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ATParser.cpp
- Committer:
- geky
- Date:
- 2015-07-17
- Revision:
- 5:26bc9255b751
- Parent:
- 4:38acbd6f9d9e
- Child:
- 6:51f1171b5ebc
File content as of revision 5:26bc9255b751:
/* Copyright (c) 2015 ARM Limited * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * @section DESCRIPTION * * Parser for the AT command syntax * */ #include "ATParser.h" // This can be defined to assist in debugging #define AT_ECHO 1 // getc/putc handling with timeouts int ATParser::putc(char c) { Timer timer; timer.start(); while (true) { if (_serial->writeable()) return _serial->putc(c); if (timer.read_ms() > _timeout) return -1; } } int ATParser::getc() { Timer timer; timer.start(); while (true) { if (_serial->readable()) return _serial->getc(); if (timer.read_ms() > _timeout) return -1; } } void ATParser::flush() { while (_serial->readable()) _serial->getc(); } // getline/putline handling with timeouts/bounds checking bool ATParser::_putline(const char *line) { for (int i = 0; line[i]; i++) { if (putc(line[i]) < 0) return false; } // Finish with newline for (int i = 0; _delimiter[i]; i++) { if (putc(_delimiter[i]) < 0) return false; } #ifdef AT_ECHO printf("AT> %s\r\n", line); #endif return true; } bool ATParser::_getline(char *line, int size) { int i = 0; while (i < size) { int c = getc(); if (c < 0) return false; line[i++] = c; // Finish when we hit a newline if (memcmp(&line[i-_delim_size], _delimiter, _delim_size) == 0) { line[i-_delim_size] = 0; #ifdef AT_ECHO printf("AT< %s\r\n", line); #endif return true; } } // Ran out of space return false; } // Command parsing with line handling bool ATParser::vsend(const char *command, va_list args) { flush(); // Create and send command if (vsprintf(_buffer, command, args) < 0) return false; if (!_putline(_buffer)) return false; return true; } bool ATParser::vrecv(const char *response, va_list args) { // Iterate through each line in the expected response while (response[0]) { // Since response is const, we need to copy it into our buffer to // add the line's null terminator and clobber value matches with asterisks. // // We just use the beginning of the buffer to avoid unecessary allocations. int i = 0; int offset = 0; while (response[i]) { if (memcmp(&response[i+1-_delim_size], _delimiter, _delim_size) == 0) { i++; break; } else if (response[i] == '%' && response[i+1] != '%' && response[i+1] != '*') { _buffer[offset++] = '%'; _buffer[offset++] = '*'; i++; } else { _buffer[offset++] = response[i++]; } } // Scanf has very poor support for catching errors // fortunately, we can abuse the %n specifier to determine // if the entire string was matched. _buffer[offset++] = '%'; _buffer[offset++] = 'n'; _buffer[offset++] = 0; // To workaround scanf's lack of error reporting, we actually // make two passes. One checks the validity with the modified // format string that only stores the matched characters (%n). // The other reads in the actual matched values. // // We keep trying the match until we succeed or some other error // derails us. while (true) { // Recieve response if (!_getline(_buffer+offset, _buffer_size-offset)) return false; int count = -1; sscanf(_buffer+offset, _buffer, &count); // We only succeed if all characters in the response is matched if (count >= 0 && (_buffer+offset)[count] == 0) { // Reuse the front end of the buffer int j; for (j = 0; j < i; j++) { _buffer[j] = response[j]; } _buffer[j] = 0; // Store the found results vsscanf(_buffer+offset, _buffer, args); // Jump to next line and continue parsing response += i; break; } } } return true; } bool ATParser::vcommand(const char *command, const char *response, va_list args) { if (command) { if (!vsend(command, args)) return false; } if (response) { if (!vrecv(response, args)) return false; } return true; } // Mapping to vararg functions bool ATParser::send(const char *command, ...) { va_list args; va_start(args, command); bool res = vsend(command, args); va_end(args); return res; } bool ATParser::recv(const char *response, ...) { va_list args; va_start(args, response); bool res = vrecv(response, args); va_end(args); return res; } bool ATParser::command(const char *command, const char *response, ...) { va_list args; va_start(args, response); bool res = vcommand(command, response, args); va_end(args); return res; }