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more HTML formatting gunk
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Anthony Bentley
@@ -1,104 +1,92 @@
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<HTML>
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<HEAD>
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<TITLE>xAsm Integer/Boolean expressions</TITLE>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
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<title>xAsm Integer/Boolean expressions</title>
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<link rel="stylesheet" type="text/css" href="../style.css">
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</HEAD>
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</head>
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<body>
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<h1>Integer and Boolean expressions</h1>
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<p>An expression can be composed of many things. Expressions are always evaluated using signed 32-bit math.</p>
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<p>The most basic expression is just a single number.</p>
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<h2>Numeric Formats</h2>
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<p>xAsm has a number of numeric formats.</p>
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<ul>
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<li>Hexadecimal: $0123456789ABCDEF. Case-insensitive
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<li>Decimal: 0123456789
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<li>Octal: &01234567
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<li>Binary: %01
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<li>Fixedpoint (16.16): 01234.56789
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<li>Character constant: "ABYZ"
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<li>Gameboy graphics: `0123
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</ul>
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<p>The last one, Gameboy graphics, is quite interesting and useful. The values are actually pixel values and it converts the “chunky” data to “planar” data as used in the Gameboy.</p>
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<pre>DW `01012323</pre>
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<p>Admittedly an expression with just a single number is quite boring. To spice things up a bit there’s a few operators you can use to perform calculations between numbers.</p>
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<h2>Operators</h2>
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<p>A great number of operators you can use in expressions are available (listed in order of precedence):</p>
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<table>
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<caption>Operators</caption>
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<thead>
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<tr>
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<th scope="col">Operator</th>
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<th scope="col">Meaning</th>
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</tr>
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</thead>
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<tr>
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<td>( )</td>
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<td>Precedence override</td>
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</tr>
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<tr>
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<td>FUNC()</td>
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<td>Functioncall</td>
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</tr>
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<tr>
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<td>~ + -</td>
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<td>Unary not/plus/minus</td>
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</tr>
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<tr>
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<td>* / %</td>
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<td>Multiply/divide/modulo</td>
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</tr>
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<tr>
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<td><< >></td>
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<td>Shift left/right</td>
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</tr>
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<tr>
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<td>& | ^</td>
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<td>Binary and/or/xor</td>
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</tr>
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<tr>
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<td>+ -</td>
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<td>Add/subtract</td>
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</tr>
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<tr>
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<td>!= == <= >= < ></td>
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<td>Boolean comparison</td>
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</tr>
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<tr>
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<td>&& ||</td>
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<td>Boolean and/or</td>
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</tr>
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<tr>
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<td>!</td>
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<td>Unary Boolean not</td>
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</tr>
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</table>
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<BODY>
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<I><H2>Integer and Boolean expressions
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</H2></I>
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<HR>
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<p>The result of the boolean operators is zero if when FALSE and non-zero when TRUE. Thus it is legal to use an integer as the condition for <a href="if.htm">IF</a> blocks. You can use symbols instead of numbers in your expression if you wish.</p>
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<P>An expression can be composed of many things. Expressions are always evaluated using signed 32-bit math.
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<P>The most basic expression is just a single number.
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<H4><BR>Numeric Formats</H4>
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<P>xAsm has a number of numeric formats.
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<UL>
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<LI>Hexadecimal: $0123456789ABCDEF. Case-insensitive
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<LI>Decimal: 0123456789
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<LI>Octal: &01234567
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<LI>Binary: %01
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<LI>Fixedpoint (16.16): 01234.56789
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<LI>Character constant: "ABYZ"
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<LI>Gameboy graphics: `0123
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</UL>
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<P>The last one, Gameboy graphics, is quite interesting and useful. The values are actually pixel values and it converts
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the "chunky" data to "planar" data as used in the Gameboy.<BR>
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<BR>
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<TABLE BORDER=0 BGCOLOR="Black" CELLPADDING=8 WIDTH="50%">
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<TR>
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<TD><FONT COLOR="#00FF00">
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<PRE>DW `01012323</PRE>
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</FONT></TD>
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</TR>
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</TABLE>
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<p>An expression is said to be constant when it doesn't change its value during linking. This basically means that you can't use labels in those expressions. The instructions in the macro-language all require expressions that are constant.</p>
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<h1>See also:</h1>
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<ul>
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<li><a href="symbols.htm">Symbols</a>
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<li><a href="expr_fix.htm">Fixed-point expressions and functions</a>
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<li><a href="expr_str.htm">String expressions, functions and formatting</a>
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<li><a href="miscfunc.htm">Other functions</a>
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</ul>
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Admittedly an expression with just a single number is quite boring. To spice things up a bit there's a few operators you can use to perform calculations between numbers.
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<H4><BR>
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Operators</H4>
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<P>A great number of operators you can use in expressions are available (listed in order of precedence):
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<TABLE BORDER=1>
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<CAPTION><I>Operators</I></CAPTION>
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<TR>
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<TD><B><I>Operator</I></B></TD>
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<TD><B><I>Meaning</I></B></TD>
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</TR>
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<TR>
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<TD>( )</TD>
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<TD>Precedence override</TD>
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</TR>
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<TR>
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<TD>FUNC()</TD>
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<TD>Functioncall</TD>
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</TR>
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<TR>
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<TD>~ + -</TD>
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<TD>Unary not/plus/minus</TD>
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</TR>
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<TR>
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<TD>* / %</TD>
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<TD>Multiply/divide/modulo</TD>
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</TR>
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<TR>
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<TD><< >></TD>
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<TD>Shift left/right</TD>
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</TR>
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<TR>
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<TD>& | ^</TD>
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<TD>Binary and/or/xor</TD>
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</TR>
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<TR>
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<TD>+ -</TD>
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<TD>Add/subtract</TD>
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</TR>
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<TR>
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<TD>!= == <= >= < ></TD>
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<TD>Boolean comparison</TD>
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</TR>
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<TR>
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<TD>&& ||</TD>
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<TD>Boolean and/or</TD>
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</TR>
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<TR>
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<TD>!</TD>
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<TD>Unary Boolean not</TD>
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</TR>
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</TABLE>
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<P>The result of the boolean operators is zero if when FALSE and non-zero when TRUE. Thus it is legal to use an integer as the condition for <A HREF="if.htm">IF</A> blocks. You can use symbols instead of numbers in your expression if you wish.
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<P>An expression is said to be constant when it doesn't change its value during linking. This basically means that you can't use labels in those expressions. The instructions in the macro-language all require expressions that are constant<BR>
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<H3>See also:</H3>
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<UL>
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<LI><A HREF="symbols.htm">Symbols</A>
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<LI><A HREF="expr_fix.htm">Fixed-point expressions and functions</A>
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<LI><A HREF="expr_str.htm">String expressions, functions and formatting</A>
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<LI><A HREF="miscfunc.htm">Other functions</A>
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</UL>
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<BR><HR>
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<FONT SIZE="-1"><I><P ALIGN=RIGHT>Last updated 21 June 1997 by <A HREF="mailto:surfsmurf@matilde.demon.co.uk">Carsten Sorensen</A></P></I></FONT>
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<hr>
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<p>Last updated 21 June 1997 by <a href="mailto:surfsmurf@matilde.demon.co.uk">Carsten Sorensen</a></p>
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</body>
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</html>
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