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depths > 8. Add some smaller optimizations for these depths. Use a more generic method for all depths >= 8, although this gives tiny pessimizations for these depths. For clearing the whole frame buffer, avoid the same pessimizations for depths > 8. Add some larger optimizations for these depths. Use an even more generic method for all depths >= 8 to give the optimizations for depths > 8 and a tiny pessimization for depth 8. The main pessimization was that old versions of bcopy() copy 1 byte at a time for all trailing bytes. (i386 still does this. amd64 now pessimizzes large sizes instead of small ones if the CPU supports ERMS. dev/fb gets this wrong by mostly not using the bcopy() family or the technically correct bus space functions but by mostly copying 2 bytes at a time using an unoptimized loop without even volatile declarations to prevent the compiler rewriting it.) The sizes here are 1, 2, 3 or 4 bytes, so depths 9-16 were up to twice as slow as necessary and depths 17-24 were up to 3 times slower than necessary. Fix this (except depths 17-24 are still up to 2 times slower than necessary) by using (builtin) memcpy() instead of bcopy() and reorganizing so that the complier can see the small constant sizes. Reduce special cases while reorganizing although this is slightly slower than adding special cases. The compiler inlining (and even -O2 vs -O0) makes little difference compared with reducing the number of accesses except on modern hardware it gives a small improvement. Clearing was also pessimized mainly by the extra accesses. Fix it quite differently by creating a MEMBUF containing 1 line (in fast memory using a slow method) and copying this. This is only slightly slower than reducing everything to efficient memset()s and bcopy()s, but simpler, especially for the segmented case. This works for planar modes too, but don't use it then since the old method was actually optimal for planar modes (it works by moving the slow i/o instructions out of inner loops), while for direct modes the slow instructions were all in the invisible inner loop in bcopy(). Use htole32() and le32toh() and some type puns instead of unoptimized functions for converting colors. This optimization is mostly in the noise. libvgl is only supported on x86, so it could hard-code the assumption that the byte order is le32, but the old conversion functions didn't hard-code this.
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