aboutsummaryrefslogtreecommitdiff
path: root/source/sa1.c
blob: 54ed8363a7e3026a4e8d9d9e2c395957d191514f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
#include "../copyright"

#include "snes9x.h"
#include "ppu.h"
#include "cpuexec.h"

#include "sa1.h"

static void S9xSA1CharConv2();
static void S9xSA1DMA();
static void S9xSA1ReadVariableLengthData(bool inc, bool no_shift);

void S9xSA1Init()
{
   SA1.NMIActive = false;
   SA1.IRQActive = 0;
   SA1.WaitingForInterrupt = false;
   SA1.Waiting = false;
   SA1.Flags = 0;
   SA1.Executing = false;
   memset(&Memory.FillRAM [0x2200], 0, 0x200);
   Memory.FillRAM [0x2200] = 0x20;
   Memory.FillRAM [0x2220] = 0x00;
   Memory.FillRAM [0x2221] = 0x01;
   Memory.FillRAM [0x2222] = 0x02;
   Memory.FillRAM [0x2223] = 0x03;
   Memory.FillRAM [0x2228] = 0xff;
   SA1.op1 = 0;
   SA1.op2 = 0;
   SA1.arithmetic_op = 0;
   SA1.sum = 0;
   SA1.overflow = false;
   SA1.S9xOpcodes = NULL;
}

void S9xSA1Reset()
{
   SA1.Registers.PB = 0;
   SA1.Registers.PC = Memory.FillRAM [0x2203] | (Memory.FillRAM [0x2204] << 8);
   SA1.Registers.D.W = 0;
   SA1.Registers.DB = 0;
   SA1.Registers.SH = 1;
   SA1.Registers.SL = 0xFF;
   SA1.Registers.XH = 0;
   SA1.Registers.YH = 0;
   SA1.Registers.P.W = 0;

   SA1.ShiftedPB = 0;
   SA1.ShiftedDB = 0;
   SA1SetFlags(MemoryFlag | IndexFlag | IRQ | Emulation);
   SA1ClearFlags(Decimal);

   SA1.WaitingForInterrupt = false;
   SA1.PC = NULL;
   SA1.PCBase = NULL;
   S9xSA1SetPCBase(SA1.Registers.PC);
   SA1.S9xOpcodes = S9xSA1OpcodesM1X1;

   S9xSA1UnpackStatus();
   S9xSA1FixCycles();
   SA1.Executing = true;
   SA1.BWRAM = Memory.SRAM;
   Memory.FillRAM [0x2225] = 0;
}

void S9xSA1SetBWRAMMemMap(uint8_t val)
{
   int32_t c;

   if (val & 0x80)
   {
      for (c = 0; c < 0x400; c += 16)
      {
         SA1.Map [c + 6] = SA1.Map [c + 0x806] = (uint8_t*) MAP_BWRAM_BITMAP2;
         SA1.Map [c + 7] = SA1.Map [c + 0x807] = (uint8_t*) MAP_BWRAM_BITMAP2;
         SA1.WriteMap [c + 6] = SA1.WriteMap [c + 0x806] = (uint8_t*) MAP_BWRAM_BITMAP2;
         SA1.WriteMap [c + 7] = SA1.WriteMap [c + 0x807] = (uint8_t*) MAP_BWRAM_BITMAP2;
      }
      SA1.BWRAM = Memory.SRAM + (val & 0x7f) * 0x2000 / 4;
   }
   else
   {
      for (c = 0; c < 0x400; c += 16)
      {
         SA1.Map [c + 6] = SA1.Map [c + 0x806] = (uint8_t*) MAP_BWRAM;
         SA1.Map [c + 7] = SA1.Map [c + 0x807] = (uint8_t*) MAP_BWRAM;
         SA1.WriteMap [c + 6] = SA1.WriteMap [c + 0x806] = (uint8_t*) MAP_BWRAM;
         SA1.WriteMap [c + 7] = SA1.WriteMap [c + 0x807] = (uint8_t*) MAP_BWRAM;
      }
      SA1.BWRAM = Memory.SRAM + (val & 7) * 0x2000;
   }
}

void S9xFixSA1AfterSnapshotLoad()
{
   SA1.ShiftedPB = (uint32_t) SA1.Registers.PB << 16;
   SA1.ShiftedDB = (uint32_t) SA1.Registers.DB << 16;

   S9xSA1SetPCBase(SA1.ShiftedPB + SA1.Registers.PC);
   S9xSA1UnpackStatus();
   S9xSA1FixCycles();
   SA1.VirtualBitmapFormat = (Memory.FillRAM [0x223f] & 0x80) ? 2 : 4;
   Memory.BWRAM = Memory.SRAM + (Memory.FillRAM [0x2224] & 7) * 0x2000;
   S9xSA1SetBWRAMMemMap(Memory.FillRAM [0x2225]);

   SA1.Waiting = (Memory.FillRAM [0x2200] & 0x60) != 0;
   SA1.Executing = !SA1.Waiting;
}

uint8_t S9xSA1GetByte(uint32_t address)
{
   uint8_t* GetAddress = SA1.Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];
   if (GetAddress >= (uint8_t*) MAP_LAST)
      return (*(GetAddress + (address & 0xffff)));

   switch ((intptr_t) GetAddress)
   {
   case MAP_PPU:
      return (S9xGetSA1(address & 0xffff));
   case MAP_LOROM_SRAM:
   case MAP_SA1RAM:
      return (*(Memory.SRAM + (address & 0xffff)));
   case MAP_BWRAM:
      return (*(SA1.BWRAM + ((address & 0x7fff) - 0x6000)));
   case MAP_BWRAM_BITMAP:
      address -= 0x600000;
      if (SA1.VirtualBitmapFormat == 2)
         return ((Memory.SRAM [(address >> 2) & 0xffff] >> ((address & 3) << 1)) & 3);
      else
         return ((Memory.SRAM [(address >> 1) & 0xffff] >> ((address & 1) << 2)) & 15);
   case MAP_BWRAM_BITMAP2:
      address = (address & 0xffff) - 0x6000;
      if (SA1.VirtualBitmapFormat == 2)
         return ((SA1.BWRAM [(address >> 2) & 0xffff] >> ((address & 3) << 1)) & 3);
      else
         return ((SA1.BWRAM [(address >> 1) & 0xffff] >> ((address & 1) << 2)) & 15);
   default:
      return OpenBus;
   }
}

uint16_t S9xSA1GetWord(uint32_t address)
{
   OpenBus = S9xSA1GetByte(address);
   return (OpenBus | (S9xSA1GetByte(address + 1) << 8));
}

void S9xSA1SetByte(uint8_t byte, uint32_t address)
{
   uint8_t* SetAddress = SA1.WriteMap [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];

   if (SetAddress >= (uint8_t*) MAP_LAST)
   {
      *(SetAddress + (address & 0xffff)) = byte;
      return;
   }

   switch ((intptr_t) SetAddress)
   {
   case MAP_PPU:
      S9xSetSA1(byte, address & 0xffff);
      return;
   case MAP_SA1RAM:
   case MAP_LOROM_SRAM:
      *(Memory.SRAM + (address & 0xffff)) = byte;
      return;
   case MAP_BWRAM:
      *(SA1.BWRAM + ((address & 0x7fff) - 0x6000)) = byte;
      return;
   case MAP_BWRAM_BITMAP:
      address -= 0x600000;
      if (SA1.VirtualBitmapFormat == 2)
      {
         uint8_t* ptr = &Memory.SRAM [(address >> 2) & 0xffff];
         *ptr &= ~(3 << ((address & 3) << 1));
         *ptr |= (byte & 3) << ((address & 3) << 1);
      }
      else
      {
         uint8_t* ptr = &Memory.SRAM [(address >> 1) & 0xffff];
         *ptr &= ~(15 << ((address & 1) << 2));
         *ptr |= (byte & 15) << ((address & 1) << 2);
      }
      break;
   case MAP_BWRAM_BITMAP2:
      address = (address & 0xffff) - 0x6000;
      if (SA1.VirtualBitmapFormat == 2)
      {
         uint8_t* ptr = &SA1.BWRAM [(address >> 2) & 0xffff];
         *ptr &= ~(3 << ((address & 3) << 1));
         *ptr |= (byte & 3) << ((address & 3) << 1);
      }
      else
      {
         uint8_t* ptr = &SA1.BWRAM [(address >> 1) & 0xffff];
         *ptr &= ~(15 << ((address & 1) << 2));
         *ptr |= (byte & 15) << ((address & 1) << 2);
      }
   default:
      return;
   }
}

void S9xSA1SetWord(uint16_t Word, uint32_t address)
{
   S9xSA1SetByte((uint8_t) Word, address);
   S9xSA1SetByte((uint8_t)(Word >> 8), address + 1);
}

void S9xSA1SetPCBase(uint32_t address)
{
   uint8_t* GetAddress = SA1.Map [(address >> MEMMAP_SHIFT) & MEMMAP_MASK];
   if (GetAddress >= (uint8_t*) MAP_LAST)
   {
      SA1.PCBase = GetAddress;
      SA1.PC = GetAddress + (address & 0xffff);
      return;
   }

   switch ((intptr_t) GetAddress)
   {
   case MAP_PPU:
      SA1.PCBase = Memory.FillRAM - 0x2000;
      break;
   case MAP_CPU:
      SA1.PCBase = Memory.FillRAM - 0x4000;
      break;
   case MAP_DSP:
      SA1.PCBase = Memory.FillRAM - 0x6000;
      break;
   case MAP_SA1RAM:
   case MAP_LOROM_SRAM:
      SA1.PCBase = Memory.SRAM;
      break;
   case MAP_BWRAM:
      SA1.PCBase = SA1.BWRAM - 0x6000;
      break;
   case MAP_HIROM_SRAM:
      SA1.PCBase = Memory.SRAM - 0x6000;
      break;
   default:
      SA1.PCBase = Memory.RAM;
      break;
   }

   SA1.PC = SA1.PCBase + (address & 0xffff);
}

void S9xSetSA1MemMap(uint32_t which1, uint8_t map)
{
   int32_t c;
   int32_t i;
   int32_t start = which1 * 0x100 + 0xc00;
   int32_t start2 = which1 * 0x200;

   if (which1 >= 2)
      start2 += 0x400;

   for (c = 0; c < 0x100; c += 16)
   {
      uint8_t* block = &Memory.ROM [(map & 7) * 0x100000 + (c << 12)];
      for (i = c; i < c + 16; i++)
         Memory.Map [start + i] = SA1.Map [start + i] = block;
   }

   for (c = 0; c < 0x200; c += 16)
   {
      uint8_t* block = &Memory.ROM [(map & 7) * 0x100000 + (c << 11) - 0x8000];
      for (i = c + 8; i < c + 16; i++)
         Memory.Map [start2 + i] = SA1.Map [start2 + i] = block;
   }
}

uint8_t S9xGetSA1(uint32_t address)
{
   switch (address)
   {
      case 0x2300:
         return ((uint8_t)((Memory.FillRAM [0x2209] & 0x5f) |
                  (CPU.IRQActive & (SA1_IRQ_SOURCE | SA1_DMA_IRQ_SOURCE))));
      case 0x2301:
         return ((Memory.FillRAM [0x2200] & 0xf) |
               (Memory.FillRAM [0x2301] & 0xf0));
      case 0x2306:
         return ((uint8_t) SA1.sum);
      case 0x2307:
         return ((uint8_t)(SA1.sum >>  8));
      case 0x2308:
         return ((uint8_t)(SA1.sum >> 16));
      case 0x2309:
         return ((uint8_t)(SA1.sum >> 24));
      case 0x230a:
         return ((uint8_t)(SA1.sum >> 32));
      case 0x230d:
         {
            uint8_t byte = Memory.FillRAM [0x230d];

            if (Memory.FillRAM [0x2258] & 0x80)
               S9xSA1ReadVariableLengthData(true, false);
            return (byte);
         }
   }

   return (Memory.FillRAM [address]);
}

void S9xSetSA1(uint8_t byte, uint32_t address)
{
   if (address < 0x2200 || address > 0x22ff)
      return;

   switch (address)
   {
   case 0x2200:
      SA1.Waiting = (byte & 0x60) != 0;

      if (!(byte & 0x20) && (Memory.FillRAM [0x2200] & 0x20))
         S9xSA1Reset();
      if (byte & 0x80)
      {
         Memory.FillRAM [0x2301] |= 0x80;
         if (Memory.FillRAM [0x220a] & 0x80)
         {
            SA1.Flags |= IRQ_PENDING_FLAG;
            SA1.IRQActive |= SNES_IRQ_SOURCE;
            SA1.Executing = !SA1.Waiting && SA1.S9xOpcodes;
         }
      }
      if (byte & 0x10)
         Memory.FillRAM [0x2301] |= 0x10;
      break;
   case 0x2201:
      if (((byte ^ Memory.FillRAM [0x2201]) & 0x80) &&
            (Memory.FillRAM [0x2300] & byte & 0x80))
         S9xSetIRQ(SA1_IRQ_SOURCE);
      if (((byte ^ Memory.FillRAM [0x2201]) & 0x20) &&
            (Memory.FillRAM [0x2300] & byte & 0x20))
         S9xSetIRQ(SA1_DMA_IRQ_SOURCE);
      break;
   case 0x2202:
      if (byte & 0x80)
      {
         Memory.FillRAM [0x2300] &= ~0x80;
         S9xClearIRQ(SA1_IRQ_SOURCE);
      }
      if (byte & 0x20)
      {
         Memory.FillRAM [0x2300] &= ~0x20;
         S9xClearIRQ(SA1_DMA_IRQ_SOURCE);
      }
      break;
   case 0x2209:
      Memory.FillRAM [0x2209] = byte;
      if (byte & 0x80)
         Memory.FillRAM [0x2300] |= 0x80;

      if (byte & Memory.FillRAM [0x2201] & 0x80)
         S9xSetIRQ(SA1_IRQ_SOURCE);
      return;
   case 0x220a:
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x80) &&
            (Memory.FillRAM [0x2301] & byte & 0x80))
      {
         SA1.Flags |= IRQ_PENDING_FLAG;
         SA1.IRQActive |= SNES_IRQ_SOURCE;
      }
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x40) &&
            (Memory.FillRAM [0x2301] & byte & 0x40))
      {
         SA1.Flags |= IRQ_PENDING_FLAG;
         SA1.IRQActive |= TIMER_IRQ_SOURCE;
      }
      if (((byte ^ Memory.FillRAM [0x220a]) & 0x20) &&
            (Memory.FillRAM [0x2301] & byte & 0x20))
      {
         SA1.Flags |= IRQ_PENDING_FLAG;
         SA1.IRQActive |= DMA_IRQ_SOURCE;
      }
      break;
   case 0x220b:
      if (byte & 0x80)
      {
         SA1.IRQActive &= ~SNES_IRQ_SOURCE;
         Memory.FillRAM [0x2301] &= ~0x80;
      }
      if (byte & 0x40)
      {
         SA1.IRQActive &= ~TIMER_IRQ_SOURCE;
         Memory.FillRAM [0x2301] &= ~0x40;
      }
      if (byte & 0x20)
      {
         SA1.IRQActive &= ~DMA_IRQ_SOURCE;
         Memory.FillRAM [0x2301] &= ~0x20;
      }
      if (byte & 0x10)
         Memory.FillRAM [0x2301] &= ~0x10; // Clear NMI
      if (!SA1.IRQActive)
         SA1.Flags &= ~IRQ_PENDING_FLAG;
      break;
   case 0x2220:
   case 0x2221:
   case 0x2222:
   case 0x2223:
      S9xSetSA1MemMap(address - 0x2220, byte);
      break;
   case 0x2224:
      Memory.BWRAM = Memory.SRAM + (byte & 7) * 0x2000;
      break;
   case 0x2225:
      if (byte != Memory.FillRAM [address])
         S9xSA1SetBWRAMMemMap(byte);
      break;
   case 0x2231:
      if (byte & 0x80)
         SA1.in_char_dma = 0;
      break;
   case 0x2236:
      Memory.FillRAM [address] = byte;
      if ((Memory.FillRAM [0x2230] & 0xa4) == 0x80)
      {
         S9xSA1DMA(); // Normal DMA to I-RAM
      }
      else if ((Memory.FillRAM [0x2230] & 0xb0) == 0xb0)
      {
         Memory.FillRAM [0x2300] |= 0x20;
         if (Memory.FillRAM [0x2201] & 0x20)
            S9xSetIRQ(SA1_DMA_IRQ_SOURCE);
         SA1.in_char_dma = 1;
      }
      return;
   case 0x2237:
      Memory.FillRAM [address] = byte;
      if ((Memory.FillRAM [0x2230] & 0xa4) == 0x84)
         S9xSA1DMA(); // Normal DMA to BW-RAM
      return;
   case 0x223f:
      SA1.VirtualBitmapFormat = (byte & 0x80) ? 2 : 4;
      break;
   case 0x224f:
      Memory.FillRAM [address] = byte;
      if ((Memory.FillRAM [0x2230] & 0xb0) == 0xa0)
      {
         // Char conversion 2 DMA enabled
         // memmove converted: Same malloc but constant non-overlapping addresses [Neb]
         memcpy(&Memory.ROM [MAX_ROM_SIZE - 0x10000] + (SA1.in_char_dma << 4),
                &Memory.FillRAM [0x2240], 16);
         SA1.in_char_dma = (SA1.in_char_dma + 1) & 7;
         if ((SA1.in_char_dma & 3) == 0)
            S9xSA1CharConv2();
      }
      return;
   case 0x2250:
      if (byte & 2)
         SA1.sum = 0;
      SA1.arithmetic_op = byte & 3;
      break;
   case 0x2251:
      SA1.op1 = (SA1.op1 & 0xff00) | byte;
      break;
   case 0x2252:
      SA1.op1 = (SA1.op1 & 0xff) | (byte << 8);
      break;
   case 0x2253:
      SA1.op2 = (SA1.op2 & 0xff00) | byte;
      break;
   case 0x2254:
      SA1.op2 = (SA1.op2 & 0xff) | (byte << 8);
      switch (SA1.arithmetic_op)
      {
      case 0: // multiply
         SA1.sum = SA1.op1 * SA1.op2;
         break;
      case 1: // divide
         if (SA1.op2 == 0)
            SA1.sum = SA1.op1 << 16;
         else
         {
            uint32_t x = (SA1.op1 / (uint16_t) SA1.op2);
            SA1.sum = x | ((SA1.op1 - (x * (uint16_t) SA1.op2)) << 16);
         }
         break;
      default: // cumulative sum
         SA1.sum += SA1.op1 * SA1.op2;
         if (SA1.sum & ((int64_t) 0xffffff << 32))
            SA1.overflow = true;
         break;
      }
      break;
   case 0x2258:    // Variable bit-field length/auto inc/start.
      Memory.FillRAM [0x2258] = byte;
      S9xSA1ReadVariableLengthData(true, false);
      return;
   case 0x2259:
   case 0x225a:
   case 0x225b:    // Variable bit-field start address
      Memory.FillRAM [address] = byte;
      // XXX: ???
      SA1.variable_bit_pos = 0;
      S9xSA1ReadVariableLengthData(false, true);
      return;
   }
   
   Memory.FillRAM [address] = byte;
}

static void S9xSA1CharConv2()
{
   uint32_t dest = Memory.FillRAM [0x2235] | (Memory.FillRAM [0x2236] << 8);
   uint32_t offset = (SA1.in_char_dma & 7) ? 0 : 1;
   int32_t depth = (Memory.FillRAM [0x2231] & 3) == 0 ? 8 :
                   (Memory.FillRAM [0x2231] & 3) == 1 ? 4 : 2;
   int32_t bytes_per_char = 8 * depth;
   uint8_t* p = &Memory.FillRAM [0x3000] + dest + offset * bytes_per_char;
   uint8_t* q = &Memory.ROM [MAX_ROM_SIZE - 0x10000] + offset * 64;

   if (depth == 8)
   {
      int32_t l;
      for (l = 0; l < 8; l++, q += 8)
      {
         int32_t b;
         for (b = 0; b < 8; b++)
         {
            uint8_t r = *(q + b);
            *(p +  0) = (*(p +  0) << 1) | ((r >> 0) & 1);
            *(p +  1) = (*(p +  1) << 1) | ((r >> 1) & 1);
            *(p + 16) = (*(p + 16) << 1) | ((r >> 2) & 1);
            *(p + 17) = (*(p + 17) << 1) | ((r >> 3) & 1);
            *(p + 32) = (*(p + 32) << 1) | ((r >> 4) & 1);
            *(p + 33) = (*(p + 33) << 1) | ((r >> 5) & 1);
            *(p + 48) = (*(p + 48) << 1) | ((r >> 6) & 1);
            *(p + 49) = (*(p + 49) << 1) | ((r >> 7) & 1);
         }
         p += 2;
      }
   }
}

static void S9xSA1DMA()
{
   uint32_t src = Memory.FillRAM [0x2232] |
                 (Memory.FillRAM [0x2233] << 8) |
                 (Memory.FillRAM [0x2234] << 16);
   uint32_t dst = Memory.FillRAM [0x2235] |
                 (Memory.FillRAM [0x2236] << 8) |
                 (Memory.FillRAM [0x2237] << 16);
   uint32_t len = Memory.FillRAM [0x2238] |
                 (Memory.FillRAM [0x2239] << 8);

   uint8_t* s;
   uint8_t* d;

   switch (Memory.FillRAM [0x2230] & 3)
   {
   case 0: // ROM
      s = SA1.Map [(src >> MEMMAP_SHIFT) & MEMMAP_MASK];
      if (s >= (uint8_t*) MAP_LAST)
         s += (src & 0xffff);
      else
         s = Memory.ROM + (src & 0xffff);
      break;
   case 1: // BW-RAM
      src &= Memory.SRAMMask;
      len &= Memory.SRAMMask;
      s = Memory.SRAM + src;
      break;
   default:
      src &= 0x3ff;
      len &= 0x3ff;
      s = &Memory.FillRAM [0x3000] + src;
      break;
   }

   if (Memory.FillRAM [0x2230] & 4)
   {
      dst &= Memory.SRAMMask;
      len &= Memory.SRAMMask;
      d = Memory.SRAM + dst;
   }
   else
   {
      dst &= 0x3ff;
      len &= 0x3ff;
      d = &Memory.FillRAM [0x3000] + dst;
   }
   // memmove required: Can overlap arbitrarily [Neb]
   memmove(d, s, len);
   Memory.FillRAM [0x2301] |= 0x20;

   if (Memory.FillRAM [0x220a] & 0x20)
   {
      SA1.Flags |= IRQ_PENDING_FLAG;
      SA1.IRQActive |= DMA_IRQ_SOURCE;
   }
}

void S9xSA1ReadVariableLengthData(bool inc, bool no_shift)
{
   uint32_t addr = Memory.FillRAM [0x2259] |
                  (Memory.FillRAM [0x225a] << 8) |
                  (Memory.FillRAM [0x225b] << 16);
   uint8_t shift = Memory.FillRAM [0x2258] & 15;

   if (no_shift)
      shift = 0;
   else if (shift == 0)
      shift = 16;

   uint8_t s = shift + SA1.variable_bit_pos;

   if (s >= 16)
   {
      addr += (s >> 4) << 1;
      s &= 15;
   }
   uint32_t data = S9xSA1GetWord(addr) | (S9xSA1GetWord(addr + 2) << 16);

   data >>= s;
   Memory.FillRAM [0x230c] = (uint8_t) data;
   Memory.FillRAM [0x230d] = (uint8_t)(data >> 8);
   if (inc)
   {
      SA1.variable_bit_pos = (SA1.variable_bit_pos + shift) & 15;
      Memory.FillRAM [0x2259] = (uint8_t) addr;
      Memory.FillRAM [0x225a] = (uint8_t)(addr >> 8);
      Memory.FillRAM [0x225b] = (uint8_t)(addr >> 16);
   }
}