Added config file key bindings, general code cleanup

[stargem2] / src / sound.cpp

diff --git a/src/sound.cpp b/src/sound.cpp
index 281aee286f8894a56175a9141a9cf26a8aa54085..4191928b2c52584c87680ab6c8701ca7990fe0d6 100755 (executable)
--- a/src/sound.cpp
+++ b/src/sound.cpp
@@ -10,6 +10,9 @@
 // ---  ----------  ------------------------------------------------------------
 // JLH  06/15/2006  Added changelog ;-)
 // JLH  06/15/2006  Scrubbed all BYTE, WORD & DWORD references from the code
+// JLH  02/10/2009  Fixed sound IRQ callback so that CPU samples are taken at
+//                  cycle exact boundaries
+// JLH  07/21/2009  Moved numeric constants into macros for sanity's sake
 //
 // Notes:
 //   The sound CPU (6808) runs at 894,750 (3,579,000 / 4) Hz.
@@ -24,13 +27,20 @@
 #include "types.h"
 #include "log.h"
 #include "v6808.h"
+#include "timing.h"
 
 //using namespace std;
 
+//#define AUDIO_SAMPLE_RATE                            44100.0
+#define AUDIO_SAMPLE_RATE                              48000.0
+#define CYCLES_TO_EXECUTE                              (M6808_CLOCK_SPEED_IN_HZ / AUDIO_SAMPLE_RATE)
+
 // Local variables
 
-SDL_AudioSpec desired;
-bool soundInitialized = false;
+static SDL_AudioSpec desired;
+static bool soundInitialized = false;
+static uint32 cyclesToExecuteWholePart;
+static double cyclesToExecuteFractionalPart;
 
 // Private function prototypes
 
@@ -43,7 +53,7 @@ void SoundInit(void)
 {
 //     memory_malloc_secure((void **)&DACBuffer, BUFFER_SIZE * sizeof(uint16), "DAC buffer");
 
-       desired.freq = 44100;                                                   // SDL will do conversion on the fly, if it can't get the exact rate. Nice!
+       desired.freq = AUDIO_SAMPLE_RATE;                               // SDL will do conversion on the fly, if it can't get the exact rate. Nice!
        desired.format = AUDIO_U8;                                              // This uses the native endian (for portability)...
        desired.channels = 1;
 //     desired.samples = 4096;                                                 // Let's try a 4K buffer (can always go lower)
@@ -53,10 +63,16 @@ void SoundInit(void)
        if (SDL_OpenAudio(&desired, NULL) < 0)                  // NULL means SDL guarantees what we want
        {
                WriteLog("Sound: Failed to initialize SDL sound.\n");
-//             exit(1);
                return;
        }
 
+       // Setup clock cycles & etc.
+       cyclesToExecuteWholePart = (uint32)CYCLES_TO_EXECUTE;
+       cyclesToExecuteFractionalPart = CYCLES_TO_EXECUTE - (double)cyclesToExecuteWholePart;
+#if 0
+printf("Cycles to execute: %lf; cycles W: %u; cycles F: %lf\n", CYCLES_TO_EXECUTE, cyclesToExecuteWholePart, cyclesToExecuteFractionalPart);
+#endif
+
        SDL_PauseAudio(false);                                                  // Start playback!
        soundInitialized = true;
        WriteLog("Sound: Successfully initialized.\n");
@@ -81,58 +97,24 @@ void SoundDone(void)
 void SDLSoundCallback(void * userdata, Uint8 * buffer, int length)
 {
        extern V6808REGS soundCPU;
-//     extern uint8 * sram;
        extern uint8 sram[];
        int cnt = 0;
 
-#define CYCLE_EXACT_SOUND
-#ifdef CYCLE_EXACT_SOUND
-       float overflow = 0.0;
-       uint32 time = 20;
-#endif
+       static float overflow = 0.0;
+       static uint32 time = cyclesToExecuteWholePart;
 
        while (cnt != length)
        {
-               // This is close, but not cycle exact (exact would be 20.289115646...)
-
-//Need to figure out how to get that fraction to execute... !!! FIX !!!
-/*
-One way would be to use a fractional accumulator, then subtract 1 every
-time it overflows. Like so:
-
-double overflow = 0;
-uint32 time = 20;
-while (!done)
-{
-       Execute6808(&soundCPU, time);
-       overflow += 0.289115646;
-       if (overflow > 1.0)
-       {
-               overflow -= 1.0;
-               time = 21;
-       }
-       else
-               time = 20;
-}
-*/
-#ifdef CYCLE_EXACT_SOUND
                Execute6808(&soundCPU, time);
                soundCPU.clock -= time;
-#else
-               Execute6808(&soundCPU, 20);
-               soundCPU.clock -= 20;
-#endif
                buffer[cnt++] = sram[0x0400];                           // Fill the buffer with the PIA output value
-#ifdef CYCLE_EXACT_SOUND
-               overflow += 0.289115646;
+               time = cyclesToExecuteWholePart;
+               overflow += cyclesToExecuteFractionalPart;
 
                if (overflow > 1.0)
                {
                        overflow -= 1.0;
-                       time = 21;
+                       time++;
                }
-               else
-                       time = 20;
-#endif
        }
 }