1 files changed, 116 insertions, 0 deletions
diff --git a/src/luma/state/write.rs b/src/luma/state/write.rs
new file mode 100644
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--- /dev/null
+++ b/src/luma/state/write.rs
@@ -0,0 +1,116 @@
+/*
+	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::luma::{Error, log_assignment, MEMORY_LENGTH};
+use crate::luma::state::{address_unused, State};
+
+macro_rules! read_only {
+	($address: expr) => {{
+		match $address {
+			0x00000000..=0x00003FFF => true,
+			0x04000130..=0x04000131 => true, // KEYINPUT
+			0x08000000..=0x0DFFFFFF => true,
+
+			_ => false,
+		}
+	}};
+}
+
+impl State {
+	#[inline(always)]
+	pub fn write_register(&mut self, register: u8, value: u32) {
+		log_assignment!("r{register}", "{value:#010X}");
+
+		let index = (register & 0b00001111) as usize;
+
+		unsafe { *self.registers.get_unchecked_mut(index) = value };
+	}
+
+	pub fn write_word(&mut self, address: u32, value: u32) {
+		log_assignment!("{address:#010X}", "{value:#010X}");
+
+		if address > MEMORY_LENGTH - 0x4 { Error::OutOfBounds( address).trap();      return; }
+		if address % 0x4 != 0x0          { Error::BadAlignment(address, 0x4).trap(); return; }
+
+		if read_only!(address) || address_unused!(address) { return };
+
+		unsafe {
+			let pointer = (self.memory.as_mut_ptr() as *mut u8).add(address as usize) as *mut u32;
+			*pointer = value;
+		}
+	}
+
+	pub fn write_halfword(&mut self, address: u32, value: u16) {
+		log_assignment!("{address:#010X}", "{value:#06X}");
+
+		if address > MEMORY_LENGTH - 0x2 { Error::OutOfBounds( address).trap();      return; }
+		if address % 0x2 != 0x0          { Error::BadAlignment(address, 0x2).trap(); return; }
+
+		if read_only!(address) || address_unused!(address) { return };
+
+		unsafe {
+			let pointer = (self.memory.as_mut_ptr() as *mut u8).add(address as usize) as *mut u16;
+			*pointer = value;
+		}
+	}
+
+	pub fn write_byte(&mut self, address: u32, value: u8) {
+		log_assignment!("{address:#010X}", "{value:#04X}");
+
+		if address > MEMORY_LENGTH - 0x1 { Error::OutOfBounds(address).trap(); return; }
+
+		if read_only!(address) || address_unused!(address) { return };
+
+		let memory = self.memory.as_mut_ptr() as *mut u8;
+
+		match address {
+			// Extend to halfwords:
+			| 0x05000000..=0x050003FF
+			| 0x06000000..=0x06017FFF
+			| 0x07000000..=0x070003FF => {
+				// Align to halfwords.
+				let address = address & 0b11111111111111111111111111111110;
+
+				// Repeat value.
+				let value = value as u16 | (value as u16) << 0x8;
+
+				unsafe {
+					let pointer = memory.add(address as usize) as *mut u16;
+					*pointer = value;
+				}
+			},
+
+			// Bytes are allowed:
+			_ => unsafe {
+				let pointer = memory.add(address as usize);
+				*pointer = value;
+			},
+		};
+	}
+
+	pub fn write_cpsr(&mut self, value: u32) {
+		log_assignment!("cpsr", "{value:#034b}");
+
+		self.cpsr = value;
+	}
+}