o cleanup

tools/bsnes/dsp/sdsp/counter.cpp

@@ -0,0 +1,52 @@
+#ifdef SDSP_CPP
+
+//counter_rate = number of samples per counter event
+//all rates are evenly divisible by counter_range (0x7800, 30720, or 2048 * 5 * 3)
+//note that rate[0] is a special case, which never triggers
+
+const uint16 sDSP::counter_rate[32] = {
+     0, 2048, 1536,
+  1280, 1024,  768,
+   640,  512,  384,
+   320,  256,  192,
+   160,  128,   96,
+    80,   64,   48,
+    40,   32,   24,
+    20,   16,   12,
+    10,    8,    6,
+     5,    4,    3,
+           2,
+           1,
+};
+
+//counter_offset = counter offset from zero
+//counters do not appear to be aligned at zero for all rates
+
+const uint16 sDSP::counter_offset[32] = {
+    0, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+  536, 0, 1040,
+       0,
+       0,
+};
+
+inline void sDSP::counter_tick() {
+  state.counter--;
+  if(state.counter < 0) state.counter = counter_range - 1;
+}
+
+//return true if counter event should trigger
+
+inline bool sDSP::counter_poll(unsigned rate) {
+  if(rate == 0) return false;
+  return (((unsigned)state.counter + counter_offset[rate]) % counter_rate[rate]) == 0;
+}
+
+#endif //ifdef SDSP_CPP