created new documentation

[software/libev.git] / ev_select.c

diff --git a/ev_select.c b/ev_select.c
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..7bbf6222fd8c635a6c1c124377c27a8d5134f0a6 100644 (file)
--- a/ev_select.c
+++ b/ev_select.c
@@ -0,0 +1,131 @@
+/*
+ * libev select fd activity backend
+ *
+ * Copyright (c) 2007 Marc Alexander Lehmann <libev@schmorp.de>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *
+ *     * Redistributions in binary form must reproduce the above
+ *       copyright notice, this list of conditions and the following
+ *       disclaimer in the documentation and/or other materials provided
+ *       with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* for broken bsd's */
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/* for unix systems */
+#include <sys/select.h>
+
+#include <string.h>
+#include <inttypes.h>
+
+static unsigned char *vec_ri, *vec_ro, *vec_wi, *vec_wo;
+static int vec_max;
+
+static void
+select_modify (int fd, int oev, int nev)
+{
+  int offs = fd >> 3;
+  int mask = 1 << (fd & 7);
+
+  if (vec_max < (fd >> 5) + 1)
+    {
+      int new_max = (fd >> 5) + 1;
+
+      vec_ri = (unsigned char *)realloc (vec_ri, new_max * 4);
+      vec_ro = (unsigned char *)realloc (vec_ro, new_max * 4); /* could free/malloc */
+      vec_wi = (unsigned char *)realloc (vec_wi, new_max * 4);
+      vec_wo = (unsigned char *)realloc (vec_wo, new_max * 4); /* could free/malloc */
+
+      for (; vec_max < new_max; ++vec_max)
+        ((uint32_t *)vec_ri)[vec_max] =
+        ((uint32_t *)vec_wi)[vec_max] = 0;
+    }
+
+  vec_ri [offs] |= mask;
+  if (!(nev & EV_READ))
+    vec_ri [offs] &= ~mask;
+
+  vec_wi [offs] |= mask;
+  if (!(nev & EV_WRITE))
+    vec_wi [offs] &= ~mask;
+}
+
+static void
+select_poll (ev_tstamp timeout)
+{
+  struct timeval tv;
+  int res;
+
+  memcpy (vec_ro, vec_ri, vec_max * 4);
+  memcpy (vec_wo, vec_wi, vec_max * 4);
+
+  tv.tv_sec  = (long)timeout;
+  tv.tv_usec = (long)((timeout - (ev_tstamp)tv.tv_sec) * 1e6);
+
+  res = select (vec_max * 32, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);
+
+  if (res > 0)
+    {
+      int word, offs;
+
+      for (word = vec_max; word--; )
+        {
+          if (((uint32_t *)vec_ro) [word] | ((uint32_t *)vec_wo) [word])
+            for (offs = 4; offs--; )
+              {
+                int idx = word * 4 + offs;
+                unsigned char byte_r = vec_ro [idx];
+                unsigned char byte_w = vec_wo [idx];
+                int bit;
+
+                if (byte_r | byte_w)
+                  for (bit = 8; bit--; )
+                    {
+                      int events = 0;
+                      events |= byte_r & (1 << bit) ? EV_READ  : 0;
+                      events |= byte_w & (1 << bit) ? EV_WRITE : 0;
+
+                      if (events)
+                        fd_event (idx * 8 + bit, events);
+                    }
+              }
+        }
+    }
+  else if (res < 0)
+    {
+      if (errno == EBADF)
+        fd_recheck ();
+    }
+}
+
+static void
+select_init (int flags)
+{
+  ev_method     = EVMETHOD_SELECT;
+  method_fudge  = 1e-2; /* needed to compensate for select returning early, very conservative */
+  method_modify = select_modify;
+  method_poll   = select_poll;
+}
+