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<title>System/ByteOrder.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-
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<a name="line-3"></a>Module : System.ByteOrder
<a name="line-4"></a>Copyright : (c) Antoine Latter 2009
<a name="line-5"></a>License : BSD3
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<a name="line-7"></a>Maintainer : Antoine Latter <aslatter@gmail.com>
<a name="line-8"></a>Stability: unstable
<a name="line-9"></a>Portability: requires FFI
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<a name="line-11"></a>-}</span>
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<a name="line-13"></a><span class='hs-comment'>{-# OPTIONS_GHC -fno-cse #-}</span>
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<a name="line-15"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>ByteOrder</span><span class='hs-layout'>(</span><span class='hs-varid'>byteOrder</span><span class='hs-layout'>,</span> <span class='hs-conid'>ByteOrder</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
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<a name="line-17"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Foreign</span>
<a name="line-18"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Word</span>
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<a name="line-20"></a><a name="ByteOrder"></a><span class='hs-comment'>-- |Indicates the byte-ordering for a 4-byte value, where '1'</span>
<a name="line-21"></a><a name="ByteOrder"></a><span class='hs-comment'>-- indicates the most-significant byte and '4' indicates the</span>
<a name="line-22"></a><a name="ByteOrder"></a><span class='hs-comment'>-- least significant byte.</span>
<a name="line-23"></a><a name="ByteOrder"></a><span class='hs-comment'>--</span>
<a name="line-24"></a><a name="ByteOrder"></a><span class='hs-comment'>-- In this format, big endian byte order would be represented as:</span>
<a name="line-25"></a><a name="ByteOrder"></a><span class='hs-comment'>-- (1,2,3,4).</span>
<a name="line-26"></a><a name="ByteOrder"></a><span class='hs-comment'>--</span>
<a name="line-27"></a><a name="ByteOrder"></a><span class='hs-comment'>-- For convinience, the most common cases (BigEndian and LittleEndian)</span>
<a name="line-28"></a><a name="ByteOrder"></a><span class='hs-comment'>-- are provided their own constructors.</span>
<a name="line-29"></a><a name="ByteOrder"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>ByteOrder</span>
<a name="line-30"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>BigEndian</span>
<a name="line-31"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>LittleEndian</span>
<a name="line-32"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Mixed</span> <span class='hs-layout'>(</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span> <span class='hs-conid'>Word8</span><span class='hs-layout'>,</span> <span class='hs-conid'>Word8</span><span class='hs-layout'>,</span> <span class='hs-conid'>Word8</span><span class='hs-layout'>)</span>
<a name="line-33"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Eq</span><span class='hs-layout'>,</span> <span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Read</span><span class='hs-layout'>,</span> <span class='hs-conid'>Ord</span><span class='hs-layout'>)</span>
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<a name="line-35"></a><a name="input"></a><span class='hs-definition'>input</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Word32</span>
<a name="line-36"></a><span class='hs-definition'>input</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>0x01020304</span>
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<a name="line-38"></a><a name="byteOrder"></a><span class='hs-comment'>-- |Returns the native byte ordering of the system.</span>
<a name="line-39"></a><span class='hs-definition'>byteOrder</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ByteOrder</span>
<a name="line-40"></a><span class='hs-definition'>byteOrder</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unsafePerformIO</span> <span class='hs-varid'>byteOrderIO</span>
<a name="line-41"></a><span class='hs-comment'>{-# NOINLINE byteOrder #-}</span>
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<a name="line-43"></a><a name="byteOrderIO"></a><span class='hs-definition'>byteOrderIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-conid'>ByteOrder</span>
<a name="line-44"></a><span class='hs-definition'>byteOrderIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>bytesToByteOrder</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>wordToBytes</span> <span class='hs-varid'>input</span>
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<a name="line-46"></a><a name="wordToBytes"></a><span class='hs-definition'>wordToBytes</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Word32</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span><span class='hs-conid'>Word8</span><span class='hs-layout'>)</span>
<a name="line-47"></a><span class='hs-definition'>wordToBytes</span> <span class='hs-varid'>word</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>alloca</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>wordPtr</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-48"></a> <span class='hs-varid'>poke</span> <span class='hs-varid'>wordPtr</span> <span class='hs-varid'>word</span>
<a name="line-49"></a> <span class='hs-keyglyph'>[</span><span class='hs-varid'>x1</span><span class='hs-layout'>,</span><span class='hs-varid'>x2</span><span class='hs-layout'>,</span><span class='hs-varid'>x3</span><span class='hs-layout'>,</span><span class='hs-varid'>x4</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>peekArray</span> <span class='hs-num'>4</span> <span class='hs-layout'>(</span><span class='hs-varid'>castPtr</span> <span class='hs-varid'>wordPtr</span><span class='hs-layout'>)</span>
<a name="line-50"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>x1</span><span class='hs-layout'>,</span><span class='hs-varid'>x2</span><span class='hs-layout'>,</span><span class='hs-varid'>x3</span><span class='hs-layout'>,</span><span class='hs-varid'>x4</span><span class='hs-layout'>)</span>
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<a name="line-52"></a><a name="bytesToByteOrder"></a><span class='hs-definition'>bytesToByteOrder</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span><span class='hs-conid'>Word8</span><span class='hs-layout'>,</span><span class='hs-conid'>Word8</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ByteOrder</span>
<a name="line-53"></a><span class='hs-definition'>bytesToByteOrder</span> <span class='hs-layout'>(</span><span class='hs-num'>1</span><span class='hs-layout'>,</span> <span class='hs-num'>2</span><span class='hs-layout'>,</span> <span class='hs-num'>3</span><span class='hs-layout'>,</span> <span class='hs-num'>4</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>BigEndian</span>
<a name="line-54"></a><span class='hs-definition'>bytesToByteOrder</span> <span class='hs-layout'>(</span><span class='hs-num'>4</span><span class='hs-layout'>,</span> <span class='hs-num'>3</span><span class='hs-layout'>,</span> <span class='hs-num'>2</span><span class='hs-layout'>,</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>LittleEndian</span>
<a name="line-55"></a><span class='hs-definition'>bytesToByteOrder</span> <span class='hs-layout'>(</span><span class='hs-varid'>x1</span><span class='hs-layout'>,</span> <span class='hs-varid'>x2</span><span class='hs-layout'>,</span> <span class='hs-varid'>x3</span><span class='hs-layout'>,</span> <span class='hs-varid'>x4</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Mixed</span> <span class='hs-layout'>(</span><span class='hs-varid'>x1</span><span class='hs-layout'>,</span><span class='hs-varid'>x2</span><span class='hs-layout'>,</span><span class='hs-varid'>x3</span><span class='hs-layout'>,</span><span class='hs-varid'>x4</span><span class='hs-layout'>)</span>
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