DSP

source/engine/dsp.c

@@ -0,0 +1,87 @@
+#include "dsp.h"
+
+#include "sound.h"
+#include "limits.h"
+#include "math.h"
+
+#define PI 3.14159265
+
+void am_mod(short *a, short *b, short *c, int n)
+{
+    for (int i = 0; i < n; i++) {
+        c[i] = (a[i]*b[i])>>15;
+    }
+}
+
+static struct wav make_wav(float freq, int sr, int ch) {
+    struct wav new;
+    new.ch = ch;
+    new.samplerate = sr;
+    new.frames = sr/freq;
+    new.data = calloc(new.frames*new.ch, sizeof(short));
+
+    return new;
+}
+
+struct wav gen_sine(float amp, float freq, int sr, int ch)
+{
+    struct wav new = make_wav(freq, sr, ch);
+
+    if (amp > 1) amp = 1;
+    if (amp < 0) amp = 0;
+    short samp = amp*SHRT_MAX;
+
+    short *data = (short*)new.data;
+
+    for (int i = 0; i < new.frames; i++) {
+        for (int j = 0; j < new.ch; j++) {
+            data[i+j] =amp * sin(2*PI*((float)i / new.frames));
+        }
+    }
+
+    return new;
+}
+
+struct wav gen_square(float amp, float freq, int sr, int ch)
+{
+    struct wav new = make_wav(freq, sr, ch);
+
+    int crossover = new.frames/2;
+
+    if (amp > 1) amp = 1;
+    if (amp < 0) amp = 0;
+
+    short samp = amp * SHRT_MAX;
+
+    short *data = (short*)new.data;
+
+    for (int i = 0; i < crossover; i++) {
+        for (int j = 0; j < new.ch; j++) {
+            data[i+j] = samp;
+        }
+    }
+
+    for (int i = crossover; i < new.frames; i++) {
+        for (int j = 0; j < new.ch; j++) {
+            data[i+j] = samp * -1;
+        }
+    }
+
+    return new;
+}
+
+struct wav gen_triangle(float amp, float freq, int sr, int ch)
+{
+    struct wav new = make_wav(freq, sr, ch);
+
+    if (amp > 1) amp = 1;
+    if (amp < 0) amp = 0;
+
+
+
+    for (int i = 0; i < new.frames; i++) {
+        for (int j = 0; j < new.ch; j++) {
+            //new.data[i+j] =
+        }
+    }
+}

source/engine/dsp.h

@@ -0,0 +1,12 @@
+#ifndef DSP_H
+#define DSP_H
+
+void am_mod(short *a, short *b, short *c, int n);
+
+struct wav;
+
+struct wav gen_sine(float amp, float freq, int sr, int ch);
+struct wav gen_square(float amp, float freq, int sr, int ch);
+struct wav gen_triangle(float amp, float freq, int sr, int ch);
+
+#endif

source/engine/sound.c

@@ -7,6 +7,8 @@
 #include "limits.h"
 #include "time.h"
 
+#include "dsp.h"
+
 
 #define DR_WAV_IMPLEMENTATION
 #include "dr_wav.h"
@@ -133,15 +135,16 @@ void sound_init()
 
     printf("Loaded wav: ch %i, sr %i, fr %i.\n", mwav.ch, mwav.samplerate, mwav.frames);
 
+    mwav = gen_square(1, 150, 48000, 2);
+
+/*
     short *tdata = mwav.data;
     mwav.frames /= 2;
     short *newdata = calloc(mwav.frames * 2, sizeof(short));
     for (int i = 0; i < mwav.frames; i++) {
         newdata[i] = tdata[i*2];
     }
-
+*/
-    free(mwav.data);
-    mwav.data = newdata;
 
     wavsound.data = &mwav;
     wavsound.loop = 1;