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ATParser.cpp@1:66a14afe650a, 2015-07-16 (annotated)
- Committer:
- geky
- Date:
- Thu Jul 16 20:42:44 2015 +0000
- Revision:
- 1:66a14afe650a
- Parent:
- 0:c741e144517c
- Child:
- 2:4d68f546861c
Worked around scanf's lack of error reporting; ; This required a rather roundabout method of performing two scanf passes, one with clobbered matches %n, and the other with the actual value matches.; ; Also the parser now scans multiple lines.
Who changed what in which revision?
User | Revision | Line number | New contents of line |
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geky | 0:c741e144517c | 1 | /* Copyright (c) 2015 ARM Limited |
geky | 0:c741e144517c | 2 | * |
geky | 0:c741e144517c | 3 | * Licensed under the Apache License, Version 2.0 (the "License"); |
geky | 0:c741e144517c | 4 | * you may not use this file except in compliance with the License. |
geky | 0:c741e144517c | 5 | * You may obtain a copy of the License at |
geky | 0:c741e144517c | 6 | * |
geky | 0:c741e144517c | 7 | * http://www.apache.org/licenses/LICENSE-2.0 |
geky | 0:c741e144517c | 8 | * |
geky | 0:c741e144517c | 9 | * Unless required by applicable law or agreed to in writing, software |
geky | 0:c741e144517c | 10 | * distributed under the License is distributed on an "AS IS" BASIS, |
geky | 0:c741e144517c | 11 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
geky | 0:c741e144517c | 12 | * See the License for the specific language governing permissions and |
geky | 0:c741e144517c | 13 | * limitations under the License. |
geky | 0:c741e144517c | 14 | * |
geky | 0:c741e144517c | 15 | * @section DESCRIPTION |
geky | 0:c741e144517c | 16 | * |
geky | 0:c741e144517c | 17 | * Parser for the AT command syntax |
geky | 0:c741e144517c | 18 | * |
geky | 0:c741e144517c | 19 | */ |
geky | 0:c741e144517c | 20 | |
geky | 0:c741e144517c | 21 | #include "ATParser.h" |
geky | 0:c741e144517c | 22 | #include <cstdarg> |
geky | 0:c741e144517c | 23 | |
geky | 0:c741e144517c | 24 | // This can be defined to assist in debugging |
geky | 1:66a14afe650a | 25 | //#define AT_ECHO 1 |
geky | 0:c741e144517c | 26 | |
geky | 0:c741e144517c | 27 | |
geky | 0:c741e144517c | 28 | // getc/putc handling with timeouts |
geky | 0:c741e144517c | 29 | int ATParser::_putc(char c) { |
geky | 0:c741e144517c | 30 | Timer timer; |
geky | 0:c741e144517c | 31 | timer.start(); |
geky | 0:c741e144517c | 32 | |
geky | 0:c741e144517c | 33 | while (true) { |
geky | 0:c741e144517c | 34 | if (_serial->writeable()) |
geky | 0:c741e144517c | 35 | return _serial->putc(c); |
geky | 0:c741e144517c | 36 | |
geky | 0:c741e144517c | 37 | if (timer.read_ms() > _timeout) |
geky | 0:c741e144517c | 38 | return -1; |
geky | 0:c741e144517c | 39 | } |
geky | 0:c741e144517c | 40 | } |
geky | 0:c741e144517c | 41 | |
geky | 0:c741e144517c | 42 | int ATParser::_getc() { |
geky | 0:c741e144517c | 43 | Timer timer; |
geky | 0:c741e144517c | 44 | timer.start(); |
geky | 0:c741e144517c | 45 | |
geky | 0:c741e144517c | 46 | while (true) { |
geky | 0:c741e144517c | 47 | if (_serial->readable()) |
geky | 0:c741e144517c | 48 | return _serial->getc(); |
geky | 0:c741e144517c | 49 | |
geky | 0:c741e144517c | 50 | if (timer.read_ms() > _timeout) |
geky | 0:c741e144517c | 51 | return -1; |
geky | 0:c741e144517c | 52 | } |
geky | 0:c741e144517c | 53 | } |
geky | 0:c741e144517c | 54 | |
geky | 0:c741e144517c | 55 | void ATParser::_flush() { |
geky | 0:c741e144517c | 56 | while (_serial->readable()) |
geky | 0:c741e144517c | 57 | _serial->getc(); |
geky | 0:c741e144517c | 58 | } |
geky | 0:c741e144517c | 59 | |
geky | 1:66a14afe650a | 60 | |
geky | 0:c741e144517c | 61 | // getline/putline handling with timeouts/bounds checking |
geky | 1:66a14afe650a | 62 | bool ATParser::_putline(const char *line) { |
geky | 0:c741e144517c | 63 | for (int i = 0; line[i]; i++) { |
geky | 0:c741e144517c | 64 | if (_putc(line[i]) < 0) |
geky | 0:c741e144517c | 65 | return false; |
geky | 0:c741e144517c | 66 | } |
geky | 0:c741e144517c | 67 | |
geky | 0:c741e144517c | 68 | // Finish with newline |
geky | 1:66a14afe650a | 69 | if (_putc('\r') < 0 || _putc('\n') < 0) |
geky | 0:c741e144517c | 70 | return false; |
geky | 0:c741e144517c | 71 | |
geky | 0:c741e144517c | 72 | #ifdef AT_ECHO |
geky | 0:c741e144517c | 73 | printf("AT> %s\r\n", line); |
geky | 0:c741e144517c | 74 | #endif |
geky | 1:66a14afe650a | 75 | |
geky | 0:c741e144517c | 76 | return true; |
geky | 0:c741e144517c | 77 | } |
geky | 0:c741e144517c | 78 | |
geky | 1:66a14afe650a | 79 | bool ATParser::_getline(char *line, int size) { |
geky | 1:66a14afe650a | 80 | int i = 0; |
geky | 1:66a14afe650a | 81 | |
geky | 1:66a14afe650a | 82 | while (i < size) { |
geky | 0:c741e144517c | 83 | int c = _getc(); |
geky | 0:c741e144517c | 84 | |
geky | 1:66a14afe650a | 85 | if (c < 0) |
geky | 1:66a14afe650a | 86 | return false; |
geky | 0:c741e144517c | 87 | |
geky | 1:66a14afe650a | 88 | // Finish when we hit a newline |
geky | 1:66a14afe650a | 89 | if (c == '\r' || c == '\n') { |
geky | 1:66a14afe650a | 90 | // Only handle newlines on \n |
geky | 1:66a14afe650a | 91 | if (c != '\n') |
geky | 1:66a14afe650a | 92 | continue; |
geky | 0:c741e144517c | 93 | |
geky | 1:66a14afe650a | 94 | line[i++] = 0; |
geky | 0:c741e144517c | 95 | #ifdef AT_ECHO |
geky | 0:c741e144517c | 96 | printf("AT< %s\r\n", line); |
geky | 0:c741e144517c | 97 | #endif |
geky | 0:c741e144517c | 98 | return true; |
geky | 0:c741e144517c | 99 | } |
geky | 0:c741e144517c | 100 | |
geky | 1:66a14afe650a | 101 | line[i++] = c; |
geky | 0:c741e144517c | 102 | } |
geky | 0:c741e144517c | 103 | |
geky | 0:c741e144517c | 104 | // Ran out of space |
geky | 0:c741e144517c | 105 | return false; |
geky | 1:66a14afe650a | 106 | } |
geky | 0:c741e144517c | 107 | |
geky | 0:c741e144517c | 108 | |
geky | 0:c741e144517c | 109 | bool ATParser::command(const char *command, const char *response, ...) { |
geky | 0:c741e144517c | 110 | va_list args; |
geky | 0:c741e144517c | 111 | va_start(args, response); |
geky | 0:c741e144517c | 112 | |
geky | 0:c741e144517c | 113 | _flush(); |
geky | 0:c741e144517c | 114 | |
geky | 0:c741e144517c | 115 | // Create and send command |
geky | 0:c741e144517c | 116 | if (vsprintf(_buffer, command, args) < 0 || |
geky | 0:c741e144517c | 117 | !_putline(_buffer)) { |
geky | 0:c741e144517c | 118 | va_end(args); |
geky | 0:c741e144517c | 119 | return false; |
geky | 0:c741e144517c | 120 | } |
geky | 0:c741e144517c | 121 | |
geky | 1:66a14afe650a | 122 | // Iterate through each line in the expected response |
geky | 1:66a14afe650a | 123 | while (response && response[0]) { |
geky | 1:66a14afe650a | 124 | // Since response is const, we need to copy it into our buffer to |
geky | 1:66a14afe650a | 125 | // add the line's null terminator and clobber value matches with asterisks. |
geky | 1:66a14afe650a | 126 | // |
geky | 1:66a14afe650a | 127 | // We just use the beginning of the buffer to avoid unecessary allocations. |
geky | 1:66a14afe650a | 128 | int i = 0; |
geky | 1:66a14afe650a | 129 | int offset = 0; |
geky | 1:66a14afe650a | 130 | |
geky | 1:66a14afe650a | 131 | while (response[i]) { |
geky | 1:66a14afe650a | 132 | // Only handle newlines on \n |
geky | 1:66a14afe650a | 133 | if (response[i] == '\n') { |
geky | 1:66a14afe650a | 134 | i++; |
geky | 1:66a14afe650a | 135 | break; |
geky | 1:66a14afe650a | 136 | } else if (response[i] == '\r') { |
geky | 1:66a14afe650a | 137 | i++; |
geky | 1:66a14afe650a | 138 | } else if (response[i] == '%' && |
geky | 1:66a14afe650a | 139 | response[i+1] != '%' && |
geky | 1:66a14afe650a | 140 | response[i+1] != '*') { |
geky | 1:66a14afe650a | 141 | i++; |
geky | 1:66a14afe650a | 142 | |
geky | 1:66a14afe650a | 143 | _buffer[offset++] = '%'; |
geky | 1:66a14afe650a | 144 | _buffer[offset++] = '*'; |
geky | 1:66a14afe650a | 145 | } else { |
geky | 1:66a14afe650a | 146 | _buffer[offset++] = response[i++]; |
geky | 1:66a14afe650a | 147 | } |
geky | 1:66a14afe650a | 148 | } |
geky | 1:66a14afe650a | 149 | |
geky | 1:66a14afe650a | 150 | // Scanf has very poor support for catching errors |
geky | 1:66a14afe650a | 151 | // fortunately, we can abuse the %n specifier to determine |
geky | 1:66a14afe650a | 152 | // if the entire string was matched. |
geky | 1:66a14afe650a | 153 | _buffer[offset++] = '%'; |
geky | 1:66a14afe650a | 154 | _buffer[offset++] = 'n'; |
geky | 1:66a14afe650a | 155 | _buffer[offset++] = 0; |
geky | 1:66a14afe650a | 156 | |
geky | 1:66a14afe650a | 157 | // To workaround scanf's lack of error reporting, we actually |
geky | 1:66a14afe650a | 158 | // make two passes. One checks the validity with the modified |
geky | 1:66a14afe650a | 159 | // format string that only stores the matched characters (%n). |
geky | 1:66a14afe650a | 160 | // The other reads in the actual matched values. |
geky | 1:66a14afe650a | 161 | // |
geky | 1:66a14afe650a | 162 | // We keep trying the match until we succeed or some other error |
geky | 1:66a14afe650a | 163 | // derails us. |
geky | 1:66a14afe650a | 164 | while (true) { |
geky | 1:66a14afe650a | 165 | // Recieve response |
geky | 1:66a14afe650a | 166 | if (!_getline(_buffer+offset, _buffer_size-offset)) { |
geky | 1:66a14afe650a | 167 | va_end(args); |
geky | 1:66a14afe650a | 168 | return false; |
geky | 1:66a14afe650a | 169 | } |
geky | 1:66a14afe650a | 170 | |
geky | 1:66a14afe650a | 171 | int count; |
geky | 1:66a14afe650a | 172 | sscanf(_buffer+offset, _buffer, &count); |
geky | 1:66a14afe650a | 173 | |
geky | 1:66a14afe650a | 174 | // We only succeed if all characters in the response is matched |
geky | 1:66a14afe650a | 175 | if ((_buffer+offset)[count] == 0) { |
geky | 1:66a14afe650a | 176 | // Reuse the front end of the buffer |
geky | 1:66a14afe650a | 177 | int j; |
geky | 1:66a14afe650a | 178 | for (j = 0; j < i; j++) { |
geky | 1:66a14afe650a | 179 | _buffer[j] = response[j]; |
geky | 1:66a14afe650a | 180 | } |
geky | 1:66a14afe650a | 181 | _buffer[j] = 0; |
geky | 1:66a14afe650a | 182 | |
geky | 1:66a14afe650a | 183 | // Store the found results |
geky | 1:66a14afe650a | 184 | vsscanf(_buffer+offset, _buffer, args); |
geky | 1:66a14afe650a | 185 | |
geky | 1:66a14afe650a | 186 | // Jump to next line and continue parsing |
geky | 1:66a14afe650a | 187 | response += i; |
geky | 1:66a14afe650a | 188 | break; |
geky | 1:66a14afe650a | 189 | } |
geky | 1:66a14afe650a | 190 | } |
geky | 0:c741e144517c | 191 | } |
geky | 0:c741e144517c | 192 | |
geky | 0:c741e144517c | 193 | va_end(args); |
geky | 0:c741e144517c | 194 | return true; |
geky | 0:c741e144517c | 195 | } |