View source for Talk:Wireworld/C

===Code replacement===
Proposing to replace C code with new code below, depending on if there are objections.  Reason: new code is more functional.

This is still using OpenGL and glut.  Hotkeys: "+"/"-" zoom, arrow keys: pan, "&gt;" and "&lt;": increase/decrease speed; space: pause; "q"/Esc: quit.
<lang C>#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <math.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <GL/glut.h>

enum {
	empty = 0,
	head,
	tail,
	conductor,
};

int gwin, width = 0, height = 0;
int win_w, win_h;
int off_x = 0, off_y = 0;
int paused = 1;
long sleep_time = 1L << 18;

unsigned char **cells, **cell_bak;
unsigned long non_empty = 0;
unsigned long zoom = 1;

int clamp(int x, int min, int max)
{
	if (x < min) x = min;
	if (x >= max) x = max - 1;
	return x;
}

void render()
{
	int i, j;
	double x0, x1, y0, y1;
	double cx, cy;
	if (zoom <= 0) zoom = 1;
	if (win_w > width * zoom) off_x = 0;
	cx = off_x + width / 2.;
	if (win_h > height* zoom) off_y = 0;
	cy = off_y + height/ 2.;
	double ex0 = cx - win_w / 2. / zoom, ex1 = cx + win_w / 2. / zoom;
	double ey0 = cy - win_h / 2. / zoom, ey1 = cy + win_h / 2. / zoom;
	int i0 = floor(ex0), i1 = floor(ex1), j0 = floor(ey0), j1 = floor(ey1);
	i0 = clamp(i0, 1, width - 1);
	i1 = clamp(i1, 1, width - 1);
	j0 = clamp(j0, 1, height - 1);
	j1 = clamp(j1, 1, height - 1);

	glClear(GL_COLOR_BUFFER_BIT);

	glLoadIdentity();
	glOrtho(ex0, ex1, ey1, ey0, -1, 1);
	for (i = i0; i <= i1; i++) {
		x0 = i;
		if (x0 > win_w) continue;
		x1 = (i + 1);
		if (x1 < 0) continue;
		for (j = j0; j <= j1; j++) {
			if (cells[j][i] == empty) continue;

			y0 = j;
			if (y0 >= win_h) continue;
			y1 = (j + 1);
			if (y1 < 0) continue;

			switch(cells[j][i]) {
			case head: glColor3ub(255, 0, 0); break;
			case tail: glColor3ub(0, 128, 255); break;
			default: glColor3ub(40, 80, 0); break;
			}
			glRectd(x0, y0, x1, y1);
		}
	}
	glFlush();
}

void evolve()
{
	int i, j, l, cnt;
	int offsets[][2] = {{1, 1}, {1, -1}, {-1, 1}, {-1, -1}, {0, 1}, {0, -1}, {1, 0}, {-1, 0}};
	if (paused) goto skip;
	memcpy(cell_bak[0], cells[0], sizeof(unsigned char) * width * height);
	for (i = 1; i < height - 1; i++) {
		for (j = 1; j < width - 1; j++) {
			switch(cell_bak[i][j]) {
			case tail: cells[i][j] = conductor; break;
			case head: cells[i][j] = tail; break;
			case conductor:
				cnt = 0;
				for (l = 0; l < 8; l++) {
					cnt += (cell_bak[i + offsets[l][0]][j + offsets[l][1]] == head);
					if (cnt > 2) break;
				}
				if (cnt ==1 || cnt == 2)
					cells[i][j] = head;
			}
		}
	}
	render();
skip:	if (sleep_time)
		usleep(sleep_time);
}

void resize(int w, int h)
{
	win_w = w;
	win_h = h;
	glViewport(0, 0, w, h);
	render();
}

void handle_key(unsigned char key, int x, int y)
{
	switch(key) {
	case 'q': case '\033':
		glFinish();
		glutDestroyWindow(gwin);
		return;
	case '+': case '=':
		zoom ++;
		break;
	case '-': case '_':
		zoom --;
		break;
	case ' ':
		paused = !paused;
		break;
	case '>': case '.':
		sleep_time /= 2;
		break;
	case '<': case ',':
		sleep_time *= 2;
		if (!sleep_time) sleep_time = 1;
		break;
	}
	render();
}

void handle_special(int key, int x, int y)
{
	switch(key) {
	case GLUT_KEY_LEFT:  off_x -= 1; break;
	case GLUT_KEY_RIGHT: off_x += 1; break;
	case GLUT_KEY_UP:    off_y -= 1; break;
	case GLUT_KEY_DOWN:  off_y += 1; break;
	}
	render();
}

int read_file(char * fn)
{
	struct stat st;
	char *buf, *ptr;
	int i, j, line_len;

	int fd = open(fn, O_RDONLY);
	if (fd == -1) return 0;
	fstat(fd, &st);

	ptr = buf = malloc(st.st_size + 1);
	read(fd, buf, st.st_size);
	buf[st.st_size] = '\0';
	close(fd);

	height = width = line_len = 0;
	while (*ptr != '\0') {
		switch(*ptr) {
		case '\n':
			if (width < line_len) width = line_len;
			line_len = 0;
			height ++;
			break;
		case 't': case 'H': case ' ': case '.':
			non_empty++;
			line_len++;
			break;
		default:
			fprintf(stderr, "bad char %d at line %d, %d\n",
				*ptr, height + 1, line_len);
		}
		ptr++;
	}
	printf("%lu non empty cells\n", non_empty);
	height += 2;
	width += 2;
	cells = malloc(sizeof(unsigned char*) * height);
	cell_bak = malloc(sizeof(unsigned char*) * height);
	cells[0] = calloc(sizeof(unsigned char), width * height);
	cell_bak[0] = calloc(sizeof(unsigned char), width * height);
	for (i = 1; i < height; i++) {
		cells[i] = cells[i - 1] + width;
		cell_bak[i] = cell_bak[i - 1] + width;
	}

	ptr = buf;
	i = j = 1;
	while (*ptr != '\0') {
		switch(*(ptr++)) {
		case '\n': i++; j = 1; 	continue;
		case 't': cells[i][j++] = tail; continue;
		case 'H': cells[i][j++] = head; continue;
		case '.': cells[i][j++] = conductor; continue;
		default: j++;
		}
	}

	return 1;
}

int main(int c, char **v)
{
	glutInit(&c, v);
	if (c <= 1) {
		fprintf(stderr, "usage: %s filename\n", v[0]);
		return 0;
	}

	if (!read_file(v[1])) exit(1);

	glutInitWindowPosition(-1, -1);

	win_w = width;
	win_h = height;
	if (win_w < 300) win_w = 300;
	if (win_h < 200) win_h = 200;
	glutInitWindowSize(win_w, win_h);
	glutInitDisplayMode(GLUT_RGB|GLUT_DEPTH);
	gwin = glutCreateWindow("Wireworld");
	glutKeyboardUpFunc(handle_key);
	glutSpecialFunc(handle_special);
	glutDisplayFunc(render);
	glutReshapeFunc(resize);
	glutIdleFunc(evolve);
	glLoadIdentity();
	glutMainLoop();
	return 0;
}</lang>

Replace or not, here are some more test files:
<pre> ..................   .........................
.                  . .                         .
 ................  .  ...   ......   ..........
                 . .     . .      . .
 ................   ...  . .      .  ..........
.                      . .  .      .           .
 ..Ht................  .  ..  . ..  .  ........
                     . .     ...  . . .
 ....................  .  . . . . . .  .....   .
.                      . ...    . . .       . . .
.  .................... . . .   . .  . .    . . .
. .                     .   .   . .   ....   .  .
. .                    ...   ...  .  . .  ..    .
 .                      .   .     .  .  .. ...  .
     ................... ... ....  . . .  ..  . .
    .                            . . .  .     . .
   .  ...........................   .  ...  .  .
   . .                                  .  . .
   .  .............................   .. . .  .
    .                              . . .  .   .
     ......................tH....tH  . . ... ...
                                    .  .  .   . .
  ...................tH..........tH.    .. ...  .
 .                                            . .
.  .........................................  . .
. .                                         . . .
. .          ........ .......       ........  . .
. .         .        .       .     .          . .
. .         .       ...  tH  . ...  ........  . .
. .         .        .  .  .  .   .         . . .
. .         .       . .. ..     .  .    ... . . .
. .         .       .          . .  ....   .  . .
. .         .    .   .    .... . . .   . .    . .
. .         .   . . ...  .    .  . . .  .... .  .
. .         .   . .  .  ...  ... .  .... .  .   .
. .         . . .  .. .. .  . .  . . . .   .    .
. .          .....  .  .  ... . .  .   .   .    .
. .         . . .  ... .     .  .  . .  .  .    .
.  .        .    .  .  .    ... . . ...  . .    .
.   .       . .   .. ..      .   .   . ..  .    .
.    .       ....  .          .     .     .     .
 .    .       .  . .    .      . . ...  ..      .
  .    .    .... . .   . .  .t  ... .  .        .
   .    .....  . . .   . . .  H. .  .  .        .
    .       ....  .    . .  ..       .. .       .
     .       .         . .              .      .
      .       .........   ..............      .
       .                                     .
        .....................................</pre>
and one from a gif file from WP:
<pre>                                                                                                                               
                                                                                                                               
                                                   .........................                                                   
                                                  ...........................                                                  
                                                 .                           .                                                 
                                                . ........................... .                                                
                                          .... .................................                                               
                                         .    .                                 .                                              
                                        .  .   .................................   .                                           
                                       .  . .   . ........................... .   . .                                          
                                      .  .. ..   .                           .   .. ..                                         
                                     .  . . . .   ...........................   . . . .                                        
                                    .  . .. .. .   .........................   . .. .. .                                       
                                   .  .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
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                                  .   .. .. .. ..                             .. .. .. ..                                      
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                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .   .. .. .. ..                             .. .. .. ..                                      
                                  .    . .. .. .   .........................   . .. .. .                                       
                                  .     . . . .   ...........................   . . . .                                        
                                  .        .     .                           .     .                                           
                                  .  ......  .  . ........................... .  . .                                           
                                  . .       .  .................................    ..                                         
                                  . . ....... .                                 ...   ...                                      
                                  . . .......  .................................   ..    .                                     
                                  . . ....   .  . ........................... .  .   ...  .                                    
                                  . . .    .     .                           .     .    .  .                                   
                                  . .   . . . .   ...........................   . . . .  .  .                                  
                                  . .  . .. .. .   .........................   . .. .. .  . .                                  
                                  . . .. .. .. ..                             .. .. .. .. . .                                  
                                  . . .. .. .. ..                             .. .. .. .. . .                                  
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                                  . . .. .. .. ..                             .. .. .. .. . .                                  
                                  . . .. .. .. ..                             .. .. .. .. . .                                  
                                  . . .. .. .. ..                             .. .. .. .. . .                                  
                                  . .  . .. .. .   .........................   . .. .. .  . .                                  
                                  .  .  . . . .   ...........................   . . . .  .  .                                  
                                  .   .  .. ..   .                           .   .. ..  .  .                                   
                                   .   .  . .   . ........................... .   . .  .  .                                    
                                    .   .  .   .................................   .  .  .                                     
                                     .  .  .  .                                 .  . .  .                                      
                                      .  .  .  ................................. . . . .                                       
                                       .  .  .  . ........................... .  . . . .                                       
                                        .  .  .  .                           .  .  . . .                                       
                                         .  .  .  ...........................  .  .  . .                                       
                                          .  .  .  .........................  .  .  .  .                                       
                                           .  .  .                           .  .  .  .                                        
                                            .  .  .......                   .  .  .  .                                         
                                             .  .        .                 .  .  .  .                                          
                                              .  .   ..  .  ..      ..    .  .  .  .                                           
                                               .  . .  . . .  .    .  . ..  .  .  .                                            
                                                .  ... .  ... .    . ...   .  .  .                                             
                                               ...  .  .   .  .    .  .   .  .   .                                             
                                              . . .  ...    ...    ...   .  .    .                                             
                                              .   .     .      .  .      .  .    .                                             
                                               ....     .      .  .  ..  .  .    .                                             
                                                   ...  .      .  . .  . .  .    .                                             
                                                      . .      .  . . ...   .    .                                             
                                                    . .  .     . .  .  .    .    .                                             
                                                   ....  .     . .  ...     .    .                                             
                                                    . .  .     . . .    ..  .    .                                             
                                                   .. ..  .    . .  .  .  . .    .                                             
                                                  . ... .  .   .  . .  . ...     .                                             
                                               . .       . .   .  . .  .  .      .                                             
                                              ....      ....   .  . .  ...       .                                             
                                               . .       . .   .  . . .      ..  .                                             
                                              .. ..     .. ..  .  . .  .    .  . .                                             
                                             . ... .   . ... .  . .  .  .   . ...                                              
                                          . .       . .       . .  . .   .  .  .                                               
                                         ....      ....      ..... .  .  .  ...                                                
                                          . .       . .       . .  .   . . .                                                   
                                         .. ..     .. ..     .. ..  .  . .  .                                                  
                                        . ... .   . ... .   . ... .  . .  . .                                                  
                                     . .       . .       . .       . .  . . .                                                  
                                    ....      ..... .   ....      ....  . .  .                                                 
                                     . .       . .       . .       . .  .  .  .                                                
                                    .. ..     .. ..     .. ..     .. ..  .  .  .                                               
                                   . ... .   . ... .   . ... .   . ... .  .  . .                                               
                                . .       . .       . .       . .       . .  . .                                               
                               ....      ....      .....     ....      ....  . .                                               
                                . .       . .       . .       . .       . .  .  .                                              
                               .. ..     .. ..     .. ..     .. ..     .. ..  .  .                                             
                              . ... .   . ... .   . ... .   . ... .   . ... .  . .                                             
                           . .       . .       . .       . .       . .       . .  .                                            
                          .....     ....      ....      .....     ....      ....  .                                            
                           . .       . .       . .       . .       . .       . .   .        .                                  
                          .. ..     .. ..     .. ..     .. ..     .. ..     .. ..  .       . .                                 
                         . ... .   . ... .   . ... .   . ... .   . ... .   . ... .  .      .  .                                
                      . .       . .       . .       . .       . .       . .       . .      .  . .                              
                     ....      ....      .....     ....      ....      ....      ....       .  ...                             
                      . .       . .       . .       . .       . .       . .       . .  .   ...  .                              
                     .. ..     .. ..     .. ..     .. ..     .. ..     .. ..     .. ... .   .   .                              
                    . ... .   . ... .   . ... .   . ... .   . ... .   . ... .   . ... .  . . .  .                              
                 . .       . .       . .       . .       . .       . .       . .      .  . . .  .                              
                ....      .....     .....     ....      ....      .....     ....       .  ... . .                              
                 . .       . .       . .       . .       . .       . .       . .  .   ...  .  . .                              
                .. ..     .. ..     .. ..     .. ..     .. ..     .. ..     .. ... .   .   .   .                               
               . ... .   . ... .   . ... .   . ... .   . ... .   . ... .   . ... .  . . .  .  ...                              
            . .       . .       . .       . .       . .       . .       . .      .  . . .  .   H                               
           .....     .....     .....     .....     ....      ....      ....       .  ... . .   t                               
            . .       . .       . .       . .       . .       . .       . .  .   ...  .  . .    .                              
           .. ..     .. ..     .. ..     .. ..     .. ..     .. ..     .. ... .   .   .   .    .                               
          . ... .   . ... .   . ... .   . ... .   . ... .   . ... .   . ... .  . . .  .  ...  .                                
       . .       . .       . .       . .       . .       . .       . .      .  . . .  .   .  .                                 
      ....      .....     ....      ....      ....      ....      .....      .  ... . .   H H                                  
       . .       . .       . .       . .       . .       . .       . .  .   ...  .  . .    t                                   
      .. ..     .. ..     .. ..     .. ..     .. ..     .. ..     .. ... .   .   .   .    .                                    
       ... .   . ... .   . ... .   . ... .   . ... .   . ... .   . ... .  . . .  .  ...  .                                     
            . .       . .       . .       . .       . .       . .      .  . . .  .   .  .                                      
           ....      .....     ....      ....      ....      .....      .  ... . .   . .                                       
            . .       . .       . .       . .       . .       . .  .   ...  .  . .    H                                        
           .. ..     .. ..     .. ..     .. ..     .. ..     .. ... .   .   .   .    t                                         
            ... .   . ... .   . ... .   . ... .   . ... .   . ... .  . . .  .  ...  .                                          
                 . .       . .       . .       . .       . .      .  . . .  .   .  .                                           
                ....      .....     .....     ....      ....       .  ... . .   . .                                            
                 . .       . .       . .       . .       . .  .   ...  .  . .    .                                             
                .. ..     .. ..     .. ..     .. ..     .. ... .   .   .   .    H                                              
                 ... .   . ... .   . ... .   . ... .   . ... .  . . .  .  ttt  t                                               
                      . .       . .       . .       . .      .  . . .  .   .  .                                                
                     ....      ....      ....      ....       .  ... . .   . .                                                 
                      . .       . .       . .       . .  .   ...  .  . .    .                                                  
                     .. ..     .. ..     .. ..     .. ... .   .   .   .    .                                                   
                      ... .   . ... .   . ... .   . ... .  . . .  .  HHH  H                                                    
                           . .       . .       . .      .  . . .  .   t  t                                                     
                          ....      .....     ....       .  ... . .   . .                                                      
                           . .       . .       . .  .   ...  .  . .    .                                                       
                          .. ..     .. ..     .. ... .   .   .   .    .                                                        
                           ... .   . ... .   . ... .  . . .  .  ...  .                                                         
                                . .       . .      .  . . .  .   H  H                                                          
                               .....     ....       .  ... . .   t t                                                           
                                . .       . .  .   ...  .  . .    .                                                            
                               .. ..     .. ... .   .   .   .    .                                                             
                                ... .   . ... .  . . .  .  ...  .                                                              
                                     . .      .  . . .  .   .  .                                                               
                                    ....       .  ... . .   H H                                                                
                                     . .  t   ttt  .  . .    t                                                                 
                                    .. ..H .   .   .   .    .                                                                  
                                     ...    . t .  .  ...  .                                                                   
                                            . H .  .   .  .                                                                    
                                        ...  ... . .   . .                                                                     
                                       .   .  .  . .    H                                                                      
                                       . . . .    .    t                                                                       
                                        ...  .   ...  .                                                                        
                                       . . ..  .  .  .                                                                         
                                       . .    H . . .                                                                          
                                       .      t .  .                                                                           
                                       .   ..  .. H                                                                            
                                       .  .  .   t                                                                             
                                       .  .  .  HHH                                                                            
                                        ..   .   .                                                                             
                                              .  .                                                                             
                                               .  ....                                                                         
                                                .     .                                                                        
                                                 .    .                                                                        
                                                  .   .                                                                        
                                                   .  .                                                                        
                                                    .  .                                                                       
                                                     .  .                                                                      
                                                      .  .                                                                     
                                                       .  .                                                                    
                                                        .  .                                                                   
                                                         .  ...................................................                
                                                          .                                                                    
                                                           ....................................................                
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               
                                                                                                                               </pre>
: I'd recommend having both, for side-by-side comparison of programming in C in a functional style vs (whatever is there) --[[User:Short Circuit|Michael Mol]] 15:01, 6 July 2011 (UTC)