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 #include <stdint.h>
   9
  10 #include "go-alloc.h"
  11 #include "go-assert.h"
  12 #include "go-panic.h"
  13 #include "channel.h"
  14
  15 struct __go_channel*
  16 __go_new_channel (const struct __go_type_descriptor *channel_type,
  17                   uintptr_t entries)
  18 {
  19   const struct __go_channel_type *ctd;
  20   const struct __go_type_descriptor *element_type;
  21   uintptr_t element_size;
  22   int ientries;
  23   struct __go_channel* ret;
  24   size_t alloc_size;
  25   int i;
  26
  27   __go_assert (channel_type->__code == GO_CHAN);
  28   ctd = (const struct __go_channel_type *) channel_type;
  29   element_type = ctd->__element_type;
  30
  31   element_size = element_type->__size;
  32
  33   ientries = (int) entries;
  34   if (ientries < 0
  35       || (uintptr_t) ientries != entries
  36       || (element_size > 0 && entries > (uintptr_t) -1 / element_size))
  37     __go_panic_msg ("chan size out of range");
  38
  39   alloc_size = (element_size + sizeof (uint64_t) - 1) / sizeof (uint64_t);
  40
  41   /* We use a circular buffer which means that when next_fetch ==
  42      next_store we don't know whether the buffer is empty or full.  So
  43      we allocate an extra space, and always leave a space open.
  44      FIXME.  */
  45   if (entries != 0)
  46     ++entries;
  47
  48   ret = (struct __go_channel*) __go_alloc (sizeof (struct __go_channel)
  49                                            + ((entries == 0 ? 1 : entries)
  50                                               * alloc_size
  51                                               * sizeof (uint64_t)));
  52   i = pthread_mutex_init (&ret->lock, NULL);
  53   __go_assert (i == 0);
  54   i = pthread_cond_init (&ret->cond, NULL);
  55   __go_assert (i == 0);
  56   ret->element_type = element_type;
  57   ret->waiting_to_send = 0;
  58   ret->waiting_to_receive = 0;
  59   ret->selected_for_send = 0;
  60   ret->selected_for_receive = 0;
  61   ret->is_closed = 0;
  62   ret->select_send_queue = NULL;
  63   ret->select_receive_queue = NULL;
  64   ret->select_mutex = NULL;
  65   ret->select_cond = NULL;
  66   ret->num_entries = entries;
  67   ret->next_store = 0;
  68   ret->next_fetch = 0;
  69   return ret;
  70 }