libgo/runtime/go-rec-nb-big.c

   1 /* go-rec-nb-big.c -- nonblocking receive of something big 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 "channel.h"
  10
  11 /* Return true if a value was received, false if not.  */
  12
  13 _Bool
  14 __go_receive_nonblocking_big (struct __go_channel* channel, void *val,
  15                               _Bool *closed)
  16 {
  17   uintptr_t element_size;
  18   size_t alloc_size;
  19   size_t offset;
  20
  21   element_size = channel->element_type->__size;
  22   alloc_size = (element_size + sizeof (uint64_t) - 1) / sizeof (uint64_t);
  23
  24   int data = __go_receive_nonblocking_acquire (channel);
  25   if (data != RECEIVE_NONBLOCKING_ACQUIRE_DATA)
  26     {
  27       __builtin_memset (val, 0, element_size);
  28       if (closed != NULL)
  29         *closed = data == RECEIVE_NONBLOCKING_ACQUIRE_CLOSED;
  30       return 0;
  31     }
  32
  33   offset = channel->next_fetch * alloc_size;
  34   __builtin_memcpy (val, &channel->data[offset], element_size);
  35
  36   __go_receive_release (channel);
  37
  38   return 1;
  39 }