libgo/runtime/go-rec-big.c

   1 /* go-rec-big.c -- receive something larger than 64 bits on a channel.
   2
   3    Copyright 2009 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include <stdint.h>
   8
   9 #include "go-panic.h"
  10 #include "channel.h"
  11
  12 /* Returns true if a value was received, false if the channel is
  13    closed.  */
  14
  15 _Bool
  16 __go_receive_big (struct __go_channel *channel, void *val, _Bool for_select)
  17 {
  18   uintptr_t element_size;
  19   size_t alloc_size;
  20   size_t offset;
  21
  22   if (channel == NULL)
  23     {
  24       /* Block forever.  */
  25       __go_select (0, 0, NULL, NULL);
  26     }
  27
  28   element_size = channel->element_type->__size;
  29   alloc_size = (element_size + sizeof (uint64_t) - 1) / sizeof (uint64_t);
  30
  31   if (!__go_receive_acquire (channel, for_select))
  32     {
  33       __builtin_memset (val, 0, element_size);
  34       return 0;
  35     }
  36
  37   offset = channel->next_fetch * alloc_size;
  38   __builtin_memcpy (val, &channel->data[offset], element_size);
  39
  40   __go_receive_release (channel);
  41
  42   return 1;
  43 }