130 lines
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130 lines
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<title>Infix Ops - Using as</title>
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<div class="node">
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<a name="Infix-Ops"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Prefix-Ops.html#Prefix-Ops">Prefix Ops</a>,
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Up: <a rel="up" accesskey="u" href="Integer-Exprs.html#Integer-Exprs">Integer Exprs</a>
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<hr>
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</div>
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<h4 class="subsection">6.2.4 Infix Operators</h4>
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<p><a name="index-infix-operators-259"></a><a name="index-operators_002c-permitted-arguments-260"></a><dfn>Infix operators</dfn> take two arguments, one on either side. Operators
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have precedence, but operations with equal precedence are performed left
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to right. Apart from <code>+</code> or <samp><span class="option">-</span></samp>, both arguments must be
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absolute, and the result is absolute.
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<ol type=1 start=1>
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<a name="index-operator-precedence-261"></a><a name="index-precedence-of-operators-262"></a>
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<li>Highest Precedence
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<dl>
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<dt><code>*</code><dd><dfn>Multiplication</dfn>.
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<br><dt><code>/</code><dd><dfn>Division</dfn>. Truncation is the same as the C operator ‘<samp><span class="samp">/</span></samp>’
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<br><dt><code>%</code><dd><dfn>Remainder</dfn>.
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<br><dt><code><<</code><dd><dfn>Shift Left</dfn>. Same as the C operator ‘<samp><span class="samp"><<</span></samp>’.
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<br><dt><code>>></code><dd><dfn>Shift Right</dfn>. Same as the C operator ‘<samp><span class="samp">>></span></samp>’.
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</dl>
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<li>Intermediate precedence
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<dl>
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<dt><code>|</code><dd>
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<dfn>Bitwise Inclusive Or</dfn>.
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<br><dt><code>&</code><dd><dfn>Bitwise And</dfn>.
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<br><dt><code>^</code><dd><dfn>Bitwise Exclusive Or</dfn>.
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<br><dt><code>!</code><dd><dfn>Bitwise Or Not</dfn>.
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</dl>
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<li>Low Precedence
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<a name="index-addition_002c-permitted-arguments-263"></a>
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<a name="index-plus_002c-permitted-arguments-264"></a>
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<a name="index-arguments-for-addition-265"></a>
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<dl><dt><code>+</code><dd><dfn>Addition</dfn>. If either argument is absolute, the result has the section of
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the other argument. You may not add together arguments from different
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sections.
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<p><a name="index-subtraction_002c-permitted-arguments-266"></a><a name="index-minus_002c-permitted-arguments-267"></a><a name="index-arguments-for-subtraction-268"></a><br><dt><code>-</code><dd><dfn>Subtraction</dfn>. If the right argument is absolute, the
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result has the section of the left argument.
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If both arguments are in the same section, the result is absolute.
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You may not subtract arguments from different sections.
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<!-- FIXME is there still something useful to say about undefined - undefined ? -->
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<p><a name="index-comparison-expressions-269"></a><a name="index-expressions_002c-comparison-270"></a><br><dt><code>==</code><dd><dfn>Is Equal To</dfn>
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<br><dt><code><></code><dt><code>!=</code><dd><dfn>Is Not Equal To</dfn>
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<br><dt><code><</code><dd><dfn>Is Less Than</dfn>
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<br><dt><code>></code><dd><dfn>Is Greater Than</dfn>
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<br><dt><code>>=</code><dd><dfn>Is Greater Than Or Equal To</dfn>
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<br><dt><code><=</code><dd><dfn>Is Less Than Or Equal To</dfn>
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<p>The comparison operators can be used as infix operators. A true results has a
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value of -1 whereas a false result has a value of 0. Note, these operators
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perform signed comparisons.
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</dl>
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<li>Lowest Precedence
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<dl>
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<dt><code>&&</code><dd><dfn>Logical And</dfn>.
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<br><dt><code>||</code><dd><dfn>Logical Or</dfn>.
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<p>These two logical operations can be used to combine the results of sub
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expressions. Note, unlike the comparison operators a true result returns a
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value of 1 but a false results does still return 0. Also note that the logical
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or operator has a slightly lower precedence than logical and.
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</dl>
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</ol>
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<p>In short, it's only meaningful to add or subtract the <em>offsets</em> in an
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address; you can only have a defined section in one of the two arguments.
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