Mercurial > repos > blastem
diff psg.c @ 1002:8d032a368dd5
Made low pass filter frequency configurable
author | Michael Pavone <pavone@retrodev.com> |
---|---|
date | Sun, 01 May 2016 13:36:14 -0700 |
parents | e6dc30231b83 |
children | c15896605bf2 |
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--- a/psg.c Sat Apr 30 20:57:29 2016 -0700 +++ b/psg.c Sun May 01 13:36:14 2016 -0700 @@ -10,9 +10,7 @@ #include <stdlib.h> #include <stdio.h> #include <math.h> -#define LOWPASS_CUTOFF 3390 - -void psg_init(psg_context * context, uint32_t sample_rate, uint32_t master_clock, uint32_t clock_div, uint32_t samples_frame) +void psg_init(psg_context * context, uint32_t sample_rate, uint32_t master_clock, uint32_t clock_div, uint32_t samples_frame, uint32_t lowpass_cutoff) { memset(context, 0, sizeof(*context)); context->audio_buffer = malloc(sizeof(*context->audio_buffer) * samples_frame); @@ -20,7 +18,7 @@ context->clock_inc = clock_div; context->sample_rate = sample_rate; context->samples_frame = samples_frame; - double rc = (1.0 / (double)LOWPASS_CUTOFF) / (2.0 * M_PI); + double rc = (1.0 / (double)lowpass_cutoff) / (2.0 * M_PI); double dt = 1.0 / ((double)master_clock / (double)clock_div); double alpha = dt / (dt + rc); context->lowpass_alpha = (int32_t)(((double)0x10000) * alpha);