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|
use crate::Word;
use super::{ Program, Address };
impl Program {
/* Intermediate code generation */
pub(crate) fn collapse_instructions(&mut self) {
// Fix instruction addresses
let mut offsets = Vec::new();
for instr in &self.instructions {
offsets.push(instr.collapse_len() + offsets.last().unwrap_or(&0));
}
offsets.insert(0, 0);
for instr in &mut self.instructions {
for arg in &mut instr.args {
match arg {
Address::Instruction(num)
=> *arg = Address::Instruction(offsets[*num]),
Address::InstructionOffset(num, offset)
=> *arg = Address::InstructionOffset(offsets[*num], *offset),
Address::InstructionConstant(num)
=> *arg = Address::InstructionConstant(offsets[*num]),
_ => {},
}
}
}
// Collapse all instructions
let mut collapsed = Vec::new();
for instr in &mut self.instructions {
collapsed.extend(instr.collapse(collapsed.len()));
}
self.instructions = collapsed;
}
/* Machine code generation */
pub(crate) fn instructions_to_constants(&mut self) {
let absolute_start = self.absolute_start + 1;
let mut constlen = self.constants.len();
for instr in &self.instructions {
for arg in &instr.args {
if let Address::InstructionConstant(_) = arg {
constlen += 1;
}
}
}
for instr in &mut self.instructions {
for arg in &mut instr.args {
if let Address::InstructionConstant(num) = arg {
self.constants.push((constlen + absolute_start + *num * 3) as Word);
*arg = Address::Constants(self.constants.len() - 1);
}
}
}
self.constants.insert(0, (absolute_start + constlen) as Word);
for instr in &mut self.instructions {
for arg in &mut instr.args {
self.constants.push(match arg {
Address::Memory(num) => *num,
Address::Constants(num) => absolute_start + *num,
Address::Instruction(num)
=> constlen + absolute_start + *num * 3,
Address::InstructionOffset(num, off)
=> *off + constlen + absolute_start + *num * 3,
_ => unreachable!("Definition addresses should've already been removed!"),
} as Word);
}
}
self.instructions.clear();
}
pub(crate) fn to_bytes(self, pc: usize) -> Vec<u8> {
let mut res = Vec::new();
res.resize(self.absolute_start, Default::default());
res[pc] = self.constants[0];
res.extend(self.constants);
res
.into_iter()
.map(|x| x.to_be_bytes())
.flatten()
.collect()
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::lexer::Token;
#[test]
fn after_two_collapses_only_subleq_remains() {
let mut prog = Program::new(vec![
Token::Operator("rts".to_string()),
Token::Operator("jsr".to_string()),
Token::Address(1000),
Token::Operator("mov".to_string()),
Token::Address(1001),
Token::Address(1002),
Token::Operator("subleq".to_string()),
Token::Address(1001),
Token::Address(1002),
Token::Address(1001),
], 10);
prog.collapse_instructions();
prog.collapse_instructions();
for i in prog.instructions {
assert_eq!(i.name, "subleq");
}
}
}
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