Fix the BR instruction, and implement the rest of the assembly logic for I-types (1db43d32) · Commits · John Jekel / legv8

src/legv8assemble.rs

+36 −11

Original line number	Diff line number	Diff line
		@@ -57,12 +57,12 @@ impl ConvenientlyBitAccessible for u32 {
		debug_assert!(low <= high);

		let num_bits_to_change = high - low + 1;
		let mask = ((1 << num_bits_to_change) - 1) << low;
		let mask_unshifted = (1 << num_bits_to_change) - 1;
		let mask = mask_unshifted << low;
		debug_assert!(value <= mask_unshifted);
		let shifted_value = value << low;

		eprintln!("Before: {}", *self);
		self = (self & !mask) \| shifted_value;
		eprintln!("After: {}", *self);
		}
		}

		@@ -365,23 +365,48 @@ fn assemble(instruction_string: &str) -> Option<(InstructionType, u32)> {
		//Determine Rn depending on the instruction type
		match instruction_type {
		InstructionType::R \| InstructionType::I \| InstructionType::D => {
		if tokens[0] != "BR" {//This one does not have the Rn operand
		if let Some(rn) = parse_register(tokens[2]) {
		instruction.set_bits(rn, 9, 5);
		} else {
		return None;
		}
		}
		}
		InstructionType::CB \| InstructionType::IM \| InstructionType::B => {}//They do not have this field
		}

		//Determine Rm if the instruction type is R
		if matches!(instruction_type, InstructionType::R) {
		if tokens[0] != "BR" {//This one does not have the Rn operand
		if let Some(rm) = parse_register(tokens[3]) {
		instruction.set_bits(rm, 20, 16);
		} else {
		return None;
		}
		}
		}

		//Determine the immediate/address to use from the 4th token depending on the instruction_type
		match instruction_type {
		InstructionType::I => {
		if let Some(immediate) = smart_parse_uint(tokens[3]) {
		if immediate > 0b111111111111 {//Too large for the field to hold
		return None;
		}
		instruction.set_bits(immediate, 21, 10);
		}
		},
		InstructionType::D => {
		if let Some(address) = smart_parse_uint(tokens[3]) {
		if address > 0b111111111 {//Too large for the field to hold
		return None;
		}
		instruction.set_bits(address, 20, 12);
		}
		},
		InstructionType::R \| InstructionType::CB \| InstructionType::IM \| InstructionType::B => {}//They do not have this field
		}

		//TODO other fields