From: simon <simon@cda61777-01e9-0310-a592-d414129be87e>
Date: Mon, 28 Aug 2006 18:26:50 +0000 (+0000)
Subject: Reading 4K at a time from a serial port turns out to be a bit
X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/commitdiff_plain/c606abbc2db403e50bf489aa0a1986d404bf2ac5

Reading 4K at a time from a serial port turns out to be a bit
unfriendly in an interactive session, because at 19200 baud it takes
nearly two seconds to receive that much data, and as long as the
data is flowing continuously Windows waits until it has a full
buffer. So here's another annoying flag in the winhandl API, which
restricts reads to length 1 so that serial output shows up as it
appears.

(I tried this yesterday, but without the OVERLAPPED fix in r6826 it
behaved very erratically. It now seems solid.)


git-svn-id: svn://svn.tartarus.org/sgt/putty@6827 cda61777-01e9-0310-a592-d414129be87e
---

diff --git a/windows/winhandl.c b/windows/winhandl.c
index 7a3cce35..222e5b93 100644
--- a/windows/winhandl.c
+++ b/windows/winhandl.c
@@ -102,6 +102,7 @@ static DWORD WINAPI handle_input_threadfunc(void *param)
     struct handle_input *ctx = (struct handle_input *) param;
     OVERLAPPED ovl, *povl;
     HANDLE oev;
+    int readlen;
 
     if (ctx->flags & HANDLE_FLAG_OVERLAPPED) {
 	povl = &ovl;
@@ -110,12 +111,17 @@ static DWORD WINAPI handle_input_threadfunc(void *param)
 	povl = NULL;
     }
 
+    if (ctx->flags & HANDLE_FLAG_UNITBUFFER)
+	readlen = 1;
+    else
+	readlen = sizeof(ctx->buffer);
+
     while (1) {
 	if (povl) {
 	    memset(povl, 0, sizeof(OVERLAPPED));
 	    povl->hEvent = oev;
 	}
-	ctx->readret = ReadFile(ctx->h, ctx->buffer, sizeof(ctx->buffer),
+	ctx->readret = ReadFile(ctx->h, ctx->buffer, readlen,
 				&ctx->len, povl);
 	if (povl && !ctx->readret && GetLastError() == ERROR_IO_PENDING) {
 	    WaitForSingleObject(povl->hEvent, INFINITE);
diff --git a/windows/winser.c b/windows/winser.c
index f50eea13..21ff9a24 100644
--- a/windows/winser.c
+++ b/windows/winser.c
@@ -241,7 +241,8 @@ static const char *serial_init(void *frontend_handle, void **backend_handle,
 				    HANDLE_FLAG_OVERLAPPED);
     serial->in = handle_input_new(serport, serial_gotdata, serial,
 				  HANDLE_FLAG_OVERLAPPED |
-				  HANDLE_FLAG_IGNOREEOF);
+				  HANDLE_FLAG_IGNOREEOF |
+				  HANDLE_FLAG_UNITBUFFER);
 
     *realhost = dupstr(cfg->serline);
 
diff --git a/windows/winstuff.h b/windows/winstuff.h
index 9244c75c..08ebb043 100644
--- a/windows/winstuff.h
+++ b/windows/winstuff.h
@@ -410,6 +410,7 @@ void init_ucs(Config *, struct unicode_data *);
  */
 #define HANDLE_FLAG_OVERLAPPED 1
 #define HANDLE_FLAG_IGNOREEOF 2
+#define HANDLE_FLAG_UNITBUFFER 3
 struct handle;
 typedef int (*handle_inputfn_t)(struct handle *h, void *data, int len);
 typedef void (*handle_outputfn_t)(struct handle *h, int new_backlog);