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<h1>include/core/SkMath.h</h1><a href="_sk_math_8h.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*</span>
<a name="l00002"></a>00002 <span class="comment"> * Copyright (C) 2006 The Android Open Source Project</span>
<a name="l00003"></a>00003 <span class="comment"> *</span>
<a name="l00004"></a>00004 <span class="comment"> * Licensed under the Apache License, Version 2.0 (the &quot;License&quot;);</span>
<a name="l00005"></a>00005 <span class="comment"> * you may not use this file except in compliance with the License.</span>
<a name="l00006"></a>00006 <span class="comment"> * You may obtain a copy of the License at</span>
<a name="l00007"></a>00007 <span class="comment"> *</span>
<a name="l00008"></a>00008 <span class="comment"> * http://www.apache.org/licenses/LICENSE-2.0</span>
<a name="l00009"></a>00009 <span class="comment"> *</span>
<a name="l00010"></a>00010 <span class="comment"> * Unless required by applicable law or agreed to in writing, software</span>
<a name="l00011"></a>00011 <span class="comment"> * distributed under the License is distributed on an &quot;AS IS&quot; BASIS,</span>
<a name="l00012"></a>00012 <span class="comment"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
<a name="l00013"></a>00013 <span class="comment"> * See the License for the specific language governing permissions and</span>
<a name="l00014"></a>00014 <span class="comment"> * limitations under the License.</span>
<a name="l00015"></a>00015 <span class="comment"> */</span>
<a name="l00016"></a>00016
<a name="l00017"></a>00017 <span class="preprocessor">#ifndef SkMath_DEFINED</span>
<a name="l00018"></a>00018 <span class="preprocessor"></span><span class="preprocessor">#define SkMath_DEFINED</span>
<a name="l00019"></a>00019 <span class="preprocessor"></span>
<a name="l00020"></a>00020 <span class="preprocessor">#include &quot;<a class="code" href="_sk_types_8h.html">SkTypes.h</a>&quot;</span>
<a name="l00021"></a>00021
<a name="l00023"></a>00023 <span class="keywordtype">int</span> <a class="code" href="_sk_math_8h.html#a84fb2d86b39452eef0b8a614b8bd7578" title="Returns the number of leading zero bits (0...32).">SkCLZ_portable</a>(uint32_t);
<a name="l00024"></a>00024
<a name="l00029"></a>00029 int32_t <a class="code" href="_sk_math_8h.html#ad1c82f373d385a5821da3a186d93c5ce">SkMulShift</a>(int32_t a, int32_t b, <span class="keywordtype">unsigned</span> shift);
<a name="l00030"></a>00030
<a name="l00035"></a>00035 int32_t <a class="code" href="_sk_math_8h.html#ae43bef67fd5c320215fe2cfdb6ab35ca">SkMulDiv</a>(int32_t numer1, int32_t numer2, int32_t denom);
<a name="l00036"></a>00036
<a name="l00041"></a>00041 int32_t <a class="code" href="_sk_math_8h.html#a1d093e44b78bf74cdbbc42cc60fad438">SkDivBits</a>(int32_t numer, int32_t denom, <span class="keywordtype">int</span> shift);
<a name="l00042"></a>00042
<a name="l00045"></a>00045 int32_t <a class="code" href="_sk_math_8h.html#ab6325ae5ffed98c2af87ef1b37a3411d">SkSqrtBits</a>(int32_t value, <span class="keywordtype">int</span> bitBias);
<a name="l00046"></a>00046
<a name="l00049"></a><a class="code" href="_sk_math_8h.html#afab08772cf54af5b56983cba9fa509c3">00049</a> <span class="preprocessor">#define SkSqrt32(n) SkSqrtBits(n, 15)</span>
<a name="l00050"></a>00050 <span class="preprocessor"></span>
<a name="l00053"></a>00053 int32_t <a class="code" href="_sk_math_8h.html#afae7d95657f0e3f7ed82e814548ad481">SkCubeRootBits</a>(int32_t value, <span class="keywordtype">int</span> bitBias);
<a name="l00054"></a>00054
<a name="l00057"></a><a class="code" href="_sk_math_8h.html#abf04f1dc3004c0ed8b5fa535e81da59d">00057</a> <span class="preprocessor">#define SkExtractSign(n) ((int32_t)(n) &gt;&gt; 31)</span>
<a name="l00058"></a>00058 <span class="preprocessor"></span>
<a name="l00062"></a>00062 <span class="keyword">static</span> <span class="keyword">inline</span> int32_t SkApplySign(int32_t n, int32_t sign) {
<a name="l00063"></a>00063 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(sign == 0 || sign == -1);
<a name="l00064"></a>00064 <span class="keywordflow">return</span> (n ^ sign) - sign;
<a name="l00065"></a>00065 }
<a name="l00066"></a>00066
<a name="l00069"></a>00069 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">int</span> SkClampPos(<span class="keywordtype">int</span> value) {
<a name="l00070"></a>00070 <span class="keywordflow">return</span> value &amp; ~(value &gt;&gt; 31);
<a name="l00071"></a>00071 }
<a name="l00072"></a>00072
<a name="l00080"></a>00080 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">int</span> SkClampMax(<span class="keywordtype">int</span> value, <span class="keywordtype">int</span> max) {
<a name="l00081"></a>00081 <span class="comment">// ensure that max is positive</span>
<a name="l00082"></a>00082 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(max &gt;= 0);
<a name="l00083"></a>00083 <span class="comment">// ensure that if value is negative, max - value doesn&apos;t wrap around</span>
<a name="l00084"></a>00084 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(value &gt;= 0 || max - value &gt; 0);
<a name="l00085"></a>00085
<a name="l00086"></a>00086 <span class="preprocessor">#ifdef SK_CPU_HAS_CONDITIONAL_INSTR</span>
<a name="l00087"></a>00087 <span class="preprocessor"></span> <span class="keywordflow">if</span> (value &lt; 0) {
<a name="l00088"></a>00088 value = 0;
<a name="l00089"></a>00089 }
<a name="l00090"></a>00090 <span class="keywordflow">if</span> (value &gt; max) {
<a name="l00091"></a>00091 value = max;
<a name="l00092"></a>00092 }
<a name="l00093"></a>00093 <span class="keywordflow">return</span> value;
<a name="l00094"></a>00094 <span class="preprocessor">#else</span>
<a name="l00095"></a>00095 <span class="preprocessor"></span>
<a name="l00096"></a>00096 <span class="keywordtype">int</span> diff = max - value;
<a name="l00097"></a>00097 <span class="comment">// clear diff if diff is positive</span>
<a name="l00098"></a>00098 diff &amp;= diff &gt;&gt; 31;
<a name="l00099"></a>00099
<a name="l00100"></a>00100 <span class="comment">// clear the result if value &lt; 0</span>
<a name="l00101"></a>00101 <span class="keywordflow">return</span> (value + diff) &amp; ~(value &gt;&gt; 31);
<a name="l00102"></a>00102 <span class="preprocessor">#endif</span>
<a name="l00103"></a>00103 <span class="preprocessor"></span>}
<a name="l00104"></a>00104
<a name="l00110"></a>00110 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> SkClampUMax(<span class="keywordtype">unsigned</span> value, <span class="keywordtype">unsigned</span> max) {
<a name="l00111"></a>00111 <span class="preprocessor">#ifdef SK_CPU_HAS_CONDITIONAL_INSTR</span>
<a name="l00112"></a>00112 <span class="preprocessor"></span> <span class="keywordflow">if</span> (value &gt; max) {
<a name="l00113"></a>00113 value = max;
<a name="l00114"></a>00114 }
<a name="l00115"></a>00115 <span class="keywordflow">return</span> value;
<a name="l00116"></a>00116 <span class="preprocessor">#else</span>
<a name="l00117"></a>00117 <span class="preprocessor"></span> <span class="keywordtype">int</span> diff = max - value;
<a name="l00118"></a>00118 <span class="comment">// clear diff if diff is positive</span>
<a name="l00119"></a>00119 diff &amp;= diff &gt;&gt; 31;
<a name="l00120"></a>00120
<a name="l00121"></a>00121 <span class="keywordflow">return</span> value + diff;
<a name="l00122"></a>00122 <span class="preprocessor">#endif</span>
<a name="l00123"></a>00123 <span class="preprocessor"></span>}
<a name="l00124"></a>00124
<a name="l00126"></a>00126
<a name="l00127"></a>00127 <span class="preprocessor">#if defined(__arm__) &amp;&amp; !defined(__thumb__)</span>
<a name="l00128"></a>00128 <span class="preprocessor"></span><span class="preprocessor"> #define SkCLZ(x) __builtin_clz(x)</span>
<a name="l00129"></a>00129 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
<a name="l00130"></a>00130 <span class="preprocessor"></span>
<a name="l00131"></a>00131 <span class="preprocessor">#ifndef SkCLZ</span>
<a name="l00132"></a><a class="code" href="_sk_math_8h.html#a238d25f0a1156c6f2c652e9b7ab78277">00132</a> <span class="preprocessor"></span><span class="preprocessor"> #define SkCLZ(x) SkCLZ_portable(x)</span>
<a name="l00133"></a>00133 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
<a name="l00134"></a>00134 <span class="preprocessor"></span>
<a name="l00136"></a>00136
<a name="l00141"></a>00141 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">int</span> SkNextPow2(<span class="keywordtype">int</span> value) {
<a name="l00142"></a>00142 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(value &gt; 0);
<a name="l00143"></a>00143 <span class="keywordflow">return</span> 1 &lt;&lt; (32 - <a class="code" href="_sk_math_8h.html#a238d25f0a1156c6f2c652e9b7ab78277">SkCLZ</a>(value - 1));
<a name="l00144"></a>00144 }
<a name="l00145"></a>00145
<a name="l00154"></a>00154 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">int</span> SkNextLog2(uint32_t value) {
<a name="l00155"></a>00155 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(value != 0);
<a name="l00156"></a>00156 <span class="keywordflow">return</span> 32 - <a class="code" href="_sk_math_8h.html#a238d25f0a1156c6f2c652e9b7ab78277">SkCLZ</a>(value - 1);
<a name="l00157"></a>00157 }
<a name="l00158"></a>00158
<a name="l00160"></a>00160
<a name="l00165"></a>00165 <span class="preprocessor">#if defined(__arm__) \</span>
<a name="l00166"></a>00166 <span class="preprocessor"> &amp;&amp; !defined(__thumb__) \</span>
<a name="l00167"></a>00167 <span class="preprocessor"> &amp;&amp; !defined(__ARM_ARCH_4__) \</span>
<a name="l00168"></a>00168 <span class="preprocessor"> &amp;&amp; !defined(__ARM_ARCH_5T__)</span>
<a name="l00169"></a>00169 <span class="preprocessor"></span> <span class="keyword">static</span> <span class="keyword">inline</span> int32_t <a class="code" href="_sk_math_8h.html#ac995b5abe886001a2be1b63bb652f0c9">SkMulS16</a>(<a class="code" href="_sk_types_8h.html#ab8a4e96e88fcbdd4adca2506a21384f6">S16CPU</a> x, <a class="code" href="_sk_types_8h.html#ab8a4e96e88fcbdd4adca2506a21384f6">S16CPU</a> y) {
<a name="l00170"></a>00170 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((int16_t)x == x);
<a name="l00171"></a>00171 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((int16_t)y == y);
<a name="l00172"></a>00172 int32_t product;
<a name="l00173"></a>00173 <span class="keyword">asm</span>(<span class="stringliteral">&quot;smulbb %0, %1, %2 \n&quot;</span>
<a name="l00174"></a>00174 : <span class="stringliteral">&quot;=r&quot;</span>(product)
<a name="l00175"></a>00175 : <span class="stringliteral">&quot;r&quot;</span>(x), <span class="stringliteral">&quot;r&quot;</span>(y)
<a name="l00176"></a>00176 );
<a name="l00177"></a>00177 <span class="keywordflow">return</span> product;
<a name="l00178"></a>00178 }
<a name="l00179"></a>00179 <span class="preprocessor">#else</span>
<a name="l00180"></a>00180 <span class="preprocessor"></span><span class="preprocessor"> #ifdef SK_DEBUG</span>
<a name="l00181"></a>00181 <span class="preprocessor"></span> <span class="keyword">static</span> <span class="keyword">inline</span> int32_t <a class="code" href="_sk_math_8h.html#ac995b5abe886001a2be1b63bb652f0c9">SkMulS16</a>(<a class="code" href="_sk_types_8h.html#ab8a4e96e88fcbdd4adca2506a21384f6">S16CPU</a> x, <a class="code" href="_sk_types_8h.html#ab8a4e96e88fcbdd4adca2506a21384f6">S16CPU</a> y) {
<a name="l00182"></a>00182 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((int16_t)x == x);
<a name="l00183"></a>00183 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((int16_t)y == y);
<a name="l00184"></a>00184 <span class="keywordflow">return</span> x * y;
<a name="l00185"></a>00185 }
<a name="l00186"></a>00186 <span class="preprocessor"> #else</span>
<a name="l00187"></a><a class="code" href="_sk_math_8h.html#ac995b5abe886001a2be1b63bb652f0c9">00187</a> <span class="preprocessor"></span><span class="preprocessor"> #define SkMulS16(x, y) ((x) * (y))</span>
<a name="l00188"></a>00188 <span class="preprocessor"></span><span class="preprocessor"> #endif</span>
<a name="l00189"></a>00189 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
<a name="l00190"></a>00190 <span class="preprocessor"></span>
<a name="l00194"></a>00194 <span class="keyword">static</span> <span class="keyword">inline</span> <a class="code" href="_sk_types_8h.html#a6882636f582abdb2a130b7e5ff38aa83">U8CPU</a> SkMulDiv255Trunc(<a class="code" href="_sk_types_8h.html#a6882636f582abdb2a130b7e5ff38aa83">U8CPU</a> a, <a class="code" href="_sk_types_8h.html#a6882636f582abdb2a130b7e5ff38aa83">U8CPU</a> b) {
<a name="l00195"></a>00195 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((uint8_t)a == a);
<a name="l00196"></a>00196 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((uint8_t)b == b);
<a name="l00197"></a>00197 <span class="keywordtype">unsigned</span> prod = <a class="code" href="_sk_math_8h.html#ac995b5abe886001a2be1b63bb652f0c9">SkMulS16</a>(a, b) + 1;
<a name="l00198"></a>00198 <span class="keywordflow">return</span> (prod + (prod &gt;&gt; 8)) &gt;&gt; 8;
<a name="l00199"></a>00199 }
<a name="l00200"></a>00200
<a name="l00204"></a>00204 <span class="keyword">static</span> <span class="keyword">inline</span> <a class="code" href="_sk_types_8h.html#a6882636f582abdb2a130b7e5ff38aa83">U8CPU</a> SkMulDiv255Round(<a class="code" href="_sk_types_8h.html#a6882636f582abdb2a130b7e5ff38aa83">U8CPU</a> a, <a class="code" href="_sk_types_8h.html#a6882636f582abdb2a130b7e5ff38aa83">U8CPU</a> b) {
<a name="l00205"></a>00205 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((uint8_t)a == a);
<a name="l00206"></a>00206 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>((uint8_t)b == b);
<a name="l00207"></a>00207 <span class="keywordtype">unsigned</span> prod = <a class="code" href="_sk_math_8h.html#ac995b5abe886001a2be1b63bb652f0c9">SkMulS16</a>(a, b) + 128;
<a name="l00208"></a>00208 <span class="keywordflow">return</span> (prod + (prod &gt;&gt; 8)) &gt;&gt; 8;
<a name="l00209"></a>00209 }
<a name="l00210"></a>00210
<a name="l00214"></a>00214 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> SkMul16ShiftRound(<span class="keywordtype">unsigned</span> a, <span class="keywordtype">unsigned</span> b, <span class="keywordtype">int</span> shift) {
<a name="l00215"></a>00215 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(a &lt;= 32767);
<a name="l00216"></a>00216 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(b &lt;= 32767);
<a name="l00217"></a>00217 <a class="code" href="_sk_types_8h.html#acc82ca88a67ae7ce95a107a9a4b81123">SkASSERT</a>(shift &gt; 0 &amp;&amp; shift &lt;= 8);
<a name="l00218"></a>00218 <span class="keywordtype">unsigned</span> prod = <a class="code" href="_sk_math_8h.html#ac995b5abe886001a2be1b63bb652f0c9">SkMulS16</a>(a, b) + (1 &lt;&lt; (shift - 1));
<a name="l00219"></a>00219 <span class="keywordflow">return</span> (prod + (prod &gt;&gt; shift)) &gt;&gt; shift;
<a name="l00220"></a>00220 }
<a name="l00221"></a>00221
<a name="l00224"></a>00224 <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">unsigned</span> SkDiv255Round(<span class="keywordtype">unsigned</span> prod) {
<a name="l00225"></a>00225 prod += 128;
<a name="l00226"></a>00226 <span class="keywordflow">return</span> (prod + (prod &gt;&gt; 8)) &gt;&gt; 8;
<a name="l00227"></a>00227 }
<a name="l00228"></a>00228
<a name="l00229"></a>00229 <span class="preprocessor">#endif</span>
<a name="l00230"></a>00230 <span class="preprocessor"></span>
</pre></div></div>
<hr size="1"/><address style="text-align: right;"><small>Generated on Tue Oct 20 11:03:40 2009 for Skia by&nbsp;
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