1 files changed, 130 insertions, 0 deletions
diff --git a/src/state/shifter_value.rs b/src/state/shifter_value.rs
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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 crate::state::State;
+
+impl State {
+	#[must_use]
+	pub fn shifter_value(&self, shifter: Shifter) -> (u32, bool) {
+		use Shifter::*;
+
+		let c = self.read_cpsr() & 0b00100000000000000000000000000000 != 0x0;
+
+		let (value, carry) = match shifter {
+			Immediate(imm, rot) => {
+				let result = (imm as u32).rotate_right(rot as u32);
+				let c      = if rot == 0x0 { c } else { result & 0b10000000000000000000000000000000 != 0x0 };
+
+				(result, c)
+			},
+
+			ArithmeticShiftRightImmediate(rm, imm) => {
+				let rm_value = self.read_register(rm);
+
+				let result = (rm_value as i32).wrapping_shr(imm as u32) as u32;
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			ArithmeticShiftRightRegister(rm, rs) => {
+				let rm_value = self.read_register(rm);
+				let rs_value = self.read_register(rs);
+
+				let result = (rm_value as i32).wrapping_shr(rs_value) as u32;
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			LogicalShiftLeftImmediate(rm, imm) => {
+				let rm_value = self.read_register(rm);
+
+				let result = rm_value.wrapping_shl(imm as u32);
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			LogicalShiftLeftRegister(rm, rs) => {
+				let rm_value = self.read_register(rm);
+				let rs_value = self.read_register(rs);
+
+				let result = rm_value.wrapping_shl(rs_value);
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			LogicalShiftRightImmediate(rm, imm) => {
+				let rm_value = self.read_register(rm);
+
+				let result = rm_value.wrapping_shr(imm as u32);
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			LogicalShiftRightRegister(rm, rs) => {
+				let rm_value = self.read_register(rm);
+				let rs_value = self.read_register(rs);
+
+				let result = rm_value.wrapping_shr(rs_value);
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			RotateRightImmediate(rm, imm) => {
+				let rm_value = self.read_register(rm);
+
+				let result = rm_value.rotate_right(imm as u32);
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			RotateRightRegister(rm, rs) => {
+				let rm_value = self.read_register(rm);
+				let rs_value = self.read_register(rs);
+
+				let result = rm_value.rotate_right(rs_value);
+				let c      = false; // TODO
+
+				(result, c)
+			},
+
+			RotateRightExtend(rm) => {
+				let rm_value = self.read_register(rm);
+
+				let result = 0x0_u32; // TODO
+				let c      = rm_value & 0b00000000000000000000000000000001 != 0x0;
+
+				(result, c)
+			},
+		};
+
+		return (value, carry);
+	}
+}