FIRE.C

FIRE.C

/**
 * Turbo C implementation of https://gist.github.com/specht/7c3fd49400643d923c66de88a272f5e5
 */

#include <conio.h>
#include <math.h>
#include <stdlib.h>
#include "vga.h"

void fire(int x1, int y1, int x2, int y2) {
  int x, y, z;
  
  for (y = y1; y <= y2; y++) {
    for (x = x1; x <= x2; x++) {
      z = getPixel(x, y + 1) * 2 +
          getPixel(x + 1, y) +
          getPixel(x - 1, y);
      z = (int)floor(z / 4);
      
      // Add random noise
      if (z > 0) z = z + random(7) - 3;
      // Clipping
      if (z < 0) z = 0;
      if (z > 63) z = 63;
      setPixel(x, y, z);
    }
  }
}

void main() {
  int i = 0;
  int heat = 10;
  char quit = 0;
  char c;
  
  setMode(0x13);
  clear();
  
  for (i = 0; i <= 15; i++) {
    setPalette(i, i * 2, 0, 0);
    setPalette(i + 16, (i + 16) * 2, 0, 0);
    setPalette(i + 32, 63, i * 4, 0);
    setPalette(i + 48, 63, 63, i * 4);
  }
  
  do {
    drawLine(80, 199, 240, 199, heat);
    fire(75, 100, 245, 198);
    
    if (kbhit()) {
      c = getch();
      if (c == 27) quit = 1;
      if (c == '-' && heat > 0) heat--;
      if (c == '+' && heat < 63) heat++;
      if (c >= '0' && c <= '9') heat = (c - '0') * 7;
    }
  } while quit == 0;
  setMode(3);
}

Instructions

In order for this to compile properly, you need to have all 3 files in the same directory.

In Turbo C, under Project, select "Open Project"
Type in a name like "FIRE.PRJ" and hit OK
Go back to the Project menu and select "Add Item..."
In the name box, type "*.C"
In the files box, select both FIRE.C and VGA.C and hit "Add"
Once both files are included, hit "Done"

Hit Ctrl-F9 and off you go!

VGA.C

#include "vga.h"

void setMode(int mode) {
  asm {
    mov ax, mode
    int 0x10
  }
}

void clear() {
  asm {
    push 0xA000
    pop es
    xor di, di
    mov cx, 16000
    db 0x66
    xor ax, ax
    db 0x66
    rep stosw
  }
}

void setPixel(int x, int y, char color) {
  asm {
    mov di, y
    mov bx, di
    shl di, 6
    shl bx, 8
    add di, bx
    add di, x
    mov al, color
    push 0xA000
    pop es
    stosb
  }
}

char getPixel(int x, int y) {
  asm {
    mov di, y
    mob bx, di
    shl di, 6
    shl bx, 8
    add di, bx
    add di, x
    push 0xA000
    pop es
    mov al, es:[di]
  }
  return (_AL);
}

void setPalette(char num, char r, char g, char b) {
  asm {
    mov dx, 0x3C8
    mov al, num
    out dx, al
    cli
    mov dx, 0x3C9
    mov al, r
    out dx, al
    mov al, g
    out dx, al
    mov al, b
    out dx, al
    sti
  }
}

void swap(int *x, int *y) {
  int t = *x;
  *x = *y;
  *y = t;
}

void drawLine(int x1, int y1, int x2, int y2, char col) {
  int dx, dy, dab, inca, incb, x, y, h1, h2;
  
  if (x1 == x2 && y1 == y1) {
    setPixel(x1, y1, col);
  }
  else {
    if (x1 > x2) {
      swap(&x1, &x2);
      swap(&y1, &y2);
    }
    dx = x2 - x1;
    dy = y2 - y1;
    h1 = dx;
    h2 = dy;
    
    if (dx < -dy && dy < 0) {
      y1 = -y1;
      y2 = -y2;
      swap(&x1, &y1);
      swap(&x2, &y2);
    }
    
    if (dx >= -dy && dy < 0) {
      y1 = -y1;
      y2 = -y2;
    }
    
    if (dx <= dy && dy > 0) {
      swap(&x1, &y1);
      swap(&x2, &y2);
    }
    
    dx = x2 - x1;
    dy = y2 - y1;
    dab = 2 * dy - dx;
    inca = 2 * (dy - dx);
    incb = 2 * dy;
    x = x1;
    y = y1;
    
    if (h1 < -h2 && h2 < 0) setPixel(y, -x, col);
    if (h1 >= -h2 && h2 < 0) setPixel(x, -y, col);
    if (h1 > h2 && h2 >= 0) setPixel(x, y, col);
    if (h1 <= h2 && h2 > 0) setPixel(y, x, col);
    
    for (x = x1 + 1; x <= x2; x++) {
      if (dab < 0) {
        dab += incb;
      }
      else {
        dab += inca;
        y++;
      }
      
      if (h1 < -h2 && h2 < 0) setPixel(y, -x, col);
      if (h1 >= -h2 && h2 < 0) setPixel(x, -y, col);
      if (h1 > h2 && h2 >= 0) setPixel(x, y, col);
      if (h1 <= h2 && h2 > 0) setPixel(y, x, col);
    }
  }
}

VGA.H

#ifndef VGA_H
#define VGA_H

void setMode(int mode);
void clear();
void setPixel(int x, int y, char color);
char getPixel(int x, int y);
void setPalette(char num, char r, char g, char b);
void drawLine(int x1, int y1, int x2, int y2, char col);

#endif

In order to compile the VGA library, you will need to enable the 80286 instruction set in the compiler options.

In Turbo C, go to Options -> Compiler -> Advanced code generation and select the 80286 option under Instruction Set.