gusemu_hal.c (23224B)
1 /* 2 * GUSEMU32 - bus interface part 3 * 4 * Copyright (C) 2000-2007 Tibor "TS" Schütz 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to deal 8 * in the Software without restriction, including without limitation the rights 9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 10 * copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 22 * THE SOFTWARE. 23 */ 24 25 /* 26 * TODO: check mixer: see 7.20 of sdk for panning pos (applies to all gus models?)? 27 */ 28 29 #include "qemu/osdep.h" 30 #include "gustate.h" 31 #include "gusemu.h" 32 33 #define GUSregb(position) (* (gusptr+(position))) 34 #define GUSregw(position) (*(uint16_t *) (gusptr+(position))) 35 #define GUSregd(position) (*(uint32_t *)(gusptr + (position))) 36 37 /* size given in bytes */ 38 unsigned int gus_read(GUSEmuState * state, int port, int size) 39 { 40 int value_read = 0; 41 42 uint8_t *gusptr; 43 gusptr = state->gusdatapos; 44 GUSregd(portaccesses)++; 45 46 switch (port & 0xff0f) 47 { 48 /* MixerCtrlReg (read not supported on GUS classic) */ 49 /* case 0x200: return GUSregb(MixerCtrlReg2x0); */ 50 case 0x206: /* IRQstatReg / SB2x6IRQ */ 51 /* adlib/sb bits set in port handlers */ 52 /* timer/voice bits set in gus_irqgen() */ 53 /* dma bit set in gus_dma_transferdata */ 54 /* midi not implemented yet */ 55 return GUSregb(IRQStatReg2x6); 56 /* case 0x308: */ /* AdLib388 */ 57 case 0x208: 58 if (GUSregb(GUS45TimerCtrl) & 1) 59 return GUSregb(TimerStatus2x8); 60 return GUSregb(AdLibStatus2x8); /* AdLibStatus */ 61 case 0x309: /* AdLib389 */ 62 case 0x209: 63 return GUSregb(AdLibData2x9); /* AdLibData */ 64 case 0x20A: 65 return GUSregb(AdLibCommand2xA); /* AdLib2x8_2xA */ 66 67 #if 0 68 case 0x20B: /* GUS hidden registers (read not supported on GUS classic) */ 69 switch (GUSregb(RegCtrl_2xF) & 0x07) 70 { 71 case 0: /* IRQ/DMA select */ 72 if (GUSregb(MixerCtrlReg2x0) & 0x40) 73 return GUSregb(IRQ_2xB); /* control register select bit */ 74 else 75 return GUSregb(DMA_2xB); 76 /* case 1-5: */ /* general purpose emulation regs */ 77 /* return ... */ /* + status reset reg (write only) */ 78 case 6: 79 return GUSregb(Jumper_2xB); /* Joystick/MIDI enable (JumperReg) */ 80 default:; 81 } 82 break; 83 #endif 84 85 case 0x20C: /* SB2xCd */ 86 value_read = GUSregb(SB2xCd); 87 if (GUSregb(StatRead_2xF) & 0x20) 88 GUSregb(SB2xCd) ^= 0x80; /* toggle MSB on read */ 89 return value_read; 90 /* case 0x20D: */ /* SB2xD is write only -> 2xE writes to it*/ 91 case 0x20E: 92 if (GUSregb(RegCtrl_2xF) & 0x80) /* 2xE read IRQ enabled? */ 93 { 94 GUSregb(StatRead_2xF) |= 0x80; 95 GUS_irqrequest(state, state->gusirq, 1); 96 } 97 return GUSregb(SB2xE); /* SB2xE */ 98 case 0x20F: /* StatRead_2xF */ 99 /*set/clear fixed bits */ 100 /*value_read = (GUSregb(StatRead_2xF) & 0xf9)|1; */ /*(LSB not set on GUS classic!)*/ 101 value_read = (GUSregb(StatRead_2xF) & 0xf9); 102 if (GUSregb(MixerCtrlReg2x0) & 0x08) 103 value_read |= 2; /* DMA/IRQ enabled flag */ 104 return value_read; 105 /* case 0x300: */ /* MIDI (not implemented) */ 106 /* case 0x301: */ /* MIDI (not implemented) */ 107 case 0x302: 108 return GUSregb(VoiceSelReg3x2); /* VoiceSelReg */ 109 case 0x303: 110 return GUSregb(FunkSelReg3x3); /* FunkSelReg */ 111 case 0x304: /* DataRegLoByte3x4 + DataRegWord3x4 */ 112 case 0x305: /* DataRegHiByte3x5 */ 113 switch (GUSregb(FunkSelReg3x3)) 114 { 115 /* common functions */ 116 case 0x41: /* DramDMAContrReg */ 117 value_read = GUSregb(GUS41DMACtrl); /* &0xfb */ 118 GUSregb(GUS41DMACtrl) &= 0xbb; 119 if (state->gusdma >= 4) 120 value_read |= 0x04; 121 if (GUSregb(IRQStatReg2x6) & 0x80) 122 { 123 value_read |= 0x40; 124 GUSregb(IRQStatReg2x6) &= 0x7f; 125 if (!GUSregb(IRQStatReg2x6)) 126 GUS_irqclear(state, state->gusirq); 127 } 128 return (uint8_t) value_read; 129 /* DramDMAmemPosReg */ 130 /* case 0x42: value_read=GUSregw(GUS42DMAStart); break;*/ 131 /* 43h+44h write only */ 132 case 0x45: 133 return GUSregb(GUS45TimerCtrl); /* TimerCtrlReg */ 134 /* 46h+47h write only */ 135 /* 48h: samp freq - write only */ 136 case 0x49: 137 return GUSregb(GUS49SampCtrl) & 0xbf; /* SampCtrlReg */ 138 /* case 4bh: */ /* joystick trim not supported */ 139 /* case 0x4c: return GUSregb(GUS4cReset); */ /* GUSreset: write only*/ 140 /* voice specific functions */ 141 case 0x80: 142 case 0x81: 143 case 0x82: 144 case 0x83: 145 case 0x84: 146 case 0x85: 147 case 0x86: 148 case 0x87: 149 case 0x88: 150 case 0x89: 151 case 0x8a: 152 case 0x8b: 153 case 0x8c: 154 case 0x8d: 155 { 156 int offset = 2 * (GUSregb(FunkSelReg3x3) & 0x0f); 157 offset += ((int) GUSregb(VoiceSelReg3x2) & 0x1f) << 5; /* = Voice*32 + Funktion*2 */ 158 value_read = GUSregw(offset); 159 } 160 break; 161 /* voice unspecific functions */ 162 case 0x8e: /* NumVoice */ 163 return GUSregb(NumVoices); 164 case 0x8f: /* irqstatreg */ 165 /* (pseudo IRQ-FIFO is processed during a gus_write(0x3X3,0x8f)) */ 166 return GUSregb(SynVoiceIRQ8f); 167 default: 168 return 0xffff; 169 } 170 if (size == 1) 171 { 172 if ((port & 0xff0f) == 0x305) 173 value_read = value_read >> 8; 174 value_read &= 0xff; 175 } 176 return (uint16_t) value_read; 177 /* case 0x306: */ /* Mixer/Version info */ 178 /* return 0xff; */ /* Pre 3.6 boards, ICS mixer NOT present */ 179 case 0x307: /* DRAMaccess */ 180 { 181 uint8_t *adr; 182 adr = state->himemaddr + (GUSregd(GUSDRAMPOS24bit) & 0xfffff); 183 return *adr; 184 } 185 default:; 186 } 187 return 0xffff; 188 } 189 190 void gus_write(GUSEmuState * state, int port, int size, unsigned int data) 191 { 192 uint8_t *gusptr; 193 gusptr = state->gusdatapos; 194 GUSregd(portaccesses)++; 195 196 switch (port & 0xff0f) 197 { 198 case 0x200: /* MixerCtrlReg */ 199 GUSregb(MixerCtrlReg2x0) = (uint8_t) data; 200 break; 201 case 0x206: /* IRQstatReg / SB2x6IRQ */ 202 if (GUSregb(GUS45TimerCtrl) & 0x20) /* SB IRQ enabled? -> set 2x6IRQ bit */ 203 { 204 GUSregb(TimerStatus2x8) |= 0x08; 205 GUSregb(IRQStatReg2x6) = 0x10; 206 GUS_irqrequest(state, state->gusirq, 1); 207 } 208 break; 209 case 0x308: /* AdLib 388h */ 210 case 0x208: /* AdLibCommandReg */ 211 GUSregb(AdLibCommand2xA) = (uint8_t) data; 212 break; 213 case 0x309: /* AdLib 389h */ 214 case 0x209: /* AdLibDataReg */ 215 if ((GUSregb(AdLibCommand2xA) == 0x04) && (!(GUSregb(GUS45TimerCtrl) & 1))) /* GUS auto timer mode enabled? */ 216 { 217 if (data & 0x80) 218 GUSregb(TimerStatus2x8) &= 0x1f; /* AdLib IRQ reset? -> clear maskable adl. timer int regs */ 219 else 220 GUSregb(TimerDataReg2x9) = (uint8_t) data; 221 } 222 else 223 { 224 GUSregb(AdLibData2x9) = (uint8_t) data; 225 if (GUSregb(GUS45TimerCtrl) & 0x02) 226 { 227 GUSregb(TimerStatus2x8) |= 0x01; 228 GUSregb(IRQStatReg2x6) = 0x10; 229 GUS_irqrequest(state, state->gusirq, 1); 230 } 231 } 232 break; 233 case 0x20A: 234 GUSregb(AdLibStatus2x8) = (uint8_t) data; 235 break; /* AdLibStatus2x8 */ 236 case 0x20B: /* GUS hidden registers */ 237 switch (GUSregb(RegCtrl_2xF) & 0x7) 238 { 239 case 0: 240 if (GUSregb(MixerCtrlReg2x0) & 0x40) 241 GUSregb(IRQ_2xB) = (uint8_t) data; /* control register select bit */ 242 else 243 GUSregb(DMA_2xB) = (uint8_t) data; 244 break; 245 /* case 1-4: general purpose emulation regs */ 246 case 5: /* clear stat reg 2xF */ 247 GUSregb(StatRead_2xF) = 0; /* ToDo: is this identical with GUS classic? */ 248 if (!GUSregb(IRQStatReg2x6)) 249 GUS_irqclear(state, state->gusirq); 250 break; 251 case 6: /* Jumper reg (Joystick/MIDI enable) */ 252 GUSregb(Jumper_2xB) = (uint8_t) data; 253 break; 254 default:; 255 } 256 break; 257 case 0x20C: /* SB2xCd */ 258 if (GUSregb(GUS45TimerCtrl) & 0x20) 259 { 260 GUSregb(TimerStatus2x8) |= 0x10; /* SB IRQ enabled? -> set 2xCIRQ bit */ 261 GUSregb(IRQStatReg2x6) = 0x10; 262 GUS_irqrequest(state, state->gusirq, 1); 263 } 264 /* fall through */ 265 case 0x20D: /* SB2xCd no IRQ */ 266 GUSregb(SB2xCd) = (uint8_t) data; 267 break; 268 case 0x20E: /* SB2xE */ 269 GUSregb(SB2xE) = (uint8_t) data; 270 break; 271 case 0x20F: 272 GUSregb(RegCtrl_2xF) = (uint8_t) data; 273 break; /* CtrlReg2xF */ 274 case 0x302: /* VoiceSelReg */ 275 GUSregb(VoiceSelReg3x2) = (uint8_t) data; 276 break; 277 case 0x303: /* FunkSelReg */ 278 GUSregb(FunkSelReg3x3) = (uint8_t) data; 279 if ((uint8_t) data == 0x8f) /* set irqstatreg, get voicereg and clear IRQ */ 280 { 281 int voice; 282 if (GUSregd(voicewavetableirq)) /* WavetableIRQ */ 283 { 284 for (voice = 0; voice < 31; voice++) 285 { 286 if (GUSregd(voicewavetableirq) & (1 << voice)) 287 { 288 GUSregd(voicewavetableirq) ^= (1 << voice); /* clear IRQ bit */ 289 GUSregb(voice << 5) &= 0x7f; /* clear voice reg irq bit */ 290 if (!GUSregd(voicewavetableirq)) 291 GUSregb(IRQStatReg2x6) &= 0xdf; 292 if (!GUSregb(IRQStatReg2x6)) 293 GUS_irqclear(state, state->gusirq); 294 GUSregb(SynVoiceIRQ8f) = voice | 0x60; /* (bit==0 => IRQ wartend) */ 295 return; 296 } 297 } 298 } 299 else if (GUSregd(voicevolrampirq)) /* VolRamp IRQ */ 300 { 301 for (voice = 0; voice < 31; voice++) 302 { 303 if (GUSregd(voicevolrampirq) & (1 << voice)) 304 { 305 GUSregd(voicevolrampirq) ^= (1 << voice); /* clear IRQ bit */ 306 GUSregb((voice << 5) + VSRVolRampControl) &= 0x7f; /* clear voice volume reg irq bit */ 307 if (!GUSregd(voicevolrampirq)) 308 GUSregb(IRQStatReg2x6) &= 0xbf; 309 if (!GUSregb(IRQStatReg2x6)) 310 GUS_irqclear(state, state->gusirq); 311 GUSregb(SynVoiceIRQ8f) = voice | 0x80; /* (bit==0 => IRQ wartend) */ 312 return; 313 } 314 } 315 } 316 GUSregb(SynVoiceIRQ8f) = 0xe8; /* kein IRQ wartet */ 317 } 318 break; 319 case 0x304: 320 case 0x305: 321 { 322 uint16_t writedata = (uint16_t) data; 323 uint16_t readmask = 0x0000; 324 if (size == 1) 325 { 326 readmask = 0xff00; 327 writedata &= 0xff; 328 if ((port & 0xff0f) == 0x305) 329 { 330 writedata = (uint16_t) (writedata << 8); 331 readmask = 0x00ff; 332 } 333 } 334 switch (GUSregb(FunkSelReg3x3)) 335 { 336 /* voice specific functions */ 337 case 0x00: 338 case 0x01: 339 case 0x02: 340 case 0x03: 341 case 0x04: 342 case 0x05: 343 case 0x06: 344 case 0x07: 345 case 0x08: 346 case 0x09: 347 case 0x0a: 348 case 0x0b: 349 case 0x0c: 350 case 0x0d: 351 { 352 int offset; 353 if (!(GUSregb(GUS4cReset) & 0x01)) 354 break; /* reset flag active? */ 355 offset = 2 * (GUSregb(FunkSelReg3x3) & 0x0f); 356 offset += (GUSregb(VoiceSelReg3x2) & 0x1f) << 5; /* = Voice*32 + Funktion*2 */ 357 GUSregw(offset) = (uint16_t) ((GUSregw(offset) & readmask) | writedata); 358 } 359 break; 360 /* voice unspecific functions */ 361 case 0x0e: /* NumVoices */ 362 GUSregb(NumVoices) = (uint8_t) data; 363 break; 364 /* case 0x0f: */ /* read only */ 365 /* common functions */ 366 case 0x41: /* DramDMAContrReg */ 367 GUSregb(GUS41DMACtrl) = (uint8_t) data; 368 if (data & 0x01) 369 GUS_dmarequest(state); 370 break; 371 case 0x42: /* DramDMAmemPosReg */ 372 GUSregw(GUS42DMAStart) = (GUSregw(GUS42DMAStart) & readmask) | writedata; 373 GUSregb(GUS50DMAHigh) &= 0xf; /* compatibility stuff... */ 374 break; 375 case 0x43: /* DRAMaddrLo */ 376 GUSregd(GUSDRAMPOS24bit) = 377 (GUSregd(GUSDRAMPOS24bit) & (readmask | 0xff0000)) | writedata; 378 break; 379 case 0x44: /* DRAMaddrHi */ 380 GUSregd(GUSDRAMPOS24bit) = 381 (GUSregd(GUSDRAMPOS24bit) & 0xffff) | ((data & 0x0f) << 16); 382 break; 383 case 0x45: /* TCtrlReg */ 384 GUSregb(GUS45TimerCtrl) = (uint8_t) data; 385 if (!(data & 0x20)) 386 GUSregb(TimerStatus2x8) &= 0xe7; /* sb IRQ dis? -> clear 2x8/2xC sb IRQ flags */ 387 if (!(data & 0x02)) 388 GUSregb(TimerStatus2x8) &= 0xfe; /* adlib data IRQ dis? -> clear 2x8 adlib IRQ flag */ 389 if (!(GUSregb(TimerStatus2x8) & 0x19)) 390 GUSregb(IRQStatReg2x6) &= 0xef; /* 0xe6; $$clear IRQ if both IRQ bits are inactive or cleared */ 391 /* catch up delayed timer IRQs: */ 392 if ((GUSregw(TimerIRQs) > 1) && (GUSregb(TimerDataReg2x9) & 3)) 393 { 394 if (GUSregb(TimerDataReg2x9) & 1) /* start timer 1 (80us decrement rate) */ 395 { 396 if (!(GUSregb(TimerDataReg2x9) & 0x40)) 397 GUSregb(TimerStatus2x8) |= 0xc0; /* maskable bits */ 398 if (data & 4) /* timer1 irq enable */ 399 { 400 GUSregb(TimerStatus2x8) |= 4; /* nonmaskable bit */ 401 GUSregb(IRQStatReg2x6) |= 4; /* timer 1 irq pending */ 402 } 403 } 404 if (GUSregb(TimerDataReg2x9) & 2) /* start timer 2 (320us decrement rate) */ 405 { 406 if (!(GUSregb(TimerDataReg2x9) & 0x20)) 407 GUSregb(TimerStatus2x8) |= 0xa0; /* maskable bits */ 408 if (data & 8) /* timer2 irq enable */ 409 { 410 GUSregb(TimerStatus2x8) |= 2; /* nonmaskable bit */ 411 GUSregb(IRQStatReg2x6) |= 8; /* timer 2 irq pending */ 412 } 413 } 414 GUSregw(TimerIRQs)--; 415 if (GUSregw(BusyTimerIRQs) > 1) 416 GUSregw(BusyTimerIRQs)--; 417 else 418 GUSregw(BusyTimerIRQs) = 419 GUS_irqrequest(state, state->gusirq, GUSregw(TimerIRQs)); 420 } 421 else 422 GUSregw(TimerIRQs) = 0; 423 424 if (!(data & 0x04)) 425 { 426 GUSregb(TimerStatus2x8) &= 0xfb; /* clear non-maskable timer1 bit */ 427 GUSregb(IRQStatReg2x6) &= 0xfb; 428 } 429 if (!(data & 0x08)) 430 { 431 GUSregb(TimerStatus2x8) &= 0xfd; /* clear non-maskable timer2 bit */ 432 GUSregb(IRQStatReg2x6) &= 0xf7; 433 } 434 if (!GUSregb(IRQStatReg2x6)) 435 GUS_irqclear(state, state->gusirq); 436 break; 437 case 0x46: /* Counter1 */ 438 GUSregb(GUS46Counter1) = (uint8_t) data; 439 break; 440 case 0x47: /* Counter2 */ 441 GUSregb(GUS47Counter2) = (uint8_t) data; 442 break; 443 /* case 0x48: */ /* sampling freq reg not emulated (same as interwave) */ 444 case 0x49: /* SampCtrlReg */ 445 GUSregb(GUS49SampCtrl) = (uint8_t) data; 446 break; 447 /* case 0x4b: */ /* joystick trim not emulated */ 448 case 0x4c: /* GUSreset */ 449 GUSregb(GUS4cReset) = (uint8_t) data; 450 if (!(GUSregb(GUS4cReset) & 1)) /* reset... */ 451 { 452 GUSregd(voicewavetableirq) = 0; 453 GUSregd(voicevolrampirq) = 0; 454 GUSregw(TimerIRQs) = 0; 455 GUSregw(BusyTimerIRQs) = 0; 456 GUSregb(NumVoices) = 0xcd; 457 GUSregb(IRQStatReg2x6) = 0; 458 GUSregb(TimerStatus2x8) = 0; 459 GUSregb(AdLibData2x9) = 0; 460 GUSregb(TimerDataReg2x9) = 0; 461 GUSregb(GUS41DMACtrl) = 0; 462 GUSregb(GUS45TimerCtrl) = 0; 463 GUSregb(GUS49SampCtrl) = 0; 464 GUSregb(GUS4cReset) &= 0xf9; /* clear IRQ and DAC enable bits */ 465 GUS_irqclear(state, state->gusirq); 466 } 467 /* IRQ enable bit checked elsewhere */ 468 /* EnableDAC bit may be used by external callers */ 469 break; 470 } 471 } 472 break; 473 case 0x307: /* DRAMaccess */ 474 { 475 uint8_t *adr; 476 adr = state->himemaddr + (GUSregd(GUSDRAMPOS24bit) & 0xfffff); 477 *adr = (uint8_t) data; 478 } 479 break; 480 } 481 } 482 483 /* Attention when breaking up a single DMA transfer to multiple ones: 484 * it may lead to multiple terminal count interrupts and broken transfers: 485 * 486 * 1. Whenever you transfer a piece of data, the gusemu callback is invoked 487 * 2. The callback may generate a TC irq (if the register was set up to do so) 488 * 3. The irq may result in the program using the GUS to reprogram the GUS 489 * 490 * Some programs also decide to upload by just checking if TC occurs 491 * (via interrupt or a cleared GUS dma flag) 492 * and then start the next transfer, without checking DMA state 493 * 494 * Thus: Always make sure to set the TC flag correctly! 495 * 496 * Note that the genuine GUS had a granularity of 16 bytes/words for low/high DMA 497 * while later cards had atomic granularity provided by an additional GUS50DMAHigh register 498 * GUSemu also uses this register to support byte-granular transfers for better compatibility 499 * with emulators other than GUSemu32 500 */ 501 502 void gus_dma_transferdata(GUSEmuState * state, char *dma_addr, unsigned int count, int TC) 503 { 504 /* this function gets called by the callback function as soon as a DMA transfer is about to start 505 * dma_addr is a translated address within accessible memory, not the physical one, 506 * count is (real dma count register)+1 507 * note that the amount of bytes transferred is fully determined by values in the DMA registers 508 * do not forget to update DMA states after transferring the entire block: 509 * DREQ cleared & TC asserted after the _whole_ transfer */ 510 511 char *srcaddr; 512 char *destaddr; 513 char msbmask = 0; 514 uint8_t *gusptr; 515 gusptr = state->gusdatapos; 516 517 srcaddr = dma_addr; /* system memory address */ 518 { 519 int offset = (GUSregw(GUS42DMAStart) << 4) + (GUSregb(GUS50DMAHigh) & 0xf); 520 if (state->gusdma >= 4) 521 offset = (offset & 0xc0000) + (2 * (offset & 0x1fff0)); /* 16 bit address translation */ 522 destaddr = (char *) state->himemaddr + offset; /* wavetable RAM address */ 523 } 524 525 GUSregw(GUS42DMAStart) += (uint16_t) (count >> 4); /* ToDo: add 16bit GUS page limit? */ 526 GUSregb(GUS50DMAHigh) = (uint8_t) ((count + GUSregb(GUS50DMAHigh)) & 0xf); /* ToDo: add 16bit GUS page limit? */ 527 528 if (GUSregb(GUS41DMACtrl) & 0x02) /* direction, 0 := sysram->gusram */ 529 { 530 char *tmpaddr = destaddr; 531 destaddr = srcaddr; 532 srcaddr = tmpaddr; 533 } 534 535 if ((GUSregb(GUS41DMACtrl) & 0x80) && (!(GUSregb(GUS41DMACtrl) & 0x02))) 536 msbmask = (const char) 0x80; /* invert MSB */ 537 for (; count > 0; count--) 538 { 539 if (GUSregb(GUS41DMACtrl) & 0x40) 540 *(destaddr++) = *(srcaddr++); /* 16 bit lobyte */ 541 else 542 *(destaddr++) = (msbmask ^ (*(srcaddr++))); /* 8 bit */ 543 if (state->gusdma >= 4) 544 *(destaddr++) = (msbmask ^ (*(srcaddr++))); /* 16 bit hibyte */ 545 } 546 547 if (TC) 548 { 549 (GUSregb(GUS41DMACtrl)) &= 0xfe; /* clear DMA request bit */ 550 if (GUSregb(GUS41DMACtrl) & 0x20) /* DMA terminal count IRQ */ 551 { 552 GUSregb(IRQStatReg2x6) |= 0x80; 553 GUS_irqrequest(state, state->gusirq, 1); 554 } 555 } 556 }