1 #ifndef __MDFN_MATH_OPS_H
2 #define __MDFN_MATH_OPS_H
3
4 // Source: http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
5 // Rounds up to the nearest power of 2.
round_up_pow2(uint64 v)6 static INLINE uint64 round_up_pow2(uint64 v)
7 {
8 v--;
9 v |= v >> 1;
10 v |= v >> 2;
11 v |= v >> 4;
12 v |= v >> 8;
13 v |= v >> 16;
14 v |= v >> 32;
15 v++;
16
17 v += (v == 0);
18
19 return(v);
20 }
21
uilog2(uint32 v)22 static INLINE uint32 uilog2(uint32 v)
23 {
24 // http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogDeBruijn
25
26 static const uint32 MultiplyDeBruijnBitPosition[32] =
27 {
28 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30,
29 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31
30 };
31
32 v |= v >> 1; // first round down to one less than a power of 2
33 v |= v >> 2;
34 v |= v >> 4;
35 v |= v >> 8;
36 v |= v >> 16;
37
38 return MultiplyDeBruijnBitPosition[(uint32_t)(v * 0x07C4ACDDU) >> 27];
39 }
40
41 // Some compilers' optimizers and some platforms might fubar the generated code from these macros,
42 // so some tests are run in...tests.cpp
43 #define sign_8_to_s16(_value) ((int16)(int8)(_value))
44 #define sign_9_to_s16(_value) (((int16)((unsigned int)(_value) << 7)) >> 7)
45 #define sign_10_to_s16(_value) (((int16)((uint32)(_value) << 6)) >> 6)
46 #define sign_11_to_s16(_value) (((int16)((uint32)(_value) << 5)) >> 5)
47 #define sign_12_to_s16(_value) (((int16)((uint32)(_value) << 4)) >> 4)
48 #define sign_13_to_s16(_value) (((int16)((uint32)(_value) << 3)) >> 3)
49 #define sign_14_to_s16(_value) (((int16)((uint32)(_value) << 2)) >> 2)
50 #define sign_15_to_s16(_value) (((int16)((uint32)(_value) << 1)) >> 1)
51
52 // This obviously won't convert higher-than-32 bit numbers to signed 32-bit ;)
53 // Also, this shouldn't be used for 8-bit and 16-bit signed numbers, since you can
54 // convert those faster with typecasts...
55 #define sign_x_to_s32(_bits, _value) (((int32)((uint32)(_value) << (32 - _bits))) >> (32 - _bits))
56
57 #endif
58