Refactoring uart interface (#341)

* uart: Major cleanups
- Adds documentation to the uart API.
- Fixes a buffer overflow issue in `uart_receive`, where the maximum parameter was ignored.
- Splits the maximum length and bytes recieved variables in `uart_receive`.
- Downsizes the receive buffer to the minimum required, saving 16MiB of RAM at runtime.
- Refactors the POSIX and Win32 implementations of uart into separate files.
- Removes the unused `uart_{get,set}_parity` functions, which were not implemented on Win32.

uart/uart.h

@@ -0,0 +1,98 @@
+/*
+ * Generic uart / rs232/ serial port library
+ *
+ * Copyright (c) 2013, Roel Verdult
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holders nor the
+ * names of its contributors may be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * @file uart.h
+ */
+
+#ifndef _PM3_UART_H_
+#define _PM3_UART_H_
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef unsigned char byte_t;
+
+/* serial_port is declared as a void*, which you should cast to whatever type
+ * makes sense to your connection method. Both the posix and win32
+ * implementations define their own structs in place.
+ */
+typedef void* serial_port;
+
+/* Returned by uart_open if the serial port specified was invalid.
+ */
+#define INVALID_SERIAL_PORT (void*)(~1)
+
+/* Returned by uart_open if the serial port specified is in use by another
+ * process.
+ */
+#define CLAIMED_SERIAL_PORT (void*)(~2)
+
+/* Given a user-specified port name, connect to the port and return a structure
+ * used for future references to that port.
+ *
+ * On errors, this method returns INVALID_SERIAL_PORT or CLAIMED_SERIAL_PORT.
+ */
+serial_port uart_open(const char* pcPortName);
+
+/* Closes the given port.
+ */
+void uart_close(const serial_port sp);
+
+/* Reads from the given serial port for up to 30ms.
+ *   pbtRx: A pointer to a buffer for the returned data to be written to.
+ *   pszMaxRxLen: The maximum data size we want to be sent.
+ *   pszRxLen: The number of bytes that we were actually sent.
+ *
+ * Returns TRUE if any data was fetched, even if it was less than pszMaxRxLen.
+ *
+ * Returns FALSE if there was an error reading from the device. Note that a
+ * partial read may have completed into the buffer by the corresponding
+ * implementation, so pszRxLen should be checked to see if any data was written. 
+ */
+bool uart_receive(const serial_port sp, byte_t* pbtRx, size_t pszMaxRxLen, size_t* pszRxLen);
+
+/* Sends a buffer to a given serial port.
+ *   pbtTx: A pointer to a buffer containing the data to send.
+ *   szTxLen: The amount of data to be sent.
+ */
+bool uart_send(const serial_port sp, const byte_t* pbtTx, const size_t szTxLen);
+
+/* Sets the current speed of the serial port, in baud.
+ */
+bool uart_set_speed(serial_port sp, const uint32_t uiPortSpeed);
+
+/* Gets the current speed of the serial port, in baud.
+ */
+uint32_t uart_get_speed(const serial_port sp);
+
+#endif // _PM3_UART_H_
+