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Modulate with the requested waveform in the ring modulator

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This commit is contained in:
Chris Robinson
2010-04-08 10:37:09 -07:00
parent 76f8c1e4e2
commit 980167c99b
1 changed files with 84 additions and 10 deletions
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Alc/alcModulator.c
+84 -10
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@@ -34,10 +34,37 @@ typedef struct ALmodulatorState {
// Must be first in all effects!
ALeffectState state;
enum {
SINUSOID,
SAWTOOTH,
SQUARE
} Waveform;
ALuint index;
ALuint step;
FILTER iirFilter;
ALfloat history[1];
} ALmodulatorState;
#define WAVEFORM_FRACBITS 16
#define WAVEFORM_FRACMASK ((1<<WAVEFORM_FRACBITS)-1)
static __inline ALfloat sin_func(ALuint index)
{
return sin(index / (double)(1<<WAVEFORM_FRACBITS) * M_PI * 2.0f);
}
static __inline ALfloat saw_func(ALuint index)
{
return index*2.0f/(1<<WAVEFORM_FRACBITS) - 1.0f;
}
static __inline ALfloat square_func(ALuint index)
{
return ((index>>(WAVEFORM_FRACBITS-1))&1) ? -1.0f : 1.0f;
}
static __inline ALfloat hpFilter1P(FILTER *iir, ALuint offset, ALfloat input)
{
@@ -70,6 +97,18 @@ static ALvoid ModulatorUpdate(ALeffectState *effect, ALCcontext *Context, const
ALmodulatorState *state = (ALmodulatorState*)effect;
ALfloat cw, a = 0.0f;
if(Effect->Modulator.Waveform == AL_RING_MODULATOR_SINUSOID)
state->Waveform = SINUSOID;
else if(Effect->Modulator.Waveform == AL_RING_MODULATOR_SAWTOOTH)
state->Waveform = SAWTOOTH;
else if(Effect->Modulator.Waveform == AL_RING_MODULATOR_SQUARE)
state->Waveform = SQUARE;
state->step = Effect->Modulator.Frequency*(1<<WAVEFORM_FRACBITS) /
Context->Device->Frequency;
if(!state->step)
state->step = 1;
cw = cos(2.0*M_PI * Effect->Modulator.HighPassCutoff / Context->Device->Frequency);
a = (2.0f-cw) - aluSqrt(aluPow(2.0f-cw, 2.0f) - 1.0f);
state->iirFilter.coeff = a;
@@ -79,23 +118,55 @@ static ALvoid ModulatorProcess(ALeffectState *effect, const ALeffectslot *Slot,
{
ALmodulatorState *state = (ALmodulatorState*)effect;
const ALfloat gain = Slot->Gain;
const ALuint step = state->step;
ALuint index = state->index;
ALfloat samp;
ALuint i;
for(i = 0;i < SamplesToDo;i++)
switch(state->Waveform)
{
samp = hpFilter1P(&state->iirFilter, 0, SamplesIn[i]);
case SINUSOID:
for(i = 0;i < SamplesToDo;i++)
{
#define FILTER_OUT(func) do { \
samp = SamplesIn[i]; \
\
index += step; \
index &= WAVEFORM_FRACMASK; \
samp *= func(index); \
\
samp = hpFilter1P(&state->iirFilter, 0, samp); \
\
/* Apply slot gain */ \
samp *= gain; \
\
SamplesOut[i][FRONT_LEFT] += samp; \
SamplesOut[i][FRONT_RIGHT] += samp; \
SamplesOut[i][SIDE_LEFT] += samp; \
SamplesOut[i][SIDE_RIGHT] += samp; \
SamplesOut[i][BACK_LEFT] += samp; \
SamplesOut[i][BACK_RIGHT] += samp; \
} while(0)
FILTER_OUT(sin_func);
}
break;
// Apply slot gain
samp *= gain;
case SAWTOOTH:
for(i = 0;i < SamplesToDo;i++)
{
FILTER_OUT(saw_func);
}
break;
SamplesOut[i][FRONT_LEFT] += samp;
SamplesOut[i][FRONT_RIGHT] += samp;
SamplesOut[i][SIDE_LEFT] += samp;
SamplesOut[i][SIDE_RIGHT] += samp;
SamplesOut[i][BACK_LEFT] += samp;
SamplesOut[i][BACK_RIGHT] += samp;
case SQUARE:
for(i = 0;i < SamplesToDo;i++)
{
FILTER_OUT(square_func);
#undef FILTER_OUT
}
break;
}
state->index = index;
}
ALeffectState *ModulatorCreate(void)
@@ -111,6 +182,9 @@ ALeffectState *ModulatorCreate(void)
state->state.Update = ModulatorUpdate;
state->state.Process = ModulatorProcess;
state->index = 0.0f;
state->step = 1.0f;
state->iirFilter.coeff = 0.0f;
state->iirFilter.history[0] = 0.0f;