1 files changed, 241 insertions, 0 deletions

diff --git a/src/uxn/devices/apu.c b/src/uxn/devices/apu.c
new file mode 100644
index 0000000..fbe7c3d
--- /dev/null
+++ b/src/uxn/devices/apu.c
@@ -0,0 +1,241 @@
+#include "samples.c"
+
+#define SAMPLE_FREQUENCY 44100
+#define NOTE_PERIOD (SAMPLE_FREQUENCY * 0x4000 / 11025)
+#define ADSR_STEP (SAMPLE_FREQUENCY / 0xf)
+
+typedef struct AudioChannel {
+    u8 *samples;
+    u16 n_samples;
+        u16 position;
+    u16 sampling_freq;
+    u8 pitch;
+    bool loop;
+    // TODO: u16 adsr; // attack, decay, sustain, release
+    // TODO: u8 pitch;  // Bit 8 is the "loop" bit
+    // TODO: u8 volume; // VOL_LEFT | (VOL_RIGHT << 4)
+        // u8 *addr;
+        // u32 count, advance, period, age, a, d, s, r;
+        // s8 volume[2];
+        // u8 pitch, repeat;
+} AudioChannel;
+
+typedef struct APU {
+    AudioChannel chan_0;
+    // u32 *samples_1;
+    // u32 *samples_2;
+    // u32 *samples_3;
+} APU;
+
+static APU apu;
+
+
+static u16 pitch_table[] = {
+    12173,
+    11490,
+    10845,
+    10237,
+    9662,
+    9120,
+    8608,
+    8125,
+    7669,
+    7238,
+    6832,
+    6448,
+    6086,
+    5745,
+    5422,
+    5118,
+    4831,
+    4560,
+    4304,
+    4062,
+    3834,
+    3619,
+    3416,
+    3224,
+    3043,
+    2872,
+    2711,
+    2559,
+    2415,
+    2280,
+    2152,
+    2031,
+    1917,
+    1809,
+    1708,
+    1612,
+    1521,
+    1436,
+    1355,
+    1279,
+    1207,
+    1140,
+    1076,
+    1015,
+    958,
+    904,
+    854,
+    806,
+    760,
+    718,
+    677,
+    639,
+    603,
+    570,
+    538,
+    507,
+    479,
+    452,
+    427,
+    403,
+    380,
+    359,
+    338,
+    319,
+    301,
+    285,
+    269,
+    253,
+    239,
+    226,
+    213,
+    201,
+    190,
+    179,
+    169,
+    159,
+    150,
+    142,
+    134,
+    126,
+    119,
+    113,
+    106,
+    100,
+    95,
+    89,
+    84,
+    79,
+    75,
+    71,
+    67,
+    63,
+    59,
+    56,
+    53,
+    50,
+    47,
+    44,
+    42,
+    39,
+    37,
+    35,
+    33,
+    31,
+    29,
+    28,
+    26,
+    25,
+    23,
+    22,
+    21,
+    19,
+    18,
+    17,
+    16,
+    15,
+    14,
+    14,
+    13,
+    12,
+    0,
+};
+
+void
+reset_sound(AudioChannel *chan) {
+    TIMER_CTRL_0 = 0;
+    TIMER_CTRL_1 = 0;
+    DMA_CTRL(1) = 0;
+    if (chan->pitch >= 108 || chan->n_samples == 0) {
+        return;
+    }
+
+    // Set max volume, left-right sound, fifo reset and use timer 0 for
+    // DirectSound A.
+    SOUND_DSOUND_MASTER = SOUND_DSOUND_RATIO_A
+        | SOUND_DSOUND_LEFT_A
+        | SOUND_DSOUND_RIGHT_A
+        | SOUND_DSOUND_RESET_A;
+
+    // Prepare DMA copy.
+    dma_transfer_copy(SOUND_FIFO_A, chan->samples, 1, 1,
+            DMA_CHUNK_32 | DMA_REFRESH | DMA_REPEAT | DMA_ENABLE);
+
+    // Timer 1 used to stop playing samples.
+    u32 sample_duration = chan->n_samples;
+    TIMER_DATA_1 = 0xFFFF - sample_duration;
+    TIMER_CTRL_1 = TIMER_CTRL_IRQ
+        | TIMER_CTRL_ENABLE
+        | TIMER_CTRL_CASCADE;
+
+    // Timer 0 used to stop sample playing.
+    // TIMER_DATA_0 = 0xFFFF - sound_freq[chan->pitch];
+    // TIMER_DATA_0 = 0xFFFF - CPU_FREQUENCY / chan->sampling_freq / chan->pitch;
+    TIMER_DATA_0 = 0xFFFF - pitch_table[chan->pitch];
+    TIMER_CTRL_0 = TIMER_CTRL_ENABLE;
+}
+
+u8 square_wave[] =  {
+    0x00 + 0x80, 0xFF + 0x80
+};
+#include "text.h"
+
+
+void
+init_sound(AudioChannel *chan) {
+    // Enable sound.
+    SOUND_STATUS = SOUND_ENABLE;
+
+    // chan->samples = &square_wave;
+    // chan->n_samples = 2;
+    // chan->samples = &samples;
+    // chan->n_samples = LEN(samples);
+    // chan->pitch++;
+    // chan->pitch = chan->pitch == LEN(pitch_table) - 1 ? 0 : chan->pitch + 1;
+    // chan->loop = true;
+    // chan->sampling_freq = pitch_table[chan->pitch];
+    // txt_printf("RATE: %lu", pitch_table[chan->pitch])
+}
+
+void
+irs_stop_sample(void) {
+    if (apu.chan_0.loop) {
+        reset_sound(&apu.chan_0);
+    } else {
+        TIMER_CTRL_0 = 0;
+        DMA_CTRL(1) = 0;
+    }
+}
+
+// void
+// apu_start(Apu *c, u16 adsr, u8 pitch) {
+//      // if(pitch < 108 && c->len)
+//      //      c->advance = advances[pitch % 12] >> (8 - pitch / 12);
+//      // else {
+//      //      c->advance = 0;
+//      //      return;
+//      // }
+//      // c->a = ADSR_STEP * (adsr >> 12);
+//      // c->d = ADSR_STEP * (adsr >> 8 & 0xf) + c->a;
+//      // c->s = ADSR_STEP * (adsr >> 4 & 0xf) + c->d;
+//      // c->r = ADSR_STEP * (adsr >> 0 & 0xf) + c->s;
+//      // c->age = 0;
+//      // c->i = 0;
+//      // if(c->len <= 0x100) /* single cycle mode */
+//      //      c->period = NOTE_PERIOD * 337 / 2 / c->len;
+//      // else /* sample repeat mode */
+//      //      c->period = NOTE_PERIOD;
+// }