libgo/runtime/chan.goc

   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 package runtime
   6 #include "config.h"
   7 #include "channel.h"
   8
   9 typedef _Bool bool;
  10 typedef unsigned char byte;
  11 typedef struct __go_channel chan;
  12
  13 /* Do a nonblocking channel receive.  */
  14
  15 func chanrecv2(c *chan, val *byte) (pres bool) {
  16         if (c->element_size > 8) {
  17                 return __go_receive_nonblocking_big(c, val);
  18         } else {
  19                 struct __go_receive_nonblocking_small rs;
  20                 union {
  21                         char b[8];
  22                         uint64_t v;
  23                 } u;
  24
  25                 rs = __go_receive_nonblocking_small (c);
  26                 if (!rs.__success) {
  27                         __builtin_memset(val, 0, c->element_size);
  28                         return 0;
  29                 }
  30                 u.v = rs.__val;
  31 #ifndef WORDS_BIGENDIAN
  32                 __builtin_memcpy(val, u.b, c->element_size);
  33 #else
  34                 __builtin_memcpy(val, u.b + 8 - c->element_size,
  35                                  c->element_size);
  36 #endif
  37                 return 1;
  38         }
  39 }