1 files changed, 79 insertions, 0 deletions
diff --git a/libopna/opnatimer.c b/libopna/opnatimer.c
new file mode 100644
index 0000000..195e426
--- /dev/null
+++ b/libopna/opnatimer.c
@@ -0,0 +1,79 @@
+#include "opnatimer.h"
+#include "opna.h"
+
+enum {
+  TIMERB_SHIFT = 4,
+  TIMERB_BITS = 8 + TIMERB_SHIFT,
+};
+
+void opna_timer_reset(struct opna_timer *timer, struct opna *opna) {
+  timer->opna = opna;
+  timer->status = 0;
+  timer->interrupt_cb = 0;
+  timer->interrupt_userptr = 0;
+  timer->mix_cb = 0;
+  timer->mix_userptr = 0;
+  timer->timerb = 0;
+  timer->timerb_load = false;
+  timer->timerb_enable = false;
+  timer->timerb_cnt = 0;
+}
+
+uint8_t opna_timer_status(const struct opna_timer *timer) {
+  return timer->status;
+}
+
+void opna_timer_set_int_callback(struct opna_timer *timer, opna_timer_int_cb_t func, void *userptr) {
+  timer->interrupt_cb = func;
+  timer->interrupt_userptr = userptr;
+}
+
+void opna_timer_set_mix_callback(struct opna_timer *timer, opna_timer_mix_cb_t func, void *userptr) {
+  timer->mix_cb = func;
+  timer->mix_userptr = userptr;
+}
+
+void opna_timer_writereg(struct opna_timer *timer, unsigned reg, unsigned val) {
+  val &= 0xff;
+  opna_writereg(timer->opna, reg, val);
+  switch (reg) {
+  case 0x26:
+    timer->timerb = val;
+    timer->timerb_cnt = timer->timerb << TIMERB_SHIFT;
+    break;
+  case 0x27:
+    timer->timerb_load = val & (1<<1);
+    timer->timerb_enable = val & (1<<3);
+    if (val & (1<<5)) {
+      //timer->timerb_cnt = timer->timerb << TIMERB_SHIFT;
+      timer->status &= ~(1<<1);
+    }
+  }
+}
+
+void opna_timer_mix(struct opna_timer *timer, int16_t *buf, unsigned samples) {
+  do {
+    unsigned generate_samples = samples;
+    if (timer->timerb_enable) {
+      unsigned timerb_samples = (1<<TIMERB_BITS) - timer->timerb_cnt;
+      if (timerb_samples < generate_samples) {
+        generate_samples = timerb_samples;
+      }
+    }
+    opna_mix(timer->opna, buf, generate_samples);
+    if (timer->mix_cb) {
+      timer->mix_cb(timer->mix_userptr, buf, generate_samples);
+    }
+    buf += generate_samples*2;
+    samples -= generate_samples;
+    if (timer->timerb_load) {
+      timer->timerb_cnt = (timer->timerb_cnt + generate_samples) & ((1<<TIMERB_BITS)-1);
+      if (!timer->timerb_cnt && timer->timerb_enable) {
+        if (!(timer->status & (1<<1))) {
+          timer->status |= (1<<1);
+          timer->interrupt_cb(timer->interrupt_userptr);
+        }
+      }
+    }
+  } while (samples);
+}