X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=serialport.c;h=9d2a50440046fd67642cd91431f3e55398aa4f29;hb=0765af56440614d73c26944f811720d3a7124f29;hp=fbeb76ee52c88c01f4ab08af5f73b09d2d0abf48;hpb=0ba3e49b45999e159dd8f9bda5abc1710d69eefb;p=libserialport.git

diff --git a/serialport.c b/serialport.c
index fbeb76e..9d2a504 100644
--- a/serialport.c
+++ b/serialport.c
@@ -60,8 +60,12 @@
 
 struct sp_port {
 	char *name;
+	int nonblocking;
 #ifdef _WIN32
 	HANDLE hdl;
+	OVERLAPPED write_ovl;
+	BYTE pending_byte;
+	BOOL writing;
 #else
 	int fd;
 #endif
@@ -153,7 +157,7 @@ void (*sp_debug_handler)(const char *format, ...) = sp_default_debug_handler;
 #define RETURN_FAIL(msg) do { DEBUG_FAIL(msg); return SP_ERR_FAIL; } while (0)
 #define RETURN_VALUE(fmt, x) do { DEBUG("%s returning " fmt, __func__, x); return x; } while (0)
 #define SET_ERROR(val, err, msg) do { DEBUG_ERROR(err, msg); val = err; } while (0)
-#define SET_FAIL(val, msg) do { DEBUG_FAIL(msg); val = err; } while (0)
+#define SET_FAIL(val, msg) do { DEBUG_FAIL(msg); val = SP_ERR_FAIL; } while (0)
 #define TRACE(fmt, ...) DEBUG("%s(" fmt ") called", __func__, ##__VA_ARGS__)
 
 #define TRY(x) do { int ret = x; if (ret != SP_OK) RETURN_CODEVAL(ret); } while (0)
@@ -578,8 +582,11 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 
 	DEBUG("Opening port %s", port->name);
 
+	port->nonblocking = (flags & SP_MODE_NONBLOCK) ? 1 : 0;
+
 #ifdef _WIN32
 	DWORD desired_access = 0, flags_and_attributes = 0;
+	COMMTIMEOUTS timeouts;
 	char *escaped_port_name;
 
 	/* Prefix port name with '\\.\' to work with ports above COM9. */
@@ -603,6 +610,30 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 
 	if (port->hdl == INVALID_HANDLE_VALUE)
 		RETURN_FAIL("CreateFile() failed");
+
+	/* All timeouts disabled. */
+	timeouts.ReadIntervalTimeout = 0;
+	timeouts.ReadTotalTimeoutMultiplier = 0;
+	timeouts.ReadTotalTimeoutConstant = 0;
+	timeouts.WriteTotalTimeoutMultiplier = 0;
+	timeouts.WriteTotalTimeoutConstant = 0;
+
+	if (port->nonblocking) {
+		/* Set read timeout such that all reads return immediately. */
+		timeouts.ReadIntervalTimeout = MAXDWORD;
+		/* Prepare OVERLAPPED structure for non-blocking writes. */
+		memset(&port->write_ovl, 0, sizeof(port->write_ovl));
+		if (!(port->write_ovl.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL))) {
+			sp_close(port);
+			RETURN_FAIL("CreateEvent() failed");
+		}
+		port->writing = FALSE;
+	}
+
+	if (SetCommTimeouts(port->hdl, &timeouts) == 0) {
+		sp_close(port);
+		RETURN_FAIL("SetCommTimeouts() failed");
+	}
 #else
 	int flags_local = 0;
 	struct port_data data;
@@ -665,6 +696,11 @@ enum sp_return sp_close(struct sp_port *port)
 	if (CloseHandle(port->hdl) == 0)
 		RETURN_FAIL("CloseHandle() failed");
 	port->hdl = INVALID_HANDLE_VALUE;
+	if (port->nonblocking) {
+		/* Close event handle created for overlapped writes. */
+		if (CloseHandle(port->write_ovl.hEvent) == 0)
+			RETURN_FAIL("CloseHandle() failed");
+	}
 #else
 	/* Returns 0 upon success, -1 upon failure. */
 	if (close(port->fd) == -1)
@@ -746,12 +782,60 @@ enum sp_return sp_write(struct sp_port *port, const void *buf, size_t count)
 
 	DEBUG("Writing up to %d bytes to port %s", count, port->name);
 
+	if (count == 0)
+		RETURN_VALUE("0", 0);
+
 #ifdef _WIN32
 	DWORD written = 0;
+	BYTE *ptr = (BYTE *) buf;
+
+	if (port->nonblocking) {
+		/* Non-blocking write. */
+
+		/* Check whether previous write is complete. */
+		if (port->writing) {
+			if (HasOverlappedIoCompleted(&port->write_ovl)) {
+				DEBUG("Previous write completed");
+				port->writing = 0;
+			} else {
+				DEBUG("Previous write not complete");
+				/* Can't take a new write until the previous one finishes. */
+				RETURN_VALUE("0", 0);
+			}
+		}
+
+		/* Keep writing data until the OS has to actually start an async IO for it.
+		 * At that point we know the buffer is full. */
+		while (written < count)
+		{
+			/* Copy first byte of user buffer. */
+			port->pending_byte = *ptr++;
+
+			/* Start asynchronous write. */
+			if (WriteFile(port->hdl, &port->pending_byte, 1, NULL, &port->write_ovl) == 0) {
+				if (GetLastError() == ERROR_IO_PENDING) {
+					DEBUG("Asynchronous write started");
+					port->writing = 1;
+					RETURN_VALUE("%d", ++written);
+				} else {
+					/* Actual failure of some kind. */
+					RETURN_FAIL("WriteFile() failed");
+				}
+			} else {
+				DEBUG("Single byte written immediately.");
+				written++;
+			}
+		}
+
+		DEBUG("All bytes written immediately.");
+
+	} else {
+		/* Blocking write. */
+		if (WriteFile(port->hdl, buf, count, &written, NULL) == 0) {
+			RETURN_FAIL("WriteFile() failed");
+		}
+	}
 
-	/* Returns non-zero upon success, 0 upon failure. */
-	if (WriteFile(port->hdl, buf, count, &written, NULL) == 0)
-		RETURN_FAIL("WriteFile() failed");
 	RETURN_VALUE("%d", written);
 #else
 	/* Returns the number of bytes written, or -1 upon failure. */
@@ -786,8 +870,14 @@ enum sp_return sp_read(struct sp_port *port, void *buf, size_t count)
 	ssize_t bytes_read;
 
 	/* Returns the number of bytes read, or -1 upon failure. */
-	if ((bytes_read = read(port->fd, buf, count)) < 0)
-		RETURN_FAIL("read() failed");
+	if ((bytes_read = read(port->fd, buf, count)) < 0) {
+		if (port->nonblocking && errno == EAGAIN)
+			/* Port is opened in nonblocking mode and there are no bytes available. */
+			bytes_read = 0;
+		else
+			/* This is an actual failure. */
+			RETURN_FAIL("read() failed");
+	}
 	RETURN_VALUE("%d", bytes_read);
 #endif
 }