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::attach(this, &BufferedSerial::rxIrq, Serial::RxIrq);
00030     this->_buf_size = buf_size;
00031     this->_tx_multiple = tx_multiple;   
00032     return;
00033 }
00034 
00035 BufferedSerial::~BufferedSerial(void)
00036 {
00037     RawSerial::attach(NULL, RawSerial::RxIrq);
00038     RawSerial::attach(NULL, RawSerial::TxIrq);
00039 
00040     return;
00041 }
00042 
00043 int BufferedSerial::readable(void)
00044 {
00045     return _rxbuf.available();  // note: look if things are in the buffer
00046 }
00047 
00048 int BufferedSerial::writeable(void)
00049 {
00050     return 1;   // buffer allows overwriting by design, always true
00051 }
00052 
00053 int BufferedSerial::getc(void)
00054 {
00055     return _rxbuf;
00056 }
00057 
00058 int BufferedSerial::putc(int c)
00059 {
00060     _txbuf = (char)c;
00061     BufferedSerial::prime();
00062 
00063     return c;
00064 }
00065 
00066 int BufferedSerial::puts(const char *s)
00067 {
00068     if (s != NULL) {
00069         const char* ptr = s;
00070     
00071         while(*(ptr) != 0) {
00072             _txbuf = *(ptr++);
00073         }
00074         _txbuf = '\n';  // done per puts definition
00075         BufferedSerial::prime();
00076     
00077         return (ptr - s) + 1;
00078     }
00079     return 0;
00080 }
00081 
00082 int BufferedSerial::printf(const char* format, ...)
00083 {
00084     char buffer[this->_buf_size];
00085     memset(buffer,0,this->_buf_size);
00086     int r = 0;
00087 
00088     va_list arg;
00089     va_start(arg, format);
00090     r = vsprintf(buffer, format, arg);
00091     // this may not hit the heap but should alert the user anyways
00092     if(r > this->_buf_size) {
00093         error("%s %d buffer overwrite (max_buf_size: %d exceeded: %d)!\r\n", __FILE__, __LINE__,this->_buf_size,r);
00094         va_end(arg);
00095         return 0;
00096     }
00097     va_end(arg);
00098     r = BufferedSerial::write(buffer, r);
00099 
00100     return r;
00101 }
00102 
00103 ssize_t BufferedSerial::write(const void *s, size_t length)
00104 {
00105     if (s != NULL && length > 0) {
00106         const char* ptr = (const char*)s;
00107         const char* end = ptr + length;
00108     
00109         while (ptr != end) {
00110             _txbuf = *(ptr++);
00111         }
00112         BufferedSerial::prime();
00113     
00114         return ptr - (const char*)s;
00115     }
00116     return 0;
00117 }
00118 
00119 
00120 void BufferedSerial::rxIrq(void)
00121 {
00122     // read from the peripheral and make sure something is available
00123     if(serial_readable(&_serial)) {
00124         _rxbuf = serial_getc(&_serial); // if so load them into a buffer
00125     }
00126 
00127     return;
00128 }
00129 
00130 void BufferedSerial::txIrq(void)
00131 {
00132     // see if there is room in the hardware fifo and if something is in the software fifo
00133     while(serial_writable(&_serial)) {
00134         if(_txbuf.available()) {
00135             serial_putc(&_serial, (int)_txbuf.get());
00136         } else {
00137             // disable the TX interrupt when there is nothing left to send
00138             RawSerial::attach(NULL, RawSerial::TxIrq);
00139             break;
00140         }
00141     }
00142 
00143     return;
00144 }
00145 
00146 void BufferedSerial::prime(void)
00147 {
00148     // if already busy then the irq will pick this up
00149     if(serial_writable(&_serial)) {
00150         RawSerial::attach(NULL, RawSerial::TxIrq);    // make sure not to cause contention in the irq
00151         BufferedSerial::txIrq();                // only write to hardware in one place
00152         RawSerial::attach(this, &BufferedSerial::txIrq, RawSerial::TxIrq);
00153     }
00154 
00155     return;
00156 }
00157 
00158