mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-12-28 09:30:41 +00:00
769 lines
16 KiB
C
769 lines
16 KiB
C
/* A Linux/SDL/C version of Hellmood's amazing 256B DOS Memories Demo */
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/* See http://www.sizecoding.org/wiki/Memories for a rundown on how it works */
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/* This is a conversion to C I did in an attempt to see how it works */
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/* and also to see if I could port any of this to the Apple II */
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/* x86 has amazing code density with powerful instructions */
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/* stos, mul, div, FPU, lots of 1-byte instructions */
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/* and old x86 hardware made it really easy to program with limited code */
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/* VGA/MCGA Mode13h (320x200 256 colors linear framebuffer) */
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/* soundblaster MIDI with only a few out instructions */
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/* Anyway this is a rough attempt to getting things going in C */
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/* The last effect (ocean) is doing lots of sketchy stuff and */
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/* depending a bit on undefined behavior so it's hit or miss */
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/* whether it will work for you */
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/* deater -- Vince Weaver -- vince@deater.net -- 23 April 2020 */
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#include <stdio.h>
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#include <unistd.h>
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#include <SDL.h>
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static unsigned short stack[128];
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static unsigned short ax,bx,cx,dx,di,bp,es;
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static int cf=0,of=0,zf=0,sf=0;
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static int sp=0;
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static unsigned char framebuffer[320*200];
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static SDL_Surface *sdl_screen=NULL;
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struct palette {
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unsigned char red[256];
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unsigned char green[256];
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unsigned char blue[256];
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};
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static struct palette pal;
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static int mode13h_graphics_init(void) {
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int mode;
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mode=SDL_SWSURFACE|SDL_HWPALETTE|SDL_HWSURFACE;
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if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
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fprintf(stderr,
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"Couldn't initialize SDL: %s\n", SDL_GetError());
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return -1;
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}
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/* Clean up on exit */
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atexit(SDL_Quit);
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/* assume 32-bit color */
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sdl_screen = SDL_SetVideoMode(320, 200, 32, mode);
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if ( sdl_screen == NULL ) {
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fprintf(stderr, "ERROR! Couldn't set 320x200 video mode: %s\n",
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SDL_GetError());
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return -1;
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}
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SDL_EnableKeyRepeat(SDL_DEFAULT_REPEAT_DELAY, SDL_DEFAULT_REPEAT_INTERVAL);
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SDL_WM_SetCaption("memories -- Linux/C/SDL","memories");
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return 0;
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}
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static int mode13h_graphics_update(unsigned char *buffer, struct palette *pal) {
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unsigned int *t_pointer;
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int x,temp;
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/* point to SDL output pixels */
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t_pointer=((Uint32 *)sdl_screen->pixels);
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for(x=0;x<320*200;x++) {
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temp=(pal->red[buffer[x]]<<16)|
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(pal->green[buffer[x]]<<8)|
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(pal->blue[buffer[x]]<<0)|0;
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t_pointer[x]=temp;
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}
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SDL_UpdateRect(sdl_screen, 0, 0, 320, 200);
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return 0;
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}
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static void set_vga_pal(void) {
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/* output of vgapal https://github.com/canidlogic/vgapal */
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unsigned char raw_pal[3*256]=
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{ 0, 0, 0, 0, 0, 170, 0, 170, 0, 0, 170, 170,
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170, 0, 0, 170, 0, 170, 170, 85, 0, 170, 170, 170,
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85, 85, 85, 85, 85, 255, 85, 255, 85, 85, 255, 255,
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255, 85, 85, 255, 85, 255, 255, 255, 85, 255, 255, 255,
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0, 0, 0, 20, 20, 20, 32, 32, 32, 44, 44, 44,
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56, 56, 56, 69, 69, 69, 81, 81, 81, 97, 97, 97,
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113, 113, 113, 130, 130, 130, 146, 146, 146, 162, 162, 162,
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182, 182, 182, 203, 203, 203, 227, 227, 227, 255, 255, 255,
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0, 0, 255, 65, 0, 255, 125, 0, 255, 190, 0, 255,
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255, 0, 255, 255, 0, 190, 255, 0, 125, 255, 0, 65,
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255, 0, 0, 255, 65, 0, 255, 125, 0, 255, 190, 0,
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255, 255, 0, 190, 255, 0, 125, 255, 0, 65, 255, 0,
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0, 255, 0, 0, 255, 65, 0, 255, 125, 0, 255, 190,
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0, 255, 255, 0, 190, 255, 0, 125, 255, 0, 65, 255,
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125, 125, 255, 158, 125, 255, 190, 125, 255, 223, 125, 255,
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255, 125, 255, 255, 125, 223, 255, 125, 190, 255, 125, 158,
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255, 125, 125, 255, 158, 125, 255, 190, 125, 255, 223, 125,
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255, 255, 125, 223, 255, 125, 190, 255, 125, 158, 255, 125,
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125, 255, 125, 125, 255, 158, 125, 255, 190, 125, 255, 223,
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125, 255, 255, 125, 223, 255, 125, 190, 255, 125, 158, 255,
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182, 182, 255, 199, 182, 255, 219, 182, 255, 235, 182, 255,
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255, 182, 255, 255, 182, 235, 255, 182, 219, 255, 182, 199,
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255, 182, 182, 255, 199, 182, 255, 219, 182, 255, 235, 182,
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255, 255, 182, 235, 255, 182, 219, 255, 182, 199, 255, 182,
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182, 255, 182, 182, 255, 199, 182, 255, 219, 182, 255, 235,
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182, 255, 255, 182, 235, 255, 182, 219, 255, 182, 199, 255,
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0, 0, 113, 28, 0, 113, 56, 0, 113, 85, 0, 113,
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113, 0, 113, 113, 0, 85, 113, 0, 56, 113, 0, 28,
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113, 0, 0, 113, 28, 0, 113, 56, 0, 113, 85, 0,
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113, 113, 0, 85, 113, 0, 56, 113, 0, 28, 113, 0,
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0, 113, 0, 0, 113, 28, 0, 113, 56, 0, 113, 85,
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0, 113, 113, 0, 85, 113, 0, 56, 113, 0, 28, 113,
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56, 56, 113, 69, 56, 113, 85, 56, 113, 97, 56, 113,
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113, 56, 113, 113, 56, 97, 113, 56, 85, 113, 56, 69,
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113, 56, 56, 113, 69, 56, 113, 85, 56, 113, 97, 56,
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113, 113, 56, 97, 113, 56, 85, 113, 56, 69, 113, 56,
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56, 113, 56, 56, 113, 69, 56, 113, 85, 56, 113, 97,
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56, 113, 113, 56, 97, 113, 56, 85, 113, 56, 69, 113,
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81, 81, 113, 89, 81, 113, 97, 81, 113, 105, 81, 113,
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113, 81, 113, 113, 81, 105, 113, 81, 97, 113, 81, 89,
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113, 81, 81, 113, 89, 81, 113, 97, 81, 113, 105, 81,
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113, 113, 81, 105, 113, 81, 97, 113, 81, 89, 113, 81,
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81, 113, 81, 81, 113, 89, 81, 113, 97, 81, 113, 105,
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81, 113, 113, 81, 105, 113, 81, 97, 113, 81, 89, 113,
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0, 0, 65, 16, 0, 65, 32, 0, 65, 48, 0, 65,
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65, 0, 65, 65, 0, 48, 65, 0, 32, 65, 0, 16,
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65, 0, 0, 65, 16, 0, 65, 32, 0, 65, 48, 0,
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65, 65, 0, 48, 65, 0, 32, 65, 0, 16, 65, 0,
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0, 65, 0, 0, 65, 16, 0, 65, 32, 0, 65, 48,
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0, 65, 65, 0, 48, 65, 0, 32, 65, 0, 16, 65,
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32, 32, 65, 40, 32, 65, 48, 32, 65, 56, 32, 65,
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65, 32, 65, 65, 32, 56, 65, 32, 48, 65, 32, 40,
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65, 32, 32, 65, 40, 32, 65, 48, 32, 65, 56, 32,
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65, 65, 32, 56, 65, 32, 48, 65, 32, 40, 65, 32,
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32, 65, 32, 32, 65, 40, 32, 65, 48, 32, 65, 56,
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32, 65, 65, 32, 56, 65, 32, 48, 65, 32, 40, 65,
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44, 44, 65, 48, 44, 65, 52, 44, 65, 60, 44, 65,
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65, 44, 65, 65, 44, 60, 65, 44, 52, 65, 44, 48,
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65, 44, 44, 65, 48, 44, 65, 52, 44, 65, 60, 44,
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65, 65, 44, 60, 65, 44, 52, 65, 44, 48, 65, 44,
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44, 65, 44, 44, 65, 48, 44, 65, 52, 44, 65, 60,
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44, 65, 65, 44, 60, 65, 44, 52, 65, 44, 48, 65,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
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};
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int i;
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for(i=0;i<256;i++) {
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pal.red[i]=raw_pal[i*3];
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pal.green[i]=raw_pal[(i*3)+1];
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pal.blue[i]=raw_pal[(i*3)+2];
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}
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return;
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}
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static int graphics_input(void) {
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SDL_Event event;
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int keypressed;
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while ( SDL_PollEvent(&event)) {
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switch(event.type) {
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case SDL_KEYDOWN:
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keypressed=event.key.keysym.sym;
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switch (keypressed) {
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case SDLK_ESCAPE:
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return 27;
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}
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break;
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}
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}
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return 0;
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}
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static void write_framebuffer(int address, int value) {
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int real_addr;
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real_addr=address-0xa0000;
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if ((real_addr<0) || (real_addr>320*200)) return;
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framebuffer[real_addr]=value;
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}
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/* unsigned multiply */
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static void mul_16(unsigned short value) {
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unsigned int result;
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result=ax*value;
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// printf("%x*%x=%x ",value,ax,result);
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ax=result&0xffff;
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dx=result>>16;
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// printf("%x:%x x=%d y=%d\n",dx,ax,
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// dx&0xff,(dx>>8)&0xff);
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if (dx==0) {
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of=0;
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cf=0;
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}
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else {
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of=1;
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cf=1;
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}
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}
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/*
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static void imul(short value) {
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int result;
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result=ax*value;
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ax=result&0xffff;
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dx=result>>16;
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}
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*/
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/* signed multiply */
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static void imul_8(char value) {
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short result;
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char src;
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src=ax;
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result=src*value;
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// printf("imul: %d*%d=%d ",src,value,result);
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ax=result;
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if (ax==(ax&0xff)) {
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cf=0;
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of=0;
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}
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else {
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cf=1;
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of=1;
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}
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}
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/* signed multiply */
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static void imul_16(short value) {
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int result;
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short src;
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src=ax;
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result=src*value;
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// printf("imul: %d*%d=%d ",src,value,result);
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ax=(result&0xffff);
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dx=((result>>16)&0xffff);
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if (dx==0) {
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cf=0;
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of=0;
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}
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else {
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cf=1;
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of=1;
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}
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}
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/* signed multiply */
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static void imul_16_bx(short value) {
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int result;
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short src;
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src=bx;
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result=src*value;
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// printf("imul: %d*%d=%d ",src,value,result);
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bx=(result&0xffff);
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if (bx==result) {
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cf=0;
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of=0;
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}
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else {
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cf=1;
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of=1;
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}
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}
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/* signed multiply */
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static void imul_16_dx(short value) {
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int result;
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short src;
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src=dx;
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result=src*value;
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// printf("imul: %d*%d=%d ",src,value,result);
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dx=(result&0xffff);
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if (dx==result) {
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cf=0;
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of=0;
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}
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else {
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cf=1;
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of=1;
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}
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}
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/* unsigned divide */
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static void div_8(unsigned char value) {
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unsigned char r,q;
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unsigned int result,remainder;
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// printf("Dividing %d (%x) by %d (%x): ",ax,ax,value,value);
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if (value==0) {
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printf("Divide by zero!\n");
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return;
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}
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result=ax/value;
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remainder=ax%value;
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q=result;
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r=remainder;
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// printf("Result: q=%d r=%d\n",q,r);
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ax=(r<<8)|(q&0xff);
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}
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static void push(int value) {
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//printf("Pushing %x\n",value);
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stack[sp]=value;
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sp++;
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}
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static short pop(void) {
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if (sp==0) {
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printf("Stack underflow!\n");
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return 0;
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}
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sp--;
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//printf("Popping %x\n",stack[sp]);
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return stack[sp];
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}
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/* tilted plane */
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/* DH=Y, DL=X */
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static void fx0(void) {
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char ah,al,dh,dl;
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unsigned short temp;
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ax=0x1329; // mov ax,0x1329 init
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al=ax&0xff; ah=(ax>>8)&0xff;
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dl=dx&0xff; dh=(dx>>8)&0xff;
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dh=dh+al; // add dh,al ; prevent divide overflow
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div_8(dh); // div dh ; reverse divide AL=C/Y'
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dx=((dh&0xff)<<8)|dl;
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temp=ax;
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ax=dx; dx=temp; // xchg dx,ax ; DL=C/Y' AL=X
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dl=dx&0xff; dh=(dx>>8)&0xff;
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imul_8(dl); // imul dl
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dx=dx-bp; // sub dx,bp
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dl=dx&0xff;
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ah=(ax>>8)&0xff;
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ah=ah^dl; // xor ah,dl
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al=ah; // mov al,ah
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ax=((ah&0xff)<<8)|(al&0xff);
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ax&=0xff1c; // and al,4+8+16
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}
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/* circles? */
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/* DH=Y, DL=X */
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static void fx1(void) {
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int temp;
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char al,dh,ah;
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// mov al,dh ; get Y in AL
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al=(dx>>8)&0xff;
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// sub al,100 ; align Y vertically
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al=al-100;
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ax=ax&0xff00;
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ax=ax|al;
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// imul al ; AL=Y*Y
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imul_8(al);
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// xchg dx,ax ; Y*Y/256 in DH, X in AL
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temp=ax;
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ax=dx;
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dx=temp;
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// imul al ; AL=X*X
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imul_8(ax&0xff);
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// add dh,ah ; DH=X*X+Y*Y/256
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dh=(dx>>8)&0xff;
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ah=(ax>>8)&0xff;
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dh=dh+ah;
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// mov al,dh ; AL = X*X+Y*Y/256
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al=dh;
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dx=dx&0xff;
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dx|=(dh<<8);
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ax=(ah<<8)|(al&0xff);
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// add ax,bp ; offset color by time
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ax=ax+bp;
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// and al,8+16 ; select special rings
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ax=ax&0x18;
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}
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/* checkers */
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static void fx2(void) {
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int temp;
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unsigned char al;
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temp=ax;
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ax=dx; dx=temp; // xchg dx,ax
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ax=ax-bp; // sub ax,bp
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temp=((ax>>8)&0xff)^(ax&0xff);
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ax=ax&0xff00;
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ax|=temp; // xor al,ah
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ax|=0xdb; // or al,0xdb
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al=ax&0xff;
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al=al+0x13;
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ax=ax&0xff00;
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ax=ax|al; // add al,13h
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// ret
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}
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/* parallax checkrboard */
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static void fx3(void) {
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cx=bp; // mov cx,bp ; set init point to time
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bx=-16; // mov bx,-16 ; limit to 16 iterations
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fx3L:
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cx=cx+di; // add cx, di ; offset by screenpointer
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ax=819; // mov ax,819 ; magic, related to Rrrola
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imul_16(cx); // imul cx ; get X',Y' in DX
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cf=dx&1; // ror dx,1 ; set carry flag on "hit"
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dx=dx>>1;
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if (cf) {
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dx|=0x8000;
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}
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else {
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dx&=0x7fff;
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}
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bx++; // inc bx ; increment iteration count
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if (bx==0) zf=1;// does not affect carry flag
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else zf=0;
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// ja fx3L ; loop until "hit" or "iter=max"
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// jump above, if cf==0 and zf==0
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if ((cf==0) && (zf==0)) goto fx3L;
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ax=bx+31; // lea ax,[bx+32] ; map value to standard gray scale
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//printf("%d %d\n",ax,bx);
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}
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/* sierpinski rotozoomer */
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static void fx4(void) {
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unsigned char dl,dh,bh,al;
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dl=dx&0xff; dh=(dx>>8)&0xff;
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cx=bp-2048; // lea cx,[bp-2048] ; center time to pass zero
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cx=cx<<3; // sal cx,3 ; speed up by factor of 8!
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ax=(dh&0xff); // movzx ax,dh ; get X into AL
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// movsx dx,dl ; get Y into DL
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if (dl&0x80) {
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dx|=0xff00;
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}
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else {
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dx&=0x00ff;
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}
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bx=ax; // mov bx,ax ; save X in BX
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imul_16_bx(cx); // imul bx,cx ; BX=X*T
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/* bl=bx&0xff; */ bh=(bx>>8)&0xff;
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dl=dx&0xff; dh=(dx>>8)&0xff;
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bh=bh+dl; // add bh,dl ; bh=x*t/256+Y
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imul_16_dx(cx); // imul dx,cx ; dx=Y*T
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dl=dx&0xff; dh=(dx>>8)&0xff;
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// sub al,dh ; al=X-Y*T/256
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al=ax&0xff; // ah=(ax>>8)&0xff;
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al=al-dh;
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// and al,bh ; AL=(X-Y*T/256)&(x*T/256+Y)
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al=al&bh;
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al=al&252; // and al,252 ; thicker sierpinksi
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if (al==0) zf=1;
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else zf=0;
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cf=0; of=0;
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// salc ; set pixel value to black
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if (cf==0) al=0;
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else al=0xff;
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/* NOTE: remove the line below and the background becomes a rainbow */
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ax=al;
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// jnz fx4q ; leave black if not sierpinksi
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if (zf==0) goto fx4q;
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ax=ax&0xff00; // mov al,0x2a ; otherwise: a nice orange
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ax|=0x2a;
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fx4q:
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;
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}
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/* raycast bent tunnel */
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static void fx5(void) {
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unsigned char al,cl;
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unsigned short temp;
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cx=cx&0xff00;
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cx|=(-9&0xff); // mov cl,-9 ; start with depth 9 (moves backwards)
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fx5L:
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cl=cx&0xff;
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push(dx); // push dx ; save DX, destroyed inside loop
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al=(dx>>8)&0xff;// mov al,dh ; get Y into AL
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al-=100; // sub al,100 ; centering Y manually
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ax=ax&0xff00;
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ax|=(al&0xff);
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imul_8(cl); // imul cl ; multiply AL=Y by current distance to get projection
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// xchg ax,dx ; gt X into AL while saving DX
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temp=ax;
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ax=dx;
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dx=temp;
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al=ax&0xff;
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al+=cl; // add al,cl ; add distance to projection (bend right)
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ax=ax&0xff00;
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ax|=(al&0xff);
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imul_8(cl); // imul cl ; multiply AL=X by the current projection
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al=(dx>>8)&0xff;// mov al,dh ; get projection(1) in AL
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al^=(ax>>8); // xor al,ah ; combine with projection(2)
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al+=4; // add al,4 ; center the walls around 0
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if (al&-8) { // test al,-8 ; test if the wall is hit
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zf=0;
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}
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else {
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zf=1;
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}
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dx=pop(); // pop dx (restore dx)
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cx&=0xff00;
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cx|=(cl&0xff);
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cx--;
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if ((cx!=0) && (zf==1)) goto fx5L;
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// loopz fx5L (repeat until "hit" or "iter=max"
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cx=cx-bp; // sub cx,bp ; offset depth by time
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al^=(cx&0xff); // xor al,cl ; XOR pattern for texture
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// ah=al/6;
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al=al%6; // aam 6 ; irregular pattern with MOD 6
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al+=20; // add al,20 ; offset into grayscale pattern
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ax=al&0xff;
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}
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/* ocean night */
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static void fx6(void) {
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char dh;
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double f;
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int edx;
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char scratch[64];
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// bx coming in is the address of the effect
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// this is a guess, too lazy to hexdump
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bx=0x1d5;
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// si=?? based on sound playing?
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// ax (sky color) is ?
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dh=dx>>8;
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// sub dh,120 ; check if pixel in the sky
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dh=dh-120;
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sf=!!(dh&0x80);
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// js fx6q ; quit if that's the case
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if (sf) goto fx6q;
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dx&=0xff;
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dx|=dh<<8;
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// mov [bx+si],dx ; move xy to memory location
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// fild word [bx+si] ; read as integer
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// fidivr dword [bx+si] ; reverse divide by constant
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// Divide m32int by ST(0) and store result in ST(0)
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// fstp dword [bx+si-1] ; store result as floating point
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// mov ax,[bx+si] ; get result into ax
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memcpy(&scratch[32],&dx,sizeof(short));
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f=dx;
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memcpy(&edx,&scratch[32],sizeof(int));
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f=f/edx;
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memcpy(&scratch[31],&f,sizeof(double));
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memcpy(&ax,&scratch[32],sizeof(short));
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ax+=bp; // add ax,bp ; modify color by time
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ax&=0xff80; // and al,128 ; threshold into two bands
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ax--; // dec ax ; beautify colors to blue/black
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fx6q: ;
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}
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int main(int argc, char **argv) {
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int temp;
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set_vga_pal();
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mode13h_graphics_init();
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di=0; // ??
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ax=0x13; // mov al,0x13
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// int 0x10 ; set 320x200x256 color mode
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bp=ax; // xchg bp,ax ; set bp to 0x13
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push(0xa000-10); // write screen address to es
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es=pop(); // pop es
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ax=0x251c; // mov ax,0x251c param for timer interrupt
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dx=0xdead; // mov dl, timer set up timer interrupt
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// int 0x21
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top:
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ax=0xcccd; // load rrrola constant
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mul_16(di); // multiply
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temp=(ax&0xff)+((ax>>8)&0xff); // add al,ah
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ax=ax&0xff00;
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ax|=(temp&0xff);
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ax=ax&0xff; // xor ah,ah
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ax=ax+bp; // add ax,bp
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ax=ax>>9; // shr ax,9
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ax=ax&0xff0f; // and al,15
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temp=ax; // xchg bx,ax
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ax=bx;
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bx=temp;
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bx=bx&0xff; // mov bh,1
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bx|=1<<8;
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// printf("%x: bx\n",bx);
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// mov bl,[byte bx+table]
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// call bx
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switch (bx&0xff) {
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case 0: fx2(); break;
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case 1: fx1(); break;
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case 2: fx0(); break;
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case 3: fx3(); break;
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case 4: fx4(); break;
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case 5: fx5(); break;
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case 6: fx6(); break;
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case 7: goto end;
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default: printf("Trying effect %d\n",bx&0xff);
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}
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// stosb
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write_framebuffer((es<<4)+di, ax&0xff);
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di++;
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// printf("Writing %d to %x (%x:%x)\n",ax&0xff,(es<<4)+di,es,di);
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di++; // inc di
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di++; // inc di
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if (di!=0) goto top;
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// printf("Done frame\n");
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mode13h_graphics_update(framebuffer,&pal);
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// timer emulate
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usleep(10000);
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bp=bp+1;
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// mov al,tempo
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// out 40h,al (set timing?)
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// in al,0x60 read keyboad
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// dec al
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if (graphics_input()) {
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return 0;
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}
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|
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// jnz top
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goto top;
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end:
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return 0;
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}
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