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copied!<pre><code>short color = /* ... */ color = ((((!!(color >> 12)) * 0xFFF)) | (!(color >> 12) * color )) & (!(color >> 15) * 0xFFF); unsigned char color8bit = 0xFF & (color >> 4); </code></pre> <p>It assumes two's complement representation.</p> <p>This has the advantage of not using any equality or relational operators. There are situations you want to avoid branches at all costs: in some security applications you don't want the attackers to perform branch predictions. Without branches (in embedded processors particularly) you can make your function run in constant time for all inputs.</p> <p>Note that: <code>x * 0xFFF</code> can be further reduced to <code>(x << 12) - x</code>. Also the multiplication in <code>(!(color >> 12) * color )</code> can also be further optimized as the left operand of <code>*</code> here is <code>0</code> or <code>1</code>.</p> <p><strong>EDIT:</strong></p> <p>I add a little explanation: the expression above simply does the same as below without the use of the conditional and relational operators:</p> <pre><code>y = ((y > 4095 ? 4095 : 0) | (y > 4095 ? 0 : y)) & (y < 0 ? 0 : 4095); </code></pre> <p><strong>EDIT2:</strong></p> <p>as @HotLicks correctly noted in his comment, the <code>!</code> is still a conceptual branch. Nevertheless it can also be computed with bitwise operators. For example <code>!!a</code> can be done with the trivial:</p> <pre><code>b = (a >> 15 | a >> 14 | ... | a >> 1 | a) & 1 </code></pre> <p>and <code>!a</code> can be done as <code>b ^ 1</code>. And I'm sure there is a nice hack to do it more effectively. </p>

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