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[+] AuBitReverse (+ aliases: AuReverseBits, AuBitsReverse)

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This commit is contained in:
Reece Wilson 2024-09-21 22:02:41 +01:00
parent 718080245c
commit e3133b775e
1 changed files with 125 additions and 0 deletions
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125
Include/auROXTL/auBitsUtils.hpp
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@ -7,6 +7,53 @@
***/
#pragma once
// options: _AU_FORCE_NO_FLIP8_MAP, _AU_DO_NOT_USE_BITFLIP_U16, _AU_DO_NOT_USE_BITFLIP_U32
namespace __audetail
{
inline const constexpr AuUInt8 kFlipBitsU4Lookup[16] {
0x0, 0x8, 0x4, 0xc, 0x2, 0xa, 0x6, 0xe,
0x1, 0x9, 0x5, 0xd, 0x3, 0xb, 0x7, 0xf
};
#if !defined(_AU_FORCE_NO_FLIP8_MAP)
#define _AU_HAS_FLIP8
inline const constexpr AuUInt8 kFlipBitsU8Lookup[256] {
0, 128, 64, 192, 32, 160, 96, 224,
16, 144, 80, 208, 48, 176, 112, 240,
8, 136, 72, 200, 40, 168, 104, 232,
24, 152, 88, 216, 56, 184, 120, 248,
4, 132, 68, 196, 36, 164, 100, 228,
20, 148, 84, 212, 52, 180, 116, 244,
12, 140, 76, 204, 44, 172, 108, 236,
28, 156, 92, 220, 60, 188, 124, 252,
2, 130, 66, 194, 34, 162, 98, 226,
18, 146, 82, 210, 50, 178, 114, 242,
10, 138, 74, 202, 42, 170, 106, 234,
26, 154, 90, 218, 58, 186, 122, 250,
6, 134, 70, 198, 38, 166, 102, 230,
22, 150, 86, 214, 54, 182, 118, 246,
14, 142, 78, 206, 46, 174, 110, 238,
30, 158, 94, 222, 62, 190, 126, 254,
1, 129, 65, 193, 33, 161, 97, 225,
17, 145, 81, 209, 49, 177, 113, 241,
9, 137, 73, 201, 41, 169, 105, 233,
25, 153, 89, 217, 57, 185, 121, 249,
5, 133, 69, 197, 37, 165, 101, 229,
21, 149, 85, 213, 53, 181, 117, 245,
13, 141, 77, 205, 45, 173, 109, 237,
29, 157, 93, 221, 61, 189, 125, 253,
3, 131, 67, 195, 35, 163, 99, 227,
19, 147, 83, 211, 51, 179, 115, 243,
11, 139, 75, 203, 43, 171, 107, 235,
27, 155, 91, 219, 59, 187, 123, 251,
7, 135, 71, 199, 39, 167, 103, 231,
23, 151, 87, 215, 55, 183, 119, 247,
15, 143, 79, 207, 47, 175, 111, 239,
31, 159, 95, 223, 63, 191, 127, 255
};
#endif
}
template <class T>
static auline bool AuTestBit(T value, AuUInt8 idx)
{
@ -325,4 +372,82 @@ static AuUInt8 AuPopCnt(T in)
}
return {};
}
template<typename T>
constexpr T AuBitReverse(T uBits);
template <>
constexpr AuUInt8 AuBitReverse(AuUInt8 uBits)
{
return (__audetail::kFlipBitsU8Lookup[uBits & 0b1111] << 4) |
(__audetail::kFlipBitsU8Lookup[uBits >> 4] );
}
template <>
constexpr AuUInt16 AuBitReverse(AuUInt16 uBits)
{
#if !defined(_AU_DO_NOT_USE_BITFLIP_U16)
uBits = ((uBits >> 1) & 0x5555u) | ((uBits & 0x5555u) << 1);
uBits = ((uBits >> 2) & 0x3333u) | ((uBits & 0x3333u) << 2);
uBits = ((uBits >> 4) & 0x0f0fu) | ((uBits & 0x0f0fu) << 4);
uBits = ((uBits >> 8) & 0x00ffu) | ((uBits & 0x00ffu) << 8);
return uBits;
#endif
#if !defined(_AU_HAS_FLIP8)
return AuUInt16(AuBitReverse(AuUInt8((uBits >> 8u) & 0xFFu))) |
AuUInt16(AuUInt16(AuBitReverse(AuUInt8(uBits & 0xFFu))) << 8u);
#else
return 0 |
AuUInt32(__audetail::kFlipBitsU8Lookup[(uBits >> 8) & 0xFF]) << 0u |
AuUInt32(__audetail::kFlipBitsU8Lookup[(uBits >> 0) & 0xFF]) << 8u;
#endif
}
template <>
constexpr AuUInt32 AuBitReverse(AuUInt32 uBits)
{
#if !defined(_AU_DO_NOT_USE_BITFLIP_U32)
uBits = ((uBits >> 1) & 0x55555555u) | ((uBits & 0x55555555u) << 1);
uBits = ((uBits >> 2) & 0x33333333u) | ((uBits & 0x33333333u) << 2);
uBits = ((uBits >> 4) & 0x0f0f0f0fu) | ((uBits & 0x0f0f0f0fu) << 4);
uBits = ((uBits >> 8) & 0x00ff00ffu) | ((uBits & 0x00ff00ffu) << 8);
uBits = ((uBits >> 16) & 0xffffu) | ((uBits & 0xffffu) << 16);
return uBits;
#endif
#if !defined(_AU_HAS_FLIP8)
return 0 |
AuUInt32(AuBitReverse<AuUInt8>((uBits >> 24) & 0xFF)) << 0ul |
AuUInt32(AuBitReverse<AuUInt8>((uBits >> 16) & 0xFF)) << 8ul |
AuUInt32(AuBitReverse<AuUInt8>((uBits >> 8) & 0xFF)) << 16ul |
AuUInt32(AuBitReverse<AuUInt8>((uBits >> 0) & 0xFF)) << 24ul;
#else
return 0 |
AuUInt32(__audetail::kFlipBitsU8Lookup[(uBits >> 24) & 0xFF]) << 0ul |
AuUInt32(__audetail::kFlipBitsU8Lookup[(uBits >> 16) & 0xFF]) << 8ul |
AuUInt32(__audetail::kFlipBitsU8Lookup[(uBits >> 8) & 0xFF]) << 16ul |
AuUInt32(__audetail::kFlipBitsU8Lookup[(uBits >> 0) & 0xFF]) << 24ul;
#endif
}
template <>
constexpr AuUInt64 AuBitReverse(AuUInt64 uBits)
{
return AuUInt64(AuBitReverse(AuUInt32((uBits >> 32ull) & 0xFFFFFFFFul))) |
AuUInt64(AuUInt64(AuBitReverse(AuUInt32(uBits & 0xFFFFFFFFul))) << 32UL);
}
template<typename T>
constexpr T AuBitsReverse(T uBits)
{
return AuBitReverse<T>(uBits);
}
template<typename T>
constexpr T AuReverseBits(T uBits)
{
return AuBitReverse<T>(uBits);
}