
  82 ALvoid AL_APIENTRY alFilteri(ALuint filter, ALenum param, ALint iValue);
  83 ALvoid AL_APIENTRY alFilteriv(ALuint filter, ALenum param, ALint *piValues);
  84 ALvoid AL_APIENTRY alFilterf(ALuint filter, ALenum param, ALfloat flValue);
  85 ALvoid AL_APIENTRY alFilterfv(ALuint filter, ALenum param, ALfloat *pflValues);
  86
  87 ALvoid AL_APIENTRY alGetFilteri(ALuint filter, ALenum param, ALint *piValue);
  88 ALvoid AL_APIENTRY alGetFilteriv(ALuint filter, ALenum param, ALint *piValues);
  89 ALvoid AL_APIENTRY alGetFilterf(ALuint filter, ALenum param, ALfloat *pflValue);
  90 ALvoid AL_APIENTRY alGetFilterfv(ALuint filter, ALenum param, ALfloat *pflValues);
  91
  92 ALvoid ReleaseALFilters(ALvoid);
  93
  94 #ifdef __cplusplus
  95 }
  96 #endif
  97
  98 #endif