Compiler
Operation
-
linking
a C
Program
• Sets up the system stack.
• Processes the runtime initialization table and autoinitializes global vari-
ables (in the
ROM model).
• Calls --main.
e Calls
exit
when
main
returns.
Section
6 describes additional runtime-support functions that
are
included in
rts
.lib.
If
your program
uses
any
of
these functions, you must link
rts
.lib
with
your object files.
3.5.2
Sample
linker
Command
File
3-14
Figure
3-5
shows a typical linker command file that
can
be used
to
link a C
program. The command file in this example
is
named
link.
cmd.
/***************************************************/
/*
Linker
command
file
link.cmd
*/
/***************************************************/
-c
/*
ROM
autoinitialization
model
*/
-m
example.map
/*
Create
a map
file
*/
-0
example.
out
/*
Output
file
name
*/
main.obj
/*
First
C
module
*/
sub.obj
/*
Second
C
module
*/
asm.obj
/*
Assembly
language
module
*/
-1
rts.lib
/*
Runtime-support
library
*/
-1
flib.lib
/*
Floating-Eoint
library
*/
-1
matrix.
lib
/*
Object
Ii
rary
*/
Figure
3-5.
An
Example
of
a
Linker
Command
File
• The command file first lists several linker options:
-c
is
one
of
the options that can be used to link C code; it tells the
linker to
use
the ROM model
of
autoinitialization.
-m
tells the linker
to
create a map file; the map file in this example is
named
example.
map.
-0
tells the linker to create
an
executable object module; the module
in this example is named
example.
out.
• Next, the command file lists all the object files to be linked. This C pro-
qram consists
of
two
C modules,
main.
c and
sub.
c,
which
were
ompiled and assembled to create
two
object files called
main.
obj
and
sub.
obj.
This example also links in
an
assembly language module
called
asm.
obj.
One
of
these files must define the symbol
main,
because
boot.
obj
calls
main
as
the start
of
your C program. All
of
these object files are linked
in.
• Finally, the command file lists all the object libraries that the linker must
search. (The libraries
are
specified
with
the -I linker option.) Since this
is
a C program, the runtime-support library
rts
.lib
must
be
included.
If
a program
uses
floating-point
routines,
it
must also link in
flib
.lib
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