Gert van der Knokke
BBC Basic in Z80 emulation on the mbed, USB serial terminal output only. LOAD and SAVE work on the local file system but there is no error signalling.
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main.cpp
00001 /* BBC Basic emulator on NXP mbed by Gert van der Knokke 00002 * Emulation of the Z80 CPU 00003 * The z80 emulator is heavily modified by me (Gert) 00004 * original Copyright (C) 1994 Ian Collier. 00005 * 00006 * This program is free software; you can redistribute it and/or modify 00007 * it under the terms of the GNU General Public License as published by 00008 * the Free Software Foundation; either version 2 of the License, or 00009 * (at your option) any later version. 00010 * 00011 * This program is distributed in the hope that it will be useful, 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 * GNU General Public License for more details. 00015 * 00016 * You should have received a copy of the GNU General Public License 00017 * along with this program; if not, write to the Free Software 00018 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 00019 */ 00020 00021 #include "mbed.h" 00022 #include "module.h" 00023 #include "z80.h" 00024 00025 #define DEBUG false 00026 00027 // define serial port for debug 00028 Serial linktopc(USBTX,USBRX); 00029 00030 00031 // VDU queue 00032 unsigned char vdu_queue[256]; // a somewhat large queue 00033 unsigned char queue_bytes=0; // vdu queue pointer 00034 unsigned char oldchar; // which VDU function needs the queue 00035 00036 volatile unsigned char flag,oldy=0; 00037 00038 00039 int background_color; // for clear screen 00040 int cursor_xpos; 00041 int cursor_ypos; 00042 int last_line_processed; 00043 int previous_line_found; 00044 00045 int current_background_color; 00046 int current_text_color; 00047 00048 00049 // prepare mbed storage for local use 00050 LocalFileSystem local("local"); // Create the local filesystem under the name "local" 00051 00052 // clear the screen 00053 void cls() { 00054 putchar(0x0c); 00055 } 00056 00057 // dummy function 00058 void set_cursor_position() { 00059 } 00060 00061 // home cursor 00062 void home_cursor() { 00063 cursor_xpos=0x00; // ypos 00064 cursor_ypos=0x00; // xpos 00065 set_cursor_position(); 00066 } 00067 00068 // prepare the screen 00069 void init_screen() { 00070 current_background_color=0; // set initial background color 00071 current_text_color=7; // initial text color attributes 00072 cls(); 00073 home_cursor(); 00074 } 00075 00076 // handle VDU calls after all bytes are in queue 00077 // Note! queue is working front to back (255 is first, 0 is last) 00078 void do_handle_queue(unsigned char code) { 00079 switch (code) { 00080 case 0x11: // select text color 00081 current_text_color=vdu_queue[255]; 00082 break; 00083 case 0x16: // Mode 00084 current_text_color=7; 00085 current_background_color=0; 00086 init_screen(); 00087 home_cursor(); 00088 break; 00089 case 0x17: // define character n 00090 break; 00091 case 0x1f: // move cursor to x,y 00092 cursor_xpos=vdu_queue[254]; 00093 cursor_ypos=vdu_queue[255]; 00094 set_cursor_position(); 00095 break; 00096 } 00097 } 00098 00099 // VDU OSWRCHR 00100 // this routine evaluates the stream characters 00101 // and prepares the queue if needed 00102 void printchar(unsigned char ch) { 00103 00104 // do we need more queue bytes ? 00105 if (queue_bytes) { 00106 vdu_queue[queue_bytes++]=ch; 00107 // all bytes in queue, now handle the call 00108 if (queue_bytes==0) 00109 do_handle_queue(oldchar); 00110 00111 } else { 00112 00113 switch (ch) { 00114 case 0x00: // NULL 00115 break; 00116 case 0x08: // CURSOR LEFT 00117 putchar(0x08); 00118 if (cursor_xpos>0) { 00119 cursor_xpos--; 00120 set_cursor_position(); 00121 } 00122 break; 00123 case 0x09: // CURSOR RIGHT 00124 if (cursor_xpos<39) { 00125 cursor_xpos++; 00126 set_cursor_position(); 00127 } 00128 break; 00129 case 0x0a: // CURSOR DOWN 00130 if (cursor_ypos<23) { 00131 cursor_ypos++; 00132 set_cursor_position(); 00133 } else { 00134 cursor_ypos=23; 00135 } 00136 break; 00137 case 0x0b: // CURSOR UP 00138 cursor_ypos++; 00139 if (cursor_ypos>0) { 00140 cursor_ypos--; 00141 set_cursor_position(); 00142 } else { 00143 cursor_ypos=0; 00144 } 00145 break; 00146 case 0x0d: // Carriage Return 00147 cursor_xpos=0; 00148 putchar(0x0d); 00149 putchar(0x0a); 00150 set_cursor_position(); 00151 break; 00152 case 0x0c: // CLEAR TEXT WINDOW 00153 case 0x10: // CLEAR GRAPHIC WINDOW 00154 cls(); 00155 cursor_xpos=0; 00156 cursor_ypos=0; 00157 set_cursor_position(); 00158 break; 00159 case 0x11: // set TEXT color 00160 oldchar=ch; // this was the code of the initial call 00161 queue_bytes=256-1; // for this call we need one more byte 00162 break; 00163 case 0x14: // reset colors 00164 current_text_color=7; 00165 current_background_color=0; 00166 break; 00167 case 0x16: // MODE select 00168 oldchar=ch; 00169 queue_bytes=256-1; 00170 break; 00171 case 0x17: // define character n 00172 break; 00173 case 0x1e: 00174 cursor_xpos=0; 00175 cursor_ypos=0; 00176 set_cursor_position(); 00177 break; 00178 case 0x1f: // set cursor to position X,Y 00179 oldchar=ch; // this was the code of the initial call 00180 queue_bytes=256-2; // for this call we need two more bytes 00181 break; 00182 // all else is put on screen literally 00183 default: 00184 putchar(ch); 00185 break; 00186 } 00187 } 00188 } 00189 00190 00191 void init_ramtop() { 00192 00193 00194 // set all MOS calls to illegal opcode 0xed55 00195 // that code is trapped by a mbed routine 00196 wrmem(OSWRCH,0xed); 00197 wrmem(OSWRCH+1,0x55); 00198 00199 wrmem(OSWORD,0xed); 00200 wrmem(OSWORD+1,0x55); 00201 00202 wrmem(OSBYTE,0xed); 00203 wrmem(OSBYTE+1,0x55); 00204 00205 wrmem(OSRDCH,0xed); 00206 wrmem(OSRDCH+1,0x55); 00207 00208 wrmem(OSNEWL,0xed); 00209 wrmem(OSNEWL+1,0x55); 00210 00211 wrmem(OSASCI,0xed); 00212 wrmem(OSASCI+1,0x55); 00213 00214 wrmem(OSRDCH,0xed); 00215 wrmem(OSRDCH+1,0x55); 00216 00217 wrmem(MAINVDU,0xed); 00218 wrmem(MAINVDU+1,0x55); 00219 00220 wrmem(GSINIT,0xed); 00221 wrmem(GSINIT+1,0x55); 00222 00223 wrmem(GSREAD,0xed); 00224 wrmem(GSREAD+1,0x55); 00225 00226 wrmem(OSRDRM,0xed); 00227 wrmem(OSRDRM+1,0x55); 00228 00229 wrmem(OSEVEN,0xed); 00230 wrmem(OSEVEN+1,0x55); 00231 00232 wrmem(OSCLI,0xed); 00233 wrmem(OSCLI+1,0x55); 00234 00235 wrmem(OSFILE,0xed); 00236 wrmem(OSFILE+1,0x55); 00237 00238 wrmem(CMDPTR,0xf0); // pointer to CR terminated string (auto start filename) 00239 wrmem(CMDPTR+1,0x00); // it is set here to 0x00f0 00240 00241 wrmem(BRKV,0x00); // break vector 00242 wrmem(BRKV+1,0x00); 00243 00244 wrmem(FAULT,0x38); // fault vector 00245 wrmem(FAULT+1,0x00); 00246 } 00247 00248 unsigned char getkey() { 00249 unsigned char key=0x00; 00250 if (linktopc.readable()) // get USB status 00251 key=linktopc.getc(); // get ASCII key 00252 return key; 00253 } 00254 00255 // crude getline routine 00256 void mygets(int ad,int max,unsigned char minasc,unsigned char maxasc) { 00257 int n=0; 00258 int key=0; 00259 00260 bool eflag=1; 00261 00262 // show cursor 00263 set_cursor_position(); 00264 00265 while (eflag) { 00266 // key=getkey(); 00267 #if !DEBUG 00268 // USB serial data ? then override key (only when NOT in debug mode) 00269 if (linktopc.readable()) // get USB status 00270 key=linktopc.getc(); // get ASCII key code 00271 else key=0; 00272 // key=getchar(); // BLOCKING MODE 00273 #endif 00274 00275 if (key) // printf("got key code: %02x\n\r",key); 00276 00277 // only ASCII should arrive here 00278 switch (key) { 00279 case 0x00: // no key 00280 break; 00281 case 0x0d: // Enter or Return 00282 wrmem(ad+n,key); 00283 h=n; 00284 // clear carry flag 00285 anda(a); // z80 way of clearing carry... 00286 eflag=0; // terminate the loop 00287 printchar(key); 00288 printchar(0x0a); 00289 break; 00290 case 0x1b: // Escape 00291 wrmem(ad+n,key); 00292 // set carry flag 00293 f=(f&0xc4)|1|(a&0x28); 00294 eflag=0; 00295 h=n; 00296 break; 00297 case 0x15: // CTRL-U (clear input) 00298 while (n) { 00299 00300 printchar(0x08); 00301 printchar(0x20); 00302 printchar(0x08); 00303 n--; 00304 } 00305 wrmem(ad,0x0d); 00306 break; 00307 case 0x7f: // DELETE 00308 if (n) { 00309 n--; 00310 printchar(0x08); // cursor left 00311 printchar(0x20); // delete character by printing a space 00312 printchar(0x08); // cursor left 00313 wrmem(ad+n,0x20); // overwrite with space 00314 } 00315 break; 00316 default: // all else 00317 // keep within maximum lenght and given ascii limits 00318 if ((key>=minasc) && (key<=maxasc) && n<max) { 00319 wrmem(ad+n,key); 00320 n++; 00321 printchar(key); 00322 } 00323 break; 00324 } 00325 } 00326 } 00327 00328 00329 // OSWORD 00330 void do_osword() { 00331 int ad,n; 00332 char buf[40]; 00333 time_t seconds; 00334 00335 // printf("OSWORD called with PC=%04x A=%02x HL=%02x%02x\n\r",pc,a,h,l); 00336 switch (a) { 00337 00338 case 0x00: // get a line from the keyboard/input channel 00339 ad=(h<<8)+l; 00340 // printf("Control block:\n\r"); 00341 // printf("buffer address %02x%02x\n\r",rdmem(ad+1),rdmem(ad)); 00342 // printf("maximum length: %d\n\r",rdmem(ad+2)); 00343 // printf("minimum ASCII value %d\n\r",rdmem(ad+3)); 00344 // printf("maximum ASCII value %d\n\r",rdmem(ad+4)); 00345 00346 mygets((rdmem(ad+1)<<8)+rdmem(ad),rdmem(ad+2),rdmem(ad+3),rdmem(ad+4)); 00347 00348 break; 00349 case 0x01: // read systemclock (long integer) 00350 break; 00351 case 0x02: // write systemclock (long integer) 00352 break; 00353 case 0x07: // emit a sound from the sound library (0-7) 00354 break; 00355 case 0x0e: // read TIME$ (not present in original BBC Basic) 00356 ad=hl; // get pointer to function number 00357 switch (rdmem(hl)) { // select function number 00358 case 0: // return time string 00359 seconds = time(NULL); // get current time from mbed RTC 00360 strftime(buf,40, "%a,%d %m %Y.%H:%M:%S\r", localtime(&seconds)); // write to temporary buffer 00361 n=0; 00362 while (buf[n]) wrmem(ad++,buf[n++]); // copy to pointer from HL 00363 break; 00364 case 1: // return BCD values of clock 00365 // On exit: 00366 // XY?0=year (&00-&99) 00367 // XY?1=month (&01-&12) 00368 // XY?2=date (&01-&31) 00369 // XY?3=day of week (&01-&07, Sun-Sat) 00370 // XY?4=hours (&00-&23) 00371 // XY?5=minutes (&00-&59) 00372 // XY?6=seconds (&00-&59). 00373 // 00374 // A year value of &80-&99 represents 1980-1999, a value of 00375 // &00-&79 represents 2000-2079. 00376 // 00377 break; 00378 case 2: // Convert BCD to string. 00379 // On entry: 00380 // XY+1..7=BCD value 00381 // On exit: 00382 // XY+1..25=CR-terminated string 00383 break; 00384 } 00385 break; 00386 case 0x0f: // write TIME$ (not present in original BBC Basic) 00387 // On entry: 00388 // XY?0=function code 00389 // XY+1.. value to use. 00390 // Functions are: 00391 // 8 - Set time to value in format "HH:MM:SS" 00392 // 16 - Set date to value in format "Day,DD Mon Year" 00393 // 24 - Set time and date to value in format 00394 // "Day,DD Mon Year.HH:MM:SS" 00395 n=0; 00396 ad=hl; 00397 // printf(" write time$ function %d\n\r",rdmem(ad)); 00398 ad++; 00399 while (rdmem(ad)!=0x0d) buf[n++]=rdmem(ad++); // copy timestring to buffer 00400 buf[n]=0; 00401 // printf("trying to set time from %s\n\r",buf); 00402 break; 00403 } 00404 } 00405 00406 // OSBYTE 00407 // on 6502 A register and X,Y are used for Low,High parameters 00408 // Z80 uses L and H (so X=L and H=Y <-> L=X and Y=H) 00409 void do_osbyte() { 00410 unsigned char temp; 00411 00412 // printf("OSBYTE called with PC=%04x A=%02x H=%02x L=%02x\n\r",pc,a,h,l); 00413 switch (a) { 00414 case 0x00: // NULL 00415 l=0xff; 00416 break; 00417 case 0x13: // ASCII 19 00418 break; 00419 case 0x7c: // clear ESCAPE state 00420 wrmem(0xff80,rdmem(0xff80)&0x7f); 00421 break; 00422 case 0x7d: // set ESCAPE state 00423 wrmem(0xff80,rdmem(0xff80)|0x80); 00424 break; 00425 case 0x7e: // acknowledge ESCAPE state ? (CLOSE ALL!) 00426 wrmem(0xff80,rdmem(0xff80)&0x7f); 00427 break; 00428 case 0x7f: // read EOF on channel 00429 l=0x01; 00430 break; 00431 case 0x80: // read ADVAL(hl) 00432 h=0; 00433 l=0; 00434 break; 00435 case 0x81: // read key within time limit 'hl' centiseconds 00436 temp=hl; // get timeout value (100th seconds) 00437 do { 00438 l=getkey(); 00439 wait(0.01); 00440 } while ((temp--) && (!l)); 00441 00442 if (l) { // we got a key 00443 if (l==0x1b) { // Escape ? 00444 f=(f&0xc4)|1|(a&0x28); // set carry 00445 h=0x1b; 00446 } else { 00447 anda(a); // clear carry 00448 h=0x00; // clear h 00449 } 00450 } else { // timeout 00451 f=(f&0xc4)|1|(a&0x28); // set carry 00452 h=0xff; // signal no key 00453 } 00454 break; // scan keyboard etc 00455 case 0x82: 00456 h=l=0; 00457 break; // Machine high order address 00458 case 0x83: 00459 h=PAGE>>8; 00460 l=(PAGE & 0xff); 00461 break; // lowest available memory address (PAGE) 00462 case 0x84: // highest available memory address (HIMEM) 00463 h=RAMEND>>8; 00464 l=RAMEND & 0xff; 00465 break; 00466 case 0x85: // read bottom of display RAM for a specific mode 00467 h=0x80; 00468 l=0x00; 00469 break; 00470 case 0x86: // return H=VPOS, L=POS 00471 h=cursor_ypos; 00472 l=cursor_xpos; 00473 break; 00474 case 0x87: // L=character on screen at cursor position 00475 h=7; 00476 l=0; 00477 break; 00478 case 0xda: // read/write the number of items in the VDU queue 00479 // on return H contains the new value, L the old 00480 temp=queue_bytes; 00481 queue_bytes=(queue_bytes & h)^l; 00482 h=queue_bytes; 00483 l=temp; 00484 break; // read/write the number of items in the VDU queue 00485 } 00486 // show_registers(); 00487 // wait(0.1); 00488 } 00489 00490 void do_osreadchar() { 00491 a=getchar(); 00492 // test for ESCAPE 00493 if (a==27) { 00494 f=(f&0xc4)|1|(a&0x28); 00495 wrmem(0xff80,rdmem(0xff80)|0x80); 00496 } 00497 } 00498 00499 void do_osnewline() { 00500 printchar(0x0a); 00501 printchar(0x0d); 00502 a=0x0d; 00503 } 00504 00505 void do_osasci() { 00506 if (a==0x0d) do_osnewline(); 00507 else printchar(a); 00508 } 00509 00510 void do_mainvdu() { 00511 printchar(a); 00512 } 00513 00514 void do_gsinit() { 00515 printf("GSINIT called with PC=%04x A=%02x\n\r",pc,a); 00516 } 00517 00518 void do_gsread() { 00519 } 00520 00521 void do_osrdrm() { 00522 printf("OSRDRM called with PC=%04x A=%02x H=%02x L=%02x\n\r",pc,a,h,l); 00523 } 00524 00525 void do_oseven() { 00526 printf("OSEVEN called with PC=%04x A=%02x H=%02x L=%02x\n\r",pc,a,h,l); 00527 } 00528 00529 void do_oscli() { 00530 printf("OSCLI called with PC=%04x A=%02x H=%02x L=%02x\n\r",pc,a,h,l); 00531 do { 00532 a=rdmem((h<<8)+l); 00533 if (!++l)h++; 00534 putchar(a); 00535 } while (a!=0x0d); 00536 } 00537 00538 void do_osfile() { 00539 char buffer[200]; 00540 int n=0; 00541 FILE *fp; 00542 // get address of control block 00543 int controlblock=hl; 00544 int offset=rdmem(controlblock)+(rdmem(controlblock+1)<<8); 00545 // create a kludgy pointer from this offset to the filename 00546 char *filename=(char *)(ram+offset-RAMSTART); 00547 long load_address=rdmem(controlblock+2)+(rdmem(controlblock+3)<<8)+(rdmem(controlblock+4)<<16)+(rdmem(controlblock+5)<<24); 00548 long execution_address=rdmem(controlblock+6)+(rdmem(controlblock+7)<<8)+(rdmem(controlblock+8)<<16)+(rdmem(controlblock+9)<<24); 00549 long start_or_length=rdmem(controlblock+10)+(rdmem(controlblock+11)<<8)+(rdmem(controlblock+12)<<16)+(rdmem(controlblock+13)<<24); 00550 long end_address_or_attributes=rdmem(controlblock+14)+(rdmem(controlblock+15)<<8)+(rdmem(controlblock+16)<<16)+(rdmem(controlblock+17)<<24); 00551 00552 00553 // printf("OSFILE called with PC=%04x A=%02x H=%02x L=%02x\n\r",pc,a,h,l); 00554 00555 // for (n=0; n<=0x11; n++) printf("offset %02x value %02x\n\r",n,rdmem(controlblock+n)); 00556 00557 n=0; 00558 while (filename[n]!=0x0d) n++; 00559 // overwrite 0x0d with end of string 00560 filename[n]=0x00; 00561 00562 // now determine what to do 00563 switch (a) { 00564 case 0x00: // save a section of memory as a named file 00565 sprintf(buffer,"/local/%s",filename); 00566 // printf("Saving file %s load adr:%08lx exec adr:%08lx start/length%08lx end/attr:%08lx\n\r",filename,load_address,execution_address,start_or_length,end_address_or_attributes); 00567 fp=fopen(buffer, "w"); 00568 if (fp) { 00569 n=start_or_length; 00570 while (n!=end_address_or_attributes) fputc(rdmem(n++),fp); 00571 fclose(fp); 00572 a=1; 00573 } else { 00574 // printf("could not write %s\n\r",buffer); 00575 a=0; 00576 pc=rdmem(0xfffa)+(rdmem(0xfffb)<<8); // do BRK 00577 } 00578 break; 00579 case 0x01: // write the catalogue information (only) for the named file (disc only) 00580 break; 00581 case 0x02: // write the load address (only) for the named file (disc only) 00582 break; 00583 case 0x03: // write the execution address (only) for the named file (disc only) 00584 break; 00585 case 0x04: // write the attributes (only) for the named file (disc only) 00586 break; 00587 case 0x05: // read the named file's catalogue information, place file type in A (disc only) 00588 break; 00589 case 0x06: // delete the named file (disc only) 00590 break; 00591 case 0xff: // load the named file and read the named file's catalogue information 00592 sprintf(buffer,"/local/%s",filename); 00593 // printf("Loading file %s load adr:%08lx exec adr:%08lx start/length%08lx end/attr:%08lx\n\r",buffer,load_address,execution_address,start_or_length,end_address_or_attributes); 00594 fp = fopen(buffer, "r"); 00595 if (fp) { 00596 n=load_address; 00597 while (!feof(fp)) wrmem(n++,fgetc(fp)); 00598 fclose(fp); 00599 a=1; // file found 00600 } else { 00601 // printf("Could not open %s\n",buffer); 00602 a=0; 00603 pc=rdmem(0xfffa)+(rdmem(0xfffb)<<8); // do BRK 00604 } 00605 break; 00606 } 00607 } 00608 00609 void terminalgets(char *buffer) { 00610 int n=0; 00611 int key=0; 00612 do { 00613 key=getchar(); 00614 buffer[n]=key; 00615 putchar(key); 00616 if (n<16) n++; 00617 } while (key != 0x0d); 00618 buffer[n]=0; 00619 } 00620 00621 00622 // here the OS calls are recognized and 00623 // diverted to the mbed routines. 00624 // this needs to be replaced by native Z80 code 00625 void do_mos() { 00626 // printf("Entering MOS emulation with PC %04x\n\r",pc); 00627 00628 // compensate pc for length of ED55 opcode 00629 switch (pc-2) { 00630 case OSBYTE: 00631 do_osbyte(); 00632 break; 00633 case OSWORD: 00634 do_osword(); 00635 break; 00636 case OSWRCH: 00637 printchar(a); 00638 break; 00639 case OSRDCH: 00640 do_osreadchar(); 00641 break; 00642 case OSNEWL: 00643 do_osnewline(); 00644 break; 00645 case OSASCI: 00646 do_osasci(); 00647 break; 00648 case MAINVDU: 00649 do_mainvdu(); 00650 break; 00651 case GSINIT: 00652 do_gsinit(); 00653 break; 00654 case GSREAD: 00655 do_gsread(); 00656 break; 00657 case OSRDRM: 00658 do_osrdrm(); 00659 break; 00660 case OSEVEN: 00661 do_oseven(); 00662 break; 00663 case OSCLI: 00664 do_oscli(); 00665 break; 00666 case OSFILE: 00667 do_osfile(); 00668 break; 00669 } 00670 } 00671 00672 void listdir(void) { 00673 DIR *d; 00674 struct dirent *p; 00675 00676 d = opendir("/sd"); 00677 if (d != NULL) { 00678 while ((p = readdir(d)) != NULL) { 00679 printf(" - %s\r\n", p->d_name); 00680 } 00681 } else { 00682 printf("Could not open directory!\n"); 00683 } 00684 closedir(d); 00685 } 00686 00687 00688 00689 00690 00691 // ================================================================ 00692 // main loop 00693 // ================================================================ 00694 int main() { 00695 00696 // serial port on at 115200 baud 00697 linktopc.baud(115200); 00698 setbuf(stdout, NULL); // no buffering for this filehandle 00699 00700 // reset all Z80 registers to some initial values 00701 a=f=b=c=d=e=h=l=a1=f1=b1=c1=d1=e1=h1=l1=i=iff1=iff2=im=r=0; 00702 ixoriy=new_ixoriy=0; 00703 ix=iy=sp=pc=0; 00704 00705 queue_bytes=0; 00706 00707 // init MOS vectors 00708 init_ramtop(); 00709 00710 init_screen(); 00711 home_cursor(); 00712 00713 // endless loop 00714 while (1) { 00715 // wait(0.01); 00716 r++; 00717 // this is some optimization for the IX and IY opcodes (DD/FD) 00718 ixoriy=new_ixoriy; 00719 new_ixoriy=0; 00720 00721 // fetch opcode and execute, the include does all the heavy decoding 00722 switch (fetch(pc++)) { 00723 #include "z80ops.h" 00724 } 00725 00726 // next is the interrupt emulator (only IM1 mode) 00727 // interrupt pending? if new_ixoriy is set or iff1==0 don't do interrupt yet (continue DD/FD opcode) 00728 // if (intpend && !new_ixoriy && iff1) { 00729 // are we HALT-ed ? then resume 00730 // if (fetch(pc)==0x76) pc++; 00731 00732 // block further interrupts for now 00733 // iff1=0; 00734 00735 // do the call to 00x38 00736 // push2(pc); // save old pc 00737 // pc=0x0038; // setup new pc 00738 // intpend=0; // release interrupt pending flag; 00739 // } // if intpend 00740 } // while 00741 }
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