// FCircle.c - Draws a circle using Frith's algorithm.
// Copyright (c) 1996  James E. Frith - All Rights Reserved.
// Email:  jfrith@compumedia.com

typedef unsigned char   uchar;
typedef unsigned int    uint;

extern void SetPixel(uint x, uint y, uchar color);


// FCircle --------------------------------------------
// Draws a circle using Frith's Algorithm.

void FCircle(int x, int y, int radius, uchar color)
{
  int balance, xoff, yoff;

  xoff = 0;
  yoff = radius;
  balance = -radius;

  do {
    SetPixel(x+xoff, y+yoff, color);
    SetPixel(x-xoff, y+yoff, color);
    SetPixel(x-xoff, y-yoff, color);
    SetPixel(x+xoff, y-yoff, color);
    SetPixel(x+yoff, y+xoff, color);
    SetPixel(x-yoff, y+xoff, color);
    SetPixel(x-yoff, y-xoff, color);
    SetPixel(x+yoff, y-xoff, color);

    if ((balance += xoff++ + xoff) >= 0)
      balance -= --yoff + yoff;

  } while (xoff <= yoff);
} // FCircle //