SerialBuffered.cpp

00001 /**
00002  * =============================================================================
00003  * LS-Y201 device driver class (Version 0.0.1)
00004  * Reference documents: LinkSprite JPEG Color Camera Serial UART Interface
00005  *                      January 2010
00006  * =============================================================================
00007  * Copyright (c) 2010 Shinichiro Nakamura (CuBeatSystems)
00008  *
00009  * Permission is hereby granted, free of charge, to any person obtaining a copy
00010  * of this software and associated documentation files (the "Software"), to deal
00011  * in the Software without restriction, including without limitation the rights
00012  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00013  * copies of the Software, and to permit persons to whom the Software is
00014  * furnished to do so, subject to the following conditions:
00015  * 
00016  * The above copyright notice and this permission notice shall be included in
00017  * all copies or substantial portions of the Software.
00018  *
00019  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00020  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00021  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00022  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00023  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00024  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00025  * THE SOFTWARE.
00026  * =============================================================================
00027  */
00028 
00029 #include <RawSerial.h>
00030 #include "mbed.h"
00031 #include "SerialBuffered.h"
00032 
00033 /**
00034  * Create a buffered serial class.
00035  *
00036  * @param tx A pin for transmit.
00037  * @param rx A pin for receive.
00038  */
00039 SerialBuffered::SerialBuffered(PinName tx, PinName rx) : RawSerial(tx, rx) {
00040     indexContentStart = 0;
00041     indexContentEnd = 0;
00042     timeout = 1;
00043     attach(this, &SerialBuffered::handleInterrupt);
00044 }
00045 
00046 /**
00047  * Destroy.
00048  */
00049 SerialBuffered::~SerialBuffered() {
00050 }
00051 
00052 /**
00053  * Set timeout for getc().
00054  *
00055  * @param ms milliseconds. (-1:Disable timeout)
00056  */
00057 void SerialBuffered::setTimeout(int ms) {
00058     timeout = ms;
00059 }
00060 
00061 /**
00062  * Read requested bytes.
00063  *
00064  * @param bytes A pointer to a buffer.
00065  * @param requested Length.
00066  *
00067  * @return Readed byte length.
00068  */
00069 size_t SerialBuffered::readBytes(uint8_t *bytes, size_t requested) {
00070     int i = 0;
00071     while (i < requested) {
00072         int c = getc();
00073         if (c < 0) {
00074             break;
00075         }
00076         bytes[i] = c;
00077         i++;
00078     }
00079     return i;
00080 }
00081 
00082 /**
00083  * Get a character.
00084  *
00085  * @return A character. (-1:timeout)
00086  */
00087 int SerialBuffered::getc() {
00088     timer.reset();
00089     timer.start();
00090     while (indexContentStart == indexContentEnd) {
00091         wait_ms(1);
00092         if ((timeout > 0) && (timer.read_ms() > timeout)) {
00093             /*
00094              * Timeout occured.
00095              */
00096             // printf("Timeout occured.\n");
00097             return EOF;
00098         }
00099     }
00100     timer.stop();
00101 
00102     uint8_t result = buffer[indexContentStart++];
00103     indexContentStart =  indexContentStart % BUFFERSIZE;
00104 
00105     return result;
00106 }
00107 
00108 /**
00109  * Returns 1 if there is a character available to read, 0 otherwise.
00110  */
00111 int SerialBuffered::readable() {
00112     return indexContentStart != indexContentEnd;
00113 }
00114 
00115 void SerialBuffered::handleInterrupt() {
00116     while (RawSerial::readable()) {
00117         if (indexContentStart == ((indexContentEnd + 1) % BUFFERSIZE)) {
00118             /*
00119              * Buffer overrun occured.
00120              */
00121             // printf("Buffer overrun occured.\n");
00122             RawSerial::getc();
00123         } else {
00124             buffer[indexContentEnd++] = RawSerial::getc();
00125             indexContentEnd = indexContentEnd % BUFFERSIZE;
00126         }
00127     }
00128 }