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copied!<p>Really you're only doing four calculations, so <strong><em>readability seems way more important</em></strong> here than efficiency. My approach to make something like this more readable is to </p> <ol> <li>Extract common code to a function</li> <li>Put similar calculations together to make the patterns more obvious</li> <li>Get rid of the intermediate variable print_zeroes and be explicit about the cases in which you output bytes even if they're zero (i.e. the preceding byte was non-zero)</li> </ol> <p>I've changed the random code block into a function and changed a few variables (underscores are giving me trouble in the markdown preview screen). I've also assumed that <em>bytes</em> is being passed in, and that whoever is passing it in will pass us a pointer so we can modify it.</p> <p>Here's the code:</p> <pre><code>/* append byte b to stream, increment index */ /* really needs to check length of stream before appending */ void output( int i, unsigned char b, char stream[], int *index ) { printf("byte %d: 0x%02x\n", i, b); stream[(*index)++] = b; } void answer( char bytestream[], unsigned int *bytes, unsigned int n) { /* mask out four bytes from word n */ first = (n & 0xFF000000) >> 24; second = (n & 0x00FF0000) >> 16; third = (n & 0x0000FF00) >> 8; fourth = (n & 0x000000FF) >> 0; /* conditionally output each byte starting with the */ /* first non-zero byte */ if (first) output( 1, first, bytestream, bytes); if (first || second) output( 2, second, bytestream, bytes); if (first || second || third) output( 3, third, bytestream, bytes); if (first || second || third || fourth) output( 4, fourth, bytestream, bytes); } </code></pre> <p>Ever so slightly more efficient, and <strong><em>maybe</em></strong> easier to understand would be this modification to the last four if statements:</p> <pre><code> if (n>0x00FFFFFF) output( 1, first, bytestream, bytes); if (n>0x0000FFFF) output( 2, second, bytestream, bytes); if (n>0x000000FF) output( 3, third, bytestream, bytes); if (1) output( 4, fourth, bytestream, bytes); </code></pre> <p>I agree, however, that compressing this field makes the receiving state machine overly complicated. But if you can't change the protocol, this code is much easier to read.</p>

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