Shamusworld >> Repos - virtualjaguar/blob - src/dac.cpp

   1 //
   2 // DAC (really, Synchronous Serial Interface) Handler
   3 //
   4 // Originally by David Raingeard
   5 // GCC/SDL port by Niels Wagenaar (Linux/WIN32) and Caz (BeOS)
   6 // Rewritten by James L. Hammons
   7 //
   8
   9 #include "SDL.h"
  10 #include "m68k.h"
  11 #include "jaguar.h"
  12 #include "settings.h"
  13 #include "dac.h"
  14
  15 //#define DEBUG_DAC
  16
  17 #define BUFFER_SIZE             0x10000                                         // Make the DAC buffers 64K x 16 bits
  18
  19 // Jaguar memory locations
  20
  21 #define LTXD                    0xF1A148
  22 #define RTXD                    0xF1A14C
  23 #define LRXD                    0xF1A148
  24 #define RRXD                    0xF1A14C
  25 #define SCLK                    0xF1A150
  26 #define SMODE                   0xF1A154
  27
  28 // Global variables
  29
  30 uint16 lrxd, rrxd;                                                                      // I2S ports (into Jaguar)
  31
  32 // Local variables
  33
  34 static uint32 LeftFIFOHeadPtr, LeftFIFOTailPtr, RightFIFOHeadPtr, RightFIFOTailPtr;
  35 static SDL_AudioSpec desired;
  36 static bool SDLSoundInitialized = false;
  37
  38 // We can get away with using native endian here because we can tell SDL to use the native
  39 // endian when looking at the sample buffer, i.e., no need to worry about it.
  40
  41 static uint16 * DACBuffer;
  42 static uint8 SCLKFrequencyDivider = 19;                         // Default is roughly 22 KHz (20774 Hz in NTSC mode)
  43 /*static*/ uint16 serialMode = 0;
  44
  45 // Private function prototypes
  46
  47 void SDLSoundCallback(void * userdata, Uint8 * buffer, int length);
  48 int GetCalculatedFrequency(void);
  49
  50 //
  51 // Initialize the SDL sound system
  52 //
  53 void DACInit(void)
  54 {
  55         memory_malloc_secure((void **)&DACBuffer, BUFFER_SIZE * sizeof(uint16), "DAC buffer");
  56
  57         desired.freq = GetCalculatedFrequency();                // SDL will do conversion on the fly, if it can't get the exact rate. Nice!
  58         desired.format = AUDIO_S16SYS;                                  // This uses the native endian (for portability)...
  59         desired.channels = 2;
  60 //      desired.samples = 4096;                                                 // Let's try a 4K buffer (can always go lower)
  61         desired.samples = 2048;                                                 // Let's try a 2K buffer (can always go lower)
  62         desired.callback = SDLSoundCallback;
  63
  64         if (SDL_OpenAudio(&desired, NULL) < 0)                  // NULL means SDL guarantees what we want
  65         {
  66 //              WriteLog("DAC: Failed to initialize SDL sound. Shutting down!\n");
  67 //              log_done();
  68 //              exit(1);
  69                 WriteLog("DAC: Failed to initialize SDL sound...\n");
  70         }
  71         else
  72         {
  73                 SDLSoundInitialized = true;
  74                 DACReset();
  75                 SDL_PauseAudio(false);                                                  // Start playback!
  76                 WriteLog("DAC: Successfully initialized.\n");
  77         }
  78 }
  79
  80 //
  81 // Reset the sound buffer FIFOs
  82 //
  83 void DACReset(void)
  84 {
  85         LeftFIFOHeadPtr = LeftFIFOTailPtr = 0, RightFIFOHeadPtr = RightFIFOTailPtr = 1;
  86 }
  87
  88 //
  89 // Close down the SDL sound subsystem
  90 //
  91 void DACDone(void)
  92 {
  93         if (SDLSoundInitialized)
  94         {
  95                 SDL_PauseAudio(true);
  96                 SDL_CloseAudio();
  97         }
  98
  99         memory_free(DACBuffer);
 100         WriteLog("DAC: Done.\n");
 101 }
 102
 103 //
 104 // SDL callback routine to fill audio buffer
 105 //
 106 // Note: The samples are packed in the buffer in 16 bit left/16 bit right pairs.
 107 //
 108 void SDLSoundCallback(void * userdata, Uint8 * buffer, int length)
 109 {
 110         // Clear the buffer to silence, in case the DAC buffer is empty (or short)
 111 //This causes choppy sound... Ick.
 112         memset(buffer, desired.silence, length);
 113 //WriteLog("DAC: Inside callback...\n");
 114         if (LeftFIFOHeadPtr != LeftFIFOTailPtr)
 115         {
 116 //WriteLog("DAC: About to write some data!\n");
 117                 int numLeftSamplesReady
 118                         = (LeftFIFOTailPtr + (LeftFIFOTailPtr < LeftFIFOHeadPtr ? BUFFER_SIZE : 0))
 119                                 - LeftFIFOHeadPtr;
 120                 int numRightSamplesReady
 121                         = (RightFIFOTailPtr + (RightFIFOTailPtr < RightFIFOHeadPtr ? BUFFER_SIZE : 0))
 122                                 - RightFIFOHeadPtr;
 123                 int numSamplesReady
 124                         = (numLeftSamplesReady < numRightSamplesReady
 125                                 ? numLeftSamplesReady : numRightSamplesReady);//Hmm. * 2;
 126
 127 //The numbers look good--it's just that the DSP can't get enough samples in the DAC buffer!
 128 //WriteLog("DAC: Left/RightFIFOHeadPtr: %u/%u, Left/RightFIFOTailPtr: %u/%u\n", LeftFIFOHeadPtr, RightFIFOHeadPtr, LeftFIFOTailPtr, RightFIFOTailPtr);
 129 //WriteLog("     numLeft/RightSamplesReady: %i/%i, numSamplesReady: %i, length of buffer: %i\n", numLeftSamplesReady, numRightSamplesReady, numSamplesReady, length);
 130
 131 /*              if (numSamplesReady > length)
 132                         numSamplesReady = length;//*/
 133                 if (numSamplesReady > length / 2)       // length / 2 because we're comparing 16-bit lengths
 134                         numSamplesReady = length / 2;
 135 //else
 136 //      WriteLog("     Not enough samples to fill the buffer (short by %u L/R samples)...\n", (length / 2) - numSamplesReady);
 137 //WriteLog("DAC: %u samples ready.\n", numSamplesReady);
 138
 139                 // Actually, it's a bit more involved than this, but this is the general idea:
 140 //              memcpy(buffer, DACBuffer, length);
 141                 for(int i=0; i<numSamplesReady; i++)
 142                         ((uint16 *)buffer)[i] = DACBuffer[(LeftFIFOHeadPtr + i) % BUFFER_SIZE];
 143                         // Could also use (as long as BUFFER_SIZE is a multiple of 2):
 144 //                      buffer[i] = DACBuffer[(LeftFIFOHeadPtr + i) & (BUFFER_SIZE - 1)];
 145
 146                 LeftFIFOHeadPtr = (LeftFIFOHeadPtr + numSamplesReady) % BUFFER_SIZE;
 147                 RightFIFOHeadPtr = (RightFIFOHeadPtr + numSamplesReady) % BUFFER_SIZE;
 148                 // Could also use (as long as BUFFER_SIZE is a multiple of 2):
 149 //              LeftFIFOHeadPtr = (LeftFIFOHeadPtr + numSamplesReady) & (BUFFER_SIZE - 1);
 150 //              RightFIFOHeadPtr = (RightFIFOHeadPtr + numSamplesReady) & (BUFFER_SIZE - 1);
 151 //WriteLog("  -> Left/RightFIFOHeadPtr: %u/%u, Left/RightFIFOTailPtr: %u/%u\n", LeftFIFOHeadPtr, RightFIFOHeadPtr, LeftFIFOTailPtr, RightFIFOTailPtr);
 152         }
 153 //Hmm. Seems that the SDL buffer isn't being starved by the DAC buffer...
 154 //      else
 155 //              WriteLog("DAC: Silence...!\n");
 156 }
 157
 158 //
 159 // Calculate the frequency of SCLK * 32 using the divider
 160 //
 161 int GetCalculatedFrequency(void)
 162 {
 163         int systemClockFrequency = (vjs.hardwareTypeNTSC ? RISC_CLOCK_RATE_NTSC : RISC_CLOCK_RATE_PAL);
 164
 165         // We divide by 32 here in order to find the frequency of 32 SCLKs in a row (transferring
 166         // 16 bits of left data + 16 bits of right data = 32 bits, 1 SCLK = 1 bit transferred).
 167         return systemClockFrequency / (32 * (2 * (SCLKFrequencyDivider + 1)));
 168 }
 169
 170 //
 171 // LTXD/RTXD/SCLK/SMODE ($F1A148/4C/50/54)
 172 //
 173 void DACWriteByte(uint32 offset, uint8 data, uint32 who/*= UNKNOWN*/)
 174 {
 175         WriteLog("DAC: %s writing BYTE %02X at %08X\n", whoName[who], data, offset);
 176         if (offset == SCLK + 3)
 177                 DACWriteWord(offset - 3, (uint16)data);
 178 }
 179
 180 void DACWriteWord(uint32 offset, uint16 data, uint32 who/*= UNKNOWN*/)
 181 {
 182         if (offset == LTXD + 2)
 183         {
 184                 // Spin until buffer has been drained (for too fast processors!)...
 185 //Small problem--if Head == 0 and Tail == buffer end, then this will fail... !!! FIX !!!
 186 //[DONE]
 187                 // Also, we're taking advantage of the fact that the buffer is a multiple of two
 188                 // in this check...
 189                 while (((LeftFIFOTailPtr + 2) & (BUFFER_SIZE - 1)) == LeftFIFOHeadPtr);
 190
 191                 SDL_LockAudio();                                                        // Is it necessary to do this? Mebbe.
 192                 // We use a circular buffer 'cause it's easy. Note that the callback function
 193                 // takes care of dumping audio to the soundcard...! Also note that we're writing
 194                 // the samples in the buffer in an interleaved L/R format.
 195                 LeftFIFOTailPtr = (LeftFIFOTailPtr + 2) % BUFFER_SIZE;
 196                 DACBuffer[LeftFIFOTailPtr] = data;
 197                 SDL_UnlockAudio();
 198         }
 199         else if (offset == RTXD + 2)
 200         {
 201                 // Spin until buffer has been drained (for too fast processors!)...
 202 //uint32 spin = 0;
 203                 while (((RightFIFOTailPtr + 2) & (BUFFER_SIZE - 1)) == RightFIFOHeadPtr);
 204 /*              {
 205 spin++;
 206 //if ((spin & 0x0FFFFFFF) == 0)
 207 //      WriteLog("Tail=%X, Head=%X, BUFFER_SIZE-1=%X\n", RightFIFOTailPtr, RightFIFOHeadPtr, BUFFER_SIZE - 1);
 208
 209 if (spin == 0xFFFF0000)
 210 {
 211 uint32 rtail = RightFIFOTailPtr, rhead = RightFIFOHeadPtr;
 212 WriteLog("Tail=%X, Head=%X\n", rtail, rhead);
 213
 214         WriteLog("\nStuck in right DAC spinlock!\nAborting!\n\n");
 215         WriteLog("Tail=%X, Head=%X, BUFFER_SIZE-1=%X\n", RightFIFOTailPtr, RightFIFOHeadPtr, BUFFER_SIZE - 1);
 216         WriteLog("From while: Tail=%X, Head=%X", (RightFIFOTailPtr + 2) & (BUFFER_SIZE - 1), RightFIFOHeadPtr);
 217         log_done();
 218         exit(0);
 219 }
 220                 }//*/
 221
 222 //This is wrong         if (RightFIFOTailPtr + 2 != RightFIFOHeadPtr)
 223 //              {
 224                 SDL_LockAudio();
 225                 RightFIFOTailPtr = (RightFIFOTailPtr + 2) % BUFFER_SIZE;
 226                 DACBuffer[RightFIFOTailPtr] = data;
 227                 SDL_UnlockAudio();
 228 //              }
 229 /*#ifdef DEBUG_DAC
 230                 else
 231                         WriteLog("DAC: Ran into FIFO's right tail pointer!\n");
 232 #endif*/
 233         }
 234         else if (offset == SCLK + 2)                                    // Sample rate
 235         {
 236                 WriteLog("DAC: Writing %u to SCLK...\n", data);
 237                 if ((uint8)data != SCLKFrequencyDivider)
 238                 {
 239                         SCLKFrequencyDivider = (uint8)data;
 240 //Of course a better way would be to query the hardware to find the upper limit...
 241                         if (data > 7)   // Anything less than 8 is too high!
 242                         {
 243                                 if (SDLSoundInitialized)
 244                                         SDL_CloseAudio();
 245
 246                                 desired.freq = GetCalculatedFrequency();// SDL will do conversion on the fly, if it can't get the exact rate. Nice!
 247                                 WriteLog("DAC: Changing sample rate to %u Hz!\n", desired.freq);
 248
 249                                 if (SDLSoundInitialized)
 250                                 {
 251                                         if (SDL_OpenAudio(&desired, NULL) < 0)  // NULL means SDL guarantees what we want
 252                                         {
 253                                                 WriteLog("DAC: Failed to initialize SDL sound: %s.\nDesired freq: %u\nShutting down!\n", SDL_GetError(), desired.freq);
 254                                                 log_done();
 255                                                 exit(1);
 256                                         }
 257                                 }
 258
 259                                 DACReset();
 260
 261                                 if (SDLSoundInitialized)
 262                                         SDL_PauseAudio(false);                  // Start playback!
 263                         }
 264                 }
 265         }
 266         else if (offset == SMODE + 2)
 267         {
 268                 serialMode = data;
 269                 WriteLog("DAC: %s writing to SMODE. Bits: %s%s%s%s%s%s [68K PC=%08X]\n", whoName[who],
 270                         (data & 0x01 ? "INTERNAL " : ""), (data & 0x02 ? "MODE " : ""),
 271                         (data & 0x04 ? "WSEN " : ""), (data & 0x08 ? "RISING " : ""),
 272                         (data & 0x10 ? "FALLING " : ""), (data & 0x20 ? "EVERYWORD" : ""),
 273                         m68k_get_reg(NULL, M68K_REG_PC));
 274         }
 275 }
 276
 277 //
 278 // LRXD/RRXD/SSTAT ($F1A148/4C/50)
 279 //
 280 uint8 DACReadByte(uint32 offset, uint32 who/*= UNKNOWN*/)
 281 {
 282 //      WriteLog("DAC: %s reading byte from %08X\n", whoName[who], offset);
 283         return 0xFF;
 284 }
 285
 286 //static uint16 fakeWord = 0;
 287 uint16 DACReadWord(uint32 offset, uint32 who/*= UNKNOWN*/)
 288 {
 289 //      WriteLog("DAC: %s reading word from %08X\n", whoName[who], offset);
 290 //      return 0xFFFF;
 291 //      WriteLog("DAC: %s reading WORD %04X from %08X\n", whoName[who], fakeWord, offset);
 292 //      return fakeWord++;
 293 //NOTE: This only works if a bunch of things are set in BUTCH which we currently don't
 294 //      check for. !!! FIX !!!
 295 // Partially fixed: We check for I2SCNTRL in the JERRY I2S routine...
 296 //      return GetWordFromButchSSI(offset, who);
 297         if (offset == LRXD || offset == RRXD)
 298                 return 0x0000;
 299         else if (offset == LRXD + 2)
 300                 return lrxd;
 301         else if (offset == RRXD + 2)
 302                 return rrxd;
 303
 304         return 0xFFFF;  // May need SSTAT as well... (but may be a Jaguar II only feature)
 305 }