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/*
Copyright 2021-2023 Gabriel Jensen.
This file is part of Luma.
Luma is free software: you can redistribute it
and/or modify it under the terms of the GNU
Affero General Public License as published by
the Free Software Foundation, either version 3
of the License, or (at your option) any later
version.
Luma 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
Affero General Public License for more details.
You should have received a copy of the GNU
Affero General Public License along with Luma.
If not, see <https://www.gnu.org/licenses/>.
*/
use crate::shifter::Shifter;
use std::hint::unreachable_unchecked;
impl Shifter {
pub fn extract(opcode: u32) -> Self {
use Shifter::*;
match opcode & 0b00000010000000000000000000000000 != 0x0 {
false => {
let rm = (opcode & 0b00000000000000000000000000001111) as u8;
let shift = (opcode & 0b00000000000000000000000001100000).wrapping_shr(0x5) as u8;
let register_shift = opcode & 0b00000000000000000000000000010000 != 0x0;
match register_shift {
false => {
let imm = (opcode & 0b00000000000000000000111110000000).wrapping_shr(0x7) as u8;
return match shift {
0b11 => match imm {
0x0 => RotateRightExtend( rm),
imm => RotateRightImmediate(rm, imm),
},
shift => {
match shift {
0b00 => LogicalShiftLeftImmediate(rm, imm),
0b01 => LogicalShiftRightImmediate(rm, match imm {
0x0 => 0x20,
imm => imm,
}),
0b10 => ArithmeticShiftRightImmediate(rm, match imm {
0x0 => 0x20,
imm => imm,
}),
_ => unsafe { unreachable_unchecked() },
}
},
};
},
true => {
let rs = (opcode & 0b0000000000000000000111100000000).wrapping_shr(0x8) as u8;
return match shift {
0b00 => LogicalShiftLeftRegister( rm, rs),
0b01 => LogicalShiftRightRegister( rm, rs),
0b10 => ArithmeticShiftRightRegister(rm, rs),
0b11 => RotateRightRegister( rm, rs),
_ => unsafe { unreachable_unchecked() },
};
},
};
},
true => {
let imm = (opcode & 0b00000000000000000000000011111111) as u8;
let rot = (opcode & 0b00000000000000000000111100000000).wrapping_shr(0x7) as u8;
return Immediate(imm, rot);
},
};
}
}
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