1 files changed, 54 insertions, 0 deletions
diff --git a/src/cpu/fetch_thumb.rs b/src/cpu/fetch_thumb.rs
new file mode 100644
index 0000000..cee6ba7
--- /dev/null
+++ b/src/cpu/fetch_thumb.rs
@@ -0,0 +1,54 @@
+/*
+	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::{Error, log};
+use crate::cpu::{Cpu, take_state};
+use crate::instruction::Instruction;
+use crate::predicate::Predicate;
+
+impl Cpu {
+	pub(super) fn fetch_thumb(&mut self) -> (Instruction, Predicate, u32) {
+		take_state!(state, self);
+
+		let address = state.read_register(0xF).wrapping_sub(0x4);
+		let opcode  = state.read_halfword(address);
+		let cpsr    = state.read_cpsr();
+
+		drop(state);
+
+		log!();
+		log!("                \u{1B}[1m{opcode:016b}\u{1B}[0m @ \u{1B}[1m{address:08X}\u{1B}[0m - ({})", self.cycle);
+
+		let (instruction, predicate) = Instruction::decode_thumb(opcode);
+
+		match (instruction, predicate) {
+			| (Instruction::Undefined, _)
+			| (_, Predicate::Nv)
+			=> Error::InvalidThumbOpcode(address, opcode).trap(),
+
+			_ => {},
+		};
+
+		return (instruction, predicate, cpsr);
+	}
+}