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date | Fri, 24 Apr 2009 22:36:09 +0000 |
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Numbers and Expressions</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REL="HOME" TITLE="LW Tool Chain" HREF="index.html"><LINK REL="UP" TITLE="LWASM" HREF="c35.html"><LINK REL="PREVIOUS" TITLE="Symbols" HREF="x135.html"><LINK REL="NEXT" TITLE="Assembler Directives" HREF="x146.html"></HEAD ><BODY CLASS="SECTION" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >LW Tool Chain</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x135.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 3. LWASM</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x146.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="AEN139" >3.5. Numbers and Expressions</A ></H1 ><P > Numbers can be expressed in binary, octal, decimal, or hexadecimal. Binary numbers may be prefixed with a "%" symbol or suffixed with a "b" or "B". Octal numbers may be prefixed with "@" or suffixed with "Q", "q", "O", or "o". Hexadecimal numbers may be prefixed with "$", "0x" or "0X", or suffixed with "H". No prefix or suffix is required for decimal numbers but they can be prefixed with "&" if desired. Any constant which begins with a letter must be expressed with the correct prefix base identifier or be prefixed with a 0. Thus hexadecimal FF would have to be written either 0FFH or $FF. Numbers are not case sensitive. </P ><P > A symbol may appear at any point where a number is acceptable. The special symbol "*" can be used to represent the starting address of the current source line within expressions. </P ><P >The ASCII value of a character can be included by prefixing it with a single quote ('). The ASCII values of two characters can be included by prefixing the characters with a quote (").</P ><P >LWASM supports the following basic binary operators: +, -, *, /, and %. These represent addition, subtraction, multiplication, division, and modulus. It also supports unary negation and unary 1's complement (- and ^ respectively). For completeness, a unary positive (+) is supported though it is a no-op.</P ><P >Operator precedence follows the usual rules. multiplication, division, and modulus take precedence over addition and subtraction. Unary operators take precedence over binary operators. To force a specific order of evaluation, parentheses can be used in the usual manner.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="x135.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x146.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Symbols</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c35.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Assembler Directives</TD ></TR ></TABLE ></DIV ></BODY ></HTML >