2 // DAC (really, Synchronous Serial Interface) Handler
4 // Originally by David Raingeard
5 // GCC/SDL port by Niels Wagenaar (Linux/WIN32) and Caz (BeOS)
6 // Rewritten by James L. Hammons
9 // Need to set up defaults that the BIOS sets for the SSI here in DACInit()... !!! FIX !!!
10 // or something like that... Seems like it already does, but it doesn't seem to
11 // work correctly...! Perhaps just need to set up SSI stuff so BUTCH doesn't get
22 #define BUFFER_SIZE 0x10000 // Make the DAC buffers 64K x 16 bits
24 // Jaguar memory locations
31 #define SMODE 0xF1A154
35 uint16 lrxd, rrxd; // I2S ports (into Jaguar)
39 static uint32 LeftFIFOHeadPtr, LeftFIFOTailPtr, RightFIFOHeadPtr, RightFIFOTailPtr;
40 static SDL_AudioSpec desired;
41 static bool SDLSoundInitialized = false;
43 // We can get away with using native endian here because we can tell SDL to use the native
44 // endian when looking at the sample buffer, i.e., no need to worry about it.
46 static uint16 * DACBuffer;
47 static uint8 SCLKFrequencyDivider = 19; // Default is roughly 22 KHz (20774 Hz in NTSC mode)
48 /*static*/ uint16 serialMode = 0;
50 // Private function prototypes
52 void SDLSoundCallback(void * userdata, Uint8 * buffer, int length);
53 int GetCalculatedFrequency(void);
56 // Initialize the SDL sound system
60 memory_malloc_secure((void **)&DACBuffer, BUFFER_SIZE * sizeof(uint16), "DAC buffer");
62 desired.freq = GetCalculatedFrequency(); // SDL will do conversion on the fly, if it can't get the exact rate. Nice!
63 desired.format = AUDIO_S16SYS; // This uses the native endian (for portability)...
65 // desired.samples = 4096; // Let's try a 4K buffer (can always go lower)
66 desired.samples = 2048; // Let's try a 2K buffer (can always go lower)
67 desired.callback = SDLSoundCallback;
69 if (SDL_OpenAudio(&desired, NULL) < 0) // NULL means SDL guarantees what we want
70 WriteLog("DAC: Failed to initialize SDL sound...\n");
73 SDLSoundInitialized = true;
75 SDL_PauseAudio(false); // Start playback!
76 WriteLog("DAC: Successfully initialized.\n");
81 // Reset the sound buffer FIFOs
85 LeftFIFOHeadPtr = LeftFIFOTailPtr = 0, RightFIFOHeadPtr = RightFIFOTailPtr = 1;
89 // Close down the SDL sound subsystem
93 if (SDLSoundInitialized)
99 memory_free(DACBuffer);
100 WriteLog("DAC: Done.\n");
104 // SDL callback routine to fill audio buffer
106 // Note: The samples are packed in the buffer in 16 bit left/16 bit right pairs.
108 void SDLSoundCallback(void * userdata, Uint8 * buffer, int length)
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)
116 //WriteLog("DAC: About to write some data!\n");
117 int numLeftSamplesReady
118 = (LeftFIFOTailPtr + (LeftFIFOTailPtr < LeftFIFOHeadPtr ? BUFFER_SIZE : 0))
120 int numRightSamplesReady
121 = (RightFIFOTailPtr + (RightFIFOTailPtr < RightFIFOHeadPtr ? BUFFER_SIZE : 0))
123 //This waits for the slower side to catch up. If writing only one side, then this
124 //causes the buffer not to drain...
126 = (numLeftSamplesReady < numRightSamplesReady
127 ? numLeftSamplesReady : numRightSamplesReady);//Hmm. * 2;
129 //Kludge, until I can figure out WTF is going on WRT Super Burnout.
130 if (numLeftSamplesReady == 0 || numRightSamplesReady == 0)
131 numSamplesReady = numLeftSamplesReady + numRightSamplesReady;
133 //The numbers look good--it's just that the DSP can't get enough samples in the DAC buffer!
134 //WriteLog("DAC: Left/RightFIFOHeadPtr: %u/%u, Left/RightFIFOTailPtr: %u/%u\n", LeftFIFOHeadPtr, RightFIFOHeadPtr, LeftFIFOTailPtr, RightFIFOTailPtr);
135 //WriteLog(" numLeft/RightSamplesReady: %i/%i, numSamplesReady: %i, length of buffer: %i\n", numLeftSamplesReady, numRightSamplesReady, numSamplesReady, length);
137 /* if (numSamplesReady > length)
138 numSamplesReady = length;//*/
139 if (numSamplesReady > length / 2) // length / 2 because we're comparing 16-bit lengths
140 numSamplesReady = length / 2;
142 // WriteLog(" Not enough samples to fill the buffer (short by %u L/R samples)...\n", (length / 2) - numSamplesReady);
143 //WriteLog("DAC: %u samples ready.\n", numSamplesReady);
145 // Actually, it's a bit more involved than this, but this is the general idea:
146 // memcpy(buffer, DACBuffer, length);
147 for(int i=0; i<numSamplesReady; i++)
148 ((uint16 *)buffer)[i] = DACBuffer[(LeftFIFOHeadPtr + i) % BUFFER_SIZE];
149 // Could also use (as long as BUFFER_SIZE is a multiple of 2):
150 // buffer[i] = DACBuffer[(LeftFIFOHeadPtr + i) & (BUFFER_SIZE - 1)];
152 LeftFIFOHeadPtr = (LeftFIFOHeadPtr + numSamplesReady) % BUFFER_SIZE;
153 RightFIFOHeadPtr = (RightFIFOHeadPtr + numSamplesReady) % BUFFER_SIZE;
154 // Could also use (as long as BUFFER_SIZE is a multiple of 2):
155 // LeftFIFOHeadPtr = (LeftFIFOHeadPtr + numSamplesReady) & (BUFFER_SIZE - 1);
156 // RightFIFOHeadPtr = (RightFIFOHeadPtr + numSamplesReady) & (BUFFER_SIZE - 1);
157 //WriteLog(" -> Left/RightFIFOHeadPtr: %04X/%04X, Left/RightFIFOTailPtr: %04X/%04X\n", LeftFIFOHeadPtr, RightFIFOHeadPtr, LeftFIFOTailPtr, RightFIFOTailPtr);
159 //Hmm. Seems that the SDL buffer isn't being starved by the DAC buffer...
161 // WriteLog("DAC: Silence...!\n");
165 // Calculate the frequency of SCLK * 32 using the divider
167 int GetCalculatedFrequency(void)
169 int systemClockFrequency = (vjs.hardwareTypeNTSC ? RISC_CLOCK_RATE_NTSC : RISC_CLOCK_RATE_PAL);
171 // We divide by 32 here in order to find the frequency of 32 SCLKs in a row (transferring
172 // 16 bits of left data + 16 bits of right data = 32 bits, 1 SCLK = 1 bit transferred).
173 return systemClockFrequency / (32 * (2 * (SCLKFrequencyDivider + 1)));
177 // LTXD/RTXD/SCLK/SMODE ($F1A148/4C/50/54)
179 void DACWriteByte(uint32 offset, uint8 data, uint32 who/*= UNKNOWN*/)
181 WriteLog("DAC: %s writing BYTE %02X at %08X\n", whoName[who], data, offset);
182 if (offset == SCLK + 3)
183 DACWriteWord(offset - 3, (uint16)data);
186 void DACWriteWord(uint32 offset, uint16 data, uint32 who/*= UNKNOWN*/)
188 if (offset == LTXD + 2)
190 // Spin until buffer has been drained (for too fast processors!)...
191 //Small problem--if Head == 0 and Tail == buffer end, then this will fail... !!! FIX !!!
193 // Also, we're taking advantage of the fact that the buffer is a multiple of two
196 while (((LeftFIFOTailPtr + 2) & (BUFFER_SIZE - 1)) == LeftFIFOHeadPtr)//;
199 //if ((spin & 0x0FFFFFFF) == 0)
200 // WriteLog("Tail=%X, Head=%X, BUFFER_SIZE-1=%X\n", RightFIFOTailPtr, RightFIFOHeadPtr, BUFFER_SIZE - 1);
202 if (spin == 0xFFFF0000)
204 uint32 ltail = LeftFIFOTailPtr, lhead = LeftFIFOHeadPtr;
205 WriteLog("Tail=%X, Head=%X", ltail, lhead);
207 WriteLog("\nStuck in left DAC spinlock! Aborting!\n");
208 WriteLog("LTail=%X, LHead=%X, BUFFER_SIZE-1=%X\n", LeftFIFOTailPtr, LeftFIFOHeadPtr, BUFFER_SIZE - 1);
209 WriteLog("RTail=%X, RHead=%X, BUFFER_SIZE-1=%X\n", RightFIFOTailPtr, RightFIFOHeadPtr, BUFFER_SIZE - 1);
210 WriteLog("From while: Tail=%X, Head=%X", (LeftFIFOTailPtr + 2) & (BUFFER_SIZE - 1), LeftFIFOHeadPtr);
216 SDL_LockAudio(); // Is it necessary to do this? Mebbe.
217 // We use a circular buffer 'cause it's easy. Note that the callback function
218 // takes care of dumping audio to the soundcard...! Also note that we're writing
219 // the samples in the buffer in an interleaved L/R format.
220 LeftFIFOTailPtr = (LeftFIFOTailPtr + 2) % BUFFER_SIZE;
221 DACBuffer[LeftFIFOTailPtr] = data;
224 else if (offset == RTXD + 2)
227 Here's what's happening now:
229 Stuck in right DAC spinlock!
232 Tail=681, Head=681, BUFFER_SIZE-1=FFFF
233 From while: Tail=683, Head=681
235 ????? What the FUCK ?????
237 & when I uncomment the lines below spin++; it *doesn't* lock here... WTF?????
239 I think it was missing parentheses causing the fuckup... Seems to work now...
241 Except for Super Burnout now...! Aarrrgggghhhhh!
244 Stuck in left DAC spinlock! Aborting!
245 Tail=AC, Head=AE, BUFFER_SIZE-1=FFFF
246 From while: Tail=AE, Head=AE
248 So it's *really* stuck here in the left FIFO. Figure out why!!!
250 Prolly 'cause it doesn't set the sample rate right away--betcha it works with the BIOS...
251 It gets farther, but then locks here (weird!):
254 Stuck in left DAC spinlock! Aborting!
255 Tail=2564, Head=2566, BUFFER_SIZE-1=FFFF
256 From while: Tail=2566, Head=2566
258 Weird--recompile with more WriteLog() entries and it *doesn't* lock...
259 Yeah, because there was no DSP running. Duh!
262 Stuck in left DAC spinlock! Aborting!
263 LTail=AC, LHead=AE, BUFFER_SIZE-1=FFFF
264 RTail=AF, RHead=AF, BUFFER_SIZE-1=FFFF
265 From while: Tail=AE, Head=AE
267 Odd: The right FIFO is empty, but the left FIFO is full!
268 And this is what is causing the lockup--the DAC callback waits for the side with
269 less samples ready and in this case it's the right channel (that never fills up)
270 that it's waiting for...!
272 Okay, with the kludge in place for the right channel not being filled, we select
273 a track and then it locks here:
276 Stuck in left DAC spinlock! Aborting!
277 LTail=60D8, LHead=60D8, BUFFER_SIZE-1=FFFF
278 RTail=DB, RHead=60D9, BUFFER_SIZE-1=FFFF
279 From while: Tail=60DA, Head=60D8
281 // Spin until buffer has been drained (for too fast processors!)...
283 while (((RightFIFOTailPtr + 2) & (BUFFER_SIZE - 1)) == RightFIFOHeadPtr)//;
286 //if ((spin & 0x0FFFFFFF) == 0)
287 // WriteLog("Tail=%X, Head=%X, BUFFER_SIZE-1=%X\n", RightFIFOTailPtr, RightFIFOHeadPtr, BUFFER_SIZE - 1);
289 if (spin == 0xFFFF0000)
291 uint32 rtail = RightFIFOTailPtr, rhead = RightFIFOHeadPtr;
292 WriteLog("Tail=%X, Head=%X", rtail, rhead);
294 WriteLog("\nStuck in right DAC spinlock! Aborting!\n");
295 WriteLog("LTail=%X, LHead=%X, BUFFER_SIZE-1=%X\n", LeftFIFOTailPtr, LeftFIFOHeadPtr, BUFFER_SIZE - 1);
296 WriteLog("RTail=%X, RHead=%X, BUFFER_SIZE-1=%X\n", RightFIFOTailPtr, RightFIFOHeadPtr, BUFFER_SIZE - 1);
297 WriteLog("From while: Tail=%X, Head=%X", (RightFIFOTailPtr + 2) & (BUFFER_SIZE - 1), RightFIFOHeadPtr);
304 RightFIFOTailPtr = (RightFIFOTailPtr + 2) % BUFFER_SIZE;
305 DACBuffer[RightFIFOTailPtr] = data;
309 WriteLog("DAC: Ran into FIFO's right tail pointer!\n");
312 else if (offset == SCLK + 2) // Sample rate
314 WriteLog("DAC: Writing %u to SCLK...\n", data);
315 if ((uint8)data != SCLKFrequencyDivider)
317 SCLKFrequencyDivider = (uint8)data;
318 //Of course a better way would be to query the hardware to find the upper limit...
319 if (data > 7) // Anything less than 8 is too high!
321 if (SDLSoundInitialized)
324 desired.freq = GetCalculatedFrequency();// SDL will do conversion on the fly, if it can't get the exact rate. Nice!
325 WriteLog("DAC: Changing sample rate to %u Hz!\n", desired.freq);
327 if (SDLSoundInitialized)
329 if (SDL_OpenAudio(&desired, NULL) < 0) // NULL means SDL guarantees what we want
331 WriteLog("DAC: Failed to initialize SDL sound: %s.\nDesired freq: %u\nShutting down!\n", SDL_GetError(), desired.freq);
339 if (SDLSoundInitialized)
340 SDL_PauseAudio(false); // Start playback!
344 else if (offset == SMODE + 2)
347 WriteLog("DAC: %s writing to SMODE. Bits: %s%s%s%s%s%s [68K PC=%08X]\n", whoName[who],
348 (data & 0x01 ? "INTERNAL " : ""), (data & 0x02 ? "MODE " : ""),
349 (data & 0x04 ? "WSEN " : ""), (data & 0x08 ? "RISING " : ""),
350 (data & 0x10 ? "FALLING " : ""), (data & 0x20 ? "EVERYWORD" : ""),
351 m68k_get_reg(NULL, M68K_REG_PC));
356 // LRXD/RRXD/SSTAT ($F1A148/4C/50)
358 uint8 DACReadByte(uint32 offset, uint32 who/*= UNKNOWN*/)
360 // WriteLog("DAC: %s reading byte from %08X\n", whoName[who], offset);
364 //static uint16 fakeWord = 0;
365 uint16 DACReadWord(uint32 offset, uint32 who/*= UNKNOWN*/)
367 // WriteLog("DAC: %s reading word from %08X\n", whoName[who], offset);
369 // WriteLog("DAC: %s reading WORD %04X from %08X\n", whoName[who], fakeWord, offset);
370 // return fakeWord++;
371 //NOTE: This only works if a bunch of things are set in BUTCH which we currently don't
372 // check for. !!! FIX !!!
373 // Partially fixed: We check for I2SCNTRL in the JERRY I2S routine...
374 // return GetWordFromButchSSI(offset, who);
375 if (offset == LRXD || offset == RRXD)
377 else if (offset == LRXD + 2)
379 else if (offset == RRXD + 2)
382 return 0xFFFF; // May need SSTAT as well... (but may be a Jaguar II only feature)