github.com/mh-cbon/go@v0.0.0-20160603070303-9e112a3fe4c0/misc/cgo/life/c-life.c (about)

     1  // Copyright 2010 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  #include <assert.h>
     6  #include "life.h"
     7  #include "_cgo_export.h"
     8  
     9  const int MYCONST = 0;
    10  
    11  // Do the actual manipulation of the life board in C.  This could be
    12  // done easily in Go, we are just using C for demonstration
    13  // purposes.
    14  void
    15  Step(int x, int y, int *a, int *n)
    16  {
    17  	struct GoStart_return r;
    18  
    19  	// Use Go to start 4 goroutines each of which handles 1/4 of the
    20  	// board.
    21  	r = GoStart(0, x, y, 0, x / 2, 0, y / 2, a, n);
    22  	assert(r.r0 == 0 && r.r1 == 100);	// test multiple returns
    23  	r = GoStart(1, x, y, x / 2, x, 0, y / 2, a, n);
    24  	assert(r.r0 == 1 && r.r1 == 101);	// test multiple returns
    25  	GoStart(2, x, y, 0, x / 2, y / 2, y, a, n);
    26  	GoStart(3, x, y, x / 2, x, y / 2, y, a, n);
    27  	GoWait(0);
    28  	GoWait(1);
    29  	GoWait(2);
    30  	GoWait(3);
    31  }
    32  
    33  // The actual computation.  This is called in parallel.
    34  void
    35  DoStep(int xdim, int ydim, int xstart, int xend, int ystart, int yend, int *a, int *n)
    36  {
    37  	int x, y, c, i, j;
    38  
    39  	for(x = xstart; x < xend; x++) {
    40  		for(y = ystart; y < yend; y++) {
    41  			c = 0;
    42  			for(i = -1; i <= 1; i++) {
    43  				for(j = -1; j <= 1; j++) {
    44  				  if(x+i >= 0 && x+i < xdim &&
    45  					y+j >= 0 && y+j < ydim &&
    46  					(i != 0 || j != 0))
    47  				    c += a[(x+i)*xdim + (y+j)] != 0;
    48  				}
    49  			}
    50  			if(c == 3 || (c == 2 && a[x*xdim + y] != 0))
    51  				n[x*xdim + y] = 1;
    52  			else
    53  				n[x*xdim + y] = 0;
    54  		}
    55  	}
    56  }