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/*
Copyright (c) 2013 Arduino LLC. All right reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "Bridge.h"
BridgeClass::BridgeClass(Stream &_stream) :
index(0), stream(_stream), started(false), max_retries(0) {
// Empty
}
void BridgeClass::begin() {
if (started)
return;
started = true;
// Wait for U-boot to finish startup
do {
dropAll();
delay(1000);
} while (stream.available()>0);
while (true) {
// Bridge interrupt:
// - Ask the bridge to close itself
uint8_t quit_cmd[] = {'X','X','X','X','X'};
max_retries = 1;
transfer(quit_cmd, 5);
// Bridge startup:
// - If the bridge is not running starts it safely
stream.print(CTRL_C);
delay(250);
stream.print(F("\n"));
delay(250);
stream.print(F("\n"));
delay(500);
// Wait for OpenWRT message
// "Press enter to activate console"
stream.print(F("run-bridge\n"));
delay(500);
dropAll();
// Reset the brigde to check if it is running
uint8_t cmd[] = {'X','X', '1','0','0'};
uint8_t res[1];
max_retries = 20;
uint16_t l = transfer(cmd, 5, res, 1);
if (l == TRANSFER_TIMEOUT) {
// Bridge didn't start...
// Maybe the board is starting-up?
// Wait and retry
delay(1000);
continue;
}
if (res[0] != 0)
while (true);
max_retries = 50;
return;
}
}
void BridgeClass::put(const char *key, const char *value) {
// TODO: do it in a more efficient way
String cmd = "D";
cmd += key;
cmd += "\xFE";
cmd += value;
transfer((uint8_t*)cmd.c_str(), cmd.length());
}
unsigned int BridgeClass::get(const char *key, uint8_t *value, unsigned int maxlen) {
uint8_t cmd[] = {'d'};
unsigned int l = transfer(cmd, 1, (uint8_t *)key, strlen(key), value, maxlen);
if (l < maxlen)
value[l] = 0; // Zero-terminate string
return l;
}
void BridgeClass::crcUpdate(uint8_t c) {
CRC = CRC ^ c;
CRC = (CRC >> 8) + (CRC << 8);
}
void BridgeClass::crcReset() {
CRC = 0xAAAA;
}
void BridgeClass::crcWrite() {
stream.write((char)(CRC >> 8));
stream.write((char)(CRC & 0xFF));
}
bool BridgeClass::crcCheck(uint16_t _CRC) {
return CRC == _CRC;
}
uint16_t BridgeClass::transfer(const uint8_t *buff1, uint16_t len1,
const uint8_t *buff2, uint16_t len2,
const uint8_t *buff3, uint16_t len3,
uint8_t *rxbuff, uint16_t rxlen)
{
uint16_t len = len1 + len2 + len3;
uint8_t retries = 0;
for ( ; retries<max_retries; retries++, delay(100), dropAll() /* Delay for retransmission */) {
// Send packet
crcReset();
stream.write((char)0xFF); // Start of packet (0xFF)
crcUpdate(0xFF);
stream.write((char)index); // Message index
crcUpdate(index);
stream.write((char)((len >> 8) & 0xFF)); // Message length (hi)
crcUpdate((len >> 8) & 0xFF);
stream.write((char)(len & 0xFF)); // Message length (lo)
crcUpdate(len & 0xFF);
for (uint16_t i=0; i<len1; i++) { // Payload
stream.write((char)buff1[i]);
crcUpdate(buff1[i]);
}
for (uint16_t i=0; i<len2; i++) { // Payload
stream.write((char)buff2[i]);
crcUpdate(buff2[i]);
}
for (uint16_t i=0; i<len3; i++) { // Payload
stream.write((char)buff3[i]);
crcUpdate(buff3[i]);
}
crcWrite(); // CRC
// Wait for ACK in 100ms
if (timedRead(100) != 0xFF)
continue;
crcReset();
crcUpdate(0xFF);
// Check packet index
if (timedRead(5) != index)
continue;
crcUpdate(index);
// Recv len
int lh = timedRead(5);
if (lh < 0)
continue;
crcUpdate(lh);
int ll = timedRead(5);
if (ll < 0)
continue;
crcUpdate(ll);
uint16_t l = lh;
l <<= 8;
l += ll;
// Recv data
for (uint16_t i=0; i<l; i++) {
int c = timedRead(5);
if (c < 0)
continue;
// Cut received data if rxbuffer is too small
if (i < rxlen)
rxbuff[i] = c;
crcUpdate(c);
}
// Check CRC
int crc_hi = timedRead(5);
if (crc_hi < 0)
continue;
int crc_lo = timedRead(5);
if (crc_lo < 0)
continue;
if (!crcCheck((crc_hi<<8)+crc_lo))
continue;
// Increase index
index++;
// Return bytes received
if (l > rxlen)
return rxlen;
return l;
}
// Max retries exceeded
return TRANSFER_TIMEOUT;
}
int BridgeClass::timedRead(unsigned int timeout) {
int c;
unsigned long _startMillis = millis();
do {
c = stream.read();
if (c >= 0) return c;
} while(millis() - _startMillis < timeout);
return -1; // -1 indicates timeout
}
void BridgeClass::dropAll() {
while (stream.available() > 0) {
stream.read();
}
}
// Bridge instance
#ifdef __AVR_ATmega32U4__
// Leonardo variants (where HardwareSerial is Serial1)
SerialBridgeClass Bridge(Serial1);
#else
SerialBridgeClass Bridge(Serial);
#endif
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