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https://github.com/libretro/beetle-psx-libretro.git
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98 lines
2.0 KiB
C
98 lines
2.0 KiB
C
#ifndef __MDFN_MATH_OPS_H
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#define __MDFN_MATH_OPS_H
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#ifdef _MSC_VER
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#include <intrin.h>
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#endif
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//
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// Result is defined for all possible inputs(including 0).
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//
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static INLINE unsigned MDFN_lzcount32(uint32 v)
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{
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#if defined(__GNUC__) || defined(__clang__) || defined(__ICC) || defined(__INTEL_COMPILER)
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return v ? __builtin_clz(v) : 32;
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#elif defined(_MSC_VER)
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unsigned long idx;
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if(!v)
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return 32;
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_BitScanReverse(&idx, v);
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return 31 - idx;
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#else
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unsigned ret = 0;
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if(!v)
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return(32);
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if(!(v & 0xFFFF0000))
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{
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v <<= 16;
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ret += 16;
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}
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if(!(v & 0xFF000000))
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{
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v <<= 8;
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ret += 8;
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}
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if(!(v & 0xF0000000))
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{
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v <<= 4;
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ret += 4;
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}
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if(!(v & 0xC0000000))
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{
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v <<= 2;
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ret += 2;
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}
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if(!(v & 0x80000000))
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{
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v <<= 1;
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ret += 1;
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}
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return(ret);
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#endif
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}
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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 uint32 round_up_pow2(uint32 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++;
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v += (v == 0);
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return(v);
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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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