diff options
Diffstat (limited to 'src/fake86/timing.c')
| -rwxr-xr-x | src/fake86/timing.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/fake86/timing.c b/src/fake86/timing.c new file mode 100755 index 0000000..b3c4b23 --- /dev/null +++ b/src/fake86/timing.c @@ -0,0 +1,136 @@ +/* + Fake86: A portable, open-source 8086 PC emulator. + Copyright (C)2010-2013 Mike Chambers + + This program is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License + as published by the Free Software Foundation; either version 2 + of the License, or (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. +*/ + +/* timing.c: critical functions to provide accurate timing for the + system timer interrupt, and to generate new audio output samples. */ + +#include "config.h" +#include <SDL/SDL.h> +#include <stdint.h> +#include <stdio.h> +#ifdef _WIN32 +#include <Windows.h> +LARGE_INTEGER queryperf; +#else +#include <sys/time.h> +struct timeval tv; +#endif +#include "i8253.h" +#include "blaster.h" + +extern struct blaster_s blaster; +extern struct i8253_s i8253; +extern void doirq (uint8_t irqnum); +extern void tickaudio(); +extern void tickssource(); +extern void tickadlib(); +extern void tickBlaster(); + +uint64_t hostfreq = 1000000, lasttick = 0, curtick = 0, tickgap, i8253tickgap, lasti8253tick, scanlinetiming, lastscanlinetick, curscanline = 0; +uint64_t sampleticks, lastsampletick, ssourceticks, lastssourcetick, adlibticks, lastadlibtick, lastblastertick, gensamplerate; + +uint16_t pit0counter = 65535; +extern uint64_t totalexec; +extern uint32_t speed; +extern uint8_t port3da, doaudio, slowsystem; + +void inittiming() { +#ifdef _WIN32 + QueryPerformanceFrequency (&queryperf); + hostfreq = queryperf.QuadPart; + QueryPerformanceCounter (&queryperf); + curtick = queryperf.QuadPart; +#else + hostfreq = 1000000; + gettimeofday (&tv, NULL); + curtick = (uint64_t) tv.tv_sec * (uint64_t) 1000000 + (uint64_t) tv.tv_usec; +#endif + lasti8253tick = lastblastertick = lastadlibtick = lastssourcetick = lastsampletick = lastscanlinetick = lasttick = curtick; + scanlinetiming = hostfreq / 31500; + ssourceticks = hostfreq / 8000; + adlibticks = hostfreq / 48000; + if (doaudio) sampleticks = hostfreq / gensamplerate; + else sampleticks = -1; + i8253tickgap = hostfreq / 119318; +} + +void timing() { + uint8_t i8253chan; + +#ifdef _WIN32 + QueryPerformanceCounter (&queryperf); + curtick = queryperf.QuadPart; +#else + gettimeofday (&tv, NULL); + curtick = (uint64_t) tv.tv_sec * (uint64_t) 1000000 + (uint64_t) tv.tv_usec; +#endif + + if (curtick >= (lastscanlinetick + scanlinetiming) ) { + curscanline = (curscanline + 1) % 525; + if (curscanline > 479) port3da = 8; + else port3da = 0; + if (curscanline & 1) port3da |= 1; + pit0counter++; + lastscanlinetick = curtick; + } + + if (i8253.active[0]) { //timer interrupt channel on i8253 + if (curtick >= (lasttick + tickgap) ) { + lasttick = curtick; + doirq (0); + } + } + + if (curtick >= (lasti8253tick + i8253tickgap) ) { + for (i8253chan=0; i8253chan<3; i8253chan++) { + if (i8253.active[i8253chan]) { + if (i8253.counter[i8253chan] < 10) i8253.counter[i8253chan] = i8253.chandata[i8253chan]; + i8253.counter[i8253chan] -= 10; + } + } + lasti8253tick = curtick; + } + + if (curtick >= (lastssourcetick + ssourceticks) ) { + tickssource(); + lastssourcetick = curtick - (curtick - (lastssourcetick + ssourceticks) ); + } + + if (blaster.samplerate > 0) { + if (curtick >= (lastblastertick + blaster.sampleticks) ) { + tickBlaster(); + lastblastertick = curtick - (curtick - (lastblastertick + blaster.sampleticks) ); + } + } + + if (curtick >= (lastsampletick + sampleticks) ) { + tickaudio(); + if (slowsystem) { + tickaudio(); + tickaudio(); + tickaudio(); + } + lastsampletick = curtick - (curtick - (lastsampletick + sampleticks) ); + } + + if (curtick >= (lastadlibtick + adlibticks) ) { + tickadlib(); + lastadlibtick = curtick - (curtick - (lastadlibtick + adlibticks) ); + } +} |