s
ATParser.cpp
- Committer:
- geky
- Date:
- 2015-07-16
- Revision:
- 1:66a14afe650a
- Parent:
- 0:c741e144517c
- Child:
- 2:4d68f546861c
File content as of revision 1:66a14afe650a:
/* 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" #include <cstdarg> // 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 if (_putc('\r') < 0 || _putc('\n') < 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; // Finish when we hit a newline if (c == '\r' || c == '\n') { // Only handle newlines on \n if (c != '\n') continue; line[i++] = 0; #ifdef AT_ECHO printf("AT< %s\r\n", line); #endif return true; } line[i++] = c; } // Ran out of space return false; } bool ATParser::command(const char *command, const char *response, ...) { va_list args; va_start(args, response); _flush(); // Create and send command if (vsprintf(_buffer, command, args) < 0 || !_putline(_buffer)) { va_end(args); return false; } // Iterate through each line in the expected response while (response && 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]) { // Only handle newlines on \n if (response[i] == '\n') { i++; break; } else if (response[i] == '\r') { i++; } else if (response[i] == '%' && response[i+1] != '%' && response[i+1] != '*') { i++; _buffer[offset++] = '%'; _buffer[offset++] = '*'; } 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)) { va_end(args); return false; } int count; sscanf(_buffer+offset, _buffer, &count); // We only succeed if all characters in the response is matched if ((_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; } } } va_end(args); return true; }