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Martin Felis
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271 lines
21 KiB
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<h1>/home/dwoods/DevIL/src-IL/include/il_manip.h</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">//-----------------------------------------------------------------------------</span>
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<a name="l00002"></a>00002 <span class="comment">//</span>
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<a name="l00003"></a>00003 <span class="comment">// ImageLib Sources</span>
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<a name="l00004"></a>00004 <span class="comment">// Copyright (C) 2001-2002 by Denton Woods</span>
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<a name="l00005"></a>00005 <span class="comment">// Last modified: 05/25/2001 <--Y2K Compliant! =]</span>
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<a name="l00006"></a>00006 <span class="comment">//</span>
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<a name="l00007"></a>00007 <span class="comment">// Filename: src-IL/include/il_manip.h</span>
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<a name="l00008"></a>00008 <span class="comment">//</span>
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<a name="l00009"></a>00009 <span class="comment">// Description: Image manipulation</span>
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<a name="l00010"></a>00010 <span class="comment">//</span>
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<a name="l00011"></a>00011 <span class="comment">//-----------------------------------------------------------------------------</span>
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<a name="l00012"></a>00012
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<a name="l00013"></a>00013 <span class="preprocessor">#ifndef MANIP_H</span>
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<a name="l00014"></a>00014 <span class="preprocessor"></span><span class="preprocessor">#define MANIP_H</span>
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<a name="l00015"></a>00015 <span class="preprocessor"></span>
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<a name="l00016"></a>00016 <span class="preprocessor">#ifdef _cplusplus</span>
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<a name="l00017"></a>00017 <span class="preprocessor"></span><span class="keyword">extern</span> <span class="stringliteral">"C"</span> {
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<a name="l00018"></a>00018 <span class="preprocessor">#endif</span>
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<a name="l00019"></a>00019 <span class="preprocessor"></span>
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<a name="l00020"></a>00020 ILboolean ilFlipImage(<span class="keywordtype">void</span>);
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<a name="l00021"></a>00021 ILboolean ilMirrorImage(<span class="keywordtype">void</span>); <span class="comment">//@JASON New routine created 03/28/2001</span>
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<a name="l00022"></a>00022
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<a name="l00023"></a>00023 <span class="comment">//-----------------------------------------------</span>
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<a name="l00024"></a>00024 <span class="comment">// Overflow handler for float-to-half conversion;</span>
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<a name="l00025"></a>00025 <span class="comment">// generates a hardware floating-point overflow,</span>
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<a name="l00026"></a>00026 <span class="comment">// which may be trapped by the operating system.</span>
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<a name="l00027"></a>00027 <span class="comment">//-----------------------------------------------</span>
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<a name="l00028"></a>00028 <span class="preprocessor">#ifndef NOINLINE</span>
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<a name="l00029"></a>00029 <span class="preprocessor"></span>
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<a name="l00030"></a>00030 <span class="preprocessor">#if defined(_MSC_VER)</span>
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<a name="l00031"></a>00031 <span class="preprocessor"></span><span class="preprocessor"> #pragma warning(push)</span>
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<a name="l00032"></a>00032 <span class="preprocessor"></span><span class="preprocessor"> #pragma warning(disable : 4756) // Disables 'named type definition in parentheses' warning</span>
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<a name="l00033"></a>00033 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
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<a name="l00034"></a>00034 <span class="preprocessor"></span>INLINE ILfloat <span class="comment">/*ILAPIENTRY*/</span> ilFloatToHalfOverflow() {
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<a name="l00035"></a>00035 ILfloat f = 1e10;
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<a name="l00036"></a>00036 ILint j;
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<a name="l00037"></a>00037 <span class="keywordflow">for</span> (j = 0; j < 10; j++)
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<a name="l00038"></a>00038 f *= f; <span class="comment">// this will overflow before</span>
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<a name="l00039"></a>00039 <span class="comment">// the for loop terminates</span>
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<a name="l00040"></a>00040 <span class="keywordflow">return</span> f;
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<a name="l00041"></a>00041 }
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<a name="l00042"></a>00042 <span class="preprocessor">#if defined(_MSC_VER)</span>
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<a name="l00043"></a>00043 <span class="preprocessor"></span><span class="preprocessor"> #pragma warning(pop)</span>
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<a name="l00044"></a>00044 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
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<a name="l00045"></a>00045 <span class="preprocessor"></span>
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<a name="l00046"></a>00046 <span class="comment">//-----------------------------------------------------</span>
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<a name="l00047"></a>00047 <span class="comment">// Float-to-half conversion -- general case, including</span>
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<a name="l00048"></a>00048 <span class="comment">// zeroes, denormalized numbers and exponent overflows.</span>
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<a name="l00049"></a>00049 <span class="comment">//-----------------------------------------------------</span>
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<a name="l00050"></a>00050 INLINE ILushort ILAPIENTRY ilFloatToHalf(ILuint i) {
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<a name="l00051"></a>00051 <span class="comment">//</span>
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<a name="l00052"></a>00052 <span class="comment">// Our floating point number, f, is represented by the bit</span>
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<a name="l00053"></a>00053 <span class="comment">// pattern in integer i. Disassemble that bit pattern into</span>
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<a name="l00054"></a>00054 <span class="comment">// the sign, s, the exponent, e, and the significand, m.</span>
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<a name="l00055"></a>00055 <span class="comment">// Shift s into the position where it will go in in the</span>
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<a name="l00056"></a>00056 <span class="comment">// resulting half number.</span>
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<a name="l00057"></a>00057 <span class="comment">// Adjust e, accounting for the different exponent bias</span>
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<a name="l00058"></a>00058 <span class="comment">// of float and half (127 versus 15).</span>
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<a name="l00059"></a>00059 <span class="comment">//</span>
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<a name="l00060"></a>00060
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<a name="l00061"></a>00061 <span class="keyword">register</span> <span class="keywordtype">int</span> s = (i >> 16) & 0x00008000;
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<a name="l00062"></a>00062 <span class="keyword">register</span> <span class="keywordtype">int</span> e = ((i >> 23) & 0x000000ff) - (127 - 15);
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<a name="l00063"></a>00063 <span class="keyword">register</span> <span class="keywordtype">int</span> m = i & 0x007fffff;
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<a name="l00064"></a>00064
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<a name="l00065"></a>00065 <span class="comment">//</span>
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<a name="l00066"></a>00066 <span class="comment">// Now reassemble s, e and m into a half:</span>
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<a name="l00067"></a>00067 <span class="comment">//</span>
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<a name="l00068"></a>00068
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<a name="l00069"></a>00069 <span class="keywordflow">if</span> (e <= 0)
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<a name="l00070"></a>00070 {
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<a name="l00071"></a>00071 <span class="keywordflow">if</span> (e < -10)
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<a name="l00072"></a>00072 {
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<a name="l00073"></a>00073 <span class="comment">//</span>
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<a name="l00074"></a>00074 <span class="comment">// E is less than -10. The absolute value of f is</span>
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<a name="l00075"></a>00075 <span class="comment">// less than HALF_MIN (f may be a small normalized</span>
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<a name="l00076"></a>00076 <span class="comment">// float, a denormalized float or a zero).</span>
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<a name="l00077"></a>00077 <span class="comment">//</span>
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<a name="l00078"></a>00078 <span class="comment">// We convert f to a half zero.</span>
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<a name="l00079"></a>00079 <span class="comment">//</span>
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<a name="l00080"></a>00080
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<a name="l00081"></a>00081 <span class="keywordflow">return</span> 0;
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<a name="l00082"></a>00082 }
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<a name="l00083"></a>00083
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<a name="l00084"></a>00084 <span class="comment">//</span>
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<a name="l00085"></a>00085 <span class="comment">// E is between -10 and 0. F is a normalized float,</span>
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<a name="l00086"></a>00086 <span class="comment">// whose magnitude is less than HALF_NRM_MIN.</span>
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<a name="l00087"></a>00087 <span class="comment">//</span>
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<a name="l00088"></a>00088 <span class="comment">// We convert f to a denormalized half.</span>
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<a name="l00089"></a>00089 <span class="comment">// </span>
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<a name="l00090"></a>00090
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<a name="l00091"></a>00091 m = (m | 0x00800000) >> (1 - e);
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<a name="l00092"></a>00092
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<a name="l00093"></a>00093 <span class="comment">//</span>
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<a name="l00094"></a>00094 <span class="comment">// Round to nearest, round "0.5" up.</span>
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<a name="l00095"></a>00095 <span class="comment">//</span>
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<a name="l00096"></a>00096 <span class="comment">// Rounding may cause the significand to overflow and make</span>
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<a name="l00097"></a>00097 <span class="comment">// our number normalized. Because of the way a half's bits</span>
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<a name="l00098"></a>00098 <span class="comment">// are laid out, we don't have to treat this case separately;</span>
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<a name="l00099"></a>00099 <span class="comment">// the code below will handle it correctly.</span>
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<a name="l00100"></a>00100 <span class="comment">// </span>
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<a name="l00101"></a>00101
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<a name="l00102"></a>00102 <span class="keywordflow">if</span> (m & 0x00001000)
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<a name="l00103"></a>00103 m += 0x00002000;
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<a name="l00104"></a>00104
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<a name="l00105"></a>00105 <span class="comment">//</span>
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<a name="l00106"></a>00106 <span class="comment">// Assemble the half from s, e (zero) and m.</span>
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<a name="l00107"></a>00107 <span class="comment">//</span>
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<a name="l00108"></a>00108
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<a name="l00109"></a>00109 <span class="keywordflow">return</span> s | (m >> 13);
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<a name="l00110"></a>00110 }
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<a name="l00111"></a>00111 <span class="keywordflow">else</span> <span class="keywordflow">if</span> (e == 0xff - (127 - 15))
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<a name="l00112"></a>00112 {
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<a name="l00113"></a>00113 <span class="keywordflow">if</span> (m == 0)
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<a name="l00114"></a>00114 {
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<a name="l00115"></a>00115 <span class="comment">//</span>
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<a name="l00116"></a>00116 <span class="comment">// F is an infinity; convert f to a half</span>
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<a name="l00117"></a>00117 <span class="comment">// infinity with the same sign as f.</span>
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<a name="l00118"></a>00118 <span class="comment">//</span>
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<a name="l00119"></a>00119
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<a name="l00120"></a>00120 <span class="keywordflow">return</span> s | 0x7c00;
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<a name="l00121"></a>00121 }
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<a name="l00122"></a>00122 <span class="keywordflow">else</span>
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<a name="l00123"></a>00123 {
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<a name="l00124"></a>00124 <span class="comment">//</span>
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<a name="l00125"></a>00125 <span class="comment">// F is a NAN; we produce a half NAN that preserves</span>
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<a name="l00126"></a>00126 <span class="comment">// the sign bit and the 10 leftmost bits of the</span>
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<a name="l00127"></a>00127 <span class="comment">// significand of f, with one exception: If the 10</span>
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<a name="l00128"></a>00128 <span class="comment">// leftmost bits are all zero, the NAN would turn </span>
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<a name="l00129"></a>00129 <span class="comment">// into an infinity, so we have to set at least one</span>
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<a name="l00130"></a>00130 <span class="comment">// bit in the significand.</span>
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<a name="l00131"></a>00131 <span class="comment">//</span>
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<a name="l00132"></a>00132
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<a name="l00133"></a>00133 m >>= 13;
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<a name="l00134"></a>00134 <span class="keywordflow">return</span> s | 0x7c00 | m | (m == 0);
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<a name="l00135"></a>00135 }
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<a name="l00136"></a>00136 }
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<a name="l00137"></a>00137 <span class="keywordflow">else</span>
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<a name="l00138"></a>00138 {
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<a name="l00139"></a>00139 <span class="comment">//</span>
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<a name="l00140"></a>00140 <span class="comment">// E is greater than zero. F is a normalized float.</span>
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<a name="l00141"></a>00141 <span class="comment">// We try to convert f to a normalized half.</span>
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<a name="l00142"></a>00142 <span class="comment">//</span>
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<a name="l00143"></a>00143
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<a name="l00144"></a>00144 <span class="comment">//</span>
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<a name="l00145"></a>00145 <span class="comment">// Round to nearest, round "0.5" up</span>
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<a name="l00146"></a>00146 <span class="comment">//</span>
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<a name="l00147"></a>00147
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<a name="l00148"></a>00148 <span class="keywordflow">if</span> (m & 0x00001000)
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<a name="l00149"></a>00149 {
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<a name="l00150"></a>00150 m += 0x00002000;
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<a name="l00151"></a>00151
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<a name="l00152"></a>00152 <span class="keywordflow">if</span> (m & 0x00800000)
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<a name="l00153"></a>00153 {
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<a name="l00154"></a>00154 m = 0; <span class="comment">// overflow in significand,</span>
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<a name="l00155"></a>00155 e += 1; <span class="comment">// adjust exponent</span>
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<a name="l00156"></a>00156 }
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<a name="l00157"></a>00157 }
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<a name="l00158"></a>00158
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<a name="l00159"></a>00159 <span class="comment">//</span>
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<a name="l00160"></a>00160 <span class="comment">// Handle exponent overflow</span>
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<a name="l00161"></a>00161 <span class="comment">//</span>
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<a name="l00162"></a>00162
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<a name="l00163"></a>00163 <span class="keywordflow">if</span> (e > 30)
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<a name="l00164"></a>00164 {
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<a name="l00165"></a>00165 ilFloatToHalfOverflow(); <span class="comment">// Cause a hardware floating point overflow;</span>
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<a name="l00166"></a>00166 <span class="keywordflow">return</span> s | 0x7c00; <span class="comment">// if this returns, the half becomes an</span>
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<a name="l00167"></a>00167 } <span class="comment">// infinity with the same sign as f.</span>
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<a name="l00168"></a>00168
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<a name="l00169"></a>00169 <span class="comment">//</span>
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<a name="l00170"></a>00170 <span class="comment">// Assemble the half from s, e and m.</span>
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<a name="l00171"></a>00171 <span class="comment">//</span>
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<a name="l00172"></a>00172
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<a name="l00173"></a>00173 <span class="keywordflow">return</span> s | (e << 10) | (m >> 13);
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<a name="l00174"></a>00174 }
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<a name="l00175"></a>00175 }
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<a name="l00176"></a>00176
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<a name="l00177"></a>00177 <span class="comment">// Taken from OpenEXR</span>
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<a name="l00178"></a>00178 INLINE ILuint ILAPIENTRY ilHalfToFloat (ILushort y) {
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<a name="l00179"></a>00179
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<a name="l00180"></a>00180 <span class="keywordtype">int</span> s = (y >> 15) & 0x00000001;
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<a name="l00181"></a>00181 <span class="keywordtype">int</span> e = (y >> 10) & 0x0000001f;
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<a name="l00182"></a>00182 <span class="keywordtype">int</span> m = y & 0x000003ff;
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<a name="l00183"></a>00183
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<a name="l00184"></a>00184 <span class="keywordflow">if</span> (e == 0)
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<a name="l00185"></a>00185 {
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<a name="l00186"></a>00186 <span class="keywordflow">if</span> (m == 0)
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<a name="l00187"></a>00187 {
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<a name="l00188"></a>00188 <span class="comment">//</span>
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<a name="l00189"></a>00189 <span class="comment">// Plus or minus zero</span>
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<a name="l00190"></a>00190 <span class="comment">//</span>
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<a name="l00191"></a>00191
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<a name="l00192"></a>00192 <span class="keywordflow">return</span> s << 31;
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<a name="l00193"></a>00193 }
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<a name="l00194"></a>00194 <span class="keywordflow">else</span>
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<a name="l00195"></a>00195 {
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<a name="l00196"></a>00196 <span class="comment">//</span>
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<a name="l00197"></a>00197 <span class="comment">// Denormalized number -- renormalize it</span>
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<a name="l00198"></a>00198 <span class="comment">//</span>
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<a name="l00199"></a>00199
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<a name="l00200"></a>00200 <span class="keywordflow">while</span> (!(m & 0x00000400))
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<a name="l00201"></a>00201 {
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<a name="l00202"></a>00202 m <<= 1;
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<a name="l00203"></a>00203 e -= 1;
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<a name="l00204"></a>00204 }
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<a name="l00205"></a>00205
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<a name="l00206"></a>00206 e += 1;
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<a name="l00207"></a>00207 m &= ~0x00000400;
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<a name="l00208"></a>00208 }
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<a name="l00209"></a>00209 }
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<a name="l00210"></a>00210 <span class="keywordflow">else</span> <span class="keywordflow">if</span> (e == 31)
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<a name="l00211"></a>00211 {
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<a name="l00212"></a>00212 <span class="keywordflow">if</span> (m == 0)
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<a name="l00213"></a>00213 {
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<a name="l00214"></a>00214 <span class="comment">//</span>
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<a name="l00215"></a>00215 <span class="comment">// Positive or negative infinity</span>
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<a name="l00216"></a>00216 <span class="comment">//</span>
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<a name="l00217"></a>00217
|
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<a name="l00218"></a>00218 <span class="keywordflow">return</span> (s << 31) | 0x7f800000;
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<a name="l00219"></a>00219 }
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<a name="l00220"></a>00220 <span class="keywordflow">else</span>
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<a name="l00221"></a>00221 {
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<a name="l00222"></a>00222 <span class="comment">//</span>
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<a name="l00223"></a>00223 <span class="comment">// Nan -- preserve sign and significand bits</span>
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<a name="l00224"></a>00224 <span class="comment">//</span>
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<a name="l00225"></a>00225
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<a name="l00226"></a>00226 <span class="keywordflow">return</span> (s << 31) | 0x7f800000 | (m << 13);
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<a name="l00227"></a>00227 }
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<a name="l00228"></a>00228 }
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<a name="l00229"></a>00229
|
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<a name="l00230"></a>00230 <span class="comment">//</span>
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<a name="l00231"></a>00231 <span class="comment">// Normalized number</span>
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<a name="l00232"></a>00232 <span class="comment">//</span>
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<a name="l00233"></a>00233
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<a name="l00234"></a>00234 e = e + (127 - 15);
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<a name="l00235"></a>00235 m = m << 13;
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<a name="l00236"></a>00236
|
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<a name="l00237"></a>00237 <span class="comment">//</span>
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<a name="l00238"></a>00238 <span class="comment">// Assemble s, e and m.</span>
|
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<a name="l00239"></a>00239 <span class="comment">//</span>
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<a name="l00240"></a>00240
|
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<a name="l00241"></a>00241 <span class="keywordflow">return</span> (s << 31) | (e << 23) | m;
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<a name="l00242"></a>00242 }
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<a name="l00243"></a>00243 <span class="preprocessor">#endif //NOINLINE</span>
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<a name="l00244"></a>00244 <span class="preprocessor"></span>
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<a name="l00245"></a>00245 <span class="preprocessor">#ifdef _cplusplus</span>
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<a name="l00246"></a>00246 <span class="preprocessor"></span>}
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<a name="l00247"></a>00247 <span class="preprocessor">#endif</span>
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<a name="l00248"></a>00248 <span class="preprocessor"></span>
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<a name="l00249"></a>00249 <span class="preprocessor">#endif//MANIP_H</span>
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</pre></div></div>
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<hr size="1"><address style="text-align: right;"><small>Generated on Sun Mar 8 20:01:41 2009 for DevIL by
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<a href="http://www.doxygen.org/index.html">
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<img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.5.6 </small></address>
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</body>
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</html>
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