Inherit from Serial and use software buffers for TX and RX. This allows the UART peripherals to operate in a IRQ driven mode. Overrides most (but not all) stdio functions as Serial did
BufferedSerial.cpp
00001 /** 00002 * @file BufferedSerial.cpp 00003 * @brief Software Buffer - Extends mbed Serial functionallity adding irq driven TX and RX 00004 * @author sam grove 00005 * @version 1.0 00006 * @see 00007 * 00008 * Copyright (c) 2013 00009 * 00010 * Licensed under the Apache License, Version 2.0 (the "License"); 00011 * you may not use this file except in compliance with the License. 00012 * You may obtain a copy of the License at 00013 * 00014 * http://www.apache.org/licenses/LICENSE-2.0 00015 * 00016 * Unless required by applicable law or agreed to in writing, software 00017 * distributed under the License is distributed on an "AS IS" BASIS, 00018 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00019 * See the License for the specific language governing permissions and 00020 * limitations under the License. 00021 */ 00022 00023 #include "BufferedSerial.h" 00024 #include <stdarg.h> 00025 00026 BufferedSerial::BufferedSerial(PinName tx, PinName rx, uint32_t buf_size, uint32_t tx_multiple, const char* name) 00027 : RawSerial(tx, rx) , _rxbuf(buf_size), _txbuf((uint32_t)(tx_multiple*buf_size)) 00028 { 00029 RawSerial::baud( 9600 ); 00030 00031 RawSerial::attach(this, &BufferedSerial::rxIrq, Serial::RxIrq); 00032 this->_buf_size = buf_size; 00033 this->_tx_multiple = tx_multiple; 00034 return; 00035 } 00036 00037 BufferedSerial::~BufferedSerial(void) 00038 { 00039 RawSerial::attach(NULL, RawSerial::RxIrq); 00040 RawSerial::attach(NULL, RawSerial::TxIrq); 00041 00042 return; 00043 } 00044 00045 int BufferedSerial::readable(void) 00046 { 00047 return _rxbuf.available(); // note: look if things are in the buffer 00048 } 00049 00050 int BufferedSerial::writeable(void) 00051 { 00052 return 1; // buffer allows overwriting by design, always true 00053 } 00054 00055 int BufferedSerial::getc(void) 00056 { 00057 return _rxbuf; 00058 } 00059 00060 int BufferedSerial::putc(int c) 00061 { 00062 _txbuf = (char)c; 00063 BufferedSerial::prime(); 00064 00065 return c; 00066 } 00067 00068 int BufferedSerial::puts(const char *s) 00069 { 00070 if (s != NULL) { 00071 const char* ptr = s; 00072 00073 while(*(ptr) != 0) { 00074 _txbuf = *(ptr++); 00075 } 00076 _txbuf = '\n'; // done per puts definition 00077 BufferedSerial::prime(); 00078 00079 return (ptr - s) + 1; 00080 } 00081 return 0; 00082 } 00083 00084 int BufferedSerial::printf(const char* format, ...) 00085 { 00086 char buffer[this->_buf_size]; 00087 memset(buffer,0,this->_buf_size); 00088 int r = 0; 00089 00090 va_list arg; 00091 va_start(arg, format); 00092 r = vsprintf(buffer, format, arg); 00093 // this may not hit the heap but should alert the user anyways 00094 if(r > this->_buf_size) { 00095 error("%s %d buffer overwrite (max_buf_size: %d exceeded: %d)!\r\n", __FILE__, __LINE__,this->_buf_size,r); 00096 va_end(arg); 00097 return 0; 00098 } 00099 va_end(arg); 00100 r = BufferedSerial::write(buffer, r); 00101 00102 return r; 00103 } 00104 00105 ssize_t BufferedSerial::write(const void *s, size_t length) 00106 { 00107 if (s != NULL && length > 0) { 00108 const char* ptr = (const char*)s; 00109 const char* end = ptr + length; 00110 00111 while (ptr != end) { 00112 _txbuf = *(ptr++); 00113 } 00114 BufferedSerial::prime(); 00115 00116 return ptr - (const char*)s; 00117 } 00118 return 0; 00119 } 00120 00121 00122 void BufferedSerial::rxIrq(void) 00123 { 00124 // read from the peripheral and make sure something is available 00125 if(serial_readable(&_serial)) { 00126 _rxbuf = serial_getc(&_serial); // if so load them into a buffer 00127 } 00128 00129 return; 00130 } 00131 00132 void BufferedSerial::txIrq(void) 00133 { 00134 // see if there is room in the hardware fifo and if something is in the software fifo 00135 while(serial_writable(&_serial)) { 00136 if(_txbuf.available()) { 00137 serial_putc(&_serial, (int)_txbuf.get()); 00138 } else { 00139 // disable the TX interrupt when there is nothing left to send 00140 RawSerial::attach(NULL, RawSerial::TxIrq); 00141 break; 00142 } 00143 } 00144 00145 return; 00146 } 00147 00148 void BufferedSerial::prime(void) 00149 { 00150 // if already busy then the irq will pick this up 00151 if(serial_writable(&_serial)) { 00152 RawSerial::attach(NULL, RawSerial::TxIrq); // make sure not to cause contention in the irq 00153 BufferedSerial::txIrq(); // only write to hardware in one place 00154 RawSerial::attach(this, &BufferedSerial::txIrq, RawSerial::TxIrq); 00155 } 00156 00157 return; 00158 } 00159 00160
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