mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-07-02 09:29:39 +00:00
596 lines
11 KiB
C
596 lines
11 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 "gr-sim.h"
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#include "tfv_zp.h"
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static unsigned short frame;
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//int m1s[256],m2s[256];
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#if 0
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static unsigned short stack[128];
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static int sp=0;
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static unsigned short ax,bx,cx,dx,es;
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static int cf=0,of=0,zf=0,sf=0;
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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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#endif
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#if 0
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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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#endif
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/* tilted plane */
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/* DH=Y, DL=X */
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static int fx0(int xx, int yy, int xprime) {
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unsigned short scaled;
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int color;
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// 0x1329 = 4905? 200*24.5 40*24.5=981=3d5
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yy=yy+0x10;//0x29; // add dh,al ; prevent divide overflow
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scaled=((0x3d5/yy)&0xff); // div dh ; reverse divide AL=C/Y'
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color=((signed char)((xprime-20)&0xff))*((signed char)(scaled&0xff));
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scaled-=frame;
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color=(color>>6)&0xff;
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color^=(scaled&0xff);
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color&=0x1c; // map colors
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return color;
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}
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/* circles? */
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/* DH=Y, DL=X */
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static int fx1(int xx, int yy, int xprime) {
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signed short yyy,xxx;
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signed short color;
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yyy=yy-24; /* align Y vertically */
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yyy=yyy*yyy;
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color=((yyy/32)&0xff);
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/* signed 8-bit multiply */
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xxx=xprime-20;
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xxx=(char)xxx*(char)xxx;
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color+=((xxx/32)&0xff);
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color+=frame; /* offset color by time */
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// color&=0x18; /* select special rings */
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// color&=0x18; /* select special rings */
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return color;
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}
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/* checkers */
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static int fx2(int xx, int yy, int xprime) {
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int color;
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color=((yy&0xff)<<8) | (xprime&0xff);
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color=color-frame; /* adjust with frame */
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color=((color>>8)&0xff)^(color&0xff); /* xor x and y */
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color|=0xdb; /* or result with 0xdb */
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color+=0x13; /* Map to yellow/grey */
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return color;
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}
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/* parallax checkerboard */
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static int fx3(int xx,int yy,int xprime) {
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unsigned short ax,bx,cx,dx;
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int cf=0,zf=0,result;
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cx=frame; // 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+(yy*40)+xx;
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// cx=cx+(yy*320)+xx; // add cx, di ; offset by screenpointer
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// ax=819; // mov ax,819 ; magic, related to Rrrola
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// 819 * 320 = 0x3ffc0
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// 819 * 1 = 0x333
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// want Z*1 = 0x40
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// 0x333 = cccd/40 (/64)
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// 40=$28 48= $30
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// 1 = $0001
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// 39 =$0027
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// 40= $0100 6.4
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// 65536/40 = 1638.4 / 40 =
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// 28f5
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ax=0x28f5;
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result=ax*cx;
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// ax=result&0xffff;
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//dx=(result>>16);
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dx=(result>>24);
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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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return ax;
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}
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/* sierpinski rotozoomer */
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static int fx4(int xx, int yy, int xprime) {
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unsigned char dh,bh;
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unsigned short color,t,xsext;
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int temp;
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t=frame-2048; // lea cx,[bp-2048] ; center time to pass zero
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t=t<<3; // sal cx,3 ; speed up by factor of 8!
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yy*=4;
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/* sign extend X */
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xsext=xprime*8; // get X into DL
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if (xsext&0x80*8) xsext|=0xff00*8;
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else xsext&=0x00ff*8;
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temp=yy*t; // temp=Y*T
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bh=(temp>>8)+xsext; // bh=((y*t)/256)+X
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temp=xsext*t; // temp=X*T
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dh=(temp>>8)&0xff; // dh=(X*T/256)
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color=(yy-dh)&bh; // color=(Y-(X*T/256))&(Y*T/256+X)
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// and al,252 ; thicker sierpinksi
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if ((color&252)==0) {
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color=0x9; // otherwise: a nice orange
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}
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else {
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color=0; // leave black if not sierpinksi
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}
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return color;
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}
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/* raycast bent tunnel */
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static int fx5(int xx, int yy, int xprime) {
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unsigned short xcoord,ycoord;
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signed short yproj,xproj;
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signed char depth;
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int zf=0;
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signed char m1,m2,color,al;
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/* adjust to be centered */
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xcoord=(xprime-10)*4;
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ycoord=(yy-10)*4;
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/* set depth to -9 (move backwards) */
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depth=-9;
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fx5L:
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/* put Ycoord into AL */
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al=ycoord&0xff;
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/* center Y. Necessary? */
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al-=24;
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/* 8x8 signed multiply Ycoord*depth to get projection */
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m1=al; //m1s[m1&0xff]++;
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m2=depth; //m2s[m2&0xff]++;
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yproj=m1*m2;
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// printf("%d %d = %x\n",m1,m2,yproj);
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/* only top used? */
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/* Get X paramater */
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al=xcoord;
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/* add distance to projection (bend right) */
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al+=depth&0xff;
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/* 8x8 signed multiply Ycoord*depth to get projection */
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m1=al; //m1s[m1&0xff]++;
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m2=depth; //m2s[m2&0xff]++;
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xproj=m1*m2;
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// printf("%d %d = %x\n",m1,m2,xproj);
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depth--;
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if (depth==0) goto putpixel;
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al=(yproj>>8)&0xff;// mov al,dh ; get projection(1) in AL
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al^=(xproj>>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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if (zf==1) goto fx5L;
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putpixel:
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// if ((depth!=0) && (zf==1)) goto fx5L;
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color=al;
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// loopz fx5L (repeat until "hit" or "iter=max"
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depth=depth-frame; // sub cx,bp ; offset depth by time
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color^=depth; // xor al,cl ; XOR pattern for texture
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color&=0x7;
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/* aam 6 ; irregular pattern with MOD 6 */
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/* add al,20 ; offset into grayscale pattern */
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//color+=20;
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return color;
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}
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/* ocean night */
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static int fx6(int xx, int yy, int xprime) {
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return 0;
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}
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#if 0
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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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dx=((yy&0xff)<<8) | (xprime&0xff);
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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+=frame; // 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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return ax;
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}
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#endif
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int main(int argc, char **argv) {
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int color=0,which,xx,yy,xprime;
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int ch;
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// int i;
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// for(i=0;i<256;i++) { m1s[i]=0; m2s[i]=0;}
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grsim_init();
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gr();
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clear_screens();
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ram[DRAW_PAGE]=0;
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// frame=0x13;
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frame=3*512;
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while(1) {
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for(yy=0;yy<48;yy++) {
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for(xx=0;xx<40;xx++) {
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// xprime=xx*256/320;
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xprime=xx;
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/* rrolla multiply by 0xcccd trick */
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which=frame/512;
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switch (which&0xff) {
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case 0: color=fx2(xx,yy,xprime); break;
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case 1: color=fx1(xx,yy,xprime); break;
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case 2: color=fx0(xx,yy,xprime); break;
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case 3: color=fx3(xx,yy,xprime); break;
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case 4: color=fx4(xx,yy,xprime); break;
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case 5: color=fx5(xx,yy,xprime); break;
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case 6: color=fx6(xx,yy,xprime); break;
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case 7: return 0;
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default: printf("Trying effect %d\n",which);
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}
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color_equals(color&0xf);
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plot(xx,yy);
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// printf("plot %d,%d = %d\n",xx,yy,color&0xf);
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// write_framebuffer((es<<4)+((yy*320)+xx), color);
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/* 320*200=64000; / 3 = 21,333R1 */
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/* 65536 / 3 = 21845 R 1 */
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/* so wraps 3 times before updating screen? */
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}
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}
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if (frame%128==0) {
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printf("frame: %d\n",frame);
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// printf("m1: ");
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// for(i=0;i<256;i++) printf("%d ",m1s[i]);
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// printf("\n");
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// printf("m2: ");
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// for(i=0;i<256;i++) printf("%d ",m2s[i]);
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// printf("\n");
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}
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grsim_update();
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usleep(30000);
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frame++;
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ch=grsim_input();
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if (ch=='q') return 0;
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if (ch==27) return 0;
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}
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return 0;
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|
}
|