mirror of
https://github.com/deater/dos33fsprogs.git
synced 2025-01-24 18:30:00 +00:00
121 lines
2.3 KiB
C
121 lines
2.3 KiB
C
/* Hellmood's Autumn demo */
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/* trying to convert it to C because he says it's straightforward */
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#include <stdio.h>
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static short ax=0,bx=0,cx=0,dx=0,di=0,sp=0;
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static short stack[64];
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static int cf=0,newcf,ebp=0;
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static signed char ah,al;
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static void push(short 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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sp--;
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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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return stack[sp];
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}
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static int debug=0;
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int main(int argc, char **argv) {
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/* init graphics */
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/*start:
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mov $0x4f02,%ax ; set super VGA mode
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mov $0x107,%bx ; 1280x1024, 256 colors
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int $0x10 ; set the mode
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*/
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ax=0x004f; /* return value on success */
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label_108:
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if (debug) printf("=================================L108====\n");
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if (debug) printf("AX=%04x BX=%04x CX=%04x DX=%04x DI=%04x BP=%x\n",
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ax,bx,cx,dx,di,ebp);
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if (debug) printf("=========================================\n");
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ax=ax<<1; // shl %ax
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push(cx); // push %cx
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cx=cx-dx; // sub %dx,%cx
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if (cx&0x8000) {
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cx=cx>>1;
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cx|=0x8000;
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}
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else {
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cx=cx>>1;
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}
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// sar %cx
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di=pop(); // pop %di
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dx=dx+di; // add %di,%dx
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cf=dx&0x1;
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if (dx&0x8000) {
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dx=dx>>1;
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dx|=0x8000;
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}
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else {
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dx=dx>>1;
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}
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// sar %dx
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newcf=ebp&1;
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ebp=ebp>>1;
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if (cf) {
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ebp|=0x80000000;
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}
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else {
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ebp&=~0x80000000;
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}
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cf=newcf; // rcr %ebp
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if (cf) goto label_11f; // jump if carry=1 jb 0x11f
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ax++; // inc %ax
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cx+=0x080; // add $0x3,%ch
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// 0x300 == 1024
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// 0x200 == 600
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// 0x100 == ??
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// 0x080 == 200
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dx=-dx; // neg %dx
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label_11f:
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al=ax&0xff;
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ah=(ax&0xff)/0x29;
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al=(ax&0xff)%0x29; // aam $0x29
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ax=(ah<<8)|(al&0xff);
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al=al&0xfc; // and $0xfc,%al
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al=al^0x12; // xor $0x12,%al
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ax=(ah<<8)|(al&0xff);
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if ((dx&0x8000)!=0) goto label_108;
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// test $0x80,%dh
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// jmp if zf==0 jne 0x108
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if ((cx&0xf000)!=0) goto label_108;
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// test $0xf0,%ch
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// jmp if zf==0 jne 0x108
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//put_pixel:
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push(ax); // push %ax
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printf("Putpixel (%d) %d,%d = %d\n",bx>>8,cx,dx,ax&0xf);
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// and $0xf,%al ; al = color
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// mov $0xc,%ah ; ah = 0xc = putpixel
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// int $0x10 ; bh=page number, cx=x,dx=y
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ax=pop(); // pop %ax
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#if 0
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check_keyboard:
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mov $0x1,%ah
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int $0x16
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#endif
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//ax=0;
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goto label_108; // je 0x108
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}
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