Module: Px4LogReader::LogFile

Defined in:
lib/px4_log_reader/log_file.rb

Constant Summary collapse

HEADER_MARKER = 
[0xA3,0x95]
HEADER_LENGTH = 
HEADER_MARKER.length + 1
FORMAT_DESCRIPTOR_TABLE = 
{ FORMAT_MESSAGE.type => FORMAT_MESSAGE }.freeze
@@debug = 
false

Class Method Summary collapse

Class Method Details

.enable_debug(enable) ⇒ Object 



43
44
45
 
# File 'lib/px4_log_reader/log_file.rb', line 43

def self.enable_debug( enable )
	@@debug = enable
end

.print_data(buffer) ⇒ Object 



202
203
204
205
206
207
208
209
210
211
212
213
214
 
# File 'lib/px4_log_reader/log_file.rb', line 202

def self.print_data( buffer )
	text = ''
	buffer.unpack( 'C*' ).each_with_index do |byte,count|
		if (count % 16) == 0
			text << "#{count/16}: "
		end
		text << ('%02X'%byte) << ' '
		if (((count+1) % 16) == 0)
			text << "\n"
		end
	end
	puts text
end

.read_descriptor(file, skip_corrupt = true, &block) ⇒ Object 



74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
 
# File 'lib/px4_log_reader/log_file.rb', line 74

def self.read_descriptor( file, skip_corrupt=true, &block )

	message_descriptor = nil
	offset             = nil

	begin

		descriptor_message, offset = read_message( file, FORMAT_DESCRIPTOR_TABLE, true, &block )

		if descriptor_message
			message_descriptor = Px4LogReader::MessageDescriptor.new
			message_descriptor.from_message( descriptor_message )
		end

	rescue Px4LogReader::InvalidDescriptorError => error

		puts "#{error.class}: #{error.message}"
		puts error.backtrace.join("\n")

		if skip_corrupt
			retry
		else
			raise error
		end

	rescue StandardError => error
		puts "#{error.class}: #{error.message}"
		puts error.backtrace.join("\n")
	end

	return message_descriptor, offset
end

.read_descriptors(file, descriptor_cache = nil, &block) ⇒ Object 



47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
 
# File 'lib/px4_log_reader/log_file.rb', line 47

def self.read_descriptors( file, descriptor_cache=nil, &block )

	message_descriptors = {}

	loop do

		message_descriptor, file_offset = read_descriptor( file )

		if message_descriptor
			if !message_descriptors.keys.include? message_descriptor.type
				message_descriptors[ message_descriptor.type ] = message_descriptor
				yield message_descriptor if block_given?
			end
		else
			break
		end

	end

	# If a cache filename was supplied, dump the descriptors to the cache
	if descriptor_cache
		descriptor_cache.write_descriptors( message_descriptors )
	end

	return message_descriptors
end

.read_message(file, message_descriptors, stop_on_no_match = false, &block) ⇒ Object 



107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
 
# File 'lib/px4_log_reader/log_file.rb', line 107

def self.read_message( file, message_descriptors, stop_on_no_match = false, &block )

	message = nil
	offset  = nil
	eof     = false

	while message.nil? && !eof do
		message_type, offset = read_message_header( file )
		eof                  = message_type.nil?

		if message_type

			message_descriptor = message_descriptors[ message_type ]

			yield offset if block_given?

			if message_descriptor

				message_data = file.read( message_descriptor.length - HEADER_LENGTH )
				print_data( message_data ) if @@debug
				message = message_descriptor.unpack_message( message_data )

			elsif stop_on_no_match

				# Seek back to the beginning of the header for the non-
				# matching message.
				file.seek( -1 * HEADER_LENGTH, IO::SEEK_CUR )
				break

			end
		end
	end

	return message, offset
end

.read_message_header(file) ⇒ Object

Read the next message header from the input stream. Returns the message type and current file offset. If no header is found, the returned message type is nil and the offset is the end of the file.



148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
 
# File 'lib/px4_log_reader/log_file.rb', line 148

def self.read_message_header( file )
	message_type = nil
	offset       = nil
	drop_count 	 = 0

	begin

		data   = file.read_nonblock( HEADER_MARKER.length )
		offset = file.pos

		if data && ( data.length == HEADER_MARKER.length )

			while !data.empty? && message_type.nil? do

				if ( byte = file.read_nonblock( 1 ) )
					data << byte
				end
				offset = file.pos

				if data.length >= ( HEADER_MARKER.length + 1 )

					unpacked_data = data.unpack('C*')
					
					if unpacked_data[ 0, HEADER_MARKER.length ] == HEADER_MARKER
						message_type = unpacked_data.last & 0xFF
					else
						data = data[1..-1]
						drop_count += 1
					end
				else
					data = []
				end

			end
		end

	rescue EOFError => error
		# Nothing to do.
	rescue StandardError => error
		puts error.message
		puts error.backtrace.join("\n")
	end

	return message_type, offset
end

.write_message(io, message) ⇒ Object 



195
196
197
198
199
 
# File 'lib/px4_log_reader/log_file.rb', line 195

def self.write_message( io, message )
	io.write( HEADER_MARKER.pack('CC') )
	io.write( [ message.descriptor.type ].pack('C') )
	io.write( message.pack )
end