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| | | } MOJODDS_Header; |
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| | | |
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| | | |
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| | | //http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn |
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| | | static const uint32_t MultiplyDeBruijnBitPosition[32] = |
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| | | { |
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| | | 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, |
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| | | 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 |
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| | | }; |
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| | | |
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| | | |
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| | | static uint32_t uintLog2(uint32_t v) { |
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| | | v |= v >> 1; // first round down to one less than a power of 2 |
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| | | v |= v >> 2; |
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| | | v |= v >> 4; |
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| | | v |= v >> 8; |
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| | | v |= v >> 16; |
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| | | |
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| | | return MultiplyDeBruijnBitPosition[(uint32_t)(v * 0x07C4ACDDU) >> 27]; |
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| | | } |
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| | | |
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| | | |
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| | | static uint32 readui32(const uint8 **_ptr, size_t *_len) |
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| | | { |
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| | | uint32 retval = 0; |
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| | |
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| | | |
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| | | *_miplevels = (header->dwCaps & DDSCAPS_MIPMAP) ? header->dwMipMapCount : 1; |
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| | | |
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| | | unsigned int calculatedMipLevels = uintLog2(MAX(width, height)) + 1; |
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| | | if (*_miplevels > 32) |
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| | | { |
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| | | // too many mip levels, width and height would be larger than 32-bit int |
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| | | // file is corrupted |
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| | | return 0; |
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| | | } |
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| | | else if (*_miplevels == 0) |
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| | | { |
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| | | // invalid, calculate it ourselves from size |
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| | | *_miplevels = calculatedMipLevels; |
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| | | } |
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| | | |
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| | | if (header->ddspf.dwFlags & DDPF_FOURCC) |
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| | | { |
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