Linker; Introduction; Link68 Inputs And Outputs - Texas Instruments TI-89 Software Manual

4.

Linker

4.1.

Introduction

The Sierra Systems linker link68 combines object files to create an executable
output file. It was developed by Sierra Systems to support certain Motorola
processors in conjunction with the rest of the Sierra C™ software package.
Under license from Sierra Systems, Texas Instruments has modified this
software to support TI BCD floating-point numbers, and support for coprocessors
has been removed. Although the software has not been modified to exclude
support for processors other than the 68000, the 68000 is the only processor
supported by Texas Instruments. The license from Texas Instruments to use
these products is restricted to development of software that is targeted to
execute only on TI calculators.
4.2.

Link68 Inputs and Outputs

The linker's actions are directed by the arguments placed on the command line.
The linker opens each file referenced in its command input and reads the file
header to determine if the file is an object or library file. If the file is an object file,
the linker resolves undefined addresses and concatenates each section in the file
to an output section of the same name. Otherwise, if the file is a library, the linker
searches the symbol table of the library file to determine if any undefined
symbols may be defined by an object file in the library. If the linker finds such a
symbol in the library, it loads the member defining that symbol from the library.
The search continues until no undefined symbols can be resolved by loading
library members. Only the library members needed to resolve undefined symbols
are loaded. The linker treats the object files loaded from a library as if the names
of the object files themselves appeared in the command input. If the file is neither
an object nor library file, the linker generates an error message and aborts.
The linker's primary output is an object file that, by default, is executable. The
linker copies code from input object files named in its command input to the
executable file, modifying the code to reflect its address in the executable.
Information needed for further linking, such as relocation entries, is removed
from the executable file.
If the command input includes the -m flag specifying a map file, the linker will
create a formatted listing of the executable file's contents, showing where each
input file is located in the generated output file. The map file's name is simply the
executable file's base name with a .map extension.
TI-89 / TI-92 Plus Sierra C Assembler Reference Manual Not for Distribution
299
Beta Version February 2, 2001