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fennec/include/fennec/lang/detail/_bits.h

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// =====================================================================================================================
// fennec, a free and open source game engine
// Copyright © 2025 Medusa Slockbower
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
// =====================================================================================================================
#ifndef FENNEC_LANG_DETAIL_BITS_H
#define FENNEC_LANG_DETAIL_BITS_H
#include <fennec/lang/types.h>
namespace fennec::detail
{
// helper for bitwise and for 1 byte
constexpr size_t _bit_and_8(void* dst, const void* src) {
*static_cast<uint8_t*>(dst) = *static_cast<uint8_t*>(dst) & *static_cast<const uint8_t*>(src); return 1;
}
// helper for bitwise and 2 bytes at once
constexpr size_t _bit_and_16(void* dst, const void* src) {
*static_cast<uint16_t*>(dst) = *static_cast<uint16_t*>(dst) & *static_cast<const uint16_t*>(src); return 2;
}
// helper for bitwise and 4 bytes at once
constexpr size_t _bit_and_32(void* dst, const void* src) {
*static_cast<uint32_t*>(dst) = *static_cast<uint32_t*>(dst) & *static_cast<const uint32_t*>(src); return 4;
}
// helper for bitwise and 8 bytes at once
constexpr size_t _bit_and_64(void* dst, const void* src) {
*static_cast<uint64_t*>(dst) = *static_cast<uint64_t*>(dst) & *static_cast<const uint64_t*>(src); return 8;
}
// helper for selecting size
constexpr size_t _bit_and(void* dst, const void* src, size_t n) {
switch (n) {
case 0:
return 0;
case 1:
return _bit_and_8(dst, src);
case 2: case 3:
return _bit_and_16(dst, src);
case 4: case 5: case 6: case 7:
return _bit_and_32(dst, src);
default:
return _bit_and_64(dst, src);
}
}
// helper for bitwise or for 1 byte
constexpr size_t _bit_or_8(void* dst, const void* src) {
*static_cast<uint8_t*>(dst) = *static_cast<uint8_t*>(dst) | *static_cast<const uint8_t*>(src); return 1;
}
// helper for bitwise or 2 bytes at once
constexpr size_t _bit_or_16(void* dst, const void* src) {
*static_cast<uint16_t*>(dst) = *static_cast<uint16_t*>(dst) | *static_cast<const uint16_t*>(src); return 2;
}
// helper for bitwise or 4 bytes at once
constexpr size_t _bit_or_32(void* dst, const void* src) {
*static_cast<uint32_t*>(dst) = *static_cast<uint32_t*>(dst) | *static_cast<const uint32_t*>(src); return 4;
}
// helper for bitwise or 8 bytes at once
constexpr size_t _bit_or_64(void* dst, const void* src) {
*static_cast<uint64_t*>(dst) = *static_cast<uint64_t*>(dst) | *static_cast<const uint64_t*>(src); return 8;
}
// helper for selecting size
constexpr size_t _bit_or(void* dst, const void* src, size_t n) {
switch (n) {
case 0:
return 0;
case 1:
return _bit_or_8(dst, src);
case 2: case 3:
return _bit_or_16(dst, src);
case 4: case 5: case 6: case 7:
return _bit_or_32(dst, src);
default:
return _bit_or_64(dst, src);
}
}
// helper for bitwise and 1 byte
constexpr size_t _bit_xor_8(void* dst, const void* src) {
*static_cast<uint8_t*>(dst) = *static_cast<uint8_t*>(dst) ^ *static_cast<const uint8_t*>(src); return 1;
}
// helper for bitwise xor 2 bytes at once
constexpr size_t _bit_xor_16(void* dst, const void* src) {
*static_cast<uint16_t*>(dst) = *static_cast<uint16_t*>(dst) ^ *static_cast<const uint16_t*>(src); return 2;
}
// helper for bitwise xor 4 bytes at once
constexpr size_t _bit_xor_32(void* dst, const void* src) {
*static_cast<uint32_t*>(dst) = *static_cast<uint32_t*>(dst) ^ *static_cast<const uint32_t*>(src); return 4;
}
// helper for bitwise xor 8 bytes at once
constexpr size_t _bit_xor_64(void* dst, const void* src) {
*static_cast<uint64_t*>(dst) = *static_cast<uint64_t*>(dst) ^ *static_cast<const uint64_t*>(src); return 8;
}
// helper for selecting size
constexpr size_t _bit_xor(void* dst, const void* src, size_t n) {
switch (n) {
case 0:
return 0;
case 1:
return _bit_xor_8(dst, src);
case 2: case 3:
return _bit_xor_16(dst, src);
case 4: case 5: case 6: case 7:
return _bit_xor_32(dst, src);
default:
return _bit_xor_64(dst, src);
}
}
}
#endif // FENNEC_LANG_DETAIL_BITS_H