Re: Generic gloss read patch

["J. Johnston" <jjohnstn at cygnus dot com>]

Ok,

  Instead of making the gloss32::read wait until len characters are available, I have
changed the patch as Frank suggested: it will read all available characters from the rx buffer
at once up to the length requested.  I changed the end of the loop to exit if we have read
from the rx buffer so we won't end up looping endlessly and lose the input thus far.

  The other part of the problem stemmed from the fact that the stdio component was only
reading one character each time it was polled which meant there was only one character
in the buffer when we came in to do a read.  This code has been changed to
try to read a maximum of 1000 bytes.

  With the change the test sequence below behaves as expected under sid gloss:

 write (1, "\nEnter 10 characters\n", 21);
 write (1, "0123456789\n", 11);
 read (0, buffer, 10);
 write (1, buffer, 10);
 write (1, "\n", 1);

I have attached the new patch.  The following are the ChangeLog entries.  Ok to commit?

sid/component/consoles/ChangeLog

2001-01-17  Jeff Johnston  <jjohnstn@redhat.com>

        * stdio.cxx (read): Change to read a reasonable size of data each
	time stdin gets polled.


sid/component/gloss/ChangeLog

2001-01-17  Jeff Johnston  <jjohnstn@redhat.com>

        * gloss.cxx (read): Change use_rx_p code to extract as much
        as possible from the rx buffer (up to the len requested)
        and to exit at the end of the main loop if any characters
        are successfully read.


-- Jeff J.
Index: consoles/stdio.cxx
===================================================================
RCS file: /cvs/src/src/sid/component/consoles/stdio.cxx,v
retrieving revision 1.1
diff -u -r1.1 stdio.cxx
--- stdio.cxx	2000/12/07 19:30:50	1.1
+++ stdio.cxx	2001/01/17 19:45:17
@@ -32,17 +32,20 @@
 void
 stdioConsole::read(host_int_4)
 {
-  unsigned char c;
+  unsigned char buf[1000];
+  int len;
   host_int_4 value;
 
   // Switch to non-blocking input.
   long flags = fcntl(0, F_GETFL);
   fcntl(0, F_SETFL, flags | O_NONBLOCK);
 
-  if (::read(0, &c, 1) > 0)
+  if ((len = ::read(0, buf, 1000)) > 0)
     {
-      value = c;
-      stdin_pin.drive(value);
+      for (int i = 0; i < len; ++i)
+	{
+	  stdin_pin.drive(buf[i]);
+	}
     }
 
   // Restore flags.
Index: gloss/gloss.cxx
===================================================================
RCS file: /cvs/src/src/sid/component/gloss/gloss.cxx,v
retrieving revision 1.3
diff -u -r1.3 gloss.cxx
--- gloss.cxx	2001/01/08 04:30:42	1.3
+++ gloss.cxx	2001/01/17 19:45:18
@@ -1038,8 +1038,13 @@
 
 	  if (rx_buffer.size() > 0)
 	    {
-	      c = rx_buffer.front();
-	      rx_buffer.erase(rx_buffer.begin());
+	      count_read = min (len, rx_buffer.size());
+	      for (int i = 0; i < count_read; ++i)
+		{
+		  c = rx_buffer.front();
+		  rx_buffer.erase (rx_buffer.begin());
+		  strbuf += c;
+		}
 	    }
 	  else
 	    {
@@ -1047,8 +1052,6 @@
 	      errcode = EAGAIN;
 	      return false;
 	    }
-	  count_read = 1;
-	  strbuf = c;
 	}
       else
 	{
@@ -1095,6 +1098,11 @@
       addr = addr + count_read;
       total_read += count_read;
       len -= count_read;
+
+      // if we have read from the rx_buffer, then we have either emptied it
+      // or read the required number of characters so we should exit the loop
+      if (use_rx_p && count_read > 0)
+	break;
     }
 
   len_read = total_read;