shithub: pt2-clone

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Changed/added a few comments

--- a/src/pt2_audio.c

+++ b/src/pt2_audio.c

@@ -658,8 +658,9 @@

 static void calculateFilterCoeffs(void)

 {

-	/* Amiga 500 filter emulation, by aciddose

+	/* Amiga 500/1200 filter emulation

 	**

+	** aciddose:

 	** First comes a static low-pass 6dB formed by the supply current

 	** from the Paula's mixture of channels A+B / C+D into the opamp with

 	** 0.1uF capacitor and 360 ohm resistor feedback in inverting mode biased by

@@ -719,7 +720,7 @@

 	fc = 1.0 / (2.0 * pi * R * C);

 	calcRCFilterCoeffs(audio.outputRate, fc, &filterLoA500);

-	// A1200 1-pole (6db/oct) static RC low-pass filter:

+	// A1200 1-pole (6dB/oct) static RC low-pass filter:

 	if (audio.outputRate >= 96000) // cutoff is too high for 44.1kHz/48kHz

 	{

 		R = 680.0;  // R321 (680 ohm resistor)

@@ -737,13 +738,13 @@

 	fb = 0.125; // Fb = 0.125 : Q ~= 1/sqrt(2)

 	calcLEDFilterCoeffs(audio.outputRate, fc, fb, &filterLED);

-	// A500 1-pole (6db/oct) static RC high-pass filter:

+	// A500 1-pole (6dB/oct) static RC high-pass filter:

 	R = 1390.0; // R324 (1K ohm resistor) + R325 (390 ohm resistor)

 	C = 2.233e-5; // C334 (22uF capacitor) + C335 (0.33�F capacitor)

 	fc = 1.0 / (2.0 * pi * R * C);

 	calcRCFilterCoeffs(audio.outputRate, fc, &filterHiA500);

-	// A1200 1-pole (6db/oct) static RC high-pass filter:

+	// A1200 1-pole (6dB/oct) static RC high-pass filter:

 	R = 1390.0; // R324 (1K ohm resistor) + R325 (390 ohm resistor)

 	C = 2.2e-5; // C334 (22uF capacitor)

 	fc = 1.0 / (2.0 * pi * R * C);

--- a/src/pt2_downsample2x.c

+++ b/src/pt2_downsample2x.c

@@ -11,6 +11,9 @@

 /*

 ** - all-pass halfband filters (2x downsample) -

+**

+** 8bitbubsy: Not sure who coded these. Possibly aciddose,

+** or maybe he found it on the internet somewhere...

 */

 static double f(const double in, double *b, const double c)

--- a/src/pt2_ledfilter.c

+++ b/src/pt2_ledfilter.c

@@ -3,7 +3,8 @@

 #include "pt2_rcfilter.h" // DENORMAL_OFFSET definition

 #include "pt2_ledfilter.h"

-/* Imperfect Amiga "LED" filter implementation. This may be further improved in the future.

+/* aciddose:

+** Imperfect Amiga "LED" filter implementation. This may be further improved in the future.

 ** Based upon ideas posted by mystran @ the kvraudio.com forum.

 **

 ** This filter may not function correctly used outside the fixed-cutoff context here!

--- a/src/pt2_rcfilter.c

+++ b/src/pt2_rcfilter.c

@@ -1,3 +1,6 @@

+// 1-pole 6dB/oct RC filters, code by aciddose (I think?)

+

+

 #include <stdint.h>

 #include <math.h>

 #include "pt2_rcfilter.h"