Diff: platform/ATCmdParser.cpp

Revision:

167:e84263d55307

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/platform/ATCmdParser.cpp	Wed Jun 21 17:46:44 2017 +0100
@@ -0,0 +1,382 @@
+/* Copyright (c) 2017 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 "ATCmdParser.h"
+#include "mbed_poll.h"
+#include "mbed_debug.h"
+
+#ifdef LF
+#undef LF
+#define LF  10
+#else
+#define LF  10
+#endif
+
+#ifdef CR
+#undef CR
+#define CR  13
+#else
+#define CR  13
+#endif
+
+// getc/putc handling with timeouts
+int ATCmdParser::putc(char c)
+{
+    pollfh fhs;
+    fhs.fh = _fh;
+    fhs.events = POLLOUT;
+
+    int count = poll(&fhs, 1, _timeout);
+    if (count > 0 && (fhs.revents & POLLOUT)) {
+        return _fh->write(&c, 1) == 1 ? 0 : -1;
+    } else {
+        return -1;
+    }
+}
+
+int ATCmdParser::getc()
+{
+    pollfh fhs;
+    fhs.fh = _fh;
+    fhs.events = POLLIN;
+
+    int count = poll(&fhs, 1, _timeout);
+    if (count > 0 && (fhs.revents & POLLIN)) {
+        unsigned char ch;
+        return _fh->read(&ch, 1) == 1 ? ch : -1;
+    } else {
+        return -1;
+    }
+}
+
+void ATCmdParser::flush()
+{
+    while (_fh->readable()) {
+        unsigned char ch;
+        _fh->read(&ch, 1);
+    }
+}
+
+
+// read/write handling with timeouts
+int ATCmdParser::write(const char *data, int size)
+{
+    int i = 0;
+    for ( ; i < size; i++) {
+        if (putc(data[i]) < 0) {
+            return -1;
+        }
+    }
+    return i;
+}
+
+int ATCmdParser::read(char *data, int size)
+{
+    int i = 0;
+    for ( ; i < size; i++) {
+        int c = getc();
+        if (c < 0) {
+            return -1;
+        }
+        data[i] = c;
+    }
+    return i;
+}
+
+
+// printf/scanf handling
+int ATCmdParser::vprintf(const char *format, va_list args)
+{
+
+    if (vsprintf(_buffer, format, args) < 0) {
+        return false;
+    }
+
+    int i = 0;
+    for ( ; _buffer[i]; i++) {
+        if (putc(_buffer[i]) < 0) {
+            return -1;
+        }
+    }
+    return i;
+}
+
+int ATCmdParser::vscanf(const char *format, va_list args)
+{
+    // Since format 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 unnecessary allocations.
+    int i = 0;
+    int offset = 0;
+
+    while (format[i]) {
+        if (format[i] == '%' && format[i+1] != '%' && format[i+1] != '*') {
+            _buffer[offset++] = '%';
+            _buffer[offset++] = '*';
+            i++;
+        } else {
+            _buffer[offset++] = format[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.
+    int j = 0;
+
+    while (true) {
+        // Ran out of space
+        if (j+1 >= _buffer_size - offset) {
+            return false;
+        }
+        // Recieve next character
+        int c = getc();
+        if (c < 0) {
+            return -1;
+        }
+        _buffer[offset + j++] = c;
+        _buffer[offset + j] = 0;
+
+        // Check for match
+        int count = -1;
+        sscanf(_buffer+offset, _buffer, &count);
+
+        // We only succeed if all characters in the response are matched
+        if (count == j) {
+            // Store the found results
+            vsscanf(_buffer+offset, format, args);
+            return j;
+        }
+    }
+}
+
+
+// Command parsing with line handling
+bool ATCmdParser::vsend(const char *command, va_list args)
+{
+    // Create and send command
+    if (vsprintf(_buffer, command, args) < 0) {
+        return false;
+    }
+
+    for (int i = 0; _buffer[i]; i++) {
+        if (putc(_buffer[i]) < 0) {
+            return false;
+        }
+    }
+
+    // Finish with newline
+    for (size_t i = 0; _output_delimiter[i]; i++) {
+        if (putc(_output_delimiter[i]) < 0) {
+            return false;
+        }
+    }
+
+    debug_if(_dbg_on, "AT> %s\n", _buffer);
+    return true;
+}
+
+bool ATCmdParser::vrecv(const char *response, va_list args)
+{
+restart:
+    _aborted = false;
+    // 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 unnecessary allocations.
+        int i = 0;
+        int offset = 0;
+        bool whole_line_wanted = false;
+
+        while (response[i]) {
+            if (response[i] == '%' && response[i+1] != '%' && response[i+1] != '*') {
+                _buffer[offset++] = '%';
+                _buffer[offset++] = '*';
+                i++;
+            } else {
+                _buffer[offset++] = response[i++];
+                // Find linebreaks, taking care not to be fooled if they're in a %[^\n] conversion specification
+                if (response[i - 1] == '\n' && !(i >= 3 && response[i-3] == '[' && response[i-2] == '^')) {
+                    whole_line_wanted = true;
+                    break;
+                }
+            }
+        }
+
+        // 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;
+
+        debug_if(_dbg_on, "AT? %s\n", _buffer);
+        // 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.
+        int j = 0;
+
+        while (true) {
+            // Receive next character
+            int c = getc();
+            if (c < 0) {
+                debug_if(_dbg_on, "AT(Timeout)\n");
+                return false;
+            }
+            // Simplify newlines (borrowed from retarget.cpp)
+            if ((c == CR && _in_prev != LF) ||
+                (c == LF && _in_prev != CR)) {
+                _in_prev = c;
+                c = '\n';
+            } else if ((c == CR && _in_prev == LF) ||
+                       (c == LF && _in_prev == CR)) {
+                _in_prev = c;
+                // onto next character
+                continue;
+            } else {
+                _in_prev = c;
+            }
+            _buffer[offset + j++] = c;
+            _buffer[offset + j] = 0;
+
+            // Check for oob data
+            for (struct oob *oob = _oobs; oob; oob = oob->next) {
+                if ((unsigned)j == oob->len && memcmp(
+                        oob->prefix, _buffer+offset, oob->len) == 0) {
+                    debug_if(_dbg_on, "AT! %s\n", oob->prefix);
+                    oob->cb();
+
+                    if (_aborted) {
+                        debug_if(_dbg_on, "AT(Aborted)\n");
+                        return false;
+                    }
+                    // oob may have corrupted non-reentrant buffer,
+                    // so we need to set it up again
+                    goto restart;
+                }
+            }
+
+            // Check for match
+            int count = -1;
+            if (whole_line_wanted && c != '\n') {
+                // Don't attempt scanning until we get delimiter if they included it in format
+                // This allows recv("Foo: %s\n") to work, and not match with just the first character of a string
+                // (scanf does not itself match whitespace in its format string, so \n is not significant to it)
+            } else {
+                sscanf(_buffer+offset, _buffer, &count);
+            }
+
+            // We only succeed if all characters in the response are matched
+            if (count == j) {
+                debug_if(_dbg_on, "AT= %s\n", _buffer+offset);
+                // Reuse the front end of the buffer
+                memcpy(_buffer, response, i);
+                _buffer[i] = 0;
+
+                // Store the found results
+                vsscanf(_buffer+offset, _buffer, args);
+
+                // Jump to next line and continue parsing
+                response += i;
+                break;
+            }
+
+            // Clear the buffer when we hit a newline or ran out of space
+            // running out of space usually means we ran into binary data
+            if (c == '\n' || j+1 >= _buffer_size - offset) {
+                debug_if(_dbg_on, "AT< %s", _buffer+offset);
+                j = 0;
+            }
+        }
+    }
+
+    return true;
+}
+
+// Mapping to vararg functions
+int ATCmdParser::printf(const char *format, ...)
+{
+    va_list args;
+    va_start(args, format);
+    int res = vprintf(format, args);
+    va_end(args);
+    return res;
+}
+
+int ATCmdParser::scanf(const char *format, ...)
+{
+    va_list args;
+    va_start(args, format);
+    int res = vscanf(format, args);
+    va_end(args);
+    return res;
+}
+
+bool ATCmdParser::send(const char *command, ...)
+{
+    va_list args;
+    va_start(args, command);
+    bool res = vsend(command, args);
+    va_end(args);
+    return res;
+}
+
+bool ATCmdParser::recv(const char *response, ...)
+{
+    va_list args;
+    va_start(args, response);
+    bool res = vrecv(response, args);
+    va_end(args);
+    return res;
+}
+
+// oob registration
+void ATCmdParser::oob(const char *prefix, Callback<void()> cb)
+{
+    struct oob *oob = new struct oob;
+    oob->len = strlen(prefix);
+    oob->prefix = prefix;
+    oob->cb = cb;
+    oob->next = _oobs;
+    _oobs = oob;
+}
+
+void ATCmdParser::abort()
+{
+    _aborted = true;
+}