1 files changed, 62 insertions, 0 deletions
diff --git a/src/cpu/isa_bl.rs b/src/cpu/isa_bl.rs
new file mode 100644
index 0000000..416ce4a
--- /dev/null
+++ b/src/cpu/isa_bl.rs
@@ -0,0 +1,62 @@
+/*
+	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::log;
+use crate::cpu::{Cpu, take_state_mut};
+
+impl Cpu {
+	pub(super) fn isa_bl(&mut self, imm: i32) {
+		take_state_mut!(state, self);
+
+		let     link_target   = state.read_register(0xF).wrapping_sub(self.instruction_size);
+		let mut branch_target = state.read_register(0xF).wrapping_add_signed(imm);
+
+		log!("bl {branch_target:#X}");
+
+		branch_target = branch_target.wrapping_add(self.instruction_size);
+		state.write_register(0xE, link_target);
+		state.write_register(0xF, branch_target);
+	}
+
+	pub(super) fn isa_bl0(&mut self, imm: i32) {
+		take_state_mut!(state, self);
+
+		let target = state.read_register(0xF).wrapping_add_signed(imm);
+
+		state.write_register(0xE, target);
+	}
+
+	pub(super) fn isa_bl1(&mut self, imm: i32) {
+		take_state_mut!(state, self);
+
+		let mut branch_target = state.read_register(0xE).wrapping_add_signed(imm);
+		let     link_target   = state.read_register(0xF).wrapping_sub(0x2);
+
+		log!("bl {branch_target:#X}");
+
+		state.write_register(0xE, link_target);
+
+		branch_target = branch_target.wrapping_add(0x2);
+		state.write_register(0xF, branch_target);
+	}
+}