libgo/runtime/go-new-channel.c

   1 /* go-new-channel.c -- allocate a new 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 <stddef.h>
   8
   9 #include "go-alloc.h"
  10 #include "go-assert.h"
  11 #include "go-panic.h"
  12 #include "channel.h"
  13
  14 struct __go_channel*
  15 __go_new_channel (size_t element_size, size_t entries)
  16 {
  17   struct __go_channel* ret;
  18   size_t alloc_size;
  19   int i;
  20
  21   if ((size_t) (int) entries != entries || entries > (size_t) -1 / element_size)
  22     __go_panic_msg ("chan size out of range");
  23
  24   alloc_size = (element_size + sizeof (uint64_t) - 1) / sizeof (uint64_t);
  25
  26   /* We use a circular buffer which means that when next_fetch ==
  27      next_store we don't know whether the buffer is empty or full.  So
  28      we allocate an extra space, and always leave a space open.
  29      FIXME.  */
  30   if (entries != 0)
  31     ++entries;
  32
  33   ret = (struct __go_channel*) __go_alloc (sizeof (struct __go_channel)
  34                                            + ((entries == 0 ? 1 : entries)
  35                                               * alloc_size
  36                                               * sizeof (uint64_t)));
  37   i = pthread_mutex_init (&ret->lock, NULL);
  38   __go_assert (i == 0);
  39   i = pthread_cond_init (&ret->cond, NULL);
  40   __go_assert (i == 0);
  41   ret->element_size = element_size;
  42   ret->closed_op_count = 0;
  43   ret->waiting_to_send = 0;
  44   ret->waiting_to_receive = 0;
  45   ret->selected_for_send = 0;
  46   ret->selected_for_receive = 0;
  47   ret->is_closed = 0;
  48   ret->saw_close = 0;
  49   ret->select_send_queue = NULL;
  50   ret->select_receive_queue = NULL;
  51   ret->select_mutex = NULL;
  52   ret->select_cond = NULL;
  53   ret->num_entries = entries;
  54   ret->next_store = 0;
  55   ret->next_fetch = 0;
  56   return ret;
  57 }