mirror of https://github.com/nmlgc/ReC98.git
98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
/* ReC98 Research
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* --------------
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* PC-98 keyboard key hold behavior test
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*/
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#pragma option -ms
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#include "../libs/master.lib/master.h"
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#if defined(__TURBOC__) && defined(__MSDOS__)
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// Remove C++ exception handler bloat on Borland compilers
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// (see https://community.embarcadero.com/article/technical-articles/162/14700)
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void _ExceptInit(void)
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{
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}
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#endif
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// Should cover the number of possible input states within a frame
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// ⌈(19200 baud / 11 bit) / 56.4 fps⌉ ≈ 31, but let's rather be extra safe...
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#define STATES_MAX 64
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void hr(int len)
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{
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int i;
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dos_puts("\r\n");
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for(i = 0; i < len; i++) {
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dos_puts("\x86\x44");
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}
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dos_puts("\r\n");
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}
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void frame(void)
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{
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char states[STATES_MAX];
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char state_prev = 0;
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unsigned int states_recorded = 0;
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unsigned int i = 0;
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int flipped = 0;
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vsync_Count1 = 0;
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do {
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int delayloop = 1024;
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unsigned char input = *(volatile unsigned char far*)(0x531);
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states[states_recorded++] = (input >> 2) & 0xF;
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while(delayloop && vsync_Count1 < 1) {
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__asm out 0x5F, AL;
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delayloop--;
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}
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} while(vsync_Count1 < 1);
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dos_puts("\r \r");
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for(i = 0; i < states_recorded; i++) {
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char state = states[i];
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if(state_prev != state && i > 0) {
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flipped++;
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dos_puts("\x1B[17m");
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} else {
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dos_puts("\x1B[0m");
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}
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dos_putch((state < 10) ? ('0' + state) : ('A' - 10 + state));
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dos_putch(' ');
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state_prev = state;
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}
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if(flipped >= 2) {
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dos_puts("\r\n");
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}
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}
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void main(void)
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{
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vsync_start();
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hr(79);
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dos_puts(
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"Hold any of the cursor keys. The line below will show all states of the cursor\r\n"
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"keys, read using the keyboard state memory bitmap at 0x52A (which is also how\r\n"
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"TH02 and later read input), within a single frame.\r\n"
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"The 0.6ms delay between the states roughly matches the keyboard UART delay.\r\n"
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"\r\n"
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"After the typematic delay, you might see the occasional wrong state popping up.\r\n"
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"This will be highlighted in\x1B[17m red \x1B[0mand kept on screen when it happens.\r\n"
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"Unlike on IBM PC/XT/AT where holding a key repeats only the down scancode,\r\r\n"
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"PC-98 keyboards repeat up AND down scancodes, leading to these state flips.\r\n"
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"So, polling the keyboard twice within a frame, ~0.6ms apart, is indeed a good\r\n"
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"idea for a game engine, which is why ZUN chose to do it from TH03 onwards.\r\n"
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"\r\n"
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"Hold Q to quit."
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);
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hr(79);
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while(!(*(volatile char far*)(0x52C) & 0x01)) {
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frame();
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}
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hr(79);
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vsync_end();
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}
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