\code
struct Parse_EthVLan : public PacketParserBase
{
- typedef Parse_UIntField < 0, 3 > Parse_Priority;
- typedef Parse_Flag < 3 > Parse_CFI;
- typedef Parse_UIntField < 4, 16 > Parse_VLanId;
- typedef Parse_UInt16 Parse_Type;
-
- SENF_PACKET_PARSER_INIT(Parse_EthVLan);
-
- SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS(
- ((OverlayField)( priority, Parse_Priority ))
- ((OverlayField)( cfi, Parse_CFI ))
- ((Field )( vlanId, Parse_VLanId ))
- ((Field )( type, Parse_Type )) );
+ # include SENF_FIXED_PARSER()
+
+ SENF_PARSER_BITFIELD( priority, 3, unsigned );
+ SENF_PARSER_BITFIELD( cfi, 1, bool );
+ SENF_PARSER_BITFIELD( vlanId, 12, unsigned );
+
+ SENF_PARSER_FIELD( type, Parse_UInt16 );
+
+ SENF_PARSER_FINALIZE(Parse_EthVLan);
};
\endcode
\li The macros provide a definition for \c init()
\li The macros define the \c bytes(), \c fixed_bytes and \c init_bytes members as needed.
- You may define either a fixed or a dynamically sized parser. Fixed size parsers are defined
- using \ref SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS, dynamically sized parsers are defined
- using \ref SENF_PACKET_PARSER_DEFINE_FIELDS. The different members are implemented such
- that:
+ You may define either a fixed or a dynamically sized parser. Fixed size parsers are defined by
+ starting the packet with <tt>\#include SENF_FIXED_PARSER()</tt>, dynamically sized parsers start
+ with <tt>\#include SENF_PARSER()</tt>. The different members are implemented such that:
\li The needed parser constructor is defined
\li \c init() calls \c defaultInit(). \c defaultInit() is defined to call \c init() on each
\li \c bytes() (on dynamically sized parser) respectively \c fixed_bytes (on fixed size
parsers) is defined to return the sum of the sizes of all fields.
\li On dynamically sized parsers, \c init_bytes is defined to return the sum of the
- \c init_size's of all fields
+ \c init_byte's of all fields
- The central definition macros are \ref SENF_PACKET_PARSER_DEFINE_FIXED_FIELDS and \ref
- SENF_PACKET_PARSER_DEFINE_FIELDS. The argument to both has the same structure. It is a
- (boost preprocessor style) sequence of field definitions where each field definition
- provides the builder macro to use and the name and type of the field to define:
- \code
- SENF_PACKET_PARSER_DEFINE[_FIXED]_FIELDS(
- (( <builder> )( <name>, <type> ))
- ...
- )
- \endcode
+ \section parserlanguage The Parser Macro micro-language
+
+ The macros provided to help implement collection parsers implement a very small declarative
+ language. This way of to think of the macros simplifies understanding, how the macros work.
- For each field, this command will define
- \li A method \a name() returning an instance of the \a type parser
- \li \a name<tt>_t</tt> as a typedef for \a type, the fields value
- \li \a name<tt>_offset</tt> to give the offset of the field from the beginning of the
- parser. If the parser is a fixed size parser, this will be a static constant, otherwise
- it will be a method.
-
- The \a builder argument selects, how the field is defined
- \li <tt>Field</tt> defines a field and increments the current position by the size of the
- field
- \li <tt>OverlayField</tt> defines a field like <tt>Field</tt> but does \e not increment the
- position. In the above example, this is used to overlay the different bitfield parsers:
- All overlaying bitfield parser except the last one (the one with the highest bit
- numbers) is marked as OverlayField.
-
- The \a name argument defines the name of the accessor method.
-
- The \a type argument is the parser to return for that field. Since none of the arguments may
- contain a comma, <em>This argument cannot be a multi-parameter template</em>. Always use
- typedefs to access templated parsers as shown above.
-
- The \ref SENF_PACKET_PARSER_INIT macro defines the constructor and the \c init() member. If
- you want to provide your own \c init() implementation, use \ref
- SENF_PACKET_PARSER_NO_INIT. The first statement in your init method should probably to call
- \c defaultInit(). This will call the \c init() member of all the fields. Afterwards you can
- set up the field values as needed:
+ Central to this language is the concept of <em>current offset</em>. The current offset is the
+ place (in bytes) from the beginning of the parser at which the next field will be added. Adding
+ fields to the parser will advance this offset by the size of the field added. Additional
+ commands allow to arbitrarily manipulate the current offset manually.
+
+ For fixed size parsers, the current offset is a single constant integral value, the number of
+ bytes from the parsers start. For dynamically sized parsers, the current offset really consists
+ of two values: One is the number of bytes from the parsers start, which however needs not be a
+ constant expression, the other value is the \c init_bytes value at this point, which is an
+ integral constant.
+
+ To demonstrate this functionality, here a more complex example (taken from MPEGDVBBundle and
+ then simplified by removing some fields)
\code
- struct SomePacket : public senf::PacketParserBase
- {
- SENF_PACKET_PARSER_NO_INIT(SomePacket);
-
- typedef senf::Parse_UInt8 Parse_Type;
- typedef senf::Parse_Vector< senf::Parse_UInt32,
- senf::SimpleVectorSizer<senf::Parse_UInt16>
- > Parse_Elements;
-
- SENF_PACKET_PARSER_DEFINE_FIELDS(
- ((Field)( type, Parse_Type ))
- ((Field)( elements, Parse_Elements ))
- );
-
- void init() const {
- defaultInit();
- type() = 0x01;
- elements().push_back(0x01020304u);
- }
- }
+ struct Parse_DSMCCSection : public PacketParserBase
+ {
+ # include SENF_FIXED_PARSER()
+
+ SENF_PARSER_FIELD ( table_id , Parse_UInt8 );
+
+ SENF_PARSER_BITFIELD ( ssi , 1 , bool );
+ SENF_PARSER_BITFIELD ( private_indicator , 1 , bool );
+ SENF_PARSER_SKIP_BITS( 2 );
+ SENF_PARSER_BITFIELD ( sec_length , 12 , unsigned );
+
+ SENF_PARSER_FIELD ( table_id_extension , Parse_UInt16 );
+
+ SENF_PARSER_FINALIZE( Parse_DSMCCSection );
+ };
+
+ struct Parse_DatagramSection : public Parse_DSMCCSection
+ {
+ # include SENF_FIXED_PARSER()
+
+ SENF_PARSER_INHERIT( Parse_DSMCCSection );
+
+ SENF_PARSER_FIELD ( mac_addr_4 , Parse_UInt8 );
+ SENF_PARSER_FIELD ( mac_addr_3 , Parse_UInt8 );
+
+ SENF_PARSER_FINALIZE( Parse_DatagramSection );
+
+ // Parse table_id_extension as two bytes
+ SENF_PARSER_GOTO( table_id_extension );
+ SENF_PARSER_FIELD ( mac_addr_6 , Parse_UInt8 );
+ SENF_PARSER_FIELD ( mac_addr_5 , Parse_UInt8 );
+ };
\endcode
+ This code defines two parsers, the second of which is based on the first. Both are fixed size
+ parsers. The definition of \c Parse_DSMCCSection is straight forward (more on bit fields
+ below).
+
+ The derived parser is a little bit more complex. It starts out the same defining itself as a
+ fixed size parser. Then the base class is imported. Among other things, this call sets the
+ current offset to the first byte after the base parser (the base parser need not be implemented
+ using the packet parser macros, it just needs to be a valid parser). The additional fields \c
+ mac_addr_4 and \c mac_addr_3 are defined. Then we finalize the parser declaration.
+
+ <em>After</em> \ref SENF_PARSER_FINALIZE we add two more fields but not at the end of the
+ parser. \ref SENF_PARSER_GOTO jumps back to a previously defined label or field. Since the base
+ parser \c Parse_DSMCCSection is defined using the packet parser macros, we can even jump to
+ labels or fields defined in the base parser. Here, we jump to the beginning of the \c
+ table_id_extension field. \c mac_addr_6 and \c mac_addr_5 are therefore defined starting at that
+ offset and therefore overlay the \c table_id_extension field.
+
+ \section parsermacroinit Parser initialization
+
+ \par ""
+ \ref SENF_FIXED_PARSER(), \ref SENF_PARSER(), \ref SENF_PARSER_INHERIT(), \ref
+ SENF_PARSER_INIT(), \ref SENF_PARSER_FINALIZE()
+
+ Every parser using the parser macros starts either with <tt>\#include SENF_PARSER()</tt> or with
+ <tt>\#include SENF_FIXED_PARSER()</tt>. This command sets the current offset to zero and defines
+ the type of parser to define.
+
+ A following optional \ref SENF_PARSER_INHERIT(\e base_class) is necessary if the parser does not
+ derive from senf::PacketParserBase. This call sets the base class and advances the current
+ offset to the end of the base parser.
+
+ \ref SENF_PARSER_INIT() is used to define the parser initialization code (the \c init()
+ member).
+
+ \ref SENF_PARSER_FINALIZE(\e class_name) is called to define the parsers constructor, the \c
+ init() member and to set the parsers size (\c fixed_bytes for fixed size parsers or \c bytes()
+ and \c init_bytes for dynamically sized parsers). It is valid to define further fields \e after
+ \ref SENF_PARSER_FINALIZE() has been called, however
+ \li Fields defined after \ref SENF_PARSER_FINALIZE() will \e not be initialized by \c
+ defaultInit() (and therefore not by the default provided \c init() member). This can be very
+ helpful when defining overlaying fields to avoid initializing some bytes multiple times.
+ \li The size of the parser is given by the current offset at the time of the \ref
+ SENF_PARSER_FINALIZE() call.
+
+ \section parsermacrofields Defining fields
+
+ \par ""
+ \ref SENF_PARSER_FIELD(), \ref SENF_PARSER_FIELD_RO(), \ref SENF_PARSER_PRIVATE_FIELD(),
+ \ref SENF_PARSER_PRIVATE_FIELD_RO(), SENF_PARSER_CUSTOM_FIELD()
+
+ There are quite a few commands available to define fields. All these macros do the same thing:
+ they define a field accessor plus some auxiliary symbols for the field:
+ \par ""
+ <em>type</em> <em>name</em><tt>()</tt> <tt>const</tt><br>
+ <tt>typedef</tt> <em>type</em> <em>name</em><tt>_t</tt><br>
+ <tt>size_type</tt> <tt>const</tt> <em>name</em><tt>_offset</tt><br>
+ <em>or</em><br>
+ <tt>size_type</tt> <em>name</em><tt>_offset()</tt> <tt>const</tt>
+
+ Here \e type is the type of the field defined (the return value of the \e name() accessor) and
+ \e name is the field name. <em>name</em><tt>_offset</tt> gives the offset of the first byte of
+ the field from the start of the parser. This member is a constant for fixed size parser and a
+ member function for dynamically sized parsers. <em>name</em><tt>_t</tt> is just an alias for the
+ fields type (more precisely the return type of the <em>name</em>() accessor).
+
+ There are some properties the field defining macros might have. These properties are parts
+ of the macro name:
+
+ \par RO: Read only fields
+ Macros with \c RO in their name define read only fields. This is only possible, if the
+ field's parser is a value parser (that is, it must have a \c value_type typedef member and
+ must provide the \c value() accessor member function). In this case, the value returned from
+ the \e name() accessor member is not the parser but the parsers value and therefore it does
+ not allow assignment to the field.
+
+ \par PRIVATE: Fields private to the parser class
+ A private field will not be accessible from the outside (it is made \c private to the parser
+ class). This is very handy when providing other accessor members to access a field in a
+ manner more suitable for the specific field, when combining several fields into a single
+ return value etc.
+
+ The field defining macros come in groups which members only differ in their properties:
+
+ \par Define standard fields:
+ \ref SENF_PARSER_FIELD(), \ref SENF_PARSER_FIELD_RO(), \ref SENF_PARSER_PRIVATE_FIELD(),
+ \ref SENF_PARSER_PRIVATE_FIELD_RO() define standard fields.
+
+ \par Define arbitrary custom field:
+ \ref SENF_PARSER_CUSTOM_FIELD()
+
+ See the documentation of each of these macros for a detailed description of the macro arguments
+ and usage. Bit-fields are handled in the following section.
+
+ \subsection parsermacrobitfields Bit-fields
+
+ \par ""
+ \ref SENF_PARSER_BITFIELD(), \ref SENF_PARSER_BITFIELD_RO(), \ref
+ SENF_PARSER_PRIVATE_BITFIELD(), \ref SENF_PARSER_PRIVATE_BITFIELD_RO() \n
+
+ Bit-fields play a special role. They are quite frequent in packet definitions but don't fit into
+ the byte offset based parsing infrastructure defined so far. Since defining the correctly
+ parameterized Parse_IntField, Parse_UIntField and Parse_Flag typedefs is quite tedious, these
+ helper macros are provided.
+
+ It is important to recognize, that the current offset does \e not include the current bit
+ position. The current offset after defining a bit-field will be the first complete byte after
+ that bit-field. Only the bit-field macros additionally take care of the current bit position
+ which is reset automatically by any intervening non-bitfield command.
+
+ So bit-field commands will come in groups. Any group of consecutive bitfield commands defines a
+ set of consecutive bits. The group as a whole will always be considered to cover a fixed number
+ of complete bytes. If the group does not cover those bytes completely (there are some bit's left
+ at the end), those bit's will be skipped.
+
+ Since consecutive bit-field commands are aggregated into a single bit-field group, the offset of
+ all these bit-fields will be the offset of the \e beginning of the bit-field irrespective of the
+ number of bits parsed so far. Changing the offset to some bitfield using \ref SENF_PARSER_GOTO()
+ will therefore always go to the position at the beginning of this bitfield group. And since the
+ current offset does not include the bit position, the bit position will be 0, the first bit. You
+ may however break a bit-field group into two groups (at a byte boundary) by placing a \ref
+ SENF_PARSER_LABEL() command between the two groups.
+
+ The additional command \ref SENF_PARSER_SKIP_BITS() can be used to skip bit's between two
+ bit-fields.
+
+ \section parsermacrooffset Manipulating the current offset
+
+ \par ""
+ \ref SENF_PARSER_SKIP(), \ref SENF_PARSER_SKIP_BITS(), \ref SENF_PARSER_GOTO(), \ref
+ SENF_PARSER_GOTO_OFFSET(), \ref SENF_PARSER_LABEL()
+
+ To define more complex parsers, there are some macro commands which change the current offset.
+
+ \ref SENF_PARSER_SKIP(\e bytes) will skip the given number of bytes. \ref
+ SENF_PARSER_SKIP_BITS(\e bits) will work within bitfield definition to skip that number of bits.
+
+ \ref SENF_PARSER_GOTO(\e label_or_field) will change the offset to the given field or label. The
+ following fields will therefore start at that offset and overlay any fields already defined.
+
+ \ref SENF_PARSER_GOTO_OFFSET(\e offset) will jump to the given byte offset from the start of the
+ parser.
+
+ \ref SENF_PARSER_LABEL(\e name) will define \e name as a label for the current offset which can
+ then later be referenced using \ref SENF_PARSER_GOTO(). This also defines
+ <em>name</em><tt>_offset</tt> as a constant or member (for fixed respectively dynamically sized
+ parsers).
+
+ It is very important to recognize, that the size of the parser is defined by the current offset
+ <em>at the time \ref SENF_PARSER_FINALIZE() is called</em>. This allows to arbitrarily
+ manipulate the size of the parser by changing the current offset accordingly. For dynamically
+ sized parsers, the offset can even be any expression involving member function calls. See the
+ documentation of the respective macros for more details.
+
\ingroup packetparser
*/
+///\ingroup packetparsermacros
+///\{
-#define SENF_FIXED_PARSER() SENF_ABSOLUTE_INCLUDE_PATH(Packets/parse_fixed_setup.hh)
-#define SENF_PARSER() SENF_ABSOLUTE_INCLUDE_PATH(Packets/parse_setup.hh)
+#define SENF_FIXED_PARSER() SENF_ABSOLUTE_INCLUDE_PATH(Packets/parse_fixed_setup.hh)
+#define SENF_PARSER() SENF_ABSOLUTE_INCLUDE_PATH(Packets/parse_setup.hh)
-#define SENF_PARSER_INHERIT BOOST_PP_CAT( SENF_PARSER_INHERIT_ , SENF_PARSER_TYPE )
+#define SENF_PARSER_INHERIT BOOST_PP_CAT(SENF_PARSER_INHERIT_, SENF_PARSER_TYPE)
-#define SENF_PARSE_FIELD BOOST_PP_CAT( SENF_PARSE_FIELD_ , SENF_PARSER_TYPE )
-#define SENF_PARSE_FIELD_RO BOOST_PP_CAT( SENF_PARSE_FIELD_RO_ , SENF_PARSER_TYPE )
-#define SENF_PARSE_CUSTOM_FIELD BOOST_PP_CAT( SENF_PARSE_CUSTOM_FIELD_ , SENF_PARSER_TYPE )
-#define SENF_PARSE_BITFIELD BOOST_PP_CAT( SENF_PARSE_BITFIELD_ , SENF_PARSER_TYPE )
-#define SENF_PARSE_BITFIELD_RO BOOST_PP_CAT( SENF_PARSE_BITFIELD_RO_ , SENF_PARSER_TYPE )
+#define SENF_PARSER_FIELD BOOST_PP_CAT(SENF_PARSER_FIELD_, SENF_PARSER_TYPE)
+#define SENF_PARSER_FIELD_RO BOOST_PP_CAT(SENF_PARSER_FIELD_RO_, SENF_PARSER_TYPE)
+#define SENF_PARSER_BITFIELD BOOST_PP_CAT(SENF_PARSER_BITFIELD_, SENF_PARSER_TYPE)
+#define SENF_PARSER_BITFIELD_RO BOOST_PP_CAT(SENF_PARSER_BITFIELD_RO_, SENF_PARSER_TYPE)
+#define SENF_PARSER_CUSTOM_FIELD BOOST_PP_CAT(SENF_PARSER_CUSTOM_FIELD_, SENF_PARSER_TYPE)
-#define SENF_PARSER_FINALIZE BOOST_PP_CAT( SENF_PARSER_FINALIZE_ , SENF_PARSER_TYPE )
+#define SENF_PARSER_PRIVATE_FIELD BOOST_PP_CAT(SENF_PARSER_P_FIELD_, SENF_PARSER_TYPE)
+#define SENF_PARSER_PRIVATE_FIELD_RO BOOST_PP_CAT(SENF_PARSER_P_FIELD_RO_, SENF_PARSER_TYPE)
+#define SENF_PARSER_PRIVATE_BITFIELD BOOST_PP_CAT(SENF_PARSER_P_BITFIELD_, SENF_PARSER_TYPE)
+#define SENF_PARSER_PRIVATE_BITFIELD_RO BOOST_PP_CAT(SENF_PARSER_P_BITFIELD_RO_, SENF_PARSER_TYPE)
+
+#define SENF_PARSER_SKIP BOOST_PP_CAT(SENF_PARSER_SKIP_, SENF_PARSER_TYPE)
+#define SENF_PARSER_SKIP_BITS BOOST_PP_CAT(SENF_PARSER_SKIP_BITS_, SENF_PARSER_TYPE)
+#define SENF_PARSER_GOTO BOOST_PP_CAT(SENF_PARSER_GOTO_, SENF_PARSER_TYPE)
+#define SENF_PARSER_GOTO_OFFSET BOOST_PP_CAT(SENF_PARSER_GOTO_OFFSET_, SENF_PARSER_TYPE)
+#define SENF_PARSER_LABEL BOOST_PP_CAT(SENF_PARSER_LABEL_, SENF_PARSER_TYPE)
+
+/** \brief Define parser initialization routine
+
+ \code
+ SENF_PARSER_INIT() {
+ defaultInit();
+ foo() = 2;
+ }
+ \endcode
+ Defining the initialization code manually skips the automatic call of defaultInit(), which may
+ be performed manually. Should the initialization code be more complex, it should be placed into
+ a non-inline private member which is called from \ref SENF_PARSER_INIT()
+
+ \hideinitializer
+ */
+#define SENF_PARSER_INIT() void init(int)
-#define SENF_PARSER_SKIP BOOST_PP_CAT( SENF_PARSER_SKIP_ , SENF_PARSER_TYPE )
-#define SENF_PARSER_GOTO BOOST_PP_CAT( SENF_PARSER_GOTO_ , SENF_PARSER_TYPE )
-#define SENF_PARSER_GOTO_OFFSET BOOST_PP_CAT( SENF_PARSER_GOTO_OFFSET_ , SENF_PARSER_TYPE )
-#define SENF_PARSER_LABEL BOOST_PP_CAT( SENF_PARSER_LABEL_ , SENF_PARSER_TYPE )
+#define SENF_PARSER_FINALIZE BOOST_PP_CAT(SENF_PARSER_FINALIZE_, SENF_PARSER_TYPE)
-#define SENF_PARSER_INIT() void init(int)
+///\}
///////////////////////////////hh.e////////////////////////////////////////
#endif
projects / senf.git / blobdiff