2 * This file is part of the libserialport project.
4 * Copyright (C) 2013 Martin Ling <martin-libserialport@earth.li>
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as
8 * published by the Free Software Foundation, either version 3 of the
9 * License, or (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * @mainpage libserialport API
26 * libserialport is a minimal library written in C that is intended to take
27 * care of the OS-specific details when writing software that uses serial ports.
29 * By writing your serial code to use libserialport, you enable it to work
30 * transparently on any platform supported by the library.
32 * The operations that are supported are:
34 * - @ref Enumeration (obtaining a list of serial ports on the system)
36 * - @ref Configuration (baud rate, parity, etc.)
37 * - @ref Signals (modem control lines, breaks, etc.)
41 * libserialport is an open source project released under the LGPL3+ license.
46 * The API is simple, and designed to be a minimal wrapper around the serial
47 * port support in each OS.
49 * Most functions take a pointer to a struct sp_port, which represents a serial
50 * port. These structures are always allocated and freed by the library, using
51 * the functions in the @ref Enumeration "Enumeration" section.
53 * Most functions have return type @ref sp_return and can return only four
54 * possible error values:
56 * - @ref SP_ERR_ARG means that a function was called with invalid
57 * arguments. This implies a bug in the caller. The arguments passed would
58 * be invalid regardless of the underlying OS or serial device involved.
60 * - @ref SP_ERR_FAIL means that the OS reported a failure. The error code or
61 * message provided by the OS can be obtained by calling sp_last_error_code()
62 * or sp_last_error_message().
64 * - @ref SP_ERR_SUPP indicates that there is no support for the requested
65 * operation in the current OS, driver or device. No error message is
66 * available from the OS in this case. There is either no way to request
67 * the operation in the first place, or libserialport does not know how to
68 * do so in the current version.
70 * - @ref SP_ERR_MEM indicates that a memory allocation failed.
72 * All of these error values are negative.
74 * Calls that succeed return @ref SP_OK, which is equal to zero. Some functions
75 * declared @ref sp_return can also return a positive value for a successful
76 * numeric result, e.g. sp_blocking_read() or sp_blocking_write().
79 #ifndef LIBSERIALPORT_LIBSERIALPORT_H
80 #define LIBSERIALPORT_LIBSERIALPORT_H
91 /* Package version macros (e.g. for conditional compilation). */
92 #define SP_PACKAGE_VERSION_MAJOR @SP_PACKAGE_VERSION_MAJOR@
93 #define SP_PACKAGE_VERSION_MINOR @SP_PACKAGE_VERSION_MINOR@
94 #define SP_PACKAGE_VERSION_MICRO @SP_PACKAGE_VERSION_MICRO@
95 #define SP_PACKAGE_VERSION_STRING "@SP_PACKAGE_VERSION@"
97 /* Library/libtool version macros (e.g. for conditional compilation). */
98 #define SP_LIB_VERSION_CURRENT @SP_LIB_VERSION_CURRENT@
99 #define SP_LIB_VERSION_REVISION @SP_LIB_VERSION_REVISION@
100 #define SP_LIB_VERSION_AGE @SP_LIB_VERSION_AGE@
101 #define SP_LIB_VERSION_STRING "@SP_LIB_VERSION@"
103 /** Return values. */
105 /** Operation completed successfully. */
107 /** Invalid arguments were passed to the function. */
109 /** A system error occured while executing the operation. */
111 /** A memory allocation failed while executing the operation. */
113 /** The requested operation is not supported by this system or device. */
117 /** Port access modes. */
119 /** Open port for read access. */
121 /** Open port for write access. */
125 /** Buffer selection. */
129 /** Output buffer. */
135 /** Parity settings. */
137 /** Special value to indicate setting should be left alone. */
138 SP_PARITY_INVALID = -1,
151 /** RTS pin behaviour. */
153 /** Special value to indicate setting should be left alone. */
159 /** RTS used for flow control. */
160 SP_RTS_FLOW_CONTROL = 2,
163 /** CTS pin behaviour. */
165 /** Special value to indicate setting should be left alone. */
169 /** CTS used for flow control. */
170 SP_CTS_FLOW_CONTROL = 1,
173 /** DTR pin behaviour. */
175 /** Special value to indicate setting should be left alone. */
181 /** DTR used for flow control. */
182 SP_DTR_FLOW_CONTROL = 2,
185 /** DSR pin behaviour. */
187 /** Special value to indicate setting should be left alone. */
191 /** DSR used for flow control. */
192 SP_DSR_FLOW_CONTROL = 1,
195 /** XON/XOFF flow control behaviour. */
197 /** Special value to indicate setting should be left alone. */
198 SP_XONXOFF_INVALID = -1,
199 /** XON/XOFF disabled. */
200 SP_XONXOFF_DISABLED = 0,
201 /** XON/XOFF enabled for input only. */
203 /** XON/XOFF enabled for output only. */
205 /** XON/XOFF enabled for input and output. */
206 SP_XONXOFF_INOUT = 3,
209 /** Standard flow control combinations. */
210 enum sp_flowcontrol {
211 /** No flow control. */
212 SP_FLOWCONTROL_NONE = 0,
213 /** Software flow control using XON/XOFF characters. */
214 SP_FLOWCONTROL_XONXOFF = 1,
215 /** Hardware flow control using RTS/CTS signals. */
216 SP_FLOWCONTROL_RTSCTS = 2,
217 /** Hardware flow control using DTR/DSR signals. */
218 SP_FLOWCONTROL_DTRDSR = 3,
221 /** Input signals. */
223 /** Clear to send. */
225 /** Data set ready. */
227 /** Data carrier detect. */
229 /** Ring indicator. */
235 * An opaque structure representing a serial port.
240 * @struct sp_port_config
241 * An opaque structure representing the configuration for a serial port.
243 struct sp_port_config;
246 @defgroup Enumeration Port enumeration
251 * Obtain a pointer to a new sp_port structure representing the named port.
253 * The user should allocate a variable of type "struct sp_port *" and pass a
254 * pointer to this to receive the result.
256 * The result should be freed after use by calling sp_free_port().
258 * If any error is returned, the variable pointed to by port_ptr will be set
259 * to NULL. Otherwise, it will be set to point to the newly allocated port.
261 * @return SP_OK upon success, a negative error code otherwise.
263 enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr);
266 * Free a port structure obtained from sp_get_port_by_name() or sp_copy_port().
268 void sp_free_port(struct sp_port *port);
271 * List the serial ports available on the system.
273 * The result obtained is an array of pointers to sp_port structures,
274 * terminated by a NULL. The user should allocate a variable of type
275 * "struct sp_port **" and pass a pointer to this to receive the result.
277 * The result should be freed after use by calling sp_free_port_list().
278 * If a port from the list is to be used after freeing the list, it must be
279 * copied first using sp_copy_port().
281 * If any error is returned, the variable pointed to by list_ptr will be set
282 * to NULL. Otherwise, it will be set to point to the newly allocated array.
284 * @return SP_OK upon success, a negative error code otherwise.
286 enum sp_return sp_list_ports(struct sp_port ***list_ptr);
289 * Make a new copy of a sp_port structure.
291 * The user should allocate a variable of type "struct sp_port *" and pass a
292 * pointer to this to receive the result.
294 * The copy should be freed after use by calling sp_free_port().
296 * If any error is returned, the variable pointed to by copy_ptr will be set
297 * to NULL. Otherwise, it will be set to point to the newly allocated copy.
299 * @return SP_OK upon success, a negative error code otherwise.
301 enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr);
304 * Free a port list obtained from sp_list_ports().
306 * This will also free all the sp_port structures referred to from the list;
307 * any that are to be retained must be copied first using sp_copy_port().
309 void sp_free_port_list(struct sp_port **ports);
313 * @defgroup Ports Opening, closing and querying ports
318 * Open the specified serial port.
320 * @param port Pointer to port structure.
321 * @param flags Flags to use when opening the serial port.
323 * @return SP_OK upon success, a negative error code otherwise.
325 enum sp_return sp_open(struct sp_port *port, enum sp_mode flags);
328 * Close the specified serial port.
330 * @return SP_OK upon success, a negative error code otherwise.
332 enum sp_return sp_close(struct sp_port *port);
335 * Get the name of a port.
337 * The name returned is whatever is normally used to refer to a port on the
338 * current operating system; e.g. for Windows it will usually be a "COMn"
339 * device name, and for Unix it will be a device path beginning with "/dev/".
341 * @param port Pointer to port structure.
343 * @return The port name, or NULL if an invalid port is passed. The name
344 * string is part of the port structure and may not be used after the
345 * port structure has been freed.
347 char *sp_get_port_name(const struct sp_port *port);
350 * Get the operating system handle for a port.
352 * The type of the handle depends on the operating system. On Unix based
353 * systems, the handle is a file descriptor of type "int". On Windows, the
354 * handle is of type "HANDLE". The user should allocate a variable of the
355 * appropriate type and pass a pointer to this to receive the result.
357 * To obtain a valid handle, the port must first be opened by calling
358 * sp_open() using the same port structure.
360 * After the port is closed or the port structure freed, the handle may
361 * no longer be valid.
363 * @warning This feature is provided so that programs may make use of
364 * OS-specific functionality where desired. Doing so obviously
365 * comes at a cost in portability. It also cannot be guaranteed
366 * that direct usage of the OS handle will not conflict with the
367 * library's own usage of the port. Be careful.
369 * @return SP_OK upon success, a negative error code otherwise.
371 enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr);
375 * @defgroup Configuration Setting port parameters
380 * Allocate a port configuration structure.
382 * The user should allocate a variable of type "struct sp_config *" and pass a
383 * pointer to this to receive the result. The variable will be updated to
384 * point to the new configuration structure. The structure is opaque and must
385 * be accessed via the functions provided.
387 * All parameters in the structure will be initialised to special values which
388 * are ignored by sp_set_config().
390 * The structure should be freed after use by calling sp_free_config().
392 * @param config_ptr Pointer to variable to receive result.
394 * @return SP_OK upon success, a negative error code otherwise.
396 enum sp_return sp_new_config(struct sp_port_config **config_ptr);
399 * Free a port configuration structure.
401 * @param config Pointer to configuration structure.
403 void sp_free_config(struct sp_port_config *config);
406 * Get the current configuration of the specified serial port.
408 * The user should allocate a configuration structure using sp_new_config()
409 * and pass this as the config parameter. The configuration structure will
410 * be updated with the port configuration.
412 * Any parameters that are configured with settings not recognised or
413 * supported by libserialport, will be set to special values that are
414 * ignored by sp_set_config().
416 * @return SP_OK upon success, a negative error code otherwise.
418 enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config);
421 * Set the configuration for the specified serial port.
423 * For each parameter in the configuration, there is a special value (usually
424 * -1, but see the documentation for each field). These values will be ignored
425 * and the corresponding setting left unchanged on the port.
427 * @return SP_OK upon success, a negative error code otherwise.
429 enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config);
432 * Set the baud rate for the specified serial port.
434 * @param port Pointer to port structure.
435 * @param baudrate Baud rate in bits per second.
437 * @return SP_OK upon success, a negative error code otherwise.
439 enum sp_return sp_set_baudrate(struct sp_port *port, int baudrate);
442 * Get the baud rate from a port configuration.
444 * The user should allocate a variable of type int and pass a pointer to this
445 * to receive the result.
447 * @param config Pointer to configuration structure.
448 * @param baudrate_ptr Pointer to variable to store result.
450 * @return SP_OK upon success, a negative error code otherwise.
452 enum sp_return sp_get_config_baudrate(const struct sp_port_config *config, int *baudrate_ptr);
455 * Set the baud rate in a port configuration.
457 * @param config Pointer to configuration structure.
458 * @param baudrate Baud rate in bits per second, or -1 to retain current setting.
460 * @return SP_OK upon success, a negative error code otherwise.
462 enum sp_return sp_set_config_baudrate(struct sp_port_config *config, int baudrate);
465 * Set the data bits for the specified serial port.
467 * @param port Pointer to port structure.
468 * @param bits Number of data bits.
470 * @return SP_OK upon success, a negative error code otherwise.
472 enum sp_return sp_set_bits(struct sp_port *port, int bits);
475 * Get the data bits from a port configuration.
477 * The user should allocate a variable of type int and pass a pointer to this
478 * to receive the result.
480 * @param config Pointer to configuration structure.
481 * @param bits_ptr Pointer to variable to store result.
483 * @return SP_OK upon success, a negative error code otherwise.
485 enum sp_return sp_get_config_bits(const struct sp_port_config *config, int *bits_ptr);
488 * Set the data bits in a port configuration.
490 * @param config Pointer to configuration structure.
491 * @param bits Number of data bits, or -1 to retain current setting.
493 * @return SP_OK upon success, a negative error code otherwise.
495 enum sp_return sp_set_config_bits(struct sp_port_config *config, int bits);
498 * Set the parity setting for the specified serial port.
500 * @param port Pointer to port structure.
501 * @param parity Parity setting.
503 * @return SP_OK upon success, a negative error code otherwise.
505 enum sp_return sp_set_parity(struct sp_port *port, enum sp_parity parity);
508 * Get the parity setting from a port configuration.
510 * The user should allocate a variable of type enum sp_parity and pass a pointer to this
511 * to receive the result.
513 * @param config Pointer to configuration structure.
514 * @param parity_ptr Pointer to variable to store result.
516 * @return SP_OK upon success, a negative error code otherwise.
518 enum sp_return sp_get_config_parity(const struct sp_port_config *config, enum sp_parity *parity_ptr);
521 * Set the parity setting in a port configuration.
523 * @param config Pointer to configuration structure.
524 * @param parity Parity setting, or -1 to retain current setting.
526 * @return SP_OK upon success, a negative error code otherwise.
528 enum sp_return sp_set_config_parity(struct sp_port_config *config, enum sp_parity parity);
531 * Set the stop bits for the specified serial port.
533 * @param port Pointer to port structure.
534 * @param stopbits Number of stop bits.
536 * @return SP_OK upon success, a negative error code otherwise.
538 enum sp_return sp_set_stopbits(struct sp_port *port, int stopbits);
541 * Get the stop bits from a port configuration.
543 * The user should allocate a variable of type int and pass a pointer to this
544 * to receive the result.
546 * @param config Pointer to configuration structure.
547 * @param stopbits_ptr Pointer to variable to store result.
549 * @return SP_OK upon success, a negative error code otherwise.
551 enum sp_return sp_get_config_stopbits(const struct sp_port_config *config, int *stopbits_ptr);
554 * Set the stop bits in a port configuration.
556 * @param config Pointer to configuration structure.
557 * @param stopbits Number of stop bits, or -1 to retain current setting.
559 * @return SP_OK upon success, a negative error code otherwise.
561 enum sp_return sp_set_config_stopbits(struct sp_port_config *config, int stopbits);
564 * Set the RTS pin behaviour for the specified serial port.
566 * @param port Pointer to port structure.
567 * @param rts RTS pin mode.
569 * @return SP_OK upon success, a negative error code otherwise.
571 enum sp_return sp_set_rts(struct sp_port *port, enum sp_rts rts);
574 * Get the RTS pin behaviour from a port configuration.
576 * The user should allocate a variable of type enum sp_rts and pass a pointer to this
577 * to receive the result.
579 * @param config Pointer to configuration structure.
580 * @param rts_ptr Pointer to variable to store result.
582 * @return SP_OK upon success, a negative error code otherwise.
584 enum sp_return sp_get_config_rts(const struct sp_port_config *config, enum sp_rts *rts_ptr);
587 * Set the RTS pin behaviour in a port configuration.
589 * @param config Pointer to configuration structure.
590 * @param rts RTS pin mode, or -1 to retain current setting.
592 * @return SP_OK upon success, a negative error code otherwise.
594 enum sp_return sp_set_config_rts(struct sp_port_config *config, enum sp_rts rts);
597 * Set the CTS pin behaviour for the specified serial port.
599 * @param port Pointer to port structure.
600 * @param cts CTS pin mode.
602 * @return SP_OK upon success, a negative error code otherwise.
604 enum sp_return sp_set_cts(struct sp_port *port, enum sp_cts cts);
607 * Get the CTS pin behaviour from a port configuration.
609 * The user should allocate a variable of type enum sp_cts and pass a pointer to this
610 * to receive the result.
612 * @param config Pointer to configuration structure.
613 * @param cts_ptr Pointer to variable to store result.
615 * @return SP_OK upon success, a negative error code otherwise.
617 enum sp_return sp_get_config_cts(const struct sp_port_config *config, enum sp_cts *cts_ptr);
620 * Set the CTS pin behaviour in a port configuration.
622 * @param config Pointer to configuration structure.
623 * @param cts CTS pin mode, or -1 to retain current setting.
625 * @return SP_OK upon success, a negative error code otherwise.
627 enum sp_return sp_set_config_cts(struct sp_port_config *config, enum sp_cts cts);
630 * Set the DTR pin behaviour for the specified serial port.
632 * @param port Pointer to port structure.
633 * @param dtr DTR pin mode.
635 * @return SP_OK upon success, a negative error code otherwise.
637 enum sp_return sp_set_dtr(struct sp_port *port, enum sp_dtr dtr);
640 * Get the DTR pin behaviour from a port configuration.
642 * The user should allocate a variable of type enum sp_dtr and pass a pointer to this
643 * to receive the result.
645 * @param config Pointer to configuration structure.
646 * @param dtr_ptr Pointer to variable to store result.
648 * @return SP_OK upon success, a negative error code otherwise.
650 enum sp_return sp_get_config_dtr(const struct sp_port_config *config, enum sp_dtr *dtr_ptr);
653 * Set the DTR pin behaviour in a port configuration.
655 * @param config Pointer to configuration structure.
656 * @param dtr DTR pin mode, or -1 to retain current setting.
658 * @return SP_OK upon success, a negative error code otherwise.
660 enum sp_return sp_set_config_dtr(struct sp_port_config *config, enum sp_dtr dtr);
663 * Set the DSR pin behaviour for the specified serial port.
665 * @param port Pointer to port structure.
666 * @param dsr DSR pin mode.
668 * @return SP_OK upon success, a negative error code otherwise.
670 enum sp_return sp_set_dsr(struct sp_port *port, enum sp_dsr dsr);
673 * Get the DSR pin behaviour from a port configuration.
675 * The user should allocate a variable of type enum sp_dsr and pass a pointer to this
676 * to receive the result.
678 * @param config Pointer to configuration structure.
679 * @param dsr_ptr Pointer to variable to store result.
681 * @return SP_OK upon success, a negative error code otherwise.
683 enum sp_return sp_get_config_dsr(const struct sp_port_config *config, enum sp_dsr *dsr_ptr);
686 * Set the DSR pin behaviour in a port configuration.
688 * @param config Pointer to configuration structure.
689 * @param dsr DSR pin mode, or -1 to retain current setting.
691 * @return SP_OK upon success, a negative error code otherwise.
693 enum sp_return sp_set_config_dsr(struct sp_port_config *config, enum sp_dsr dsr);
696 * Set the XON/XOFF configuration for the specified serial port.
698 * @param port Pointer to port structure.
699 * @param xon_xoff XON/XOFF mode.
701 * @return SP_OK upon success, a negative error code otherwise.
703 enum sp_return sp_set_xon_xoff(struct sp_port *port, enum sp_xonxoff xon_xoff);
706 * Get the XON/XOFF configuration from a port configuration.
708 * The user should allocate a variable of type enum sp_xonxoff and pass a pointer to this
709 * to receive the result.
711 * @param config Pointer to configuration structure.
712 * @param xon_xoff_ptr Pointer to variable to store result.
714 * @return SP_OK upon success, a negative error code otherwise.
716 enum sp_return sp_get_config_xon_xoff(const struct sp_port_config *config, enum sp_xonxoff *xon_xoff_ptr);
719 * Set the XON/XOFF configuration in a port configuration.
721 * @param config Pointer to configuration structure.
722 * @param xon_xoff XON/XOFF mode, or -1 to retain current setting.
724 * @return SP_OK upon success, a negative error code otherwise.
726 enum sp_return sp_set_config_xon_xoff(struct sp_port_config *config, enum sp_xonxoff xon_xoff);
729 * Set the flow control type in a port configuration.
731 * This function is a wrapper that sets the RTS, CTS, DTR, DSR and
732 * XON/XOFF settings as necessary for the specified flow control
733 * type. For more fine-grained control of these settings, use their
734 * individual configuration functions.
736 * @param config Pointer to configuration structure.
737 * @param flowcontrol Flow control setting to use.
739 * @return SP_OK upon success, a negative error code otherwise.
741 enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config, enum sp_flowcontrol flowcontrol);
744 * Set the flow control type for the specified serial port.
746 * This function is a wrapper that sets the RTS, CTS, DTR, DSR and
747 * XON/XOFF settings as necessary for the specified flow control
748 * type. For more fine-grained control of these settings, use their
749 * individual configuration functions.
751 * @param port Pointer to port structure.
752 * @param flowcontrol Flow control setting to use.
754 * @return SP_OK upon success, a negative error code otherwise.
756 enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol);
760 * @defgroup Data Reading, writing, and flushing data
765 * Read bytes from the specified serial port, blocking until complete.
767 * @warning If your program runs on Unix, defines its own signal handlers, and
768 * needs to abort blocking reads when these are called, then you
769 * should not use this function. It repeats system calls that return
770 * with EINTR. To be able to abort a read from a signal handler, you
771 * should implement your own blocking read using sp_nonblocking_read()
772 * together with a blocking method that makes sense for your program.
773 * E.g. you can obtain the file descriptor for an open port using
774 * sp_get_port_handle() and use this to call select() or pselect(),
775 * with appropriate arrangements to return if a signal is received.
777 * @param port Pointer to port structure.
778 * @param buf Buffer in which to store the bytes read.
779 * @param count Requested number of bytes to read.
780 * @param timeout Timeout in milliseconds, or zero to wait indefinitely.
782 * @return The number of bytes read on success, or a negative error code. If
783 * the number of bytes returned is less than that requested, the
784 * timeout was reached before the requested number of bytes was
785 * available. If timeout is zero, the function will always return
786 * either the requested number of bytes or a negative error code.
788 enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, unsigned int timeout);
791 * Read bytes from the specified serial port, without blocking.
793 * @param port Pointer to port structure.
794 * @param buf Buffer in which to store the bytes read.
795 * @param count Maximum number of bytes to read.
797 * @return The number of bytes read on success, or a negative error code. The
798 * number of bytes returned may be any number from zero to the maximum
799 * that was requested.
801 enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count);
804 * Write bytes to the specified serial port, blocking until complete.
806 * Note that this function only ensures that the accepted bytes have been
807 * written to the OS; they may be held in driver or hardware buffers and not
808 * yet physically transmitted. To check whether all written bytes have actually
809 * been transmitted, use the sp_output_waiting() function. To wait until all
810 * written bytes have actually been transmitted, use the sp_drain() function.
812 * @warning If your program runs on Unix, defines its own signal handlers, and
813 * needs to abort blocking writes when these are called, then you
814 * should not use this function. It repeats system calls that return
815 * with EINTR. To be able to abort a write from a signal handler, you
816 * should implement your own blocking write using sp_nonblocking_write()
817 * together with a blocking method that makes sense for your program.
818 * E.g. you can obtain the file descriptor for an open port using
819 * sp_get_port_handle() and use this to call select() or pselect(),
820 * with appropriate arrangements to return if a signal is received.
822 * @param port Pointer to port structure.
823 * @param buf Buffer containing the bytes to write.
824 * @param count Requested number of bytes to write.
825 * @param timeout Timeout in milliseconds, or zero to wait indefinitely.
827 * @return The number of bytes written on success, or a negative error code.
828 * If the number of bytes returned is less than that requested, the
829 * timeout was reached before the requested number of bytes was
830 * written. If timeout is zero, the function will always return
831 * either the requested number of bytes or a negative error code. In
832 * the event of an error there is no way to determine how many bytes
833 * were sent before the error occured.
835 enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t count, unsigned int timeout);
838 * Write bytes to the specified serial port, without blocking.
840 * Note that this function only ensures that the accepted bytes have been
841 * written to the OS; they may be held in driver or hardware buffers and not
842 * yet physically transmitted. To check whether all written bytes have actually
843 * been transmitted, use the sp_output_waiting() function. To wait until all
844 * written bytes have actually been transmitted, use the sp_drain() function.
846 * @param port Pointer to port structure.
847 * @param buf Buffer containing the bytes to write.
848 * @param count Maximum number of bytes to write.
850 * @return The number of bytes written on success, or a negative error code.
851 * The number of bytes returned may be any number from zero to the
852 * maximum that was requested.
854 enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_t count);
857 * Gets the number of bytes waiting in the input buffer.
859 * @param port Pointer to port structure.
861 * @return Number of bytes waiting on success, a negative error code otherwise.
863 enum sp_return sp_input_waiting(struct sp_port *port);
866 * Gets the number of bytes waiting in the output buffer.
868 * @param port Pointer to port structure.
870 * @return Number of bytes waiting on success, a negative error code otherwise.
872 enum sp_return sp_output_waiting(struct sp_port *port);
875 * Flush serial port buffers. Data in the selected buffer(s) is discarded.
877 * @param port Pointer to port structure.
878 * @param buffers Which buffer(s) to flush.
880 * @return SP_OK upon success, a negative error code otherwise.
882 enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers);
885 * Wait for buffered data to be transmitted.
887 * @warning If your program runs on Unix, defines its own signal handlers, and
888 * needs to abort draining the output buffer when when these are
889 * called, then you should not use this function. It repeats system
890 * calls that return with EINTR. To be able to abort a drain from a
891 * signal handler, you would need to implement your own blocking
892 * drain by polling the result of sp_output_waiting().
894 * @param port Pointer to port structure.
896 * @return SP_OK upon success, a negative error code otherwise.
898 enum sp_return sp_drain(struct sp_port *port);
902 * @defgroup Signals Port signalling operations
907 * Gets the status of the control signals for the specified port.
909 * The user should allocate a variable of type "enum sp_signal" and pass a
910 * pointer to this variable to receive the result. The result is a bitmask
911 * in which individual signals can be checked by bitwise OR with values of
912 * the sp_signal enum.
914 * @param port Pointer to port structure.
915 * @param signals Pointer to variable to receive result.
917 * @return SP_OK upon success, a negative error code otherwise.
919 enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals);
922 * Put the port transmit line into the break state.
924 * @param port Pointer to port structure.
926 * @return SP_OK upon success, a negative error code otherwise.
928 enum sp_return sp_start_break(struct sp_port *port);
931 * Take the port transmit line out of the break state.
933 * @param port Pointer to port structure.
935 * @return SP_OK upon success, a negative error code otherwise.
937 enum sp_return sp_end_break(struct sp_port *port);
941 * @defgroup Errors Obtaining error information
946 * Get the error code for a failed operation.
948 * In order to obtain the correct result, this function should be called
949 * straight after the failure, before executing any other system operations.
951 * @return The system's numeric code for the error that caused the last
954 int sp_last_error_code(void);
957 * Get the error message for a failed operation.
959 * In order to obtain the correct result, this function should be called
960 * straight after the failure, before executing other system operations.
962 * @return The system's message for the error that caused the last
963 * operation to fail. This string may be allocated by the function,
964 * and should be freed after use by calling sp_free_error_message().
966 char *sp_last_error_message(void);
969 * Free an error message returned by sp_last_error_message().
971 void sp_free_error_message(char *message);
974 * Set the handler function for library debugging messages.
976 * Debugging messages are generated by the library during each operation,
977 * to help in diagnosing problems. The handler will be called for each
978 * message. The handler can be set to NULL to ignore all debug messages.
980 * The handler function should accept a format string and variable length
981 * argument list, in the same manner as e.g. printf().
983 * The default handler is sp_default_debug_handler().
985 void sp_set_debug_handler(void (*handler)(const char *format, ...));
988 * Default handler function for library debugging messages.
990 * This function prints debug messages to the standard error stream if the
991 * environment variable LIBSERIALPORT_DEBUG is set. Otherwise, they are
994 void sp_default_debug_handler(const char *format, ...);