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163 lines
5.2 KiB
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<html><head>
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<META http-equiv="content-type" content="text/html; charset=utf-8">
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<title>std.intrinsic</title>
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</head><body>
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<h1>std.intrinsic</h1>
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<!-- Generated by Ddoc from ../kernel/runtime/std/intrinsic.d -->
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These functions are built-in intrinsics to the compiler.
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<br><br>
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Intrinsic functions are functions built in to the compiler,
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usually to take advantage of specific CPU features that
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are inefficient to handle via external functions.
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The compiler's optimizer and code generator are fully
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integrated in with <u>intrinsic</u> functions, bringing to bear
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their full power on them.
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This can result in some surprising speedups.
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<br><br>
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<dl><dt><big>int <u>bsf</u>(uint <i>v</i>);
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</big></dt>
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<dd>Scans the bits in <i>v</i> starting with bit 0, looking
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for the first set bit.
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<br><br>
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<b>Returns:</b><br>
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The bit number of the first bit set.
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The return value is undefined if <i>v</i> is zero.<br><br>
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</dd>
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<dt><big>int <u>bsr</u>(uint <i>v</i>);
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</big></dt>
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<dd>Scans the bits in <i>v</i> from the most significant bit
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to the least significant bit, looking
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for the first set bit.
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<br><br>
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<b>Returns:</b><br>
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The bit number of the first bit set.
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The return value is undefined if <i>v</i> is zero.
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<br><br>
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<b>Example:</b><br>
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<pre class="d_code"> <font color=blue>import</font> std.intrinsic;
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<font color=blue>int</font> main()
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{
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<font color=blue>uint</font> <i>v</i>;
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<font color=blue>int</font> x;
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<i>v</i> = 0x21;
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x = bsf(<i>v</i>);
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printf(<font color=red>"bsf(x%x) = %d\n"</font>, <i>v</i>, x);
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x = <u>bsr</u>(<i>v</i>);
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printf(<font color=red>"bsr(x%x) = %d\n"</font>, <i>v</i>, x);
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<font color=blue>return</font> 0;
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}
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</pre>
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<br><br>
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<b>Output:</b><br>
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bsf(x21) = 0<br>
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<u>bsr</u>(x21) = 5<br><br>
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</dd>
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<dt><big>int <u>bt</u>(uint* <i>p</i>, uint <i>bitnum</i>);
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</big></dt>
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<dd>Tests the bit.<br><br>
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</dd>
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<dt><big>int <u>btc</u>(uint* <i>p</i>, uint <i>bitnum</i>);
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</big></dt>
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<dd>Tests and complements the bit.<br><br>
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</dd>
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<dt><big>int <u>btr</u>(uint* <i>p</i>, uint <i>bitnum</i>);
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</big></dt>
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<dd>Tests and resets (sets to 0) the bit.<br><br>
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</dd>
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<dt><big>int <u>bts</u>(uint* <i>p</i>, uint <i>bitnum</i>);
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</big></dt>
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<dd>Tests and sets the bit.
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<br><br>
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<b>Params:</b><br>
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<table><tr><td>uint* <i>p</i></td>
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<td>a non-NULL pointer to an array of uints.</td></tr>
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<tr><td>index</td>
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<td>a bit number, starting with bit 0 of <i>p</i>[0],
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and progressing. It addresses bits like the expression:
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<pre class="d_code"><i>p</i>[index / (<font color=blue>uint</font>.sizeof*8)] & (1 << (index & ((<font color=blue>uint</font>.sizeof*8) - 1)))
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</pre>
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</td></tr>
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</table><br>
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<b>Returns:</b><br>
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A non-zero value if the bit was set, and a zero
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if it was clear.
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<br><br>
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<b>Example:</b><br>
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<pre class="d_code"><font color=blue>import</font> std.intrinsic;
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<font color=blue>int</font> main()
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{
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<font color=blue>uint</font> array[2];
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array[0] = 2;
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array[1] = 0x100;
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printf(<font color=red>"btc(array, 35) = %d\n"</font>, <b>btc</b>(array, 35));
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printf(<font color=red>"array = [0]:x%x, [1]:x%x\n"</font>, array[0], array[1]);
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printf(<font color=red>"btc(array, 35) = %d\n"</font>, <b>btc</b>(array, 35));
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printf(<font color=red>"array = [0]:x%x, [1]:x%x\n"</font>, array[0], array[1]);
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printf(<font color=red>"bts(array, 35) = %d\n"</font>, <b><u>bts</u></b>(array, 35));
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printf(<font color=red>"array = [0]:x%x, [1]:x%x\n"</font>, array[0], array[1]);
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printf(<font color=red>"btr(array, 35) = %d\n"</font>, <b>btr</b>(array, 35));
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printf(<font color=red>"array = [0]:x%x, [1]:x%x\n"</font>, array[0], array[1]);
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printf(<font color=red>"bt(array, 1) = %d\n"</font>, <b>bt</b>(array, 1));
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printf(<font color=red>"array = [0]:x%x, [1]:x%x\n"</font>, array[0], array[1]);
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<font color=blue>return</font> 0;
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}
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</pre>
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<br><br>
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<b>Output:</b><br>
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<pre>
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btc(array, 35) = 0
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array = [0]:x2, [1]:x108
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btc(array, 35) = -1
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array = [0]:x2, [1]:x100
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<u>bts</u>(array, 35) = 0
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array = [0]:x2, [1]:x108
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btr(array, 35) = -1
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array = [0]:x2, [1]:x100
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bt(array, 1) = -1
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array = [0]:x2, [1]:x100
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</pre><br><br>
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</dd>
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<dt><big>uint <u>bswap</u>(uint <i>v</i>);
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</big></dt>
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<dd>Swaps bytes in a 4 byte uint end-to-end, i.e. byte 0 becomes
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byte 3, byte 1 becomes byte 2, byte 2 becomes byte 1, byte 3
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becomes byte 0.<br><br>
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</dd>
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<dt><big>ubyte <u>inp</u>(uint <i>port_address</i>);
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<br>ushort <u>inpw</u>(uint <i>port_address</i>);
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<br>uint <u>inpl</u>(uint <i>port_address</i>);
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</big></dt>
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<dd>Reads I/O port at <i>port_address</i>.<br><br>
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</dd>
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<dt><big>ubyte <u>outp</u>(uint <i>port_address</i>, ubyte <i>value</i>);
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<br>ushort <u>outpw</u>(uint <i>port_address</i>, ushort <i>value</i>);
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<br>uint <u>outpl</u>(uint <i>port_address</i>, uint <i>value</i>);
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</big></dt>
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<dd>Writes and returns <i>value</i> to I/O port at <i>port_address</i>.<br><br>
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</dd>
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</dl>
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<hr><small>Page generated by <a href="http://www.digitalmars.com/d/1.0/ddoc.html">Ddoc</a>. </small>
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</body></html>
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