[BRLTTY] [Nvda-dev] Braille support?

[Samuel Thibault]

Samuel Thibault, le Tue 23 Sep 2008 03:01:28 +0200, a écrit :
> Now, about the CPU consumption, I've noticed something bad with my irda
> port: awaitInput doesn't wait.  It may be that we are just missing and
> end of file condition, I'll investigate more later.

It's actually that ReadFile(0) doesn't wait.  I've looked deep into the
comm documentation, and couldn't find any way to poll a comm handler...
There is WaitCommEvent but it doesn't accept a timeout, unless turning
the handle into overlapped mode, which would make the whole code a lot
messy...  The only sane way I could find is the attached patch: use
ReadFile(1) and remember the character for later use.  Lee and James,
could you try it?

Samuel
-------------- next part --------------
Index: Programs/serial.c
===================================================================
--- Programs/serial.c	(r?vision 3933)
+++ Programs/serial.c	(copie de travail)
@@ -163,6 +163,7 @@
 
 #ifdef __MINGW32__
   HANDLE fileHandle;
+  int pending;
 #endif /* __MINGW32__ */
 
 #ifdef __MSDOS__
@@ -1025,6 +1026,7 @@
   if (!serialFlushAttributes(serial)) return 0;
 
 #ifdef __MINGW32__
+  if (serial->pending != -1) return 1;
   COMMTIMEOUTS timeouts = {MAXDWORD, 0, timeout, 0, 0};
   DWORD bytesRead;
   int ret;
@@ -1034,10 +1036,12 @@
     return 0;
   }
 
-  ret = ReadFile(serial->fileHandle, &c, 0, &bytesRead, NULL);
-  if (!ret)
-    LogWindowsError("ReadFile");
-  return ret;
+  ret = ReadFile(serial->fileHandle, &c, 1, &bytesRead, NULL);
+  if (bytesRead) {
+    serial->pending = c;
+    return 1;
+  }
+  return 0;
 #else /* __MINGW32__ */
   return awaitInput(serial->fileDescriptor, timeout);
 #endif /* __MINGW32__ */
@@ -1055,21 +1059,27 @@
   COMMTIMEOUTS timeouts = {MAXDWORD, 0, initialTimeout, 0, 0};
   DWORD bytesRead;
 
-  if (!(SetCommTimeouts(serial->fileHandle, &timeouts))) {
-    LogWindowsError("SetCommTimeouts serialReadChunk1");
-    setSystemErrno();
-    return 0;
-  }
+  if (serial->pending) {
+    * (unsigned char *) buffer = serial->pending;
+    serial->pending = -1;
+    bytesRead = 1;
+  } else {
+    if (!(SetCommTimeouts(serial->fileHandle, &timeouts))) {
+      LogWindowsError("SetCommTimeouts serialReadChunk1");
+      setSystemErrno();
+      return 0;
+    }
 
-  if (!ReadFile(serial->fileHandle, buffer+*offset, count, &bytesRead, NULL)) {
-    LogWindowsError("ReadFile");
-    setSystemErrno();
-    return 0;
-  }
+    if (!ReadFile(serial->fileHandle, buffer+*offset, count, &bytesRead, NULL)) {
+      LogWindowsError("ReadFile");
+      setSystemErrno();
+      return 0;
+    }
 
-  if (!bytesRead) {
-    errno = EAGAIN;
-    return 0;
+    if (!bytesRead) {
+      errno = EAGAIN;
+      return 0;
+    }
   }
 
   count -= bytesRead;