2012-06-03 15:48:14 +00:00
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#ifndef __MDFN_MATH_OPS_H
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#define __MDFN_MATH_OPS_H
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2012-08-15 19:26:44 +00:00
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// Source: http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
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// Rounds up to the nearest power of 2.
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static INLINE uint64 round_up_pow2(uint64 v)
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{
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v--;
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v |= v >> 1;
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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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v |= v >> 32;
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v++;
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v += (v == 0);
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return(v);
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}
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2012-06-03 15:48:14 +00:00
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static INLINE uint32 uilog2(uint32 v)
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{
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// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn
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static const uint32 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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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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return MultiplyDeBruijnBitPosition[(uint32_t)(v * 0x07C4ACDDU) >> 27];
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}
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// Some compilers' optimizers and some platforms might fubar the generated code from these macros,
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// so some tests are run in...tests.cpp
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#define sign_8_to_s16(_value) ((int16)(int8)(_value))
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#define sign_9_to_s16(_value) (((int16)((unsigned int)(_value) << 7)) >> 7)
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#define sign_10_to_s16(_value) (((int16)((uint32)(_value) << 6)) >> 6)
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#define sign_11_to_s16(_value) (((int16)((uint32)(_value) << 5)) >> 5)
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#define sign_12_to_s16(_value) (((int16)((uint32)(_value) << 4)) >> 4)
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#define sign_13_to_s16(_value) (((int16)((uint32)(_value) << 3)) >> 3)
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#define sign_14_to_s16(_value) (((int16)((uint32)(_value) << 2)) >> 2)
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#define sign_15_to_s16(_value) (((int16)((uint32)(_value) << 1)) >> 1)
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// This obviously won't convert higher-than-32 bit numbers to signed 32-bit ;)
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// Also, this shouldn't be used for 8-bit and 16-bit signed numbers, since you can
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// convert those faster with typecasts...
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#define sign_x_to_s32(_bits, _value) (((int32)((uint32)(_value) << (32 - _bits))) >> (32 - _bits))
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#endif
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