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><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="AEN144"
>3.6. Assembler Directives</A
></H1
><P
>Various directives can be used to control the behaviour of the
assembler or to include non-code/data in the resulting output. Those directives
that are not described in detail in other sections of this document are
described below.</P
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="AEN147"
>3.6.1. Data Directives</A
></H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>FCB <CODE
CLASS="PARAMETER"
>expr[,...]</CODE
></DT
><DD
><P
>Include one or more constant bytes (separated by commas) in the output.</P
></DD
><DT
>FDB <CODE
CLASS="PARAMETER"
>expr[,...]</CODE
></DT
><DD
><P
>Include one or more words (separated by commas) in the output.</P
></DD
><DT
>FQB <CODE
CLASS="PARAMETER"
>expr[,...]</CODE
></DT
><DD
><P
>Include one or more double words (separated by commas) in the output.</P
></DD
><DT
>FCC <CODE
CLASS="PARAMETER"
>string</CODE
></DT
><DD
><P
>Include a string of text in the output. The first character of the operand
is the delimiter which must appear as the last character and cannot appear
within the string. The string is included with no modifications&#62;</P
></DD
><DT
>FCN <CODE
CLASS="PARAMETER"
>string</CODE
></DT
><DD
><P
>Include a NUL terminated string of text in the output. The first character of
the operand is the delimiter which must appear as the last character and
cannot appear within the string. A NUL byte is automatically appended to
the string.</P
></DD
><DT
>FCS <CODE
CLASS="PARAMETER"
>string</CODE
></DT
><DD
><P
>Include a string of text in the output with bit 7 of the final byte set. The
first character of the operand is the delimiter which must appear as the last
character and cannot appear within the string.</P
></DD
><DT
>ZMB <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Include a number of NUL bytes in the output. The number must be fully resolvable
during pass 1 of assembly so no forward or external references are permitted.</P
></DD
><DT
>ZMD <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Include a number of zero words in the output. The number must be fully
resolvable during pass 1 of assembly so no forward or external references are
permitted.</P
></DD
><DT
>ZMQ <CODE
CLASS="PARAMETER"
>expr<CODE
CLASS="PARAMETER"
></CODE
></CODE
></DT
><DD
><P
>Include a number of zero double-words in the output. The number must be fully
resolvable during pass 1 of assembly so no forward or external references are
permitted.</P
></DD
><DT
>RMB <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Reserve a number of bytes in the output. The number must be fully resolvable
during pass 1 of assembly so no forward or external references are permitted.
The value of the bytes is undefined.</P
></DD
><DT
>RMD <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Reserve a number of words in the output. The number must be fully
resolvable during pass 1 of assembly so no forward or external references are
permitted. The value of the words is undefined.</P
></DD
><DT
>RMQ <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Reserve a number of double-words in the output. The number must be fully
resolvable during pass 1 of assembly so no forward or external references are
permitted. The value of the double-words is undefined.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="AEN211"
>3.6.2. Address Definition</A
></H2
><P
>The directives in this section all control the addresses of symbols
or the assembly process itself.</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>ORG <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Set the assembly address. The address must be fully resolvable on the
first pass so no external or forward references are permitted. ORG is not
permitted within sections when outputting to object files. For the DECB
target, each ORG directive after which output is generated will cause
a new preamble to be output. ORG is only used to determine the addresses
of symbols when the raw target is used.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>sym</CODE
> EQU <CODE
CLASS="PARAMETER"
>expr</CODE
>, <CODE
CLASS="PARAMETER"
>sym</CODE
> = <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Define the value of <CODE
CLASS="PARAMETER"
>sym</CODE
> to be <CODE
CLASS="PARAMETER"
>expr</CODE
>.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>sym</CODE
> SET <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Define the value of <CODE
CLASS="PARAMETER"
>sym</CODE
> to be <CODE
CLASS="PARAMETER"
>expr</CODE
>.
Unlike EQU, SET permits symbols to be defined multiple times as long as SET
is used for all instances. Use of the symbol before the first SET statement
that sets its value is undefined.</P
></DD
><DT
>SETDP <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Inform the assembler that it can assume the DP register contains
<CODE
CLASS="PARAMETER"
>expr</CODE
>. This directive is only advice to the assembler
to determine whether an address is in the direct page and has no effect
on the contents of the DP register. The value must be fully resolved during
the first assembly pass because it affects the sizes of subsequent instructions.</P
><P
>This directive has no effect in the object file target.</P
></DD
><DT
>ALIGN <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>Force the current assembly address to be a multiple of <CODE
CLASS="PARAMETER"
>expr</CODE
>.
A series of NUL bytes is output to force the alignment, if required. The
alignment value must be fully resolved on the first pass because it affects
the addresses of subsquent instructions.</P
><P
>This directive is not suitable for inclusion in the middle of actual
code. It is intended to appear where the bytes output will not be executed.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="AEN253"
>3.6.3. Conditional Assembly</A
></H2
><P
>Portions of the source code can be excluded or included based on conditions
known at assembly time. Conditionals can be nested arbitrarily deeply. The
directives associated with conditional assembly are described in this section.</P
><P
>All conditionals must be fully bracketed. That is, every conditional
statement must eventually be followed by an ENDC at the same level of nesting.</P
><P
>Conditional expressions are only evaluated on the first assembly pass.
It is not possible to game the assembly process by having a conditional
change its value between assembly passes. Thus there is not and never will
be any equivalent of IFP1 or IFP2 as provided by other assemblers.</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>IFEQ <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>expr</CODE
> evaluates to zero, the conditional
will be considered true.</P
></DD
><DT
>IFNE <CODE
CLASS="PARAMETER"
>expr</CODE
>, IF <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>expr</CODE
> evaluates to a non-zero value, the conditional
will be considered true.</P
></DD
><DT
>IFGT <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>expr</CODE
> evaluates to a value greater than zero, the conditional
will be considered true.</P
></DD
><DT
>IFGE <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>expr</CODE
> evaluates to a value greater than or equal to zero, the conditional
will be considered true.</P
></DD
><DT
>IFLT <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>expr</CODE
> evaluates to a value less than zero, the conditional
will be considered true.</P
></DD
><DT
>IFLE <CODE
CLASS="PARAMETER"
>expr</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>expr</CODE
> evaluates to a value less than or equal to zero , the conditional
will be considered true.</P
></DD
><DT
>IFDEF <CODE
CLASS="PARAMETER"
>sym</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>sym</CODE
> is defined at this point in the assembly
process, the conditional
will be considered true.</P
></DD
><DT
>IFNDEF <CODE
CLASS="PARAMETER"
>sym</CODE
></DT
><DD
><P
>If <CODE
CLASS="PARAMETER"
>sym</CODE
> is not defined at this point in the assembly
process, the conditional
will be considered true.</P
></DD
><DT
>ELSE</DT
><DD
><P
>If the preceding conditional at the same level of nesting was false, the
statements following will be assembled. If the preceding conditional at
the same level was true, the statements following will not be assembled.
Note that the preceding conditional might have been another ELSE statement
although this behaviour is not guaranteed to be supported in future versions
of LWASM.</P
></DD
><DT
>ENDC</DT
><DD
><P
>This directive marks the end of a conditional construct. Every conditional
construct must end with an ENDC directive.</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="AEN317"
>3.6.4. Miscelaneous Directives</A
></H2
><P
>This section includes directives that do not fit into the other
categories.</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>INCLUDE <CODE
CLASS="PARAMETER"
>filename</CODE
></DT
><DD
><P
>Include the contents of <CODE
CLASS="PARAMETER"
>filename</CODE
> at this point in
the assembly as though it were a part of the file currently being processed.
Note that whitespace cannot appear in the name of the file.</P
></DD
><DT
>END <CODE
CLASS="PARAMETER"
>[expr]</CODE
></DT
><DD
><P
>This directive causes the assembler to stop assembling immediately as though
it ran out of input. For the DECB target only, <CODE
CLASS="PARAMETER"
>expr</CODE
>
can be used to set the execution address of the resulting binary. For all
other targets, specifying <CODE
CLASS="PARAMETER"
>expr</CODE
> will cause an error.</P
></DD
><DT
>ERROR <CODE
CLASS="PARAMETER"
>string</CODE
></DT
><DD
><P
>Causes a custom error message to be printed at this line. This will cause
assembly to fail. This directive is most useful inside conditional constructs
to cause assembly to fail if some condition that is known bad happens.</P
></DD
></DL
></DIV
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