libgo/misc/cgo/life/c-life.c

   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 }