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Rupert Swarbrick authored
There are six pieces of code in reconinter.c and two in rdopt.c which iterate over the blocks along the top or left edge of the current block for OBMC. Before this patch, each bit of code has its own implementation of the iteration, which is reasonably finicky to get right. This patch factors out that logic into a pair of helpers (foreach_overlappable_nb_above and foreach_overlappable_nb_left). The functions take a "fun" parameter, which contains the loop body. Note that the iteration is too complicated for us to be able to define a macro that could be used like FOREACH_NB_ABOVE(rel_pos, nb_size, nb_mi) { ... } While C's syntax doesn't seem to let you do that, once the compiler's optimisation pass is done inlining everything, the results are essentially the same. The iteration logic is also slightly generalised: the old code checked whether a block was shorter or narrower than 8 pixels by comparing a block size with BLOCK_8X8. This doesn't work when you have a 4x16 or 16x4 block because e.g. BLOCK_16X4 is not less than BLOCK_8X8. This generalisation is (unsurprisingly) needed in order to to support 16x4 or 4x16 blocks. This patch doesn't address the CONFIG_NCOBMC functions in reconinter.c that do prediction from right and bottom edges. This patch shouldn't affect the generated bitstream in any way: the code is supposed to be equivalent. Change-Id: I9e5a116b012c18645604a7d98fb98be99697d363
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