Add square wave and fix lowpass styling

1 files changed, 139 insertions, 139 deletions

diff --git a/src/lowpass.c b/src/lowpass.c
index 304ad9f..ccb41dd 100644
--- a/src/lowpass.c
+++ b/src/lowpass.c
@@ -1,8 +1,8 @@
 /*
-Resonant low pass filter source code.
-By baltrax@hotmail.com (Zxform)
+  Resonant low pass filter source code.
+  By baltrax@hotmail.com (Zxform)
 
-- little changes and optimizations by Brett Paterson for FMOD example.
+  - little changes and optimizations by Brett Paterson for FMOD example.
 
 */
 
@@ -46,79 +46,79 @@ FILTER   iir;
  * Allocation errors cause an error message and a call to exit.
  * --------------------------------------------------------------------
  */
-float LowPass_Filter(float input)
+float lpf_filter(float input)
 {
-    unsigned int i;
-    float *hist1_ptr,*hist2_ptr,*coef_ptr;
-    float output,new_hist,history1,history2;
-    static float dc = (float)1E-25;
-    input += dc;
-    dc = -dc;
+  unsigned int i;
+  float *hist1_ptr,*hist2_ptr,*coef_ptr;
+  float output,new_hist,history1,history2;
+  static float dc = (float)1E-25;
+  input += dc;
+  dc = -dc;
 
-	/* allocate history array if different size than last call */
+  /* allocate history array if different size than last call */
 
-    coef_ptr = iir.coef;                /* coefficient pointer */
+  coef_ptr = iir.coef;                /* coefficient pointer */
 
-    hist1_ptr = iir.history;            /* first history */
-    hist2_ptr = hist1_ptr + 1;           /* next history */
+  hist1_ptr = iir.history;            /* first history */
+  hist2_ptr = hist1_ptr + 1;           /* next history */
 
-    /* 1st number of coefficients array is overall input scale factor,
-     * or filter gain */
-    output = input * (*coef_ptr++);
+  /* 1st number of coefficients array is overall input scale factor,
+   * or filter gain */
+  output = input * (*coef_ptr++);
 
-    for (i = 0 ; i < iir.length; i++)
+  for (i = 0 ; i < iir.length; i++)
     {
-        history1 = *hist1_ptr;           /* history values */
-        history2 = *hist2_ptr;
+      history1 = *hist1_ptr;           /* history values */
+      history2 = *hist2_ptr;
 
-        output   = output - history1 * coef_ptr[0];
-        new_hist = output - history2 * coef_ptr[1];    /* poles */
+      output   = output - history1 * coef_ptr[0];
+      new_hist = output - history2 * coef_ptr[1];    /* poles */
 
-        output = new_hist + history1 * coef_ptr[2];
-        output = output   + history2 * coef_ptr[3];    /* zeros */
+      output = new_hist + history1 * coef_ptr[2];
+      output = output   + history2 * coef_ptr[3];    /* zeros */
 
-        coef_ptr += 4;
-        *hist2_ptr++ = *hist1_ptr;
-        *hist1_ptr++ = new_hist;
-        hist1_ptr++;
-        hist2_ptr++;
+      coef_ptr += 4;
+      *hist2_ptr++ = *hist1_ptr;
+      *hist1_ptr++ = new_hist;
+      hist1_ptr++;
+      hist2_ptr++;
     }
 
-    return(output);
+  return(output);
 }
 
 
-void LowPass_Update(float resonance, float cutoff, int samplerate)
+void lpf_update(float resonance, float cutoff, int samplerate)
 {
-    unsigned nInd;
-    double   a0, a1, a2, b0, b1, b2;
-    double   fs;    /* Sampling frequency, cutoff frequency */
-    double   k;           /* overall gain factor */
-    float    *coef;
-
-	k = 1.0;				/* Set overall filter gain */
-	coef = iir.coef + 1;		/* Skip k, or gain */
-	fs = (double)samplerate;    /* Sampling frequency (Hz) */
-
-/*
- * Compute z-domain coefficients for each biquad section
- * for new Cutoff Frequency and Resonance
- */
-    for (nInd = 0; nInd < iir.length; nInd++)
+  unsigned nInd;
+  double   a0, a1, a2, b0, b1, b2;
+  double   fs;    /* Sampling frequency, cutoff frequency */
+  double   k;           /* overall gain factor */
+  float    *coef;
+
+  k = 1.0;				/* Set overall filter gain */
+  coef = iir.coef + 1;		/* Skip k, or gain */
+  fs = (double)samplerate;    /* Sampling frequency (Hz) */
+
+  /*
+   * Compute z-domain coefficients for each biquad section
+   * for new Cutoff Frequency and Resonance
+   */
+  for (nInd = 0; nInd < iir.length; nInd++)
     {
-             a0 = ProtoCoef[nInd].a0;
-             a1 = ProtoCoef[nInd].a1;
-             a2 = ProtoCoef[nInd].a2;
-
-             b0 = ProtoCoef[nInd].b0;
-             b1 = ProtoCoef[nInd].b1 / resonance;      /* Divide by resonance or Q */
-             b2 = ProtoCoef[nInd].b2;
-             szxform(&a0, &a1, &a2, &b0, &b1, &b2, cutoff, fs, &k, coef);
-             coef += 4;                       /* Point to next filter section */
+      a0 = ProtoCoef[nInd].a0;
+      a1 = ProtoCoef[nInd].a1;
+      a2 = ProtoCoef[nInd].a2;
+
+      b0 = ProtoCoef[nInd].b0;
+      b1 = ProtoCoef[nInd].b1 / resonance;      /* Divide by resonance or Q */
+      b2 = ProtoCoef[nInd].b2;
+      szxform(&a0, &a1, &a2, &b0, &b1, &b2, cutoff, fs, &k, coef);
+      coef += 4;                       /* Point to next filter section */
     }
 
-    /* Update overall filter gain in coef array */
-    iir.coef[0] = (float)k;
+  /* Update overall filter gain in coef array */
+  iir.coef[0] = (float)k;
 }
 
 
@@ -132,54 +132,54 @@ void LowPass_Update(float resonance, float cutoff, int samplerate)
  * of two second order sections.
  * --------------------------------------------------------------------
  */
-signed char LowPass_Init()
+signed char lpf_init()
 {
 
-/*
- * Setup filter s-domain coefficients
- */
-	/* Section 1 */
-	ProtoCoef[0].a0 = 1.0;
-	ProtoCoef[0].a1 = 0;
-	ProtoCoef[0].a2 = 0;
-	ProtoCoef[0].b0 = 1.0;
-	ProtoCoef[0].b1 = 0.765367;
-	ProtoCoef[0].b2 = 1.0;
+  /*
+   * Setup filter s-domain coefficients
+   */
+  /* Section 1 */
+  ProtoCoef[0].a0 = 1.0;
+  ProtoCoef[0].a1 = 0;
+  ProtoCoef[0].a2 = 0;
+  ProtoCoef[0].b0 = 1.0;
+  ProtoCoef[0].b1 = 0.765367;
+  ProtoCoef[0].b2 = 1.0;
 	
-	/* Section 2 */
-	ProtoCoef[1].a0 = 1.0;
-	ProtoCoef[1].a1 = 0;
-	ProtoCoef[1].a2 = 0;
-	ProtoCoef[1].b0 = 1.0;
-	ProtoCoef[1].b1 = 1.847759;
-	ProtoCoef[1].b2 = 1.0;
+  /* Section 2 */
+  ProtoCoef[1].a0 = 1.0;
+  ProtoCoef[1].a1 = 0;
+  ProtoCoef[1].a2 = 0;
+  ProtoCoef[1].b0 = 1.0;
+  ProtoCoef[1].b1 = 1.847759;
+  ProtoCoef[1].b2 = 1.0;
+
+  iir.length = FILTER_SECTIONS;         /* Number of filter sections */
+
+  /*
+   * Allocate array of z-domain coefficients for each filter section
+   * plus filter gain variable
+   */
+  iir.coef = (float *) calloc(4 * iir.length + 1, sizeof(float));
+  if (!iir.coef)
+    {
+      //		 printf("Unable to allocate coef array, exiting\n");
+      return 0;
+    }
 
-	iir.length = FILTER_SECTIONS;         /* Number of filter sections */
+  lpf_update(1.0, 5000.0, 44100);
 
-/*
- * Allocate array of z-domain coefficients for each filter section
- * plus filter gain variable
- */
-	iir.coef = (float *) calloc(4 * iir.length + 1, sizeof(float));
-	if (!iir.coef)
-	{
-//		 printf("Unable to allocate coef array, exiting\n");
-		 return 0;
-	}
-
-	LowPass_Update(1.0, 5000.0, 44100);
-
-    /* Display filter coefficients */
-//    for (nInd = 0; nInd < (iir.length * 4 + 1); nInd++)
-//             printf("C[%d] = %15.10f\n", nInd, iir.coef[nInd]);
-/*
- * To process audio samples, call function iir_filter()
- * for each audio sample
- */
-   return 1;
+  /* Display filter coefficients */
+  //    for (nInd = 0; nInd < (iir.length * 4 + 1); nInd++)
+  //             printf("C[%d] = %15.10f\n", nInd, iir.coef[nInd]);
+  /*
+   * To process audio samples, call function iir_filter()
+   * for each audio sample
+   */
+  return 1;
 }
 
-void LowPass_Close()
+void lpf_close()
 {
 }
 
@@ -254,11 +254,11 @@ void LowPass_Close()
 
 void prewarp(double *a0, double *a1, double *a2, double fc, double fs);
 void bilinear(
-    double a0, double a1, double a2,    /* numerator coefficients */
-    double b0, double b1, double b2,    /* denominator coefficients */
-    double *k,                                   /* overall gain factor */
-    double fs,                                   /* sampling rate */
-    float *coef);                         /* pointer to 4 iir coefficients */
+              double a0, double a1, double a2,    /* numerator coefficients */
+              double b0, double b1, double b2,    /* denominator coefficients */
+              double *k,                                   /* overall gain factor */
+              double fs,                                   /* sampling rate */
+              float *coef);                         /* pointer to 4 iir coefficients */
 
 
 /*
@@ -269,16 +269,16 @@ void bilinear(
  * ----------------------------------------------------------
  */
 void prewarp(
-    double *a0, double *a1, double *a2,
-    double fc, double fs)
+             double *a0, double *a1, double *a2,
+             double fc, double fs)
 {
-    double wp, pi;
+  double wp, pi;
 
-    pi = 4.0 * atan(1.0);
-    wp = 2.0 * fs * tan(pi * fc / fs);
+  pi = 4.0 * atan(1.0);
+  wp = 2.0 * fs * tan(pi * fc / fs);
 
-    *a2 = (*a2) / (wp * wp);
-    *a1 = (*a1) / wp;
+  *a2 = (*a2) / (wp * wp);
+  *a1 = (*a1) / wp;
 }
 
 
@@ -312,30 +312,30 @@ void prewarp(
  * ----------------------------------------------------------
  */
 void bilinear(
-    double a0, double a1, double a2,	/* numerator coefficients */
-    double b0, double b1, double b2,	/* denominator coefficients */
-    double *k,							/* overall gain factor */
-    double fs,							/* sampling rate */
-    float *coef							/* pointer to 4 iir coefficients */
-)
+              double a0, double a1, double a2,	/* numerator coefficients */
+              double b0, double b1, double b2,	/* denominator coefficients */
+              double *k,							/* overall gain factor */
+              double fs,							/* sampling rate */
+              float *coef							/* pointer to 4 iir coefficients */
+              )
 {
-    double ad, bd;
+  double ad, bd;
 
-	/* alpha (Numerator in s-domain) */
-    ad = 4. * a2 * fs * fs + 2. * a1 * fs + a0;
-	/* beta (Denominator in s-domain) */
-    bd = 4. * b2 * fs * fs + 2. * b1* fs + b0;
+  /* alpha (Numerator in s-domain) */
+  ad = 4. * a2 * fs * fs + 2. * a1 * fs + a0;
+  /* beta (Denominator in s-domain) */
+  bd = 4. * b2 * fs * fs + 2. * b1* fs + b0;
 
-	/* update gain constant for this section */
-    *k *= ad/bd;
+  /* update gain constant for this section */
+  *k *= ad/bd;
 
-	/* Denominator */
-    *coef++ = (float)((2. * b0 - 8. * b2 * fs * fs)           / bd); /* beta1 */
-    *coef++ = (float)((4. * b2 * fs * fs - 2. * b1 * fs + b0) / bd); /* beta2 */
+  /* Denominator */
+  *coef++ = (float)((2. * b0 - 8. * b2 * fs * fs)           / bd); /* beta1 */
+  *coef++ = (float)((4. * b2 * fs * fs - 2. * b1 * fs + b0) / bd); /* beta2 */
 
-	/* Nominator */
-    *coef++ = (float)((2. * a0 - 8. * a2 * fs * fs) / ad);			 /* alpha1 */
-    *coef   = (float)((4. * a2 * fs * fs - 2. * a1 * fs + a0) / ad); /* alpha2 */
+  /* Nominator */
+  *coef++ = (float)((2. * a0 - 8. * a2 * fs * fs) / ad);			 /* alpha1 */
+  *coef   = (float)((4. * a2 * fs * fs - 2. * a1 * fs + a0) / ad); /* alpha2 */
 }
 
 
@@ -355,17 +355,17 @@ void bilinear(
  * ----------------------------------------------------------
  */
 void szxform(
-    double *a0, double *a1, double *a2, /* numerator coefficients */
-    double *b0, double *b1, double *b2, /* denominator coefficients */
-    double fc,         /* Filter cutoff frequency */
-    double fs,         /* sampling rate */
-    double *k,         /* overall gain factor */
-    float *coef)         /* pointer to 4 iir coefficients */
+             double *a0, double *a1, double *a2, /* numerator coefficients */
+             double *b0, double *b1, double *b2, /* denominator coefficients */
+             double fc,         /* Filter cutoff frequency */
+             double fs,         /* sampling rate */
+             double *k,         /* overall gain factor */
+             float *coef)         /* pointer to 4 iir coefficients */
 {
-                 /* Calculate a1 and a2 and overwrite the original values */
-        prewarp(a0, a1, a2, fc, fs);
-        prewarp(b0, b1, b2, fc, fs);
-        bilinear(*a0, *a1, *a2, *b0, *b1, *b2, k, fs, coef);
+  /* Calculate a1 and a2 and overwrite the original values */
+  prewarp(a0, a1, a2, fc, fs);
+  prewarp(b0, b1, b2, fc, fs);
+  bilinear(*a0, *a1, *a2, *b0, *b1, *b2, k, fs, coef);
 }