Avoid 64 bit float constants in ladder filter

filter_ladder.cpp

@@ -13,11 +13,11 @@
 #include "filter_ladder.h"
 #include <math.h>
 #include <stdint.h>
-#define MOOG_PI 3.14159265358979323846264338327950288
+#define MOOG_PI ((float)3.14159265358979323846264338327950288)
 
 float AudioFilterLadder::LPF(float s, int i)
 {
-	float ft = s * (1/1.3) + (0.3/1.3) * z0[i] - z1[i];
+	float ft = s * (1.0f/1.3f) + (0.3f/1.3f) * z0[i] - z1[i];
 	ft = ft * alpha + z1[i];
 	z1[i] = ft;
 	z0[i] = s;
@@ -43,12 +43,12 @@ void AudioFilterLadder::frequency(float c)
 
 void AudioFilterLadder::compute_coeffs(float c)
 {
-	if (c > 0.49 * AUDIO_SAMPLE_RATE_EXACT)
-		c = 0.49 * AUDIO_SAMPLE_RATE_EXACT;
+	if (c > 0.49f * AUDIO_SAMPLE_RATE_EXACT)
+		c = 0.49f * AUDIO_SAMPLE_RATE_EXACT;
 	else if (c < 1)
 		c = 1;
 
-	float wc = c * (2.0 * MOOG_PI / AUDIO_SAMPLE_RATE_EXACT);
+	float wc = c * (float)(2.0f * MOOG_PI / AUDIO_SAMPLE_RATE_EXACT);
 	float wc2 = wc * wc;
 	alpha = 0.9892f * wc - 0.4324f * wc2 + 0.1381f * wc * wc2 - 0.0202f * wc2 * wc2;
 }
@@ -56,7 +56,7 @@ void AudioFilterLadder::compute_coeffs(float c)
 static inline float fast_tanh(float x)
 {
 	float x2 = x * x;
-	return x * (27.0 + x2) / (27.0 + 9.0 * x2);
+	return x * (27.0f + x2) / (27.0f + 9.0f * x2);
 }
 
 void AudioFilterLadder::update(void)
@@ -84,20 +84,20 @@ void AudioFilterLadder::update(void)
 	}
 	if (!blockb) FCmodActive = false;
 	for (int i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
-		float input = blocka->data[i] * (1.0/32768);
+		float input = blocka->data[i] * (1.0f/32768.0f);
 		ftot = Fbase;
 		if (FCmodActive) {
-			FCmod = blockb->data[i] * (1.0/32768);
+			FCmod = blockb->data[i] * (1.0f/32768.0f);
 			ftot += Fbase * FCmod;
 			if (FCmod != 0) compute_coeffs(ftot);
 		}
-		float u = input - (z1[3] - 0.5 * input) * K;
+		float u = input - (z1[3] - 0.5f * input) * K;
 		u = fast_tanh(u);
-		float stage1 = LPF(u,0);
-		float stage2 = LPF(stage1,1);
-		float stage3 = LPF(stage2,2);
-		float stage4 = LPF(stage3,3);
-		blocka->data[i] = stage4 * 32767.0;
+		float stage1 = LPF(u, 0);
+		float stage2 = LPF(stage1, 1);
+		float stage3 = LPF(stage2, 2);
+		float stage4 = LPF(stage3, 3);
+		blocka->data[i] = stage4 * 32767.0f;
 	}
 	transmit(blocka);
 	release(blocka);