<chapter>
<title>The C Compiler System</title>

<section>
<title>Introduction</title>
<para>
The "C" programming language is rapidly growing in popularity
and seems destined to become one of the most popular programming
languages used for microcomputers. The rapid rise in the use of C
is not surprising. C is an incredibly versatile and efficient
language that can handle tasks that previously would have required
complex assembly language programming.
</para>

</section>
<section>
<title>The Language Implementation</title>
<para>
OS-9 C is implemented almost exactly as described in 'The C
Programming Language' by Kernighan and Ritchie (hereafter referred
to as K&amp;R).
</para>
<para>
Allthough this version of C follows the specification faithfully,
there are some differences. The differences mostly reflect
parts of C that are obsolete or the constraints imposed by memory
size limitations.
</para>

</section>
<section>
<title>Compiler Option Flags</title>
<para>
The compiler recognizes several command-line option flags which
modify the compilation process where needed. All flags are
recognized before compilation commences so the flags may be placed
anywhere on the command line. Flags may be ran together as in "-ro",
except where a flag is followed by something else; see "-f=" and
"-d" for examples.
</para>
<para>
-A
suppresses assembly, leaving the output as assembler code in a
file whose name is postfixed ".a".
</para>
<para>
-E=&lt;number&gt;
Set the edition number constant byte to the number given. This is
an OS-9 convention for memory modules.
</para>
<para>
-O
inhibits the assembly code optimizer pass. The optimizer will
shorten object code by about 11% with a comparable increase in speed
and is recommended for production versions of de-bugged programs.
</para>
<para>
-P
invokes the profiler to generate function frequency
statistics after program execution.
</para>
<para>
-R
suppresses linking library modules into an executable program.
Outputs are left in files with postfixes ".r".
</para>
<para>
-M=&lt;memory size&gt;
will instruct the linker to allocate &lt;memory size&gt;
for data, stack, and parameter area. Memory size may be expressed
in pages (an integer) or in kilobytes by appending "k" to an 
integer. For more details of the use of this option, see the
"Memory Management" section of this manual.
</para>
<para>
-L=&lt;filename&gt;
specifies a library to be searched by the linker
before the Standard Library and system interface.
</para>
<para>
-F=&lt;path&gt;
overrides the above output file naming. The output file
will be left with &lt;filename&gt; as its name. This flag does not make
sense in multiple source mode, and either the -a or -r flag is also
present. The module will be called the last name in &lt;path&gt;.
</para>
<para>
-C
will output the source code as comments with the assembler code.
</para>
<para>
-S
stops the generation of stack-checking code. -S should only be
used with great care when the appication is extremely time-critical
and when the use of the stack by compiler generated code is fully
understood.
</para>
<para>
-D&lt;identifier&gt;
is equivalent to "#define &lt;identifier&gt;" written in
the source file. -D is useful where different versions of a program
are maintained in one source file and differentiated by means of the
"#ifdef" of "#ifndef" pre-processor directives. If the &lt;identifier&gt;
is used as a macro for expansion by the pre-processor, "1"(one) will
be the expanded "value" unless the form "-d&lt;identifier&gt;=&lt;string&gt;" is
used in which case the expansion will be &lt;string&gt;.
</para>
<table frame="none">
<title>Command Line and Option Flag Examples</title>
<tgroup cols="3">
<colspec colwidth="1.5in" colname="c1">
<colspec colwidth="1.5in" colname="c2">
<colspec colwidth="1.5in" colname="c3">
<thead>
    <row>
	<entry>command line</entry>
	<entry>action</entry>
	<entry>output file(s)</entry>
    </row>
</thead>
<tbody>
    <row>
	<entry>cc prg.c</entry>
	<entry>compile to an executable program</entry>
	<entry>prg</entry>
	<entry></entry>
    </row>
    <row>
	<entry>cc prg.c -a</entry>
	<entry>compile to assembly language source code</entry>
	<entry>prg.a</entry>
    </row>
    <row>
	<entry>cc prg.c -r</entry>
	<entry>compile to relocatable module</entry>
	<entry>prg.r</entry>
    </row>
    <row>
	<entry>cc prg1.c prg2.c prg3.c</entry>
	<entry>compile to executable program</entry>
	<entry>prg1.r, prg2.r, prg3.r, output</entry>
    </row>
    <row>
	<entry>cc prg1.c prg2.a prg3.r</entry>
	<entry>compile prg1.c, assemble prg2.a and combine all into
and executable program</entry>
	<entry>prg1.r, prg2.r</entry>
    </row>
    <row>
	<entry>cc prg1.c prg2.c -a</entry>
	<entry>compile to assembly language source code</entry>
	<entry>prg1.a, prg2.a</entry>
    </row>
    <row>
	<entry>cc prg1.c prg2.c -f=prg</entry>
	<entry>compile to executable program</entry>
	<entry>prg</entry>
    </row>
    </tbody>
</tgroup>
</table>

</section>
</chapter>