X-Git-Url: http://sigrok.org/gitweb/?p=libserialport.git;a=blobdiff_plain;f=serialport.c;h=7b45229cca8281abf2cd9b1173ad031376ed8a76;hp=290786a4c1ce92945baac78208033b54b6452e71;hb=1a584c45b02456ebcb197ba801b0ceae810e84e3;hpb=e4ce975a54c60cda6615e4829ae1408adaec8fcf

diff --git a/serialport.c b/serialport.c
index 290786a..7b45229 100644
--- a/serialport.c
+++ b/serialport.c
@@ -2,8 +2,8 @@
  * This file is part of the libserialport project.
  *
  * Copyright (C) 2010-2012 Bert Vermeulen <bert@biot.com>
- * Copyright (C) 2010-2012 Uwe Hermann <uwe@hermann-uwe.de>
- * Copyright (C) 2013 Martin Ling <martin-libserialport@earth.li>
+ * Copyright (C) 2010-2015 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2013-2015 Martin Ling <martin-libserialport@earth.li>
  * Copyright (C) 2013 Matthias Heidbrink <m-sigrok@heidbrink.biz>
  * Copyright (C) 2014 Aurelien Jacobs <aurel@gnuage.org>
  *
@@ -21,10 +21,11 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <config.h>
 #include "libserialport.h"
 #include "libserialport_internal.h"
 
-const struct std_baudrate std_baudrates[] = {
+static const struct std_baudrate std_baudrates[] = {
 #ifdef _WIN32
 	/*
 	 * The baudrates 50/75/134/150/200/1800/230400/460800 do not seem to
@@ -44,6 +45,8 @@ const struct std_baudrate std_baudrates[] = {
 #endif
 };
 
+#define NUM_STD_BAUDRATES ARRAY_SIZE(std_baudrates)
+
 void (*sp_debug_handler)(const char *format, ...) = sp_default_debug_handler;
 
 static enum sp_return get_config(struct sp_port *port, struct port_data *data,
@@ -52,10 +55,12 @@ static enum sp_return get_config(struct sp_port *port, struct port_data *data,
 static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	const struct sp_port_config *config);
 
-enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr)
+SP_API enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr)
 {
 	struct sp_port *port;
+#ifndef NO_PORT_METADATA
 	enum sp_return ret;
+#endif
 	int len;
 
 	TRACE("%s, %p", portname, port_ptr);
@@ -68,7 +73,7 @@ enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_p
 	if (!portname)
 		RETURN_ERROR(SP_ERR_ARG, "Null port name");
 
-	DEBUG("Building structure for port %s", portname);
+	DEBUG_FMT("Building structure for port %s", portname);
 
 	if (!(port = malloc(sizeof(struct sp_port))))
 		RETURN_ERROR(SP_ERR_MEM, "Port structure malloc failed");
@@ -83,6 +88,7 @@ enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_p
 	memcpy(port->name, portname, len);
 
 #ifdef _WIN32
+	port->usb_path = NULL;
 	port->hdl = INVALID_HANDLE_VALUE;
 #else
 	port->fd = -1;
@@ -111,38 +117,38 @@ enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_p
 	RETURN_OK();
 }
 
-char *sp_get_port_name(const struct sp_port *port)
+SP_API char *sp_get_port_name(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port)
 		return NULL;
 
-	RETURN_VALUE("%s", port->name);
+	RETURN_STRING(port->name);
 }
 
-char *sp_get_port_description(struct sp_port *port)
+SP_API char *sp_get_port_description(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port || !port->description)
 		return NULL;
 
-	RETURN_VALUE("%s", port->description);
+	RETURN_STRING(port->description);
 }
 
-enum sp_transport sp_get_port_transport(struct sp_port *port)
+SP_API enum sp_transport sp_get_port_transport(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port)
 		RETURN_ERROR(SP_ERR_ARG, "Null port");
 
-	RETURN_VALUE("%d", port->transport);
+	RETURN_INT(port->transport);
 }
 
-enum sp_return sp_get_port_usb_bus_address(const struct sp_port *port,
-                                           int *usb_bus, int *usb_address)
+SP_API enum sp_return sp_get_port_usb_bus_address(const struct sp_port *port,
+                                                  int *usb_bus,int *usb_address)
 {
 	TRACE("%p", port);
 
@@ -153,14 +159,16 @@ enum sp_return sp_get_port_usb_bus_address(const struct sp_port *port,
 	if (port->usb_bus < 0 || port->usb_address < 0)
 		RETURN_ERROR(SP_ERR_SUPP, "Bus and address values are not available");
 
-	if (usb_bus)      *usb_bus     = port->usb_bus;
-	if (usb_address)  *usb_address = port->usb_address;
+	if (usb_bus)
+		*usb_bus = port->usb_bus;
+	if (usb_address)
+		*usb_address = port->usb_address;
 
 	RETURN_OK();
 }
 
-enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port,
-                                       int *usb_vid, int *usb_pid)
+SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port,
+                                              int *usb_vid, int *usb_pid)
 {
 	TRACE("%p", port);
 
@@ -171,43 +179,45 @@ enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port,
 	if (port->usb_vid < 0 || port->usb_pid < 0)
 		RETURN_ERROR(SP_ERR_SUPP, "VID:PID values are not available");
 
-	if (usb_vid)  *usb_vid = port->usb_vid;
-	if (usb_pid)  *usb_pid = port->usb_pid;
+	if (usb_vid)
+		*usb_vid = port->usb_vid;
+	if (usb_pid)
+		*usb_pid = port->usb_pid;
 
 	RETURN_OK();
 }
 
-char *sp_get_port_usb_manufacturer(const struct sp_port *port)
+SP_API char *sp_get_port_usb_manufacturer(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port || port->transport != SP_TRANSPORT_USB || !port->usb_manufacturer)
 		return NULL;
 
-	RETURN_VALUE("%s", port->usb_manufacturer);
+	RETURN_STRING(port->usb_manufacturer);
 }
 
-char *sp_get_port_usb_product(const struct sp_port *port)
+SP_API char *sp_get_port_usb_product(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port || port->transport != SP_TRANSPORT_USB || !port->usb_product)
 		return NULL;
 
-	RETURN_VALUE("%s", port->usb_product);
+	RETURN_STRING(port->usb_product);
 }
 
-char *sp_get_port_usb_serial(const struct sp_port *port)
+SP_API char *sp_get_port_usb_serial(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port || port->transport != SP_TRANSPORT_USB || !port->usb_serial)
 		return NULL;
 
-	RETURN_VALUE("%s", port->usb_serial);
+	RETURN_STRING(port->usb_serial);
 }
 
-char *sp_get_port_bluetooth_address(const struct sp_port *port)
+SP_API char *sp_get_port_bluetooth_address(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -215,15 +225,18 @@ char *sp_get_port_bluetooth_address(const struct sp_port *port)
 	    || !port->bluetooth_address)
 		return NULL;
 
-	RETURN_VALUE("%s", port->bluetooth_address);
+	RETURN_STRING(port->bluetooth_address);
 }
 
-enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr)
+SP_API enum sp_return sp_get_port_handle(const struct sp_port *port,
+                                         void *result_ptr)
 {
 	TRACE("%p, %p", port, result_ptr);
 
 	if (!port)
 		RETURN_ERROR(SP_ERR_ARG, "Null port");
+	if (!result_ptr)
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
 #ifdef _WIN32
 	HANDLE *handle_ptr = result_ptr;
@@ -236,7 +249,8 @@ enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr)
 	RETURN_OK();
 }
 
-enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr)
+SP_API enum sp_return sp_copy_port(const struct sp_port *port,
+                                   struct sp_port **copy_ptr)
 {
 	TRACE("%p, %p", port, copy_ptr);
 
@@ -253,10 +267,10 @@ enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_pt
 
 	DEBUG("Copying port structure");
 
-	RETURN_VALUE("%p", sp_get_port_by_name(port->name, copy_ptr));
+	RETURN_INT(sp_get_port_by_name(port->name, copy_ptr));
 }
 
-void sp_free_port(struct sp_port *port)
+SP_API void sp_free_port(struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -289,7 +303,8 @@ void sp_free_port(struct sp_port *port)
 	RETURN();
 }
 
-struct sp_port **list_append(struct sp_port **list, const char *portname)
+SP_PRIV struct sp_port **list_append(struct sp_port **list,
+                                     const char *portname)
 {
 	void *tmp;
 	unsigned int count;
@@ -308,44 +323,44 @@ fail:
 	return NULL;
 }
 
-enum sp_return sp_list_ports(struct sp_port ***list_ptr)
+SP_API enum sp_return sp_list_ports(struct sp_port ***list_ptr)
 {
+#ifndef NO_ENUMERATION
 	struct sp_port **list;
 	int ret;
+#endif
 
 	TRACE("%p", list_ptr);
 
 	if (!list_ptr)
 		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
+	*list_ptr = NULL;
+
+#ifdef NO_ENUMERATION
+	RETURN_ERROR(SP_ERR_SUPP, "Enumeration not supported on this platform");
+#else
 	DEBUG("Enumerating ports");
 
-	if (!(list = malloc(sizeof(struct sp_port **))))
+	if (!(list = malloc(sizeof(struct sp_port *))))
 		RETURN_ERROR(SP_ERR_MEM, "Port list malloc failed");
 
 	list[0] = NULL;
 
-#ifdef NO_ENUMERATION
-	ret = SP_ERR_SUPP;
-#else
 	ret = list_ports(&list);
-#endif
 
-	switch (ret) {
-	case SP_OK:
+	if (ret == SP_OK) {
 		*list_ptr = list;
-		RETURN_OK();
-	case SP_ERR_SUPP:
-		DEBUG_ERROR(SP_ERR_SUPP, "Enumeration not supported on this platform");
-	default:
-		if (list)
-			sp_free_port_list(list);
+	} else {
+		sp_free_port_list(list);
 		*list_ptr = NULL;
-		return ret;
 	}
+
+	RETURN_CODEVAL(ret);
+#endif
 }
 
-void sp_free_port_list(struct sp_port **list)
+SP_API void sp_free_port_list(struct sp_port **list)
 {
 	unsigned int i;
 
@@ -366,9 +381,9 @@ void sp_free_port_list(struct sp_port **list)
 }
 
 #define CHECK_PORT() do { \
-	if (port == NULL) \
+	if (!port) \
 		RETURN_ERROR(SP_ERR_ARG, "Null port"); \
-	if (port->name == NULL) \
+	if (!port->name) \
 		RETURN_ERROR(SP_ERR_ARG, "Null port name"); \
 } while (0)
 #ifdef _WIN32
@@ -387,7 +402,44 @@ void sp_free_port_list(struct sp_port **list)
 	CHECK_PORT_HANDLE(); \
 } while (0)
 
-enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
+#ifdef WIN32
+/** To be called after port receive buffer is emptied. */
+static enum sp_return restart_wait(struct sp_port *port)
+{
+	DWORD wait_result;
+
+	if (port->wait_running) {
+		/* Check status of running wait operation. */
+		if (GetOverlappedResult(port->hdl, &port->wait_ovl,
+				&wait_result, FALSE)) {
+			DEBUG("Previous wait completed");
+			port->wait_running = FALSE;
+		} else if (GetLastError() == ERROR_IO_INCOMPLETE) {
+			DEBUG("Previous wait still running");
+			RETURN_OK();
+		} else {
+			RETURN_FAIL("GetOverlappedResult() failed");
+		}
+	}
+
+	if (!port->wait_running) {
+		/* Start new wait operation. */
+		if (WaitCommEvent(port->hdl, &port->events,
+				&port->wait_ovl)) {
+			DEBUG("New wait returned, events already pending");
+		} else if (GetLastError() == ERROR_IO_PENDING) {
+			DEBUG("New wait running in background");
+			port->wait_running = TRUE;
+		} else {
+			RETURN_FAIL("WaitCommEvent() failed");
+		}
+	}
+
+	RETURN_OK();
+}
+#endif
+
+SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 {
 	struct port_data data;
 	struct sp_port_config config;
@@ -397,10 +449,10 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 
 	CHECK_PORT();
 
-	if (flags > (SP_MODE_READ | SP_MODE_WRITE))
+	if (flags > SP_MODE_READ_WRITE)
 		RETURN_ERROR(SP_ERR_ARG, "Invalid flags");
 
-	DEBUG("Opening port %s", port->name);
+	DEBUG_FMT("Opening port %s", port->name);
 
 #ifdef _WIN32
 	DWORD desired_access = 0, flags_and_attributes = 0, errors;
@@ -425,7 +477,7 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 	free(escaped_port_name);
 
 	if (port->hdl == INVALID_HANDLE_VALUE)
-		RETURN_FAIL("port CreateFile() failed");
+		RETURN_FAIL("Port CreateFile() failed");
 
 	/* All timeouts initially disabled. */
 	port->timeouts.ReadIntervalTimeout = 0;
@@ -460,21 +512,20 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 		RETURN_FAIL("SetCommMask() failed");
 	}
 
-	/* Start background operation for RX and error events. */
-	if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-		if (GetLastError() != ERROR_IO_PENDING) {
-			sp_close(port);
-			RETURN_FAIL("WaitCommEvent() failed");
-		}
-	}
-
 	port->writing = FALSE;
+	port->wait_running = FALSE;
+
+	ret = restart_wait(port);
 
+	if (ret < 0) {
+		sp_close(port);
+		RETURN_CODEVAL(ret);
+	}
 #else
 	int flags_local = O_NONBLOCK | O_NOCTTY;
 
 	/* Map 'flags' to the OS-specific settings. */
-	if (flags & (SP_MODE_READ | SP_MODE_WRITE))
+	if ((flags & SP_MODE_READ_WRITE) == SP_MODE_READ_WRITE)
 		flags_local |= O_RDWR;
 	else if (flags & SP_MODE_READ)
 		flags_local |= O_RDONLY;
@@ -498,7 +549,7 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 	data.dcb.fDsrSensitivity = FALSE;
 	data.dcb.fErrorChar = FALSE;
 	data.dcb.fNull = FALSE;
-	data.dcb.fAbortOnError = TRUE;
+	data.dcb.fAbortOnError = FALSE;
 #else
 	/* Turn off all fancy termios tricks, give us a raw channel. */
 	data.term.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IMAXBEL);
@@ -553,18 +604,18 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 	RETURN_OK();
 }
 
-enum sp_return sp_close(struct sp_port *port)
+SP_API enum sp_return sp_close(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Closing port %s", port->name);
+	DEBUG_FMT("Closing port %s", port->name);
 
 #ifdef _WIN32
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (CloseHandle(port->hdl) == 0)
-		RETURN_FAIL("port CloseHandle() failed");
+		RETURN_FAIL("Port CloseHandle() failed");
 	port->hdl = INVALID_HANDLE_VALUE;
 
 	/* Close event handles for overlapped structures. */
@@ -587,7 +638,7 @@ enum sp_return sp_close(struct sp_port *port)
 	RETURN_OK();
 }
 
-enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
+SP_API enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 {
 	TRACE("%p, 0x%x", port, buffers);
 
@@ -598,7 +649,8 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 
 	const char *buffer_names[] = {"no", "input", "output", "both"};
 
-	DEBUG("Flushing %s buffers on port %s", buffer_names[buffers], port->name);
+	DEBUG_FMT("Flushing %s buffers on port %s",
+		buffer_names[buffers], port->name);
 
 #ifdef _WIN32
 	DWORD flags = 0;
@@ -610,13 +662,16 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (PurgeComm(port->hdl, flags) == 0)
 		RETURN_FAIL("PurgeComm() failed");
+
+	if (buffers & SP_BUF_INPUT)
+		TRY(restart_wait(port));
 #else
 	int flags = 0;
-	if (buffers & SP_BUF_BOTH)
+	if (buffers == SP_BUF_BOTH)
 		flags = TCIOFLUSH;
-	else if (buffers & SP_BUF_INPUT)
+	else if (buffers == SP_BUF_INPUT)
 		flags = TCIFLUSH;
-	else if (buffers & SP_BUF_OUTPUT)
+	else if (buffers == SP_BUF_OUTPUT)
 		flags = TCOFLUSH;
 
 	/* Returns 0 upon success, -1 upon failure. */
@@ -626,13 +681,13 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 	RETURN_OK();
 }
 
-enum sp_return sp_drain(struct sp_port *port)
+SP_API enum sp_return sp_drain(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Draining port %s", port->name);
+	DEBUG_FMT("Draining port %s", port->name);
 
 #ifdef _WIN32
 	/* Returns non-zero upon success, 0 upon failure. */
@@ -662,22 +717,25 @@ enum sp_return sp_drain(struct sp_port *port)
 #endif
 }
 
-enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t count, unsigned int timeout)
+SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
+                                        size_t count, unsigned int timeout_ms)
 {
-	TRACE("%p, %p, %d, %d", port, buf, count, timeout);
+	TRACE("%p, %p, %d, %d", port, buf, count, timeout_ms);
 
 	CHECK_OPEN_PORT();
 
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	if (timeout)
-		DEBUG("Writing %d bytes to port %s, timeout %d ms", count, port->name, timeout);
+	if (timeout_ms)
+		DEBUG_FMT("Writing %d bytes to port %s, timeout %d ms",
+			count, port->name, timeout_ms);
 	else
-		DEBUG("Writing %d bytes to port %s, no timeout", count, port->name);
+		DEBUG_FMT("Writing %d bytes to port %s, no timeout",
+			count, port->name);
 
 	if (count == 0)
-		RETURN_VALUE("0", 0);
+		RETURN_INT(0);
 
 #ifdef _WIN32
 	DWORD bytes_written = 0;
@@ -694,56 +752,62 @@ enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t c
 	}
 
 	/* Set timeout. */
-	port->timeouts.WriteTotalTimeoutConstant = timeout;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.WriteTotalTimeoutConstant != timeout_ms) {
+		port->timeouts.WriteTotalTimeoutConstant = timeout_ms;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
 	/* Start write. */
-	if (WriteFile(port->hdl, buf, count, NULL, &port->write_ovl) == 0) {
-		if (GetLastError() == ERROR_IO_PENDING) {
-			DEBUG("Waiting for write to complete");
-			GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE);
-			DEBUG("Write completed, %d/%d bytes written", bytes_written, count);
-			RETURN_VALUE("%d", bytes_written);
-		} else {
-			RETURN_FAIL("WriteFile() failed");
-		}
-	} else {
+	if (WriteFile(port->hdl, buf, count, NULL, &port->write_ovl)) {
 		DEBUG("Write completed immediately");
-		RETURN_VALUE("%d", count);
+		RETURN_INT(count);
+	} else if (GetLastError() == ERROR_IO_PENDING) {
+		DEBUG("Waiting for write to complete");
+		if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0)
+			RETURN_FAIL("GetOverlappedResult() failed");
+		DEBUG_FMT("Write completed, %d/%d bytes written", bytes_written, count);
+		RETURN_INT(bytes_written);
+	} else {
+		RETURN_FAIL("WriteFile() failed");
 	}
 #else
 	size_t bytes_written = 0;
 	unsigned char *ptr = (unsigned char *) buf;
 	struct timeval start, delta, now, end = {0, 0};
+	int started = 0;
 	fd_set fds;
 	int result;
 
-	if (timeout) {
+	if (timeout_ms) {
 		/* Get time at start of operation. */
 		gettimeofday(&start, NULL);
 		/* Define duration of timeout. */
-		delta.tv_sec = timeout / 1000;
-		delta.tv_usec = (timeout % 1000) * 1000;
+		delta.tv_sec = timeout_ms / 1000;
+		delta.tv_usec = (timeout_ms % 1000) * 1000;
 		/* Calculate time at which we should give up. */
 		timeradd(&start, &delta, &end);
 	}
 
+	FD_ZERO(&fds);
+	FD_SET(port->fd, &fds);
+
 	/* Loop until we have written the requested number of bytes. */
-	while (bytes_written < count)
-	{
-		/* Wait until space is available. */
-		FD_ZERO(&fds);
-		FD_SET(port->fd, &fds);
-		if (timeout) {
+	while (bytes_written < count) {
+		/*
+		 * Check timeout only if we have run select() at least once,
+		 * to avoid any issues if a short timeout is reached before
+		 * select() is even run.
+		 */
+		if (timeout_ms && started) {
 			gettimeofday(&now, NULL);
-			if (timercmp(&now, &end, >)) {
-				DEBUG("write timed out");
-				RETURN_VALUE("%d", bytes_written);
-			}
+			if (timercmp(&now, &end, >))
+				/* Timeout has expired. */
+				break;
 			timersub(&end, &now, &delta);
 		}
-		result = select(port->fd + 1, NULL, &fds, NULL, timeout ? &delta : NULL);
+		result = select(port->fd + 1, NULL, &fds, NULL, timeout_ms ? &delta : NULL);
+		started = 1;
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -752,8 +816,8 @@ enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t c
 				RETURN_FAIL("select() failed");
 			}
 		} else if (result == 0) {
-			DEBUG("write timed out");
-			RETURN_VALUE("%d", bytes_written);
+			/* Timeout has expired. */
+			break;
 		}
 
 		/* Do write. */
@@ -772,11 +836,15 @@ enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t c
 		ptr += result;
 	}
 
-	RETURN_VALUE("%d", bytes_written);
+	if (bytes_written < count)
+		DEBUG("Write timed out");
+
+	RETURN_INT(bytes_written);
 #endif
 }
 
-enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_t count)
+SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
+                                           const void *buf, size_t count)
 {
 	TRACE("%p, %p, %d", port, buf, count);
 
@@ -785,10 +853,10 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	DEBUG("Writing up to %d bytes to port %s", count, port->name);
+	DEBUG_FMT("Writing up to %d bytes to port %s", count, port->name);
 
 	if (count == 0)
-		RETURN_VALUE("0", 0);
+		RETURN_INT(0);
 
 #ifdef _WIN32
 	DWORD written = 0;
@@ -802,19 +870,22 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 		} else {
 			DEBUG("Previous write not complete");
 			/* Can't take a new write until the previous one finishes. */
-			RETURN_VALUE("0", 0);
+			RETURN_INT(0);
 		}
 	}
 
 	/* Set timeout. */
-	port->timeouts.WriteTotalTimeoutConstant = 0;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.WriteTotalTimeoutConstant != 0) {
+		port->timeouts.WriteTotalTimeoutConstant = 0;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
-	/* 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)
-	{
+	/*
+	 * 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++;
 
@@ -829,7 +900,7 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 				} else {
 					DEBUG("Asynchronous write running");
 					port->writing = 1;
-					RETURN_VALUE("%d", ++written);
+					RETURN_INT(++written);
 				}
 			} else {
 				/* Actual failure of some kind. */
@@ -843,7 +914,7 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 
 	DEBUG("All bytes written immediately");
 
-	RETURN_VALUE("%d", written);
+	RETURN_INT(written);
 #else
 	/* Returns the number of bytes written, or -1 upon failure. */
 	ssize_t written = write(port->fd, buf, count);
@@ -851,89 +922,118 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 	if (written < 0)
 		RETURN_FAIL("write() failed");
 	else
-		RETURN_VALUE("%d", written);
+		RETURN_INT(written);
 #endif
 }
 
-enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, unsigned int timeout)
+#ifdef _WIN32
+/* Restart wait operation if buffer was emptied. */
+static enum sp_return restart_wait_if_needed(struct sp_port *port, unsigned int bytes_read)
 {
-	TRACE("%p, %p, %d, %d", port, buf, count, timeout);
+	DWORD errors;
+	COMSTAT comstat;
+
+	if (bytes_read == 0)
+		RETURN_OK();
+
+	if (ClearCommError(port->hdl, &errors, &comstat) == 0)
+		RETURN_FAIL("ClearCommError() failed");
+
+	if (comstat.cbInQue == 0)
+		TRY(restart_wait(port));
+
+	RETURN_OK();
+}
+#endif
+
+SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
+                                       size_t count, unsigned int timeout_ms)
+{
+	TRACE("%p, %p, %d, %d", port, buf, count, timeout_ms);
 
 	CHECK_OPEN_PORT();
 
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	if (timeout)
-		DEBUG("Reading %d bytes from port %s, timeout %d ms", count, port->name, timeout);
+	if (timeout_ms)
+		DEBUG_FMT("Reading %d bytes from port %s, timeout %d ms",
+			count, port->name, timeout_ms);
 	else
-		DEBUG("Reading %d bytes from port %s, no timeout", count, port->name);
+		DEBUG_FMT("Reading %d bytes from port %s, no timeout",
+			count, port->name);
 
 	if (count == 0)
-		RETURN_VALUE("0", 0);
+		RETURN_INT(0);
 
 #ifdef _WIN32
 	DWORD bytes_read = 0;
 
 	/* Set timeout. */
-	port->timeouts.ReadIntervalTimeout = 0;
-	port->timeouts.ReadTotalTimeoutConstant = timeout;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.ReadIntervalTimeout != 0 ||
+			port->timeouts.ReadTotalTimeoutMultiplier != 0 ||
+			port->timeouts.ReadTotalTimeoutConstant != timeout_ms) {
+		port->timeouts.ReadIntervalTimeout = 0;
+		port->timeouts.ReadTotalTimeoutMultiplier = 0;
+		port->timeouts.ReadTotalTimeoutConstant = timeout_ms;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
 	/* Start read. */
-	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl) == 0) {
-		if (GetLastError() == ERROR_IO_PENDING) {
-			DEBUG("Waiting for read to complete");
-			GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE);
-			DEBUG("Read completed, %d/%d bytes read", bytes_read, count);
-		} else {
-			RETURN_FAIL("ReadFile() failed");
-		}
-	} else {
+	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl)) {
 		DEBUG("Read completed immediately");
 		bytes_read = count;
+	} else if (GetLastError() == ERROR_IO_PENDING) {
+		DEBUG("Waiting for read to complete");
+		if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
+			RETURN_FAIL("GetOverlappedResult() failed");
+		DEBUG_FMT("Read completed, %d/%d bytes read", bytes_read, count);
+	} else {
+		RETURN_FAIL("ReadFile() failed");
 	}
 
-	/* Start background operation for subsequent events. */
-	if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-		if (GetLastError() != ERROR_IO_PENDING)
-			RETURN_FAIL("WaitCommEvent() failed");
-	}
+	TRY(restart_wait_if_needed(port, bytes_read));
 
-	RETURN_VALUE("%d", bytes_read);
+	RETURN_INT(bytes_read);
 
 #else
 	size_t bytes_read = 0;
 	unsigned char *ptr = (unsigned char *) buf;
 	struct timeval start, delta, now, end = {0, 0};
+	int started = 0;
 	fd_set fds;
 	int result;
 
-	if (timeout) {
+	if (timeout_ms) {
 		/* Get time at start of operation. */
 		gettimeofday(&start, NULL);
 		/* Define duration of timeout. */
-		delta.tv_sec = timeout / 1000;
-		delta.tv_usec = (timeout % 1000) * 1000;
+		delta.tv_sec = timeout_ms / 1000;
+		delta.tv_usec = (timeout_ms % 1000) * 1000;
 		/* Calculate time at which we should give up. */
 		timeradd(&start, &delta, &end);
 	}
 
+	FD_ZERO(&fds);
+	FD_SET(port->fd, &fds);
+
 	/* Loop until we have the requested number of bytes. */
-	while (bytes_read < count)
-	{
-		/* Wait until data is available. */
-		FD_ZERO(&fds);
-		FD_SET(port->fd, &fds);
-		if (timeout) {
+	while (bytes_read < count) {
+		/*
+		 * Check timeout only if we have run select() at least once,
+		 * to avoid any issues if a short timeout is reached before
+		 * select() is even run.
+		 */
+		if (timeout_ms && started) {
 			gettimeofday(&now, NULL);
 			if (timercmp(&now, &end, >))
 				/* Timeout has expired. */
-				RETURN_VALUE("%d", bytes_read);
+				break;
 			timersub(&end, &now, &delta);
 		}
-		result = select(port->fd + 1, &fds, NULL, NULL, timeout ? &delta : NULL);
+		result = select(port->fd + 1, &fds, NULL, NULL, timeout_ms ? &delta : NULL);
+		started = 1;
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -942,8 +1042,8 @@ enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, u
 				RETURN_FAIL("select() failed");
 			}
 		} else if (result == 0) {
-			DEBUG("read timed out");
-			RETURN_VALUE("%d", bytes_read);
+			/* Timeout has expired. */
+			break;
 		}
 
 		/* Do read. */
@@ -951,7 +1051,10 @@ enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, u
 
 		if (result < 0) {
 			if (errno == EAGAIN)
-				/* This shouldn't happen because we did a select() first, but handle anyway. */
+				/*
+				 * This shouldn't happen because we did a
+				 * select() first, but handle anyway.
+				 */
 				continue;
 			else
 				/* This is an actual failure. */
@@ -962,11 +1065,149 @@ enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, u
 		ptr += result;
 	}
 
-	RETURN_VALUE("%d", bytes_read);
+	if (bytes_read < count)
+		DEBUG("Read timed out");
+
+	RETURN_INT(bytes_read);
 #endif
 }
 
-enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count)
+SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
+                                            size_t count, unsigned int timeout_ms)
+{
+	TRACE("%p, %p, %d, %d", port, buf, count, timeout_ms);
+
+	CHECK_OPEN_PORT();
+
+	if (!buf)
+		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
+
+	if (count == 0)
+		RETURN_ERROR(SP_ERR_ARG, "Zero count");
+
+	if (timeout_ms)
+		DEBUG_FMT("Reading next max %d bytes from port %s, timeout %d ms",
+			count, port->name, timeout_ms);
+	else
+		DEBUG_FMT("Reading next max %d bytes from port %s, no timeout",
+			count, port->name);
+
+#ifdef _WIN32
+	DWORD bytes_read = 0;
+
+	/* If timeout_ms == 0, set maximum timeout. */
+	DWORD timeout_val = (timeout_ms == 0 ? MAXDWORD - 1 : timeout_ms);
+
+	/* Set timeout. */
+	if (port->timeouts.ReadIntervalTimeout != MAXDWORD ||
+			port->timeouts.ReadTotalTimeoutMultiplier != MAXDWORD ||
+			port->timeouts.ReadTotalTimeoutConstant != timeout_val) {
+		port->timeouts.ReadIntervalTimeout = MAXDWORD;
+		port->timeouts.ReadTotalTimeoutMultiplier = MAXDWORD;
+		port->timeouts.ReadTotalTimeoutConstant = timeout_val;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
+
+	/* Loop until we have at least one byte, or timeout is reached. */
+	while (bytes_read == 0) {
+		/* Start read. */
+		if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl)) {
+			DEBUG("Read completed immediately");
+			bytes_read = count;
+		} else if (GetLastError() == ERROR_IO_PENDING) {
+			DEBUG("Waiting for read to complete");
+			if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
+				RETURN_FAIL("GetOverlappedResult() failed");
+			if (bytes_read > 0) {
+				DEBUG("Read completed");
+			} else if (timeout_ms > 0) {
+				DEBUG("Read timed out");
+				break;
+			} else {
+				DEBUG("Restarting read");
+			}
+		} else {
+			RETURN_FAIL("ReadFile() failed");
+		}
+	}
+
+	TRY(restart_wait_if_needed(port, bytes_read));
+
+	RETURN_INT(bytes_read);
+
+#else
+	size_t bytes_read = 0;
+	struct timeval start, delta, now, end = {0, 0};
+	int started = 0;
+	fd_set fds;
+	int result;
+
+	if (timeout_ms) {
+		/* Get time at start of operation. */
+		gettimeofday(&start, NULL);
+		/* Define duration of timeout. */
+		delta.tv_sec = timeout_ms / 1000;
+		delta.tv_usec = (timeout_ms % 1000) * 1000;
+		/* Calculate time at which we should give up. */
+		timeradd(&start, &delta, &end);
+	}
+
+	FD_ZERO(&fds);
+	FD_SET(port->fd, &fds);
+
+	/* Loop until we have at least one byte, or timeout is reached. */
+	while (bytes_read == 0) {
+		/*
+		 * Check timeout only if we have run select() at least once,
+		 * to avoid any issues if a short timeout is reached before
+		 * select() is even run.
+		 */
+		if (timeout_ms && started) {
+			gettimeofday(&now, NULL);
+			if (timercmp(&now, &end, >))
+				/* Timeout has expired. */
+				break;
+			timersub(&end, &now, &delta);
+		}
+		result = select(port->fd + 1, &fds, NULL, NULL, timeout_ms ? &delta : NULL);
+		started = 1;
+		if (result < 0) {
+			if (errno == EINTR) {
+				DEBUG("select() call was interrupted, repeating");
+				continue;
+			} else {
+				RETURN_FAIL("select() failed");
+			}
+		} else if (result == 0) {
+			/* Timeout has expired. */
+			break;
+		}
+
+		/* Do read. */
+		result = read(port->fd, buf, count);
+
+		if (result < 0) {
+			if (errno == EAGAIN)
+				/* This shouldn't happen because we did a select() first, but handle anyway. */
+				continue;
+			else
+				/* This is an actual failure. */
+				RETURN_FAIL("read() failed");
+		}
+
+		bytes_read = result;
+	}
+
+	if (bytes_read == 0)
+		DEBUG("Read timed out");
+
+	RETURN_INT(bytes_read);
+#endif
+}
+
+SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
+                                          size_t count)
 {
 	TRACE("%p, %p, %d", port, buf, count);
 
@@ -975,16 +1216,21 @@ enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	DEBUG("Reading up to %d bytes from port %s", count, port->name);
+	DEBUG_FMT("Reading up to %d bytes from port %s", count, port->name);
 
 #ifdef _WIN32
 	DWORD bytes_read;
 
 	/* Set timeout. */
-	port->timeouts.ReadIntervalTimeout = MAXDWORD;
-	port->timeouts.ReadTotalTimeoutConstant = 0;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.ReadIntervalTimeout != MAXDWORD ||
+			port->timeouts.ReadTotalTimeoutMultiplier != 0 ||
+			port->timeouts.ReadTotalTimeoutConstant != 0) {
+		port->timeouts.ReadIntervalTimeout = MAXDWORD;
+		port->timeouts.ReadTotalTimeoutMultiplier = 0;
+		port->timeouts.ReadTotalTimeoutConstant = 0;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
 	/* Do read. */
 	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl) == 0)
@@ -994,15 +1240,9 @@ enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count
 	if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
 		RETURN_FAIL("GetOverlappedResult() failed");
 
-	if (bytes_read > 0) {
-		/* Start background operation for subsequent events. */
-		if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-			if (GetLastError() != ERROR_IO_PENDING)
-				RETURN_FAIL("WaitCommEvent() failed");
-		}
-	}
+	TRY(restart_wait_if_needed(port, bytes_read));
 
-	RETURN_VALUE("%d", bytes_read);
+	RETURN_INT(bytes_read);
 #else
 	ssize_t bytes_read;
 
@@ -1015,17 +1255,17 @@ enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count
 			/* This is an actual failure. */
 			RETURN_FAIL("read() failed");
 	}
-	RETURN_VALUE("%d", bytes_read);
+	RETURN_INT(bytes_read);
 #endif
 }
 
-enum sp_return sp_input_waiting(struct sp_port *port)
+SP_API enum sp_return sp_input_waiting(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Checking input bytes waiting on port %s", port->name);
+	DEBUG_FMT("Checking input bytes waiting on port %s", port->name);
 
 #ifdef _WIN32
 	DWORD errors;
@@ -1033,22 +1273,22 @@ enum sp_return sp_input_waiting(struct sp_port *port)
 
 	if (ClearCommError(port->hdl, &errors, &comstat) == 0)
 		RETURN_FAIL("ClearCommError() failed");
-	RETURN_VALUE("%d", comstat.cbInQue);
+	RETURN_INT(comstat.cbInQue);
 #else
 	int bytes_waiting;
 	if (ioctl(port->fd, TIOCINQ, &bytes_waiting) < 0)
 		RETURN_FAIL("TIOCINQ ioctl failed");
-	RETURN_VALUE("%d", bytes_waiting);
+	RETURN_INT(bytes_waiting);
 #endif
 }
 
-enum sp_return sp_output_waiting(struct sp_port *port)
+SP_API enum sp_return sp_output_waiting(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Checking output bytes waiting on port %s", port->name);
+	DEBUG_FMT("Checking output bytes waiting on port %s", port->name);
 
 #ifdef _WIN32
 	DWORD errors;
@@ -1056,16 +1296,16 @@ enum sp_return sp_output_waiting(struct sp_port *port)
 
 	if (ClearCommError(port->hdl, &errors, &comstat) == 0)
 		RETURN_FAIL("ClearCommError() failed");
-	RETURN_VALUE("%d", comstat.cbOutQue);
+	RETURN_INT(comstat.cbOutQue);
 #else
 	int bytes_waiting;
 	if (ioctl(port->fd, TIOCOUTQ, &bytes_waiting) < 0)
 		RETURN_FAIL("TIOCOUTQ ioctl failed");
-	RETURN_VALUE("%d", bytes_waiting);
+	RETURN_INT(bytes_waiting);
 #endif
 }
 
-enum sp_return sp_new_event_set(struct sp_event_set **result_ptr)
+SP_API enum sp_return sp_new_event_set(struct sp_event_set **result_ptr)
 {
 	struct sp_event_set *result;
 
@@ -1096,13 +1336,14 @@ static enum sp_return add_handle(struct sp_event_set *event_set,
 
 	if (!(new_handles = realloc(event_set->handles,
 			sizeof(event_handle) * (event_set->count + 1))))
-		RETURN_ERROR(SP_ERR_MEM, "handle array realloc() failed");
+		RETURN_ERROR(SP_ERR_MEM, "Handle array realloc() failed");
+
+	event_set->handles = new_handles;
 
 	if (!(new_masks = realloc(event_set->masks,
 			sizeof(enum sp_event) * (event_set->count + 1))))
-		RETURN_ERROR(SP_ERR_MEM, "mask array realloc() failed");
+		RETURN_ERROR(SP_ERR_MEM, "Mask array realloc() failed");
 
-	event_set->handles = new_handles;
 	event_set->masks = new_masks;
 
 	((event_handle *) event_set->handles)[event_set->count] = handle;
@@ -1113,7 +1354,7 @@ static enum sp_return add_handle(struct sp_event_set *event_set,
 	RETURN_OK();
 }
 
-enum sp_return sp_add_port_events(struct sp_event_set *event_set,
+SP_API enum sp_return sp_add_port_events(struct sp_event_set *event_set,
 	const struct sp_port *port, enum sp_event mask)
 {
 	TRACE("%p, %p, %d", event_set, port, mask);
@@ -1143,7 +1384,7 @@ enum sp_return sp_add_port_events(struct sp_event_set *event_set,
 	RETURN_OK();
 }
 
-void sp_free_event_set(struct sp_event_set *event_set)
+SP_API void sp_free_event_set(struct sp_event_set *event_set)
 {
 	TRACE("%p", event_set);
 
@@ -1164,22 +1405,24 @@ void sp_free_event_set(struct sp_event_set *event_set)
 	RETURN();
 }
 
-enum sp_return sp_wait(struct sp_event_set *event_set, unsigned int timeout)
+SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
+                              unsigned int timeout_ms)
 {
-	TRACE("%p, %d", event_set, timeout);
+	TRACE("%p, %d", event_set, timeout_ms);
 
 	if (!event_set)
 		RETURN_ERROR(SP_ERR_ARG, "Null event set");
 
 #ifdef _WIN32
 	if (WaitForMultipleObjects(event_set->count, event_set->handles, FALSE,
-			timeout ? timeout : INFINITE) == WAIT_FAILED)
+			timeout_ms ? timeout_ms : INFINITE) == WAIT_FAILED)
 		RETURN_FAIL("WaitForMultipleObjects() failed");
 
 	RETURN_OK();
 #else
 	struct timeval start, delta, now, end = {0, 0};
-	int result, timeout_remaining;
+	int started = 0;
+	int result, timeout_remaining_ms;
 	struct pollfd *pollfds;
 	unsigned int i;
 
@@ -1198,30 +1441,39 @@ enum sp_return sp_wait(struct sp_event_set *event_set, unsigned int timeout)
 			pollfds[i].events |= POLLERR;
 	}
 
-	if (timeout) {
+	if (timeout_ms) {
 		/* Get time at start of operation. */
 		gettimeofday(&start, NULL);
 		/* Define duration of timeout. */
-		delta.tv_sec = timeout / 1000;
-		delta.tv_usec = (timeout % 1000) * 1000;
+		delta.tv_sec = timeout_ms / 1000;
+		delta.tv_usec = (timeout_ms % 1000) * 1000;
 		/* Calculate time at which we should give up. */
 		timeradd(&start, &delta, &end);
 	}
 
 	/* Loop until an event occurs. */
-	while (1)
-	{
-		if (timeout) {
+	while (1) {
+		/*
+		 * Check timeout only if we have run poll() at least once,
+		 * to avoid any issues if a short timeout is reached before
+		 * poll() is even run.
+		 */
+		if (!timeout_ms) {
+			timeout_remaining_ms = -1;
+		} else if (!started) {
+			timeout_remaining_ms = timeout_ms;
+		} else {
 			gettimeofday(&now, NULL);
 			if (timercmp(&now, &end, >)) {
-				DEBUG("wait timed out");
+				DEBUG("Wait timed out");
 				break;
 			}
 			timersub(&end, &now, &delta);
-			timeout_remaining = delta.tv_sec * 1000 + delta.tv_usec / 1000;
+			timeout_remaining_ms = delta.tv_sec * 1000 + delta.tv_usec / 1000;
 		}
 
-		result = poll(pollfds, event_set->count, timeout ? timeout_remaining : -1);
+		result = poll(pollfds, event_set->count, timeout_remaining_ms);
+		started = 1;
 
 		if (result < 0) {
 			if (errno == EINTR) {
@@ -1259,7 +1511,7 @@ static enum sp_return get_baudrate(int fd, int *baudrate)
 
 	if (ioctl(fd, get_termios_get_ioctl(), data) < 0) {
 		free(data);
-		RETURN_FAIL("getting termios failed");
+		RETURN_FAIL("Getting termios failed");
 	}
 
 	*baudrate = get_termios_speed(data);
@@ -1282,7 +1534,7 @@ static enum sp_return set_baudrate(int fd, int baudrate)
 
 	if (ioctl(fd, get_termios_get_ioctl(), data) < 0) {
 		free(data);
-		RETURN_FAIL("getting termios failed");
+		RETURN_FAIL("Getting termios failed");
 	}
 
 	DEBUG("Setting baud rate");
@@ -1291,7 +1543,7 @@ static enum sp_return set_baudrate(int fd, int baudrate)
 
 	if (ioctl(fd, get_termios_set_ioctl(), data) < 0) {
 		free(data);
-		RETURN_FAIL("setting termios failed");
+		RETURN_FAIL("Setting termios failed");
 	}
 
 	free(data);
@@ -1314,7 +1566,7 @@ static enum sp_return get_flow(int fd, struct port_data *data)
 
 	if (ioctl(fd, TCGETX, termx) < 0) {
 		free(termx);
-		RETURN_FAIL("getting termiox failed");
+		RETURN_FAIL("Getting termiox failed");
 	}
 
 	get_termiox_flow(termx, &data->rts_flow, &data->cts_flow,
@@ -1338,7 +1590,7 @@ static enum sp_return set_flow(int fd, struct port_data *data)
 
 	if (ioctl(fd, TCGETX, termx) < 0) {
 		free(termx);
-		RETURN_FAIL("getting termiox failed");
+		RETURN_FAIL("Getting termiox failed");
 	}
 
 	DEBUG("Setting advanced flow control");
@@ -1348,7 +1600,7 @@ static enum sp_return set_flow(int fd, struct port_data *data)
 
 	if (ioctl(fd, TCSETX, termx) < 0) {
 		free(termx);
-		RETURN_FAIL("setting termiox failed");
+		RETURN_FAIL("Setting termiox failed");
 	}
 
 	free(termx);
@@ -1364,7 +1616,7 @@ static enum sp_return get_config(struct sp_port *port, struct port_data *data,
 
 	TRACE("%p, %p, %p", port, data, config);
 
-	DEBUG("Getting configuration for port %s", port->name);
+	DEBUG_FMT("Getting configuration for port %s", port->name);
 
 #ifdef _WIN32
 	if (!GetCommState(port->hdl, &data->dcb))
@@ -1581,7 +1833,7 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 
 	TRACE("%p, %p, %p", port, data, config);
 
-	DEBUG("Setting configuration for port %s", port->name);
+	DEBUG_FMT("Setting configuration for port %s", port->name);
 
 #ifdef _WIN32
 	if (config->baudrate >= 0) {
@@ -1932,8 +2184,10 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	if (baud_nonstd != B0) {
 		if (ioctl(port->fd, IOSSIOSPEED, &baud_nonstd) == -1)
 			RETURN_FAIL("IOSSIOSPEED ioctl failed");
-		/* Set baud rates in data->term to correct, but incompatible
-		 * with tcsetattr() value, same as delivered by tcgetattr(). */
+		/*
+		 * Set baud rates in data->term to correct, but incompatible
+		 * with tcsetattr() value, same as delivered by tcgetattr().
+		 */
 		if (cfsetspeed(&data->term, baud_nonstd) < 0)
 			RETURN_FAIL("cfsetspeed() failed");
 	}
@@ -1953,7 +2207,7 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	RETURN_OK();
 }
 
-enum sp_return sp_new_config(struct sp_port_config **config_ptr)
+SP_API enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 {
 	struct sp_port_config *config;
 
@@ -1965,7 +2219,7 @@ enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 	*config_ptr = NULL;
 
 	if (!(config = malloc(sizeof(struct sp_port_config))))
-		RETURN_ERROR(SP_ERR_MEM, "config malloc failed");
+		RETURN_ERROR(SP_ERR_MEM, "Config malloc failed");
 
 	config->baudrate = -1;
 	config->bits = -1;
@@ -1981,7 +2235,7 @@ enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 	RETURN_OK();
 }
 
-void sp_free_config(struct sp_port_config *config)
+SP_API void sp_free_config(struct sp_port_config *config)
 {
 	TRACE("%p", config);
 
@@ -1993,7 +2247,8 @@ void sp_free_config(struct sp_port_config *config)
 	RETURN();
 }
 
-enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config)
+SP_API enum sp_return sp_get_config(struct sp_port *port,
+                                    struct sp_port_config *config)
 {
 	struct port_data data;
 
@@ -2009,7 +2264,8 @@ enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config
 	RETURN_OK();
 }
 
-enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config)
+SP_API enum sp_return sp_set_config(struct sp_port *port,
+                                    const struct sp_port_config *config)
 {
 	struct port_data data;
 	struct sp_port_config prev_config;
@@ -2028,7 +2284,7 @@ enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *
 }
 
 #define CREATE_ACCESSORS(x, type) \
-enum sp_return sp_set_##x(struct sp_port *port, type x) { \
+SP_API enum sp_return sp_set_##x(struct sp_port *port, type x) { \
 	struct port_data data; \
 	struct sp_port_config config; \
 	TRACE("%p, %d", port, x); \
@@ -2038,14 +2294,18 @@ enum sp_return sp_set_##x(struct sp_port *port, type x) { \
 	TRY(set_config(port, &data, &config)); \
 	RETURN_OK(); \
 } \
-enum sp_return sp_get_config_##x(const struct sp_port_config *config, type *x) { \
+SP_API enum sp_return sp_get_config_##x(const struct sp_port_config *config, \
+                                        type *x) { \
 	TRACE("%p, %p", config, x); \
+	if (!x) \
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer"); \
 	if (!config) \
 		RETURN_ERROR(SP_ERR_ARG, "Null config"); \
 	*x = config->x; \
 	RETURN_OK(); \
 } \
-enum sp_return sp_set_config_##x(struct sp_port_config *config, type x) { \
+SP_API enum sp_return sp_set_config_##x(struct sp_port_config *config, \
+                                        type x) { \
 	TRACE("%p, %d", config, x); \
 	if (!config) \
 		RETURN_ERROR(SP_ERR_ARG, "Null config"); \
@@ -2063,7 +2323,8 @@ CREATE_ACCESSORS(dtr, enum sp_dtr)
 CREATE_ACCESSORS(dsr, enum sp_dsr)
 CREATE_ACCESSORS(xon_xoff, enum sp_xonxoff)
 
-enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config, enum sp_flowcontrol flowcontrol)
+SP_API enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config,
+                                                enum sp_flowcontrol flowcontrol)
 {
 	if (!config)
 		RETURN_ERROR(SP_ERR_ARG, "Null configuration");
@@ -2097,7 +2358,8 @@ enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config, enum sp_
 	RETURN_OK();
 }
 
-enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol)
+SP_API enum sp_return sp_set_flowcontrol(struct sp_port *port,
+                                         enum sp_flowcontrol flowcontrol)
 {
 	struct port_data data;
 	struct sp_port_config config;
@@ -2115,7 +2377,8 @@ enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flow
 	RETURN_OK();
 }
 
-enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
+SP_API enum sp_return sp_get_signals(struct sp_port *port,
+                                     enum sp_signal *signals)
 {
 	TRACE("%p, %p", port, signals);
 
@@ -2124,7 +2387,7 @@ enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
 	if (!signals)
 		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
-	DEBUG("Getting control signals for port %s", port->name);
+	DEBUG_FMT("Getting control signals for port %s", port->name);
 
 	*signals = 0;
 #ifdef _WIN32
@@ -2155,7 +2418,7 @@ enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
 	RETURN_OK();
 }
 
-enum sp_return sp_start_break(struct sp_port *port)
+SP_API enum sp_return sp_start_break(struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -2171,7 +2434,7 @@ enum sp_return sp_start_break(struct sp_port *port)
 	RETURN_OK();
 }
 
-enum sp_return sp_end_break(struct sp_port *port)
+SP_API enum sp_return sp_end_break(struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -2187,25 +2450,25 @@ enum sp_return sp_end_break(struct sp_port *port)
 	RETURN_OK();
 }
 
-int sp_last_error_code(void)
+SP_API int sp_last_error_code(void)
 {
-	TRACE("");
+	TRACE_VOID();
 #ifdef _WIN32
-	RETURN_VALUE("%d", GetLastError());
+	RETURN_INT(GetLastError());
 #else
-	RETURN_VALUE("%d", errno);
+	RETURN_INT(errno);
 #endif
 }
 
-char *sp_last_error_message(void)
+SP_API char *sp_last_error_message(void)
 {
-	TRACE("");
+	TRACE_VOID();
 
 #ifdef _WIN32
-	LPVOID message;
+	TCHAR *message;
 	DWORD error = GetLastError();
 
-	FormatMessage(
+	DWORD length = FormatMessage(
 		FORMAT_MESSAGE_ALLOCATE_BUFFER |
 		FORMAT_MESSAGE_FROM_SYSTEM |
 		FORMAT_MESSAGE_IGNORE_INSERTS,
@@ -2215,13 +2478,16 @@ char *sp_last_error_message(void)
 		(LPTSTR) &message,
 		0, NULL );
 
-	RETURN_VALUE("%s", message);
+	if (length >= 2 && message[length - 2] == '\r')
+		message[length - 2] = '\0';
+
+	RETURN_STRING(message);
 #else
-	RETURN_VALUE("%s", strerror(errno));
+	RETURN_STRING(strerror(errno));
 #endif
 }
 
-void sp_free_error_message(char *message)
+SP_API void sp_free_error_message(char *message)
 {
 	TRACE("%s", message);
 
@@ -2234,7 +2500,7 @@ void sp_free_error_message(char *message)
 	RETURN();
 }
 
-void sp_set_debug_handler(void (*handler)(const char *format, ...))
+SP_API void sp_set_debug_handler(void (*handler)(const char *format, ...))
 {
 	TRACE("%p", handler);
 
@@ -2243,7 +2509,7 @@ void sp_set_debug_handler(void (*handler)(const char *format, ...))
 	RETURN();
 }
 
-void sp_default_debug_handler(const char *format, ...)
+SP_API void sp_default_debug_handler(const char *format, ...)
 {
 	va_list args;
 	va_start(args, format);
@@ -2254,42 +2520,42 @@ void sp_default_debug_handler(const char *format, ...)
 	va_end(args);
 }
 
-int sp_get_major_package_version(void)
+SP_API int sp_get_major_package_version(void)
 {
 	return SP_PACKAGE_VERSION_MAJOR;
 }
 
-int sp_get_minor_package_version(void)
+SP_API int sp_get_minor_package_version(void)
 {
 	return SP_PACKAGE_VERSION_MINOR;
 }
 
-int sp_get_micro_package_version(void)
+SP_API int sp_get_micro_package_version(void)
 {
 	return SP_PACKAGE_VERSION_MICRO;
 }
 
-const char *sp_get_package_version_string(void)
+SP_API const char *sp_get_package_version_string(void)
 {
 	return SP_PACKAGE_VERSION_STRING;
 }
 
-int sp_get_current_lib_version(void)
+SP_API int sp_get_current_lib_version(void)
 {
 	return SP_LIB_VERSION_CURRENT;
 }
 
-int sp_get_revision_lib_version(void)
+SP_API int sp_get_revision_lib_version(void)
 {
 	return SP_LIB_VERSION_REVISION;
 }
 
-int sp_get_age_lib_version(void)
+SP_API int sp_get_age_lib_version(void)
 {
 	return SP_LIB_VERSION_AGE;
 }
 
-const char *sp_get_lib_version_string(void)
+SP_API const char *sp_get_lib_version_string(void)
 {
 	return SP_LIB_VERSION_STRING;
 }