ref: b0d33c09ff8fdb48e12843046033d1df68c9c54f
dir: /sys/src/games/md/md.c/
#include <u.h> #include <libc.h> #include <thread.h> #include <draw.h> #include <keyboard.h> #include "../eui.h" #include "dat.h" #include "fns.h" u16int *prg; int nprg; u8int *sram; u32int sramctl, nsram, sram0, sram1; int savefd = -1; int dmaclock, vdpclock, z80clock, audioclock, ymclock, saveclock; void flushram(void) { if(savefd >= 0) pwrite(savefd, sram, nsram, 0); saveclock = 0; } static void loadbat(char *file) { static char buf[512]; strncpy(buf, file, sizeof buf - 5); strcat(buf, ".sav"); savefd = create(buf, ORDWR | OEXCL, 0666); if(savefd < 0) savefd = open(buf, ORDWR); if(savefd < 0) print("open: %r\n"); else readn(savefd, sram, nsram); } static void loadrom(char *file) { static uchar hdr[512], buf[4096]; u32int v; u16int *p; int fd, rc, i; fd = open(file, OREAD); if(fd < 0) sysfatal("open: %r"); if(readn(fd, hdr, 512) < 512) sysfatal("read: %r"); if(memcmp(hdr + 0x100, "SEGA MEGA DRIVE ", 16) != 0 && memcmp(hdr + 0x100, "SEGA GENESIS ", 16) != 0) sysfatal("invalid rom"); v = hdr[0x1a0] << 24 | hdr[0x1a1] << 16 | hdr[0x1a2] << 8 | hdr[0x1a3]; if(v != 0) sysfatal("rom starts at nonzero address"); v = hdr[0x1a4] << 24 | hdr[0x1a5] << 16 | hdr[0x1a6] << 8 | hdr[0x1a7]; nprg = v = v+2 & ~1; if(nprg == 0) sysfatal("invalid rom"); p = prg = malloc(v); if(prg == nil) sysfatal("malloc: %r"); seek(fd, 0, 0); while(v != 0){ rc = readn(fd, buf, sizeof buf); if(rc == 0) break; if(rc < 0) sysfatal("read: %r"); if(rc > v) rc = v; for(i = 0; i < rc; i += 2) *p++ = buf[i] << 8 | buf[i+1]; v -= rc; } close(fd); if(hdr[0x1b0] == 0x52 && hdr[0x1b1] == 0x41){ sramctl = SRAM | hdr[0x1b2] >> 1 & ADDRMASK; if((hdr[0x1b2] & 0x40) != 0) sramctl |= BATTERY; sram0 = hdr[0x1b4] << 24 | hdr[0x1b5] << 16 | hdr[0x1b6] << 8 | hdr[0x1b7] & 0xfe; sram1 = hdr[0x1b8] << 24 | hdr[0x1b9] << 16 | hdr[0x1ba] << 8 | hdr[0x1bb] | 1; if(sram1 <= sram0){ print("SRAM of size <= 0?\n"); sramctl = 0; }else{ nsram = sram1 - sram0; if((sramctl & ADDRMASK) != ADDRBOTH) nsram >>= 1; sram = malloc(nsram); if(sram == nil) sysfatal("malloc: %r"); if((sramctl & BATTERY) != 0){ loadbat(file); atexit(flushram); } } } } void usage(void) { fprint(2, "usage: %s [-a] [-x scale] rom\n", argv0); exits("usage"); } void threadmain(int argc, char **argv) { int t; ARGBEGIN{ case 'a': initaudio(); break; case 'x': fixscale = strtol(EARGF(usage()), nil, 0); break; default: usage(); } ARGEND; if(argc < 1) usage(); loadrom(*argv); initemu(320, 224, 4, XRGB32, 1, nil); regkey("a", 'c', 1<<5); regkey("b", 'x', 1<<4); regkey("y", 'z', 1<<12); regkey("start", '\n', 1<<13); regkey("up", Kup, 0x101); regkey("down", Kdown, 0x202); regkey("left", Kleft, 1<<2); regkey("right", Kright, 1<<3); cpureset(); vdpmode(); ymreset(); for(;;){ if(paused != 0){ qlock(&pauselock); qunlock(&pauselock); } if(dma != 1){ t = step() * CPUDIV; if(dma != 0) dmastep(); }else{ t = CPUDIV; dmastep(); } z80clock -= t; vdpclock -= t; audioclock += t; ymclock += t; while(vdpclock < 0){ vdpstep(); vdpclock += 8; } while(z80clock < 0) z80clock += z80step() * Z80DIV; while(audioclock >= SAMPDIV){ audiosample(); audioclock -= SAMPDIV; } while(ymclock >= YMDIV){ ymstep(); ymclock -= YMDIV; } if(saveclock > 0){ saveclock -= t; if(saveclock <= 0){ saveclock = 0; flushram(); } } } } void flush(void) { flushmouse(1); flushscreen(); flushaudio(audioout); }