Relocatable Object Module Format (OMF) Specification

Relocatable Object Module Format
94H or 95H LINNUM—Line Numbers Record
Description
The LINNUM record relates line numbers in source code to addresses in object code.
History
Record type 95H is added for 32-bit linkers; allowing for 32-bit debugger style-specific information.
Note: For instantiated inline functions in Microsoft C 7.0, line numbers are output in LINSYM records
with a reference to the function name instead of the segment.
Record Format
1 2 1 or 2 1 or 2 1
94 Record Base Base Debugger Checksum
or 95 Length Group Segment Style-specific
Information
Base Group and Base Segment Fields
The Base Group and Base Segment fields contain indexes specifying previously defined GRPDEF and SEGDEF
records.
Notes
The debugger style-specific information is indicated by comment class A1.
Although the complete Intel 8086 specification allows the Base Group and Base Segment fields to refer
to a group or to an absolute segment as well as to a relocatable segment, some linkers commonly
restrict references in this field to relocatable segments.
The following discussion uses the Microsoft debugger style-specific information. The debugger stylespecific
information field in the LINNUM record is composed as follows:
2 2 or 4
Line
Number
Line Number
Offset
For Microsoft LINK LINNUM records, the Line Number field contains a 16-bit quantity, in the range 0
through 7FFF and is, as its name indicates, a line number in the source code. The Line Number Offset
field contains a 2-byte or 4-byte quantity that gives the translated code or data's start byte in the
program segment defined by the SEGDEF index (4 bytes if the record type is 95H; 2 bytes for type
94H).
The Line Number and Line Number Offset fields can be repeated, so a single LINNUM record can
specify multiple line numbers in the same segment.
Tool Interface Standards (TIS) OMF Specification, Version 1.1 33