mirror of https://github.com/cc65/cc65.git
145 lines
2.9 KiB
C
145 lines
2.9 KiB
C
// --------------------------------------------------------------------------
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// Conway's Game of Life for KIM-1
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//
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// Assumes the MTU Visible Memory Board mapped at 0x8000 for 8K of video RAM
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//
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// Dave Plummer on a rainy Thursday
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//
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// davepl@davepl.com
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// --------------------------------------------------------------------------
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#include <stdio.h> // For printf
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#include <stdlib.h> // For rand, srand
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#include <string.h> // For memcpy
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typedef unsigned char byte;
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// World size
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#define WIDTH 320
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#define HEIGHT 200
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#define NUMBITS 64000
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#define NUMBYTES 8000
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#define DENSITY 50
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// Screen memory is placed at 8000, our world copy at A000, and they use the same layout so
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// that we can memcpy from one to the other without translating
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byte * world = (byte *) 0x8000;
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byte * new_world = (byte *) 0xA000;
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// BITARRAY
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//
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// Access individual bits in a block of memory
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// Access to the screen bitmap
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byte GETBIT(byte *p, int n)
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{
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return (p[n >> 3] & (1 << (n & 7))) ? 1 : 0;
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}
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void SETBIT(byte *p, int n)
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{
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p[n >> 3] |= (1 << (n & 7));
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}
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void CLRBIT(byte *p, int n)
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{
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p[n >> 3] &= ~(1 << (n & 7));
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}
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void SETPIXEL(byte * p, int x, int y, byte b)
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{
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if (b)
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SETBIT(p, y * WIDTH + x);
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else
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CLRBIT(p, y * WIDTH + x);
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}
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byte GETPIXEL(byte *p, int x, int y)
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{
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return GETBIT(p, y * WIDTH + x);
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}
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// RandomFillWorld
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//
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// Populates the initial world with random cells
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void RandomFillWorld()
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{
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int x, y;
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// I need a better way to see the RNG or it'll be the same game every time!
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srand(0);
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for (x = 0; x < WIDTH; x++)
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{
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for (y = 0; y < HEIGHT; y++)
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{
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byte b = ((rand() % 100) < DENSITY) ? 1 : 0;
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SETPIXEL(world, x, y, b);
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}
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}
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}
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// CountNeighbors
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//
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// Count the number of live cells around the given spot, excluding the actual spot specified
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int CountNeighbors(int x, int y)
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{
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int i, j, nx, ny, count = 0;
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for (j = -1; j <= 1; j++)
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{
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for (i = -1; i <= 1; i++)
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{
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if (i != 0 || j != 0)
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{
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nx = (x + i + WIDTH) % WIDTH;
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ny = (y + j + HEIGHT) % HEIGHT;
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count += GETPIXEL(world, nx, ny) ? 1 : 0;
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}
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}
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}
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return count;
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}
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// UpdateWorld
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//
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// Applies the rules of Conway's Game of Life to the cells
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void UpdateWorld()
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{
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int x, y;
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for (y = 0; y < HEIGHT; y++)
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{
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for (x = 0; x < WIDTH; x++)
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{
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int neighbors = CountNeighbors(x, y);
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if (GETPIXEL(world, x, y))
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SETPIXEL(new_world, x, y, (neighbors == 2 || neighbors == 3));
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else
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SETPIXEL(new_world, x, y, (neighbors == 3));
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}
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}
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}
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int main (void)
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{
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printf("\r\nStarting Conway's Game of Life: Randomizing World...\r\n");
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RandomFillWorld();
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printf("World Ready, Running!\r\n");
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for (;;)
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{
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UpdateWorld();
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printf("[");
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memcpy(world, new_world, NUMBYTES);
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printf("]");
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}
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return 0;
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}
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