X-Git-Url: http://sigrok.org/gitweb/?a=blobdiff_plain;f=serialport.c;h=7ab8258511aed5fdb801ac8539f0b451cd73ec58;hb=bccc7c9fa0f00b762392438bea16d4672a984526;hp=6a6e305bb2988ecc20d421b9a1f1b576f33dd2b4;hpb=9069c2fbb2f4b9f07e1bf9729e61044c65e09027;p=libserialport.git

diff --git a/serialport.c b/serialport.c
index 6a6e305..7ab8258 100644
--- a/serialport.c
+++ b/serialport.c
@@ -4,6 +4,7 @@
  * 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) 2013 Matthias Heidbrink <m-sigrok@heidbrink.biz>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as
@@ -26,6 +27,8 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <errno.h>
+#include <stdio.h>
+#include <stdarg.h>
 #ifdef _WIN32
 #include <windows.h>
 #include <tchar.h>
@@ -37,96 +40,244 @@
 #ifdef __APPLE__
 #include <IOKit/IOKitLib.h>
 #include <IOKit/serial/IOSerialKeys.h>
+#include <IOKit/serial/ioss.h>
 #include <sys/syslimits.h>
 #endif
 #ifdef __linux__
 #include "libudev.h"
 #include "linux/serial.h"
+#include "linux_termios.h"
+#if defined(TCGETX) && defined(TCSETX) && defined(HAVE_TERMIOX)
+#define USE_TERMIOX
+#endif
+#endif
+
+#ifndef _WIN32
+#include "linux_termios.h"
 #endif
 
 #include "libserialport.h"
 
-struct sp_port_data {
+struct sp_port {
+	char *name;
+	int nonblocking;
+#ifdef _WIN32
+	HANDLE hdl;
+	OVERLAPPED write_ovl;
+	BYTE pending_byte;
+	BOOL writing;
+#else
+	int fd;
+#endif
+};
+
+struct sp_port_config {
+	int baudrate;
+	int bits;
+	enum sp_parity parity;
+	int stopbits;
+	enum sp_rts rts;
+	enum sp_cts cts;
+	enum sp_dtr dtr;
+	enum sp_dsr dsr;
+	enum sp_xonxoff xon_xoff;
+};
+
+struct port_data {
 #ifdef _WIN32
 	DCB dcb;
 #else
 	struct termios term;
-	int rts;
-	int cts;
-	int dtr;
-	int dsr;
+	int controlbits;
+	int termiox_supported;
+	int flow;
+#endif
+};
+
+/* Standard baud rates. */
+#ifdef _WIN32
+#define BAUD_TYPE DWORD
+#define BAUD(n) {CBR_##n, n}
+#else
+#define BAUD_TYPE speed_t
+#define BAUD(n) {B##n, n}
+#endif
+
+struct std_baudrate {
+	BAUD_TYPE index;
+	int value;
+};
+
+const struct std_baudrate std_baudrates[] = {
+#ifdef _WIN32
+	/*
+	 * The baudrates 50/75/134/150/200/1800/230400/460800 do not seem to
+	 * have documented CBR_* macros.
+	 */
+	BAUD(110), BAUD(300), BAUD(600), BAUD(1200), BAUD(2400), BAUD(4800),
+	BAUD(9600), BAUD(14400), BAUD(19200), BAUD(38400), BAUD(57600),
+	BAUD(115200), BAUD(128000), BAUD(256000),
+#else
+	BAUD(50), BAUD(75), BAUD(110), BAUD(134), BAUD(150), BAUD(200),
+	BAUD(300), BAUD(600), BAUD(1200), BAUD(1800), BAUD(2400), BAUD(4800),
+	BAUD(9600), BAUD(19200), BAUD(38400), BAUD(57600), BAUD(115200),
+	BAUD(230400),
+#if !defined(__APPLE__) && !defined(__OpenBSD__)
+	BAUD(460800),
+#endif
 #endif
 };
 
-/* Helper functions for configuring ports. */
-static int start_config(struct sp_port *port, struct sp_port_data *data);
-static int set_baudrate(struct sp_port_data *data, int baudrate);
-static int set_bits(struct sp_port_data *data, int bits);
-static int set_parity(struct sp_port_data *data, int parity);
-static int set_stopbits(struct sp_port_data *data, int stopbits);
-static int set_rts(struct sp_port_data *data, int rts);
-static int set_cts(struct sp_port_data *data, int cts);
-static int set_dtr(struct sp_port_data *data, int dtr);
-static int set_dsr(struct sp_port_data *data, int dsr);
-static int set_xon_xoff(struct sp_port_data *data, int xon_xoff);
-static int apply_config(struct sp_port *port, struct sp_port_data *data);
-
-int sp_get_port_by_name(const char *portname, struct sp_port **port_ptr)
+void (*sp_debug_handler)(const char *format, ...) = sp_default_debug_handler;
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
+#define NUM_STD_BAUDRATES ARRAY_SIZE(std_baudrates)
+
+/* Debug output macros. */
+#define DEBUG(fmt, ...) do { if (sp_debug_handler) sp_debug_handler(fmt ".\n", ##__VA_ARGS__); } while (0)
+#define DEBUG_ERROR(err, msg) DEBUG("%s returning " #err ": " msg, __func__)
+#define DEBUG_FAIL(msg) do { \
+	char *errmsg = sp_last_error_message(); \
+	DEBUG("%s returning SP_ERR_FAIL: " msg ": %s", __func__, errmsg); \
+	sp_free_error_message(errmsg); \
+} while (0);
+#define RETURN() do { DEBUG("%s returning", __func__); return; } while(0)
+#define RETURN_CODE(x) do { DEBUG("%s returning " #x, __func__); return x; } while (0)
+#define RETURN_CODEVAL(x) do { \
+	switch (x) { \
+		case SP_OK: RETURN_CODE(SP_OK); \
+		case SP_ERR_ARG: RETURN_CODE(SP_ERR_ARG); \
+		case SP_ERR_FAIL: RETURN_CODE(SP_ERR_FAIL); \
+		case SP_ERR_MEM: RETURN_CODE(SP_ERR_MEM); \
+		case SP_ERR_SUPP: RETURN_CODE(SP_ERR_SUPP); \
+	} \
+} while (0)
+#define RETURN_OK() RETURN_CODE(SP_OK);
+#define RETURN_ERROR(err, msg) do { DEBUG_ERROR(err, msg); return err; } while (0)
+#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 = 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)
+
+/* Helper functions. */
+static struct sp_port **list_append(struct sp_port **list, const char *portname);
+static enum sp_return get_config(struct sp_port *port, struct port_data *data,
+	struct sp_port_config *config);
+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)
 {
 	struct sp_port *port;
 	int len;
 
+	TRACE("%s, %p", portname, port_ptr);
+
 	if (!port_ptr)
-		return SP_ERR_ARG;
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
 	*port_ptr = NULL;
 
 	if (!portname)
-		return SP_ERR_ARG;
+		RETURN_ERROR(SP_ERR_ARG, "Null port name");
+
+	DEBUG("Building structure for port %s", portname);
 
 	if (!(port = malloc(sizeof(struct sp_port))))
-		return SP_ERR_MEM;
+		RETURN_ERROR(SP_ERR_MEM, "Port structure malloc failed");
 
 	len = strlen(portname) + 1;
 
-	if (!(port->name = malloc(len)))
-	{
+	if (!(port->name = malloc(len))) {
 		free(port);
-		return SP_ERR_MEM;
+		RETURN_ERROR(SP_ERR_MEM, "Port name malloc failed");
 	}
 
 	memcpy(port->name, portname, len);
 
+#ifdef _WIN32
+	port->hdl = INVALID_HANDLE_VALUE;
+#else
+	port->fd = -1;
+#endif
+
 	*port_ptr = port;
 
-	return SP_OK;
+	RETURN_OK();
+}
+
+char *sp_get_port_name(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	if (!port)
+		return NULL;
+
+	RETURN_VALUE("%s", port->name);
+}
+
+enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr)
+{
+	TRACE("%p", port);
+
+	if (!port)
+		RETURN_ERROR(SP_ERR_ARG, "Null port");
+
+#ifdef _WIN32
+	HANDLE *handle_ptr = result_ptr;
+	*handle_ptr = port->hdl;
+#else
+	int *fd_ptr = result_ptr;
+	*fd_ptr = port->fd;
+#endif
+
+	RETURN_OK();
 }
 
-int sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr)
+enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr)
 {
+	TRACE("%p, %p", port, copy_ptr);
+
 	if (!copy_ptr)
-		return SP_ERR_ARG;
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
 	*copy_ptr = NULL;
 
-	if (!port || !port->name)
-		return SP_ERR_ARG;
+	if (!port)
+		RETURN_ERROR(SP_ERR_ARG, "Null port");
+
+	if (!port->name)
+		RETURN_ERROR(SP_ERR_ARG, "Null port name");
 
-	return sp_get_port_by_name(port->name, copy_ptr);
+	DEBUG("Copying port structure");
+
+	RETURN_VALUE("%p", sp_get_port_by_name(port->name, copy_ptr));
 }
 
 void sp_free_port(struct sp_port *port)
 {
+	TRACE("%p", port);
+
 	if (!port)
-		return;
+	{
+		DEBUG("Null port");
+		RETURN();
+	}
+
+	DEBUG("Freeing port structure");
 
 	if (port->name)
 		free(port->name);
 
 	free(port);
+
+	RETURN();
 }
 
-static struct sp_port **sp_list_append(struct sp_port **list, const char *portname)
+static struct sp_port **list_append(struct sp_port **list, const char *portname)
 {
 	void *tmp;
 	unsigned int count;
@@ -145,13 +296,20 @@ fail:
 	return NULL;
 }
 
-int sp_list_ports(struct sp_port ***list_ptr)
+enum sp_return sp_list_ports(struct sp_port ***list_ptr)
 {
 	struct sp_port **list;
-	int ret = SP_OK;
+	int ret = SP_ERR_SUPP;
+
+	TRACE("%p", list_ptr);
+
+	if (!list_ptr)
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
+
+	DEBUG("Enumerating ports");
 
 	if (!(list = malloc(sizeof(struct sp_port **))))
-		return SP_ERR_MEM;
+		RETURN_ERROR(SP_ERR_MEM, "Port list malloc failed");
 
 	list[0] = NULL;
 
@@ -164,29 +322,30 @@ int sp_list_ports(struct sp_port ***list_ptr)
 	char *name;
 	int name_len;
 
+	ret = SP_OK;
+
+	DEBUG("Opening registry key");
 	if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("HARDWARE\\DEVICEMAP\\SERIALCOMM"),
-			0, KEY_QUERY_VALUE, &key) != ERROR_SUCCESS)
-	{
-		ret = SP_ERR_FAIL;
+			0, KEY_QUERY_VALUE, &key) != ERROR_SUCCESS) {
+		SET_FAIL(ret, "RegOpenKeyEx() failed");
 		goto out_done;
 	}
+	DEBUG("Querying registry key value and data sizes");
 	if (RegQueryInfoKey(key, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
-				&max_value_len, &max_data_size, NULL, NULL) != ERROR_SUCCESS)
-	{
-		ret = SP_ERR_FAIL;
+				&max_value_len, &max_data_size, NULL, NULL) != ERROR_SUCCESS) {
+		SET_FAIL(ret, "RegQueryInfoKey() failed");
 		goto out_close;
 	}
 	max_data_len = max_data_size / sizeof(TCHAR);
-	if (!(value = malloc((max_value_len + 1) * sizeof(TCHAR))))
-	{
-		ret = SP_ERR_MEM;
+	if (!(value = malloc((max_value_len + 1) * sizeof(TCHAR)))) {
+		SET_ERROR(ret, SP_ERR_MEM, "registry value malloc failed");
 		goto out_close;
 	}
-	if (!(data = malloc((max_data_len + 1) * sizeof(TCHAR))))
-	{
-		ret = SP_ERR_MEM;
+	if (!(data = malloc((max_data_len + 1) * sizeof(TCHAR)))) {
+		SET_ERROR(ret, SP_ERR_MEM, "registry data malloc failed");
 		goto out_free_value;
 	}
+	DEBUG("Iterating over values");
 	while (
 		value_len = max_value_len + 1,
 		data_size = max_data_size,
@@ -200,9 +359,8 @@ int sp_list_ports(struct sp_port ***list_ptr)
 #else
 		name_len = data_len + 1;
 #endif
-		if (!(name = malloc(name_len)))
-		{
-			ret = SP_ERR_MEM;
+		if (!(name = malloc(name_len))) {
+			SET_ERROR(ret, SP_ERR_MEM, "registry port name malloc failed");
 			goto out;
 		}
 #ifdef UNICODE
@@ -210,10 +368,12 @@ int sp_list_ports(struct sp_port ***list_ptr)
 #else
 		strcpy(name, data);
 #endif
-		if (type == REG_SZ && !(list = sp_list_append(list, name)))
-		{
-			ret = SP_ERR_MEM;
-			goto out;
+		if (type == REG_SZ) {
+			DEBUG("Found port %s", name);
+			if (!(list = list_append(list, name))) {
+				SET_ERROR(ret, SP_ERR_MEM, "list append failed");
+				goto out;
+			}
 		}
 		index++;
 	}
@@ -234,33 +394,35 @@ out_done:
 	CFTypeRef cf_path;
 	Boolean result;
 
-	if (IOMasterPort(MACH_PORT_NULL, &master) != KERN_SUCCESS)
-	{
-		ret = SP_ERR_FAIL;
+	ret = SP_OK;
+
+	DEBUG("Getting IOKit master port");
+	if (IOMasterPort(MACH_PORT_NULL, &master) != KERN_SUCCESS) {
+		SET_FAIL(ret, "IOMasterPort() failed");
 		goto out_done;
 	}
 
-	if (!(classes = IOServiceMatching(kIOSerialBSDServiceValue)))
-	{
-		ret = SP_ERR_FAIL;
+	DEBUG("Creating matching dictionary");
+	if (!(classes = IOServiceMatching(kIOSerialBSDServiceValue))) {
+		SET_FAIL(ret, "IOServiceMatching() failed");
 		goto out_done;
 	}
 
 	CFDictionarySetValue(classes,
 			CFSTR(kIOSerialBSDTypeKey), CFSTR(kIOSerialBSDAllTypes));
 
-	if (IOServiceGetMatchingServices(master, classes, &iter) != KERN_SUCCESS)
-	{
-		ret = SP_ERR_FAIL;
+	DEBUG("Getting matching services");
+	if (IOServiceGetMatchingServices(master, classes, &iter) != KERN_SUCCESS) {
+		SET_FAIL(ret, "IOServiceGetMatchingServices() failed");
 		goto out_done;
 	}
 
-	if (!(path = malloc(PATH_MAX)))
-	{
-		ret = SP_ERR_MEM;
+	if (!(path = malloc(PATH_MAX))) {
+		SET_ERROR(ret, SP_ERR_MEM, "device path malloc failed");
 		goto out_release;
 	}
 
+	DEBUG("Iterating over results");
 	while ((port = IOIteratorNext(iter))) {
 		cf_path = IORegistryEntryCreateCFProperty(port,
 				CFSTR(kIOCalloutDeviceKey), kCFAllocatorDefault, 0);
@@ -268,11 +430,13 @@ out_done:
 			result = CFStringGetCString(cf_path,
 					path, PATH_MAX, kCFStringEncodingASCII);
 			CFRelease(cf_path);
-			if (result && !(list = sp_list_append(list, path)))
-			{
-				ret = SP_ERR_MEM;
-				IOObjectRelease(port);
-				goto out;
+			if (result) {
+				DEBUG("Found port %s", path);
+				if (!(list = list_append(list, path))) {
+					SET_ERROR(ret, SP_ERR_MEM, "list append failed");
+					IOObjectRelease(port);
+					goto out;
+				}
 			}
 		}
 		IOObjectRelease(port);
@@ -295,19 +459,23 @@ out_done:
 	int fd, ioctl_result;
 	struct serial_struct serial_info;
 
+	ret = SP_OK;
+
+	DEBUG("Enumerating tty devices");
 	ud = udev_new();
 	ud_enumerate = udev_enumerate_new(ud);
 	udev_enumerate_add_match_subsystem(ud_enumerate, "tty");
 	udev_enumerate_scan_devices(ud_enumerate);
 	ud_list = udev_enumerate_get_list_entry(ud_enumerate);
-	udev_list_entry_foreach(ud_entry, ud_list)
-	{
+	DEBUG("Iterating over results");
+	udev_list_entry_foreach(ud_entry, ud_list) {
 		path = udev_list_entry_get_name(ud_entry);
+		DEBUG("Found device %s", path);
 		ud_dev = udev_device_new_from_syspath(ud, path);
 		/* If there is no parent device, this is a virtual tty. */
 		ud_parent = udev_device_get_parent(ud_dev);
-		if (ud_parent == NULL)
-		{
+		if (ud_parent == NULL) {
+			DEBUG("No parent device, assuming virtual tty");
 			udev_device_unref(ud_dev);
 			continue;
 		}
@@ -316,23 +484,29 @@ out_done:
 		 * The only way to tell which actually exist on a given system
 		 * is to try to open them and make an ioctl call. */
 		driver = udev_device_get_driver(ud_parent);
-		if (driver && !strcmp(driver, "serial8250"))
-		{
-			if ((fd = open(name, O_RDWR | O_NONBLOCK | O_NOCTTY)) < 0)
+		if (driver && !strcmp(driver, "serial8250")) {
+			DEBUG("serial8250 device, attempting to open");
+			if ((fd = open(name, O_RDWR | O_NONBLOCK | O_NOCTTY)) < 0) {
+				DEBUG("open failed, skipping");
 				goto skip;
+			}
 			ioctl_result = ioctl(fd, TIOCGSERIAL, &serial_info);
 			close(fd);
-			if (ioctl_result != 0)
+			if (ioctl_result != 0) {
+				DEBUG("ioctl failed, skipping");
 				goto skip;
-			if (serial_info.type == PORT_UNKNOWN)
+			}
+			if (serial_info.type == PORT_UNKNOWN) {
+				DEBUG("port type is unknown, skipping");
 				goto skip;
+			}
 		}
-		list = sp_list_append(list, name);
+		DEBUG("Found port %s", name);
+		list = list_append(list, name);
 skip:
 		udev_device_unref(ud_dev);
-		if (!list)
-		{
-			ret = SP_ERR_MEM;
+		if (!list) {
+			SET_ERROR(ret, SP_ERR_MEM, "list append failed");
 			goto out;
 		}
 	}
@@ -341,64 +515,94 @@ out:
 	udev_unref(ud);
 #endif
 
-	if (ret == SP_OK)
-	{
+	switch (ret) {
+	case SP_OK:
 		*list_ptr = list;
-	}
-	else
-	{
+		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);
-
 		*list_ptr = NULL;
+		return ret;
 	}
-
-	return ret;
 }
 
 void sp_free_port_list(struct sp_port **list)
 {
 	unsigned int i;
 
+	TRACE("%p", list);
+
+	if (!list) {
+		DEBUG("Null list");
+		RETURN();
+	}
+
+	DEBUG("Freeing port list");
+
 	for (i = 0; list[i]; i++)
 		sp_free_port(list[i]);
 	free(list);
+
+	RETURN();
 }
 
-static int sp_validate_port(struct sp_port *port)
-{
-	if (port == NULL)
-		return 0;
+#define CHECK_PORT() do { \
+	if (port == NULL) \
+		RETURN_ERROR(SP_ERR_ARG, "Null port"); \
+	if (port->name == NULL) \
+		RETURN_ERROR(SP_ERR_ARG, "Null port name"); \
+} while (0)
 #ifdef _WIN32
-	if (port->hdl == INVALID_HANDLE_VALUE)
-		return 0;
+#define CHECK_PORT_HANDLE() do { \
+	if (port->hdl == INVALID_HANDLE_VALUE) \
+		RETURN_ERROR(SP_ERR_ARG, "Invalid port handle"); \
+} while (0)
 #else
-	if (port->fd < 0)
-		return 0;
+#define CHECK_PORT_HANDLE() do { \
+	if (port->fd < 0) \
+		RETURN_ERROR(SP_ERR_ARG, "Invalid port fd"); \
+} while (0)
 #endif
-	return 1;
-}
+#define CHECK_OPEN_PORT() do { \
+	CHECK_PORT(); \
+	CHECK_PORT_HANDLE(); \
+} while (0)
 
-#define CHECK_PORT() do { if (!sp_validate_port(port)) return SP_ERR_ARG; } while (0)
-
-int sp_open(struct sp_port *port, int flags)
+enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 {
-	if (!port)
-		return SP_ERR_ARG;
+	struct port_data data;
+	struct sp_port_config config;
+	enum sp_return ret;
+
+	TRACE("%p, %x", port, flags);
+
+	CHECK_PORT();
+
+	if (flags > (SP_MODE_READ | SP_MODE_WRITE | SP_MODE_NONBLOCK))
+		RETURN_ERROR(SP_ERR_ARG, "Invalid 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. */
 	if (!(escaped_port_name = malloc(strlen(port->name + 5))))
-		return SP_ERR_MEM;
+		RETURN_ERROR(SP_ERR_MEM, "Escaped port name malloc failed");
 	sprintf(escaped_port_name, "\\\\.\\%s", port->name);
 
 	/* Map 'flags' to the OS-specific settings. */
-	desired_access |= GENERIC_READ;
 	flags_and_attributes = FILE_ATTRIBUTE_NORMAL;
-	if (flags & SP_MODE_RDWR)
+	if (flags & SP_MODE_READ)
+		desired_access |= GENERIC_READ;
+	if (flags & SP_MODE_WRITE)
 		desired_access |= GENERIC_WRITE;
 	if (flags & SP_MODE_NONBLOCK)
 		flags_and_attributes |= FILE_FLAG_OVERLAPPED;
@@ -409,587 +613,1225 @@ int sp_open(struct sp_port *port, int flags)
 	free(escaped_port_name);
 
 	if (port->hdl == INVALID_HANDLE_VALUE)
-		return SP_ERR_FAIL;
+		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 sp_port_data data;
 
 	/* Map 'flags' to the OS-specific settings. */
-	if (flags & SP_MODE_RDWR)
+	if (flags & (SP_MODE_READ | SP_MODE_WRITE))
 		flags_local |= O_RDWR;
-	if (flags & SP_MODE_RDONLY)
+	else if (flags & SP_MODE_READ)
 		flags_local |= O_RDONLY;
+	else if (flags & SP_MODE_WRITE)
+		flags_local |= O_WRONLY;
 	if (flags & SP_MODE_NONBLOCK)
 		flags_local |= O_NONBLOCK;
 
 	if ((port->fd = open(port->name, flags_local)) < 0)
-		return SP_ERR_FAIL;
+		RETURN_FAIL("open() failed");
+#endif
+
+	ret = get_config(port, &data, &config);
 
-	start_config(port, &data);
+	if (ret < 0) {
+		sp_close(port);
+		RETURN_CODEVAL(ret);
+	}
 
-	/* Turn off all serial port cooking. */
-	data.term.c_iflag &= ~(ISTRIP | INLCR | ICRNL);
-	data.term.c_oflag &= ~(ONLCR | OCRNL | ONOCR);
-#if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__NetBSD__)
+	/* Set sane port settings. */
+#ifdef _WIN32
+	data.dcb.fBinary = TRUE;
+	data.dcb.fDsrSensitivity = FALSE;
+	data.dcb.fErrorChar = FALSE;
+	data.dcb.fNull = FALSE;
+	data.dcb.fAbortOnError = TRUE;
+#else
+	/* Turn off all fancy termios tricks, give us a raw channel. */
+	data.term.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL|IUCLC|IMAXBEL);
+	data.term.c_oflag &= ~(OPOST|OLCUC|ONLCR|OCRNL|ONOCR|ONLRET|NLDLY|CRDLY|TABDLY|BSDLY|VTDLY|FFDLY);
+#ifdef OFILL
 	data.term.c_oflag &= ~OFILL;
 #endif
-	/* Disable canonical mode, and don't echo input characters. */
-	data.term.c_lflag &= ~(ICANON | ECHO);
-
-	/* Ignore modem status lines; enable receiver */
-	data.term.c_cflag |= (CLOCAL | CREAD);
+	data.term.c_lflag &= ~(ISIG|ICANON|ECHO|IEXTEN);
+	data.term.c_cc[VMIN] = 0;
+	data.term.c_cc[VTIME] = 0;
 
-	apply_config(port, &data);
+	/* Ignore modem status lines; enable receiver; leave control lines alone on close. */
+	data.term.c_cflag |= (CLOCAL | CREAD | HUPCL);
 #endif
 
-	return SP_OK;
+	ret = set_config(port, &data, &config);
+
+	if (ret < 0) {
+		sp_close(port);
+		RETURN_CODEVAL(ret);
+	}
+
+	RETURN_OK();
 }
 
-int sp_close(struct sp_port *port)
+enum sp_return sp_close(struct sp_port *port)
 {
-	CHECK_PORT();
+	TRACE("%p", port);
+
+	CHECK_OPEN_PORT();
+
+	DEBUG("Closing port %s", port->name);
 
 #ifdef _WIN32
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (CloseHandle(port->hdl) == 0)
-		return SP_ERR_FAIL;
+		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)
-		return SP_ERR_FAIL;
+		RETURN_FAIL("close() failed");
+	port->fd = -1;
 #endif
 
-	return SP_OK;
+	RETURN_OK();
 }
 
-int sp_flush(struct sp_port *port)
+enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 {
-	CHECK_PORT();
+	TRACE("%p, %x", port, buffers);
+
+	CHECK_OPEN_PORT();
+
+	if (buffers > SP_BUF_BOTH)
+		RETURN_ERROR(SP_ERR_ARG, "Invalid buffer selection");
+
+	const char *buffer_names[] = {"no", "input", "output", "both"};
+
+	DEBUG("Flushing %s buffers on port %s", buffer_names[buffers], port->name);
 
 #ifdef _WIN32
+	DWORD flags = 0;
+	if (buffers & SP_BUF_INPUT)
+		flags |= PURGE_RXCLEAR;
+	if (buffers & SP_BUF_OUTPUT)
+		flags |= PURGE_TXCLEAR;
+
 	/* Returns non-zero upon success, 0 upon failure. */
-	if (PurgeComm(port->hdl, PURGE_RXCLEAR | PURGE_TXCLEAR) == 0)
-		return SP_ERR_FAIL;
+	if (PurgeComm(port->hdl, flags) == 0)
+		RETURN_FAIL("PurgeComm() failed");
 #else
+	int flags = 0;
+	if (buffers & SP_BUF_BOTH)
+		flags = TCIOFLUSH;
+	else if (buffers & SP_BUF_INPUT)
+		flags = TCIFLUSH;
+	else if (buffers & SP_BUF_OUTPUT)
+		flags = TCOFLUSH;
+
 	/* Returns 0 upon success, -1 upon failure. */
-	if (tcflush(port->fd, TCIOFLUSH) < 0)
-		return SP_ERR_FAIL;
+	if (tcflush(port->fd, flags) < 0)
+		RETURN_FAIL("tcflush() failed");
 #endif
-	return SP_OK;
+	RETURN_OK();
 }
 
-int sp_write(struct sp_port *port, const void *buf, size_t count)
+enum sp_return sp_drain(struct sp_port *port)
 {
-	CHECK_PORT();
+	TRACE("%p", port);
+
+	CHECK_OPEN_PORT();
+
+	DEBUG("Draining port %s", port->name);
+
+#ifdef _WIN32
+	/* Returns non-zero upon success, 0 upon failure. */
+	if (FlushFileBuffers(port->hdl) == 0)
+		RETURN_FAIL("FlushFileBuffers() failed");
+#else
+	/* Returns 0 upon success, -1 upon failure. */
+	if (tcdrain(port->fd) < 0)
+		RETURN_FAIL("tcdrain() failed");
+#endif
+
+	RETURN_OK();
+}
+
+enum sp_return sp_write(struct sp_port *port, const void *buf, size_t count)
+{
+	TRACE("%p, %p, %d", port, buf, count);
+
+	CHECK_OPEN_PORT();
 
 	if (!buf)
-		return SP_ERR_ARG;
+		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
+
+	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);
+			}
+		}
 
-	/* Returns non-zero upon success, 0 upon failure. */
-	if (WriteFile(port->hdl, buf, count, &written, NULL) == 0)
-		return SP_ERR_FAIL;
-	return written;
+		/* 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");
+		}
+	}
+
+	RETURN_VALUE("%d", written);
 #else
 	/* Returns the number of bytes written, or -1 upon failure. */
 	ssize_t written = write(port->fd, buf, count);
 
 	if (written < 0)
-		return SP_ERR_FAIL;
+		RETURN_FAIL("write() failed");
 	else
-		return written;
+		RETURN_VALUE("%d", written);
 #endif
 }
 
-int sp_read(struct sp_port *port, void *buf, size_t count)
+enum sp_return sp_read(struct sp_port *port, void *buf, size_t count)
 {
-	CHECK_PORT();
+	TRACE("%p, %p, %d", port, buf, count);
+
+	CHECK_OPEN_PORT();
 
 	if (!buf)
-		return SP_ERR_ARG;
+		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
+
+	DEBUG("Reading up to %d bytes from port %s", count, port->name);
 
 #ifdef _WIN32
 	DWORD bytes_read = 0;
 
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (ReadFile(port->hdl, buf, count, &bytes_read, NULL) == 0)
-		return SP_ERR_FAIL;
-	return bytes_read;
+		RETURN_FAIL("ReadFile() failed");
+	RETURN_VALUE("%d", bytes_read);
 #else
 	ssize_t bytes_read;
 
 	/* Returns the number of bytes read, or -1 upon failure. */
-	if ((bytes_read = read(port->fd, buf, count)) < 0)
-		return SP_ERR_FAIL;
-	return bytes_read;
+	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
 }
 
-static int start_config(struct sp_port *port, struct sp_port_data *data)
+#ifdef __linux__
+static enum sp_return get_baudrate(int fd, int *baudrate)
 {
-	CHECK_PORT();
-#ifdef _WIN32
-	if (!GetCommState(port->hdl, &data->dcb))
-		return SP_ERR_FAIL;
-#else
-	int controlbits;
+	void *data;
 
-	if (tcgetattr(port->fd, &data->term) < 0)
-		return SP_ERR_FAIL;
+	TRACE("%d, %p", fd, baudrate);
 
-	if (ioctl(port->fd, TIOCMGET, &controlbits) < 0)
-		return SP_ERR_FAIL;
+	DEBUG("Getting baud rate");
 
-	if (data->term.c_cflag & CRTSCTS) {
-		data->rts = SP_RTS_FLOW_CONTROL;
-		data->cts = SP_CTS_FLOW_CONTROL;
-	} else {
-		data->rts = (controlbits & TIOCM_RTS) ? SP_RTS_ON : SP_RTS_OFF;
-		data->cts = SP_CTS_IGNORE;
+	if (!(data = malloc(get_termios_size())))
+		RETURN_ERROR(SP_ERR_MEM, "termios malloc failed");
+
+	if (ioctl(fd, get_termios_get_ioctl(), data) < 0) {
+		free(data);
+		RETURN_FAIL("getting termios failed");
 	}
 
-	data->dtr = (controlbits & TIOCM_DTR) ? SP_DTR_ON : SP_DTR_OFF;
-	data->dsr = SP_DSR_IGNORE;
-#endif
-	return SP_OK;
+	*baudrate = get_termios_speed(data);
+
+	free(data);
+
+	RETURN_OK();
 }
 
-static int set_baudrate(struct sp_port_data *data, int baudrate)
+static enum sp_return set_baudrate(int fd, int baudrate)
 {
-#ifdef _WIN32
-	switch (baudrate) {
-	/*
-	 * The baudrates 50/75/134/150/200/1800/230400/460800 do not seem to
-	 * have documented CBR_* macros.
-	 */
-	case 110:
-		data->dcb.BaudRate = CBR_110;
-		break;
-	case 300:
-		data->dcb.BaudRate = CBR_300;
-		break;
-	case 600:
-		data->dcb.BaudRate = CBR_600;
-		break;
-	case 1200:
-		data->dcb.BaudRate = CBR_1200;
-		break;
-	case 2400:
-		data->dcb.BaudRate = CBR_2400;
-		break;
-	case 4800:
-		data->dcb.BaudRate = CBR_4800;
-		break;
-	case 9600:
-		data->dcb.BaudRate = CBR_9600;
-		break;
-	case 14400:
-		data->dcb.BaudRate = CBR_14400; /* Not available on Unix? */
-		break;
-	case 19200:
-		data->dcb.BaudRate = CBR_19200;
-		break;
-	case 38400:
-		data->dcb.BaudRate = CBR_38400;
-		break;
-	case 57600:
-		data->dcb.BaudRate = CBR_57600;
-		break;
-	case 115200:
-		data->dcb.BaudRate = CBR_115200;
-		break;
-	case 128000:
-		data->dcb.BaudRate = CBR_128000; /* Not available on Unix? */
-		break;
-	case 256000:
-		data->dcb.BaudRate = CBR_256000; /* Not available on Unix? */
-		break;
-	default:
-		return SP_ERR_ARG;
-	}
-#else
-	speed_t baud;
-	switch (baudrate) {
-	case 50:
-		baud = B50;
-		break;
-	case 75:
-		baud = B75;
-		break;
-	case 110:
-		baud = B110;
-		break;
-	case 134:
-		baud = B134;
-		break;
-	case 150:
-		baud = B150;
-		break;
-	case 200:
-		baud = B200;
-		break;
-	case 300:
-		baud = B300;
-		break;
-	case 600:
-		baud = B600;
-		break;
-	case 1200:
-		baud = B1200;
-		break;
-	case 1800:
-		baud = B1800;
-		break;
-	case 2400:
-		baud = B2400;
-		break;
-	case 4800:
-		baud = B4800;
-		break;
-	case 9600:
-		baud = B9600;
-		break;
-	case 19200:
-		baud = B19200;
-		break;
-	case 38400:
-		baud = B38400;
-		break;
-	case 57600:
-		baud = B57600;
-		break;
-	case 115200:
-		baud = B115200;
-		break;
-	case 230400:
-		baud = B230400;
-		break;
-#if !defined(__APPLE__) && !defined(__OpenBSD__)
-	case 460800:
-		baud = B460800;
-		break;
-#endif
-	default:
-		return SP_ERR_ARG;
+	void *data;
+
+	TRACE("%d, %d", fd, baudrate);
+
+	DEBUG("Getting baud rate");
+
+	if (!(data = malloc(get_termios_size())))
+		RETURN_ERROR(SP_ERR_MEM, "termios malloc failed");
+
+	if (ioctl(fd, get_termios_get_ioctl(), data) < 0) {
+		free(data);
+		RETURN_FAIL("getting termios failed");
 	}
 
-	if (cfsetospeed(&data->term, baud) < 0)
-		return SP_ERR_FAIL;
+	DEBUG("Setting baud rate");
 
-	if (cfsetispeed(&data->term, baud) < 0)
-		return SP_ERR_FAIL;
+	set_termios_speed(data, baudrate);
 
-#endif
-	return SP_OK;
+	if (ioctl(fd, get_termios_set_ioctl(), data) < 0) {
+		free(data);
+		RETURN_FAIL("setting termios failed");
+	}
+
+	free(data);
+
+	RETURN_OK();
 }
 
-static int set_bits(struct sp_port_data *data, int bits)
+#ifdef USE_TERMIOX
+static enum sp_return get_flow(int fd, int *flow)
 {
-#ifdef _WIN32
-	data->dcb.ByteSize = bits;
-#else
-	data->term.c_cflag &= ~CSIZE;
-	switch (bits) {
-	case 8:
-		data->term.c_cflag |= CS8;
-		break;
-	case 7:
-		data->term.c_cflag |= CS7;
-		break;
-	case 6:
-		data->term.c_cflag |= CS6;
-		break;
-	default:
-		return SP_ERR_ARG;
+	void *data;
+
+	TRACE("%d, %p", fd, flow);
+
+	DEBUG("Getting advanced flow control");
+
+	if (!(data = malloc(get_termiox_size())))
+		RETURN_ERROR(SP_ERR_MEM, "termiox malloc failed");
+
+	if (ioctl(fd, TCGETX, data) < 0) {
+		free(data);
+		RETURN_FAIL("getting termiox failed");
 	}
-#endif
-	return SP_OK;
+
+	*flow = get_termiox_flow(data);
+
+	free(data);
+
+	RETURN_OK();
 }
 
-static int set_parity(struct sp_port_data *data, int parity)
+static enum sp_return set_flow(int fd, int flow)
 {
-#ifdef _WIN32
-	switch (parity) {
-	/* Note: There's also SPACEPARITY, MARKPARITY (unneeded so far). */
-	case SP_PARITY_NONE:
-		data->dcb.Parity = NOPARITY;
-		break;
-	case SP_PARITY_EVEN:
-		data->dcb.Parity = EVENPARITY;
-		break;
-	case SP_PARITY_ODD:
-		data->dcb.Parity = ODDPARITY;
-		break;
-	default:
-		return SP_ERR_ARG;
+	void *data;
+
+	TRACE("%d, %d", fd, flow);
+
+	DEBUG("Getting advanced flow control");
+
+	if (!(data = malloc(get_termiox_size())))
+		RETURN_ERROR(SP_ERR_MEM, "termiox malloc failed");
+
+	if (ioctl(fd, TCGETX, data) < 0) {
+		free(data);
+		RETURN_FAIL("getting termiox failed");
 	}
-#else
-	data->term.c_iflag &= ~IGNPAR;
-	data->term.c_cflag &= ~(PARENB | PARODD);
-	switch (parity) {
-	case SP_PARITY_NONE:
-		data->term.c_iflag |= IGNPAR;
-		break;
-	case SP_PARITY_EVEN:
-		data->term.c_cflag |= PARENB;
-		break;
-	case SP_PARITY_ODD:
-		data->term.c_cflag |= PARENB | PARODD;
-		break;
-	default:
-		return SP_ERR_ARG;
+
+	DEBUG("Setting advanced flow control");
+
+	set_termiox_flow(data, flow);
+
+	if (ioctl(fd, TCSETX, data) < 0) {
+		free(data);
+		RETURN_FAIL("setting termiox failed");
 	}
-#endif
-	return SP_OK;
+
+	free(data);
+
+	RETURN_OK();
 }
+#endif /* USE_TERMIOX */
+#endif /* __linux__ */
 
-static int set_stopbits(struct sp_port_data *data, int stopbits)
+static enum sp_return get_config(struct sp_port *port, struct port_data *data,
+	struct sp_port_config *config)
 {
+	unsigned int i;
+
+	TRACE("%p, %p, %p", port, data, config);
+
+	DEBUG("Getting configuration for port %s", port->name);
+
 #ifdef _WIN32
-	switch (stopbits) {
-	/* Note: There's also ONE5STOPBITS == 1.5 (unneeded so far). */
-	case 1:
-		data->dcb.StopBits = ONESTOPBIT;
+	if (!GetCommState(port->hdl, &data->dcb))
+		RETURN_FAIL("GetCommState() failed");
+
+	for (i = 0; i < NUM_STD_BAUDRATES; i++) {
+		if (data->dcb.BaudRate == std_baudrates[i].index) {
+			config->baudrate = std_baudrates[i].value;
+			break;
+		}
+	}
+
+	if (i == NUM_STD_BAUDRATES)
+		/* BaudRate field can be either an index or a custom baud rate. */
+		config->baudrate = data->dcb.BaudRate;
+
+	config->bits = data->dcb.ByteSize;
+
+	if (data->dcb.fParity)
+		switch (data->dcb.Parity) {
+		case NOPARITY:
+			config->parity = SP_PARITY_NONE;
+			break;
+		case ODDPARITY:
+			config->parity = SP_PARITY_ODD;
+			break;
+		case EVENPARITY:
+			config->parity = SP_PARITY_EVEN;
+			break;
+		case MARKPARITY:
+			config->parity = SP_PARITY_MARK;
+			break;
+		case SPACEPARITY:
+			config->parity = SP_PARITY_SPACE;
+			break;
+		default:
+			config->parity = -1;
+		}
+	else
+		config->parity = SP_PARITY_NONE;
+
+	switch (data->dcb.StopBits) {
+	case ONESTOPBIT:
+		config->stopbits = 1;
 		break;
-	case 2:
-		data->dcb.StopBits = TWOSTOPBITS;
+	case TWOSTOPBITS:
+		config->stopbits = 2;
 		break;
 	default:
-		return SP_ERR_ARG;
+		config->stopbits = -1;
 	}
-#else
-	data->term.c_cflag &= ~CSTOPB;
-	switch (stopbits) {
-	case 1:
-		data->term.c_cflag &= ~CSTOPB;
+
+	switch (data->dcb.fRtsControl) {
+	case RTS_CONTROL_DISABLE:
+		config->rts = SP_RTS_OFF;
+		break;
+	case RTS_CONTROL_ENABLE:
+		config->rts = SP_RTS_ON;
 		break;
-	case 2:
-		data->term.c_cflag |= CSTOPB;
+	case RTS_CONTROL_HANDSHAKE:
+		config->rts = SP_RTS_FLOW_CONTROL;
 		break;
 	default:
-		return SP_ERR_ARG;
+		config->rts = -1;
 	}
-#endif
-	return SP_OK;
-}
 
-static int set_rts(struct sp_port_data *data, int rts)
-{
-#ifdef _WIN32
-	switch (rts) {
-	case SP_RTS_OFF:
-		data->dcb.fRtsControl = RTS_CONTROL_DISABLE;
+	config->cts = data->dcb.fOutxCtsFlow ? SP_CTS_FLOW_CONTROL : SP_CTS_IGNORE;
+
+	switch (data->dcb.fDtrControl) {
+	case DTR_CONTROL_DISABLE:
+		config->dtr = SP_DTR_OFF;
 		break;
-	case SP_RTS_ON:
-		data->dcb.fRtsControl = RTS_CONTROL_ENABLE;
+	case DTR_CONTROL_ENABLE:
+		config->dtr = SP_DTR_ON;
 		break;
-	case SP_RTS_FLOW_CONTROL:
-		data->dcb.fRtsControl = RTS_CONTROL_HANDSHAKE;
+	case DTR_CONTROL_HANDSHAKE:
+		config->dtr = SP_DTR_FLOW_CONTROL;
 		break;
 	default:
-		return SP_ERR_ARG;
+		config->dtr = -1;
+	}
+
+	config->dsr = data->dcb.fOutxDsrFlow ? SP_DSR_FLOW_CONTROL : SP_DSR_IGNORE;
+
+	if (data->dcb.fInX) {
+		if (data->dcb.fOutX)
+			config->xon_xoff = SP_XONXOFF_INOUT;
+		else
+			config->xon_xoff = SP_XONXOFF_IN;
+	} else {
+		if (data->dcb.fOutX)
+			config->xon_xoff = SP_XONXOFF_OUT;
+		else
+			config->xon_xoff = SP_XONXOFF_DISABLED;
 	}
+
+#else // !_WIN32
+
+	if (tcgetattr(port->fd, &data->term) < 0)
+		RETURN_FAIL("tcgetattr() failed");
+
+	if (ioctl(port->fd, TIOCMGET, &data->controlbits) < 0)
+		RETURN_FAIL("TIOCMGET ioctl failed");
+
+#ifdef USE_TERMIOX
+	int ret = get_flow(port->fd, &data->flow);
+
+	if (ret == SP_ERR_FAIL && errno == EINVAL)
+		data->termiox_supported = 0;
+	else if (ret < 0)
+		RETURN_CODEVAL(ret);
+	else
+		data->termiox_supported = 1;
 #else
-	data->rts = rts;
+	data->termiox_supported = 0;
 #endif
-	return SP_OK;
-}
 
-static int set_cts(struct sp_port_data *data, int cts)
-{
-#ifdef _WIN32
-	switch (cts) {
-	case SP_CTS_IGNORE:
-		data->dcb.fOutxCtsFlow = FALSE;
-		break;
-	case SP_CTS_FLOW_CONTROL:
-		data->dcb.fOutxCtsFlow = TRUE;
-		break;
-	default:
-		return SP_ERR_ARG;
+	for (i = 0; i < NUM_STD_BAUDRATES; i++) {
+		if (cfgetispeed(&data->term) == std_baudrates[i].index) {
+			config->baudrate = std_baudrates[i].value;
+			break;
+		}
 	}
+
+	if (i == NUM_STD_BAUDRATES) {
+#ifdef __APPLE__
+		config->baudrate = (int)data->term.c_ispeed;
+#elif defined(__linux__)
+		TRY(get_baudrate(port->fd, &config->baudrate));
 #else
-	data->cts = cts;
+		config->baudrate = -1;
 #endif
-	return SP_OK;
-}
+	}
 
-static int set_dtr(struct sp_port_data *data, int dtr)
-{
-#ifdef _WIN32
-	switch (dtr) {
-	case SP_DTR_OFF:
-		data->dcb.fDtrControl = DTR_CONTROL_DISABLE;
+	switch (data->term.c_cflag & CSIZE) {
+	case CS8:
+		config->bits = 8;
 		break;
-	case SP_DTR_ON:
-		data->dcb.fDtrControl = DTR_CONTROL_ENABLE;
+	case CS7:
+		config->bits = 7;
 		break;
-	case SP_DTR_FLOW_CONTROL:
-		data->dcb.fDtrControl = DTR_CONTROL_HANDSHAKE;
+	case CS6:
+		config->bits = 6;
+		break;
+	case CS5:
+		config->bits = 5;
 		break;
 	default:
-		return SP_ERR_ARG;
+		config->bits = -1;
+	}
+
+	if (!(data->term.c_cflag & PARENB) && (data->term.c_iflag & IGNPAR))
+		config->parity = SP_PARITY_NONE;
+	else if (!(data->term.c_cflag & PARENB) || (data->term.c_iflag & IGNPAR))
+		config->parity = -1;
+	else if (data->term.c_cflag & CMSPAR)
+		config->parity = (data->term.c_cflag & PARODD) ? SP_PARITY_MARK : SP_PARITY_SPACE;
+	else
+		config->parity = (data->term.c_cflag & PARODD) ? SP_PARITY_ODD : SP_PARITY_EVEN;
+
+	config->stopbits = (data->term.c_cflag & CSTOPB) ? 2 : 1;
+
+	if (data->term.c_cflag & CRTSCTS) {
+		config->rts = SP_RTS_FLOW_CONTROL;
+		config->cts = SP_CTS_FLOW_CONTROL;
+	} else {
+		if (data->termiox_supported && data->flow & RTS_FLOW)
+			config->rts = SP_RTS_FLOW_CONTROL;
+		else
+			config->rts = (data->controlbits & TIOCM_RTS) ? SP_RTS_ON : SP_RTS_OFF;
+
+		config->cts = (data->termiox_supported && data->flow & CTS_FLOW) ?
+			SP_CTS_FLOW_CONTROL : SP_CTS_IGNORE;
+	}
+
+	if (data->termiox_supported && data->flow & DTR_FLOW)
+		config->dtr = SP_DTR_FLOW_CONTROL;
+	else
+		config->dtr = (data->controlbits & TIOCM_DTR) ? SP_DTR_ON : SP_DTR_OFF;
+
+	config->dsr = (data->termiox_supported && data->flow & DSR_FLOW) ?
+		SP_DSR_FLOW_CONTROL : SP_DSR_IGNORE;
+
+	if (data->term.c_iflag & IXOFF) {
+		if (data->term.c_iflag & IXON)
+			config->xon_xoff = SP_XONXOFF_INOUT;
+		else
+			config->xon_xoff = SP_XONXOFF_IN;
+	} else {
+		if (data->term.c_iflag & IXON)
+			config->xon_xoff = SP_XONXOFF_OUT;
+		else
+			config->xon_xoff = SP_XONXOFF_DISABLED;
 	}
-#else
-	data->dtr = dtr;
 #endif
-	return SP_OK;
+
+	RETURN_OK();
 }
 
-static int set_dsr(struct sp_port_data *data, int dsr)
+static enum sp_return set_config(struct sp_port *port, struct port_data *data,
+	const struct sp_port_config *config)
 {
+	unsigned int i;
+#ifdef __APPLE__
+	BAUD_TYPE baud_nonstd;
+
+	baud_nonstd = B0;
+#endif
+#ifdef __linux__
+	int baud_nonstd = 0;
+#endif
+
+	TRACE("%p, %p, %p", port, data, config);
+
+	DEBUG("Setting configuration for port %s", port->name);
+
 #ifdef _WIN32
-	switch (dsr) {
-	case SP_DSR_IGNORE:
-		data->dcb.fOutxDsrFlow = FALSE;
-		break;
-	case SP_DSR_FLOW_CONTROL:
-		data->dcb.fOutxDsrFlow = TRUE;
-		break;
-	default:
-		return SP_ERR_ARG;
+	if (config->baudrate >= 0) {
+		for (i = 0; i < NUM_STD_BAUDRATES; i++) {
+			if (config->baudrate == std_baudrates[i].value) {
+				data->dcb.BaudRate = std_baudrates[i].index;
+				break;
+			}
+		}
+
+		if (i == NUM_STD_BAUDRATES)
+			data->dcb.BaudRate = config->baudrate;
 	}
+
+	if (config->bits >= 0)
+		data->dcb.ByteSize = config->bits;
+
+	if (config->parity >= 0) {
+		switch (config->parity) {
+		/* Note: There's also SPACEPARITY, MARKPARITY (unneeded so far). */
+		case SP_PARITY_NONE:
+			data->dcb.Parity = NOPARITY;
+			break;
+		case SP_PARITY_ODD:
+			data->dcb.Parity = ODDPARITY;
+			break;
+		case SP_PARITY_EVEN:
+			data->dcb.Parity = EVENPARITY;
+			break;
+		case SP_PARITY_MARK:
+			data->dcb.Parity = MARKPARITY;
+			break;
+		case SP_PARITY_SPACE:
+			data->dcb.Parity = SPACEPARITY;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid parity setting");
+		}
+	}
+
+	if (config->stopbits >= 0) {
+		switch (config->stopbits) {
+		/* Note: There's also ONE5STOPBITS == 1.5 (unneeded so far). */
+		case 1:
+			data->dcb.StopBits = ONESTOPBIT;
+			break;
+		case 2:
+			data->dcb.StopBits = TWOSTOPBITS;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid stop bit setting");
+		}
+	}
+
+	if (config->rts >= 0) {
+		switch (config->rts) {
+		case SP_RTS_OFF:
+			data->dcb.fRtsControl = RTS_CONTROL_DISABLE;
+			break;
+		case SP_RTS_ON:
+			data->dcb.fRtsControl = RTS_CONTROL_ENABLE;
+			break;
+		case SP_RTS_FLOW_CONTROL:
+			data->dcb.fRtsControl = RTS_CONTROL_HANDSHAKE;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid RTS setting");
+		}
+	}
+
+	if (config->cts >= 0) {
+		switch (config->cts) {
+		case SP_CTS_IGNORE:
+			data->dcb.fOutxCtsFlow = FALSE;
+			break;
+		case SP_CTS_FLOW_CONTROL:
+			data->dcb.fOutxCtsFlow = TRUE;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid CTS setting");
+		}
+	}
+
+	if (config->dtr >= 0) {
+		switch (config->dtr) {
+		case SP_DTR_OFF:
+			data->dcb.fDtrControl = DTR_CONTROL_DISABLE;
+			break;
+		case SP_DTR_ON:
+			data->dcb.fDtrControl = DTR_CONTROL_ENABLE;
+			break;
+		case SP_DTR_FLOW_CONTROL:
+			data->dcb.fDtrControl = DTR_CONTROL_HANDSHAKE;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid DTR setting");
+		}
+	}
+
+	if (config->dsr >= 0) {
+		switch (config->dsr) {
+		case SP_DSR_IGNORE:
+			data->dcb.fOutxDsrFlow = FALSE;
+			break;
+		case SP_DSR_FLOW_CONTROL:
+			data->dcb.fOutxDsrFlow = TRUE;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid DSR setting");
+		}
+	}
+
+	if (config->xon_xoff >= 0) {
+		switch (config->xon_xoff) {
+		case SP_XONXOFF_DISABLED:
+			data->dcb.fInX = FALSE;
+			data->dcb.fOutX = FALSE;
+			break;
+		case SP_XONXOFF_IN:
+			data->dcb.fInX = TRUE;
+			data->dcb.fOutX = FALSE;
+			break;
+		case SP_XONXOFF_OUT:
+			data->dcb.fInX = FALSE;
+			data->dcb.fOutX = TRUE;
+			break;
+		case SP_XONXOFF_INOUT:
+			data->dcb.fInX = TRUE;
+			data->dcb.fOutX = TRUE;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid XON/XOFF setting");
+		}
+	}
+
+	if (!SetCommState(port->hdl, &data->dcb))
+		RETURN_FAIL("SetCommState() failed");
+
+#else /* !_WIN32 */
+
+	int controlbits;
+
+	if (config->baudrate >= 0) {
+		for (i = 0; i < NUM_STD_BAUDRATES; i++) {
+			if (config->baudrate == std_baudrates[i].value) {
+				if (cfsetospeed(&data->term, std_baudrates[i].index) < 0)
+					RETURN_FAIL("cfsetospeed() failed");
+
+				if (cfsetispeed(&data->term, std_baudrates[i].index) < 0)
+					RETURN_FAIL("cfsetispeed() failed");
+				break;
+			}
+		}
+
+		/* Non-standard baud rate */
+		if (i == NUM_STD_BAUDRATES) {
+#ifdef __APPLE__
+			/* Set "dummy" baud rate. */
+			if (cfsetspeed(&data->term, B9600) < 0)
+				RETURN_FAIL("cfsetspeed() failed");
+			baud_nonstd = config->baudrate;
+#elif defined(__linux__)
+			baud_nonstd = 1;
 #else
-	data->dsr = dsr;
+			RETURN_ERROR(SP_ERR_SUPP, "Non-standard baudrate not supported");
 #endif
-	return SP_OK;
-}
+		}
+	}
 
-static int set_xon_xoff(struct sp_port_data *data, int xon_xoff)
-{
-#ifdef _WIN32
-	switch (xon_xoff) {
-	case SP_XONXOFF_DISABLED:
-		data->dcb.fInX = FALSE;
-		data->dcb.fOutX = FALSE;
-		break;
-	case SP_XONXOFF_IN:
-		data->dcb.fInX = TRUE;
-		data->dcb.fOutX = FALSE;
-		break;
-	case SP_XONXOFF_OUT:
-		data->dcb.fInX = FALSE;
-		data->dcb.fOutX = TRUE;
-		break;
-	case SP_XONXOFF_INOUT:
-		data->dcb.fInX = TRUE;
-		data->dcb.fOutX = TRUE;
-		break;
-	default:
-		return SP_ERR_ARG;
+	if (config->bits >= 0) {
+		data->term.c_cflag &= ~CSIZE;
+		switch (config->bits) {
+		case 8:
+			data->term.c_cflag |= CS8;
+			break;
+		case 7:
+			data->term.c_cflag |= CS7;
+			break;
+		case 6:
+			data->term.c_cflag |= CS6;
+			break;
+		case 5:
+			data->term.c_cflag |= CS5;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid data bits setting");
+		}
 	}
-#else
-	data->term.c_iflag &= ~(IXON | IXOFF | IXANY);
-	switch (xon_xoff) {
-	case SP_XONXOFF_DISABLED:
-		break;
-	case SP_XONXOFF_IN:
-		data->term.c_iflag |= IXOFF;
-		break;
-	case SP_XONXOFF_OUT:
-		data->term.c_iflag |= IXON | IXANY;
-		break;
-	case SP_XONXOFF_INOUT:
-		data->term.c_iflag |= IXON | IXOFF | IXANY;
-		break;
-	default:
-		return SP_ERR_ARG;
+
+	if (config->parity >= 0) {
+		data->term.c_iflag &= ~IGNPAR;
+		data->term.c_cflag &= ~(PARENB | PARODD | CMSPAR);
+		switch (config->parity) {
+		case SP_PARITY_NONE:
+			data->term.c_iflag |= IGNPAR;
+			break;
+		case SP_PARITY_EVEN:
+			data->term.c_cflag |= PARENB;
+			break;
+		case SP_PARITY_ODD:
+			data->term.c_cflag |= PARENB | PARODD;
+			break;
+		case SP_PARITY_MARK:
+			data->term.c_cflag |= PARENB | PARODD | CMSPAR;
+			break;
+		case SP_PARITY_SPACE:
+			data->term.c_cflag |= PARENB | CMSPAR;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid parity setting");
+		}
+	}
+
+	if (config->stopbits >= 0) {
+		data->term.c_cflag &= ~CSTOPB;
+		switch (config->stopbits) {
+		case 1:
+			data->term.c_cflag &= ~CSTOPB;
+			break;
+		case 2:
+			data->term.c_cflag |= CSTOPB;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid stop bits setting");
+		}
 	}
+
+	if (config->rts >= 0 || config->cts >= 0) {
+		if (data->termiox_supported) {
+			data->flow &= ~(RTS_FLOW | CTS_FLOW);
+			switch (config->rts) {
+			case SP_RTS_OFF:
+			case SP_RTS_ON:
+				controlbits = TIOCM_RTS;
+				if (ioctl(port->fd, config->rts == SP_RTS_ON ? TIOCMBIS : TIOCMBIC, &controlbits) < 0)
+					RETURN_FAIL("Setting RTS signal level failed");
+				break;
+			case SP_RTS_FLOW_CONTROL:
+				data->flow |= RTS_FLOW;
+				break;
+			default:
+				break;
+			}
+			if (config->cts == SP_CTS_FLOW_CONTROL)
+				data->flow |= CTS_FLOW;
+
+			if (data->flow & (RTS_FLOW | CTS_FLOW))
+				data->term.c_iflag |= CRTSCTS;
+			else
+				data->term.c_iflag &= ~CRTSCTS;
+		} else {
+			/* Asymmetric use of RTS/CTS not supported. */
+			if (data->term.c_iflag & CRTSCTS) {
+				/* Flow control can only be disabled for both RTS & CTS together. */
+				if (config->rts >= 0 && config->rts != SP_RTS_FLOW_CONTROL) {
+					if (config->cts != SP_CTS_IGNORE)
+						RETURN_ERROR(SP_ERR_SUPP, "RTS & CTS flow control must be disabled together");
+				}
+				if (config->cts >= 0 && config->cts != SP_CTS_FLOW_CONTROL) {
+					if (config->rts <= 0 || config->rts == SP_RTS_FLOW_CONTROL)
+						RETURN_ERROR(SP_ERR_SUPP, "RTS & CTS flow control must be disabled together");
+				}
+			} else {
+				/* Flow control can only be enabled for both RTS & CTS together. */
+				if (((config->rts == SP_RTS_FLOW_CONTROL) && (config->cts != SP_CTS_FLOW_CONTROL)) ||
+					((config->cts == SP_CTS_FLOW_CONTROL) && (config->rts != SP_RTS_FLOW_CONTROL)))
+					RETURN_ERROR(SP_ERR_SUPP, "RTS & CTS flow control must be enabled together");
+			}
+
+			if (config->rts >= 0) {
+				if (config->rts == SP_RTS_FLOW_CONTROL) {
+					data->term.c_iflag |= CRTSCTS;
+				} else {
+					controlbits = TIOCM_RTS;
+					if (ioctl(port->fd, config->rts == SP_RTS_ON ? TIOCMBIS : TIOCMBIC,
+							&controlbits) < 0)
+						RETURN_FAIL("Setting RTS signal level failed");
+				}
+			}
+		}
+	}
+
+	if (config->dtr >= 0 || config->dsr >= 0) {
+		if (data->termiox_supported) {
+			data->flow &= ~(DTR_FLOW | DSR_FLOW);
+			switch (config->dtr) {
+			case SP_DTR_OFF:
+			case SP_DTR_ON:
+				controlbits = TIOCM_DTR;
+				if (ioctl(port->fd, config->dtr == SP_DTR_ON ? TIOCMBIS : TIOCMBIC, &controlbits) < 0)
+					RETURN_FAIL("Setting DTR signal level failed");
+				break;
+			case SP_DTR_FLOW_CONTROL:
+				data->flow |= DTR_FLOW;
+				break;
+			default:
+				break;
+			}
+			if (config->dsr == SP_DSR_FLOW_CONTROL)
+				data->flow |= DSR_FLOW;
+		} else {
+			/* DTR/DSR flow control not supported. */
+			if (config->dtr == SP_DTR_FLOW_CONTROL || config->dsr == SP_DSR_FLOW_CONTROL)
+				RETURN_ERROR(SP_ERR_SUPP, "DTR/DSR flow control not supported");
+
+			if (config->dtr >= 0) {
+				controlbits = TIOCM_DTR;
+				if (ioctl(port->fd, config->dtr == SP_DTR_ON ? TIOCMBIS : TIOCMBIC,
+						&controlbits) < 0)
+					RETURN_FAIL("Setting DTR signal level failed");
+			}
+		}
+	}
+
+	if (config->xon_xoff >= 0) {
+		data->term.c_iflag &= ~(IXON | IXOFF | IXANY);
+		switch (config->xon_xoff) {
+		case SP_XONXOFF_DISABLED:
+			break;
+		case SP_XONXOFF_IN:
+			data->term.c_iflag |= IXOFF;
+			break;
+		case SP_XONXOFF_OUT:
+			data->term.c_iflag |= IXON | IXANY;
+			break;
+		case SP_XONXOFF_INOUT:
+			data->term.c_iflag |= IXON | IXOFF | IXANY;
+			break;
+		default:
+			RETURN_ERROR(SP_ERR_ARG, "Invalid XON/XOFF setting");
+		}
+	}
+
+	if (tcsetattr(port->fd, TCSANOW, &data->term) < 0)
+		RETURN_FAIL("tcsetattr() failed");
+
+#ifdef __APPLE__
+	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(). */
+		if (cfsetspeed(&data->term, baud_nonstd) < 0)
+			RETURN_FAIL("cfsetspeed() failed");
+	}
+#elif defined(__linux__)
+	if (baud_nonstd)
+		TRY(set_baudrate(port->fd, config->baudrate));
+#ifdef USE_TERMIOX
+	if (data->termiox_supported)
+		TRY(set_flow(port->fd, data->flow));
+#endif
 #endif
-	return SP_OK;
+
+#endif /* !_WIN32 */
+
+	RETURN_OK();
 }
 
-static int apply_config(struct sp_port *port, struct sp_port_data *data)
+enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 {
-#ifdef _WIN32
-	if (!SetCommState(port->hdl, &data->dcb))
-		return SP_ERR_FAIL;
-#else
-	int controlbits;
+	TRACE("%p", config_ptr);
+	struct sp_port_config *config;
+
+	if (!config_ptr)
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
+
+	*config_ptr = NULL;
 
-	/* Asymmetric use of RTS/CTS not supported yet. */
-	if ((data->rts == SP_RTS_FLOW_CONTROL) != (data->cts == SP_CTS_FLOW_CONTROL))
-		return SP_ERR_ARG;
+	if (!(config = malloc(sizeof(struct sp_port_config))))
+		RETURN_ERROR(SP_ERR_MEM, "config malloc failed");
 
-	/* DTR/DSR flow control not supported yet. */
-	if (data->dtr == SP_DTR_FLOW_CONTROL || data->dsr == SP_DSR_FLOW_CONTROL)
-		return SP_ERR_ARG;
+	config->baudrate = -1;
+	config->bits = -1;
+	config->parity = -1;
+	config->stopbits = -1;
+	config->rts = -1;
+	config->cts = -1;
+	config->dtr = -1;
+	config->dsr = -1;
 
-	if (data->rts == SP_RTS_FLOW_CONTROL)
-		data->term.c_iflag |= CRTSCTS;
+	*config_ptr = config;
+
+	RETURN_OK();
+}
+
+void sp_free_config(struct sp_port_config *config)
+{
+	TRACE("%p", config);
+
+	if (!config)
+		DEBUG("Null config");
 	else
-	{
-		controlbits = TIOCM_RTS;
-		if (ioctl(port->fd, data->rts == SP_RTS_ON ? TIOCMBIS : TIOCMBIC,
-				&controlbits) < 0)
-			return SP_ERR_FAIL;
+		free(config);
+
+	RETURN();
+}
+
+enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config)
+{
+	struct port_data data;
+
+	TRACE("%p, %p", port, config);
+
+	CHECK_OPEN_PORT();
+
+	if (!config)
+		RETURN_ERROR(SP_ERR_ARG, "Null config");
+
+	TRY(get_config(port, &data, config));
+
+	RETURN_OK();
+}
+
+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;
+
+	TRACE("%p, %p", port, config);
+
+	CHECK_OPEN_PORT();
+
+	if (!config)
+		RETURN_ERROR(SP_ERR_ARG, "Null config");
+
+	TRY(get_config(port, &data, &prev_config));
+	TRY(set_config(port, &data, config));
+
+	RETURN_OK();
+}
+
+#define CREATE_ACCESSORS(x, type) \
+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); \
+	CHECK_OPEN_PORT(); \
+	TRY(get_config(port, &data, &config)); \
+	config.x = x; \
+	TRY(set_config(port, &data, &config)); \
+	RETURN_OK(); \
+} \
+enum sp_return sp_get_config_##x(const struct sp_port_config *config, type *x) { \
+	TRACE("%p", config); \
+	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) { \
+	TRACE("%p, %d", config, x); \
+	if (!config) \
+		RETURN_ERROR(SP_ERR_ARG, "Null config"); \
+	config->x = x; \
+	RETURN_OK(); \
+}
+
+CREATE_ACCESSORS(baudrate, int)
+CREATE_ACCESSORS(bits, int)
+CREATE_ACCESSORS(parity, enum sp_parity)
+CREATE_ACCESSORS(stopbits, int)
+CREATE_ACCESSORS(rts, enum sp_rts)
+CREATE_ACCESSORS(cts, enum sp_cts)
+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)
+{
+	if (!config)
+		RETURN_ERROR(SP_ERR_ARG, "Null configuration");
+
+	if (flowcontrol > SP_FLOWCONTROL_DTRDSR)
+		RETURN_ERROR(SP_ERR_ARG, "Invalid flow control setting");
+
+	if (flowcontrol == SP_FLOWCONTROL_XONXOFF)
+		config->xon_xoff = SP_XONXOFF_INOUT;
+	else
+		config->xon_xoff = SP_XONXOFF_DISABLED;
+
+	if (flowcontrol == SP_FLOWCONTROL_RTSCTS) {
+		config->rts = SP_RTS_FLOW_CONTROL;
+		config->cts = SP_CTS_FLOW_CONTROL;
+	} else {
+		if (config->rts == SP_RTS_FLOW_CONTROL)
+			config->rts = SP_RTS_ON;
+		config->cts = SP_CTS_IGNORE;
 	}
 
-	controlbits = TIOCM_DTR;
-	if (ioctl(port->fd, data->dtr == SP_DTR_ON ? TIOCMBIS : TIOCMBIC,
-			&controlbits) < 0)
-		return SP_ERR_FAIL;
+	if (flowcontrol == SP_FLOWCONTROL_DTRDSR) {
+		config->dtr = SP_DTR_FLOW_CONTROL;
+		config->dsr = SP_DSR_FLOW_CONTROL;
+	} else {
+		if (config->dtr == SP_DTR_FLOW_CONTROL)
+			config->dtr = SP_DTR_ON;
+		config->dsr = SP_DSR_IGNORE;
+	}
 
-	/* Write the configured settings. */
-	if (tcsetattr(port->fd, TCSADRAIN, &data->term) < 0)
-		return SP_ERR_FAIL;
-#endif
-	return SP_OK;
+	RETURN_OK();
 }
 
-#define TRY(x) do { int ret = x; if (ret != SP_OK) return ret; } while (0)
-#define TRY_SET(x) do { if (config->x >= 0) TRY(set_##x(&data, config->x)); } while (0)
+enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol)
+{
+	struct port_data data;
+	struct sp_port_config config;
+
+	TRACE("%p, %d", port, flowcontrol);
+
+	CHECK_OPEN_PORT();
 
-int sp_set_config(struct sp_port *port, struct sp_port_config *config)
+	TRY(get_config(port, &data, &config));
+
+	TRY(sp_set_config_flowcontrol(&config, flowcontrol));
+
+	TRY(set_config(port, &data, &config));
+
+	RETURN_OK();
+}
+
+enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
 {
-	struct sp_port_data data;
+	TRACE("%p, %p", port, signals);
+
+	CHECK_OPEN_PORT();
 
-	TRY(start_config(port, &data));
-	TRY_SET(baudrate);
-	TRY_SET(bits);
-	TRY_SET(parity);
-	TRY_SET(stopbits);
-	TRY_SET(rts);
-	TRY_SET(cts);
-	TRY_SET(dtr);
-	TRY_SET(dsr);
-	TRY_SET(xon_xoff);
-	TRY(apply_config(port, &data));
+	if (!signals)
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
-	return SP_OK;
+	DEBUG("Getting control signals for port %s", port->name);
+
+	*signals = 0;
+#ifdef _WIN32
+	DWORD bits;
+	if (GetCommModemStatus(port->hdl, &bits) == 0)
+		RETURN_FAIL("GetCommModemStatus() failed");
+	if (bits & MS_CTS_ON)
+		*signals |= SP_SIG_CTS;
+	if (bits & MS_DSR_ON)
+		*signals |= SP_SIG_DSR;
+	if (bits & MS_RLSD_ON)
+		*signals |= SP_SIG_DCD;
+	if (bits & MS_RING_ON)
+		*signals |= SP_SIG_RI;
+#else
+	int bits;
+	if (ioctl(port->fd, TIOCMGET, &bits) < 0)
+		RETURN_FAIL("TIOCMGET ioctl failed");
+	if (bits & TIOCM_CTS)
+		*signals |= SP_SIG_CTS;
+	if (bits & TIOCM_DSR)
+		*signals |= SP_SIG_DSR;
+	if (bits & TIOCM_CAR)
+		*signals |= SP_SIG_DCD;
+	if (bits & TIOCM_RNG)
+		*signals |= SP_SIG_RI;
+#endif
+	RETURN_OK();
 }
 
-#define CREATE_SETTER(x) int sp_set_##x(struct sp_port *port, int x) { \
-	struct sp_port_data data; \
-	TRY(start_config(port, &data)); \
-	TRY(set_##x(&data, x)); \
-	TRY(apply_config(port, &data)); \
-	return SP_OK; \
+enum sp_return sp_start_break(struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	CHECK_OPEN_PORT();
+#ifdef _WIN32
+	if (SetCommBreak(port->hdl) == 0)
+		RETURN_FAIL("SetCommBreak() failed");
+#else
+	if (ioctl(port->fd, TIOCSBRK, 1) < 0)
+		RETURN_FAIL("TIOCSBRK ioctl failed");
+#endif
+
+	RETURN_OK();
 }
 
-CREATE_SETTER(baudrate)
-CREATE_SETTER(bits)
-CREATE_SETTER(parity)
-CREATE_SETTER(stopbits)
-CREATE_SETTER(rts)
-CREATE_SETTER(cts)
-CREATE_SETTER(dtr)
-CREATE_SETTER(dsr)
-CREATE_SETTER(xon_xoff)
+enum sp_return sp_end_break(struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	CHECK_OPEN_PORT();
+#ifdef _WIN32
+	if (ClearCommBreak(port->hdl) == 0)
+		RETURN_FAIL("ClearCommBreak() failed");
+#else
+	if (ioctl(port->fd, TIOCCBRK, 1) < 0)
+		RETURN_FAIL("TIOCCBRK ioctl failed");
+#endif
+
+	RETURN_OK();
+}
 
 int sp_last_error_code(void)
 {
+	TRACE("");
 #ifdef _WIN32
-	return GetLastError();
+	RETURN_VALUE("%d", GetLastError());
 #else
-	return errno;
+	RETURN_VALUE("%d", errno);
 #endif
 }
 
 char *sp_last_error_message(void)
 {
+	TRACE("");
+
 #ifdef _WIN32
 	LPVOID message;
 	DWORD error = GetLastError();
@@ -1004,17 +1846,41 @@ char *sp_last_error_message(void)
 		(LPTSTR) &message,
 		0, NULL );
 
-	return message;
+	RETURN_VALUE("%s", message);
 #else
-	return strerror(errno);
+	RETURN_VALUE("%s", strerror(errno));
 #endif
 }
 
 void sp_free_error_message(char *message)
 {
+	TRACE("%s", message);
+
 #ifdef _WIN32
 	LocalFree(message);
 #else
 	(void)message;
 #endif
+
+	RETURN();
+}
+
+void sp_set_debug_handler(void (*handler)(const char *format, ...))
+{
+	TRACE("%p", handler);
+
+	sp_debug_handler = handler;
+
+	RETURN();
+}
+
+void sp_default_debug_handler(const char *format, ...)
+{
+	va_list args;
+	va_start(args, format);
+	if (getenv("LIBSERIALPORT_DEBUG")) {
+		fputs("libserialport: ", stderr);
+		vfprintf(stderr, format, args);
+	}
+	va_end(args);
 }