(flex.info)Tables File Format
22.3 Tables File Format
=======================
This section defines the file format of serialized 'flex' tables.
The tables format allows for one or more sets of tables to be
specified, where each set corresponds to a given scanner. Scanners are
indexed by name, as described below. The file format is as follows:
TABLE SET 1
+-------------------------------+
Header | uint32 th_magic; |
| uint32 th_hsize; |
| uint32 th_ssize; |
| uint16 th_flags; |
| char th_version[]; |
| char th_name[]; |
| uint8 th_pad64[]; |
+-------------------------------+
Table 1 | uint16 td_id; |
| uint16 td_flags; |
| uint32 td_hilen; |
| uint32 td_lolen; |
| void td_data[]; |
| uint8 td_pad64[]; |
+-------------------------------+
Table 2 | |
. . .
. . .
. . .
. . .
Table n | |
+-------------------------------+
TABLE SET 2
.
.
.
TABLE SET N
The above diagram shows that a complete set of tables consists of a
header followed by multiple individual tables. Furthermore, multiple
complete sets may be present in the same file, each set with its own
header and tables. The sets are contiguous in the file. The only way
to know if another set follows is to check the next four bytes for the
magic number (or check for EOF). The header and tables sections are
padded to 64-bit boundaries. Below we describe each field in detail.
This format does not specify how the scanner will expand the given data,
i.e., data may be serialized as int8, but expanded to an int32 array at
runtime. This is to reduce the size of the serialized data where
possible. Remember, _all integer values are in network byte order_.
Fields of a table header:
'th_magic'
Magic number, always 0xF13C57B1.
'th_hsize'
Size of this entire header, in bytes, including all fields plus any
padding.
'th_ssize'
Size of this entire set, in bytes, including the header, all
tables, plus any padding.
'th_flags'
Bit flags for this table set. Currently unused.
'th_version[]'
Flex version in NULL-terminated string format. e.g., '2.5.13a'.
This is the version of flex that was used to create the serialized
tables.
'th_name[]'
Contains the name of this table set. The default is 'yytables',
and is prefixed accordingly, e.g., 'footables'. Must be
NULL-terminated.
'th_pad64[]'
Zero or more NULL bytes, padding the entire header to the next
64-bit boundary as calculated from the beginning of the header.
Fields of a table:
'td_id'
Specifies the table identifier. Possible values are:
'YYTD_ID_ACCEPT (0x01)'
'yy_accept'
'YYTD_ID_BASE (0x02)'
'yy_base'
'YYTD_ID_CHK (0x03)'
'yy_chk'
'YYTD_ID_DEF (0x04)'
'yy_def'
'YYTD_ID_EC (0x05)'
'yy_ec '
'YYTD_ID_META (0x06)'
'yy_meta'
'YYTD_ID_NUL_TRANS (0x07)'
'yy_NUL_trans'
'YYTD_ID_NXT (0x08)'
'yy_nxt'. This array may be two dimensional. See the
'td_hilen' field below.
'YYTD_ID_RULE_CAN_MATCH_EOL (0x09)'
'yy_rule_can_match_eol'
'YYTD_ID_START_STATE_LIST (0x0A)'
'yy_start_state_list'. This array is handled specially
because it is an array of pointers to structs. See the
'td_flags' field below.
'YYTD_ID_TRANSITION (0x0B)'
'yy_transition'. This array is handled specially because it
is an array of structs. See the 'td_lolen' field below.
'YYTD_ID_ACCLIST (0x0C)'
'yy_acclist'
'td_flags'
Bit flags describing how to interpret the data in 'td_data'. The
data arrays are one-dimensional by default, but may be two
dimensional as specified in the 'td_hilen' field.
'YYTD_DATA8 (0x01)'
The data is serialized as an array of type int8.
'YYTD_DATA16 (0x02)'
The data is serialized as an array of type int16.
'YYTD_DATA32 (0x04)'
The data is serialized as an array of type int32.
'YYTD_PTRANS (0x08)'
The data is a list of indexes of entries in the expanded
'yy_transition' array. Each index should be expanded to a
pointer to the corresponding entry in the 'yy_transition'
array. We count on the fact that the 'yy_transition' array
has already been seen.
'YYTD_STRUCT (0x10)'
The data is a list of yy_trans_info structs, each of which
consists of two integers. There is no padding between struct
elements or between structs. The type of each member is
determined by the 'YYTD_DATA*' bits.
'td_hilen'
If 'td_hilen' is non-zero, then the data is a two-dimensional
array. Otherwise, the data is a one-dimensional array. 'td_hilen'
contains the number of elements in the higher dimensional array,
and 'td_lolen' contains the number of elements in the lowest
dimension.
Conceptually, 'td_data' is either 'sometype td_data[td_lolen]', or
'sometype td_data[td_hilen][td_lolen]', where 'sometype' is
specified by the 'td_flags' field. It is possible for both
'td_lolen' and 'td_hilen' to be zero, in which case 'td_data' is a
zero length array, and no data is loaded, i.e., this table is
simply skipped. Flex does not currently generate tables of zero
length.
'td_lolen'
Specifies the number of elements in the lowest dimension array. If
this is a one-dimensional array, then it is simply the number of
elements in this array. The element size is determined by the
'td_flags' field.
'td_data[]'
The table data. This array may be a one- or two-dimensional array,
of type 'int8', 'int16', 'int32', 'struct yy_trans_info', or
'struct yy_trans_info*', depending upon the values in the
'td_flags', 'td_hilen', and 'td_lolen' fields.
'td_pad64[]'
Zero or more NULL bytes, padding the entire table to the next
64-bit boundary as calculated from the beginning of this table.
automatically generated by info2www version 1.2.2.9