prepare code and sketch emulator function prototypes

src/engine/platform/sound/sid3.c

@@ -0,0 +1,38 @@
+#include "sid3.h"
+
+#define SAFETY_HEADER if(sid3 == NULL) return;
+
+SID3* sid3_create()
+{
+    SID3* sid3 = (SID3*)malloc(sizeof(SID3));
+    return sid3;
+}
+
+void sid3_reset(SID3* sid3)
+{
+    SAFETY_HEADER
+
+    memset(sid3, 0, sizeof(SID3));
+}
+
+void sid3_write(SID3* sid3, uint8_t address, uint8_t data)
+{
+    SAFETY_HEADER
+}
+
+void sid3_clock(SID3* sid3)
+{
+    SAFETY_HEADER
+}
+
+void sid3_set_is_muted(SID3* sid3, uint8_t ch, bool mute)
+{
+    SAFETY_HEADER
+}
+
+void sid3_free(SID3* sid3)
+{
+    SAFETY_HEADER
+
+    free(sid3);
+}

src/engine/platform/sound/sid3.h

@@ -0,0 +1,86 @@
+#ifndef SID3_H
+#define SID3_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#define SID3_NUM_CHANNELS 7
+#define SID3_NUM_FILTERS 4
+#define SID3_NUM_REGISTERS 256
+#define SID3_MAX_VOL 255
+
+#define SID3_WAVETABLE_LENGTH 512
+
+typedef struct
+{
+    int input;
+    int output;
+
+    // State of filter.
+    float Vhp; // highpass
+    float Vbp; // bandpass
+    float Vlp; // lowpass
+
+    // Cutoff frequency, resonance.
+    float w0, w0_ceil_1;
+    float _1024_div_Q;
+} sid3_filter;
+
+typedef struct
+{
+    sid3_filter filt[SID3_NUM_FILTERS];
+    uint32_t connection_matrix;
+} sid3_filters_block;
+
+typedef struct
+{
+    uint32_t accumulator;
+    uint32_t frequency;
+
+    sid3_filters_block filt;
+
+    uint8_t panning;
+} sid3_channel;
+
+typedef struct
+{
+    uint32_t accumulator;
+    uint32_t frequency;
+
+    uint16_t streamed_sample;
+    uint8_t wavetable[SID3_WAVETABLE_LENGTH];
+
+    sid3_filters_block filt;
+
+    uint8_t panning;
+} sid3_wavetable_chan;
+
+typedef struct
+{
+    sid3_channel chan[SID3_NUM_CHANNELS - 1];
+    sid3_wavetable_chan wave_chan;
+
+    int output_l, output_r;
+
+    //emulation-only helpers
+    int channel_output[SID3_NUM_CHANNELS];
+    bool muted[SID3_NUM_CHANNELS];
+} SID3;
+
+SID3* sid3_create();
+void sid3_reset(SID3* sid3);
+void sid3_write(SID3* sid3, uint8_t address, uint8_t data);
+void sid3_clock(SID3* sid3);
+void sid3_set_is_muted(SID3* sid3, uint8_t ch, bool mute);
+void sid3_free(SID3* sid3);
+
+#ifdef __cplusplus
+};
+#endif
+#endif