ref: 75d6267a5f788162d92e7a5ae126cd8b0770aa8a
dir: /sys/src/games/nes/nes.c/
#include <u.h> #include <libc.h> #include <draw.h> #include <thread.h> #include <keyboard.h> #include "../eui.h" #include "dat.h" #include "fns.h" extern uchar ppuram[16384]; int nprg, nchr, map, chrram; uchar *prg, *chr; int clock, ppuclock, apuclock, dmcclock, dmcfreq, sampclock, msgclock, saveclock; int oflag, savefd = -1; int mirr; void message(char *fmt, ...) { va_list va; static char buf[512]; va_start(va, fmt); vsnprint(buf, sizeof buf, fmt, va); string(screen, Pt(10, 10), display->black, ZP, display->defaultfont, buf); msgclock = FREQ; va_end(va); } void flushram(void) { if(savefd >= 0) pwrite(savefd, mem + 0x6000, 0x2000, 0); saveclock = 0; } void loadrom(char *file, int sflag) { int fd; int nes20; char *s; static uchar header[16]; static u32int flags; static char buf[512]; fd = open(file, OREAD); if(fd < 0) sysfatal("open: %r"); if(readn(fd, header, sizeof(header)) < sizeof(header)) sysfatal("read: %r"); if(memcmp(header, "NES\x1a", 4) != 0) sysfatal("not a ROM"); if(header[15] != 0) memset(header + 7, 0, 9); flags = header[6] | header[7] << 8; nes20 = (flags & FLNES20M) == FLNES20V; if(flags & (FLVS | FLPC10)) sysfatal("ROM not supported"); nprg = header[HPRG]; if(nes20) nprg |= (header[HROMH] & 0xf) << 8; if(nprg == 0) sysfatal("invalid ROM"); nchr = header[HCHR]; if(nes20) nchr |= (header[HROMH] & 0xf0) << 4; map = (flags >> FLMAPPERL) & 0x0f | (((flags >> FLMAPPERH) & 0x0f) << 4); if(nes20) map |= (header[8] & 0x0f) << 8; if(map >= 256 || mapper[map] == nil) sysfatal("unimplemented mapper %d", map); memset(mem, 0, sizeof(mem)); if((flags & FLTRAINER) != 0 && readn(fd, mem + 0x7000, 512) < 512) sysfatal("read: %r"); prg = malloc(nprg * PRGSZ); if(prg == nil) sysfatal("malloc: %r"); if(readn(fd, prg, nprg * PRGSZ) < nprg * PRGSZ) sysfatal("read: %r"); chrram = nchr == 0; if(nchr != 0){ chr = malloc(nchr * CHRSZ); if(chr == nil) sysfatal("malloc: %r"); if(readn(fd, chr, nchr * CHRSZ) < 1) sysfatal("read: %r"); }else{ nchr = 1; chr = malloc(nchr * CHRSZ); if(chr == nil) sysfatal("malloc: %r"); } if((flags & FLFOUR) != 0) mirr = MFOUR; else if((flags & FLMIRROR) != 0) mirr = MVERT; else mirr = MHORZ; if(sflag){ strncpy(buf, file, sizeof buf - 5); s = buf + strlen(buf) - 4; if(s < buf || strcmp(s, ".nes") != 0) s += 4; strcpy(s, ".sav"); savefd = create(buf, ORDWR | OEXCL, 0666); if(savefd < 0) savefd = open(buf, ORDWR); if(savefd < 0) message("open: %r"); else readn(savefd, mem + 0x6000, 0x2000); atexit(flushram); } mapper[map](INIT, 0); } void usage(void) { fprint(2, "usage: %s [-aos] [-x scale] rom\n", argv0); exits("usage"); } void threadmain(int argc, char **argv) { int t, sflag; sflag = 0; ARGBEGIN { case 'a': initaudio(); break; case 'o': oflag = 1; break; case 's': sflag = 1; break; case 'x': fixscale = strtol(EARGF(usage()), nil, 0); break; default: usage(); } ARGEND; if(argc < 1) usage(); loadrom(argv[0], sflag); initemu(256, 240 - oflag * 16, 4, XRGB32, 1, nil); regkey("b", 'z', 1<<1); regkey("a", 'x', 1<<0); regkey("control", Kshift, 1<<2); regkey("start", '\n', 1<<3); regkey("up", Kup, 1<<4); regkey("down", Kdown, 1<<5); regkey("left", Kleft, 1<<6); regkey("right", Kright, 1<<7); pc = memread(0xFFFC) | memread(0xFFFD) << 8; rP = FLAGI; dmcfreq = 12 * 428; for(;;){ if(savereq){ savestate("nes.save"); savereq = 0; } if(loadreq){ loadstate("nes.save"); loadreq = 0; } if(paused){ qlock(&pauselock); qunlock(&pauselock); } t = step() * 12; clock += t; ppuclock += t; apuclock += t; sampclock += t; dmcclock += t; while(ppuclock >= 4){ ppustep(); ppuclock -= 4; } if(apuclock >= APUDIV){ apustep(); apuclock -= APUDIV; } if(sampclock >= SAMPDIV){ audiosample(); sampclock -= SAMPDIV; } if(dmcclock >= dmcfreq){ dmcstep(); dmcclock -= dmcfreq; } if(msgclock > 0){ msgclock -= t; if(msgclock <= 0){ extern Image *bg; draw(screen, screen->r, bg, nil, ZP); msgclock = 0; } } if(saveclock > 0){ saveclock -= t; if(saveclock <= 0) flushram(); } } }