96 lines
2.0 KiB
C
96 lines
2.0 KiB
C
// --------------------------------------------------------------
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// --------------------------------------------------------------
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#include <stdlib.h>
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#include <math.h>
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#include "synth_defs.h"
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#include "sine.h"
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// --------------------------------------------------------------
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// internal funcs
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// --------------------------------------------------------------
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// --------------------------------------------------------------
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// Exported functions
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// --------------------------------------------------------------
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void Sine_Init(sine_gen_t *pObj, synth_float_t fs)
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{
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Sine_SetFS(pObj, fs);
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Sine_Prepare(pObj);
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}
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void Sine_Free(sine_gen_t *pObj)
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{
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}
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void Sine_SetFS(sine_gen_t *pObj, synth_float_t fs)
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{
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pObj->fs = SINE_OVERSAMPLING*fs;
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pObj->pitch = -1;
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}
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void Sine_Reset(sine_gen_t *pObj, synth_float_t phase)
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{
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pObj->y[0] = cos(2*jsy_pi*phase);
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pObj->y[1] = sin(2*jsy_pi*phase);
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pObj->fscale = 1;
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}
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void Sine_Start(sine_gen_t *pObj)
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{
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pObj->pitch = -1;
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pObj->CV_fm = -1;
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}
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void Sine_Prepare(sine_gen_t *pObj)
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{
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Sine_Reset(pObj, (synth_float_t)rand()/RAND_MAX);
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}
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void Sine_Update(sine_gen_t *pObj)
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{
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synth_float_t freq;
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freq = pObj->fscale * pObj->pitch;
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pObj->b = 2.0 * sin(freq*jsy_pi / pObj->fs);
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}
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synth_float_t Sine_Process_Scalar(sine_gen_t *pObj, synth_float_t pitch, synth_float_t CV_fm)
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{
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int i;
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synth_float_t a, phi;
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// ToDo: amplitude drift correction
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// y[0]^2 + y[1]^2 = a;
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if (pObj->CV_fm != CV_fm)
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{
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pObj->CV_fm = CV_fm;
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pObj->fscale = (synth_float_t)pow((synth_float_t)2, CV_fm);
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Sine_Update(pObj);
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}
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if (pObj->pitch != pitch)
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{
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pObj->pitch = pitch;
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Sine_Update(pObj);
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}
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for (i=0; i < SINE_OVERSAMPLING; i++)
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{
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pObj->y[0] = pObj->y[0] - pObj->b*pObj->y[1];
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pObj->y[1] = pObj->y[1] + pObj->b*pObj->y[0];
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}
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a = pObj->y[0]*pObj->y[0] + pObj->y[1]*pObj->y[1];
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if (fabs(a - 1) > 0.5)
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{
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phi = atan2(pObj->y[0], pObj->y[1]);
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pObj->y[0] = sin(phi);
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pObj->y[1] = cos(phi);
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}
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return -pObj->y[0];
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}
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