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 
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