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use token::Token;
use token::Token::*;
#[derive(Default)]
struct CompileState {
output: String,
loopnum: i32,
ifnum: i32,
outbuffsize: i32,
}
/// Takes an offset from the current cell, and returns a string in assembly code
/// representing the register or memory region it is stored in
fn offset_to_operand(offset: i32) -> String {
if offset == 0 {
"%r12".to_string()
} else {
format!("{}(%rbx)", (offset * 8))
}
}
fn compile_iter(state: &mut CompileState, tokens: Vec<Token>) {
let mut outbuffpos = 0;
for token in tokens {
match token {
Add(offset, value) => {
let dest = offset_to_operand(offset);
if value == 1 && dest == "%r12" {
state.output.push_str(" inc %r12\n");
} else if value >= 1 {
state.output.push_str(&format!(" addq ${}, {}\n", value, dest));
} else if value == -1 && dest == "%r12" {
state.output.push_str(" dec %r12\n");
} else if value <= -1 {
state.output.push_str(&format!(" subq ${}, {}\n", -value, dest));
}
}
MulCopy(src_idx, dest_idx, mul) => {
let mut src = offset_to_operand(src_idx);
let dest = offset_to_operand(dest_idx);
if mul != -1 && mul != 1 {
state.output.push_str(&format!(concat!(" movq {}, %rax\n",
" movq ${}, %rdx\n",
" mulq %rdx\n"),
src,
mul.abs()));
src = "%rax".to_string();
} else if src != "%r12" && dest != "%r12" {
// x86 cannot move memory to memory
state.output.push_str(&format!(" movq {}, %rax\n", src));
src = "%rax".to_string();
}
if mul > 0 {
state.output.push_str(&format!(" addq {}, {}\n", src, dest));
} else {
state.output.push_str(&format!(" subq {}, {}\n", src, dest));
}
}
Set(offset, value) => {
if offset == 0 && value == 0 {
state.output.push_str(" xor %r12, %r12\n");
} else {
state.output
.push_str(&format!(" movq ${}, {}\n", value, offset_to_operand(offset)));
}
}
Move(offset) => {
if offset != 0 {
state.output.push_str(&format!(concat!(" movq %r12, (%rbx)\n",
" {add_sub} ${shift}, %rbx\n",
" movq (%rbx), %r12\n"),
add_sub =
if offset > 0 { "addq" } else { "subq" },
shift = offset.abs() * 8));
}
}
Loop(content) => {
state.loopnum += 1;
let curloop = state.loopnum;
state.output.push_str(&format!(concat!(" jmp endloop{}\n", " loop{}:\n"),
curloop,
curloop));
compile_iter(state, content);
state.output.push_str(&format!(concat!(" endloop{}:\n",
" test %r12, %r12\n",
" jnz loop{}\n"),
curloop,
curloop))
}
If(offset, content) => {
state.ifnum += 1;
let curif = state.ifnum;
if offset == 0 {
state.output.push_str(" test %r12, %r12\n");
} else {
state.output.push_str(&format!(" cmpq $0, {}(%rbx)\n", offset * 8));
}
state.output.push_str(&format!(" jz endif{}\n", curif));
compile_iter(state, content);
state.output.push_str(&format!(" endif{}:\n", curif))
}
Scan(offset) => {
// Slighly more optimal than normal loop and move
state.loopnum += 1;
state.output.push_str(&format!(concat!(" movq %r12, (%rbx)\n",
" jmp endloop{num}\n",
" loop{num}:\n",
" {add_sub} ${shift}, %rbx\n",
" endloop{num}:\n",
" cmp $0, (%rbx)\n",
" jnz loop{num}\n",
" movq (%rbx), %r12\n"),
num = state.loopnum,
add_sub = if offset > 0 { "addq" } else { "subq" },
shift = offset.abs() * 8));
}
Input => {
state.output.push_str(concat!("\n xor %rax, %rax\n",
" xor %rdi, %rdi\n",
" movq %rbx, %rsi\n",
" movq $1, %rdx\n",
" syscall\n",
" movq (%rbx), %r12\n\n"))
}
LoadOut(offset, add) => {
let outaddr = format!("(strbuff+{})", outbuffpos);
if offset == 0 {
state.output.push_str(&format!(" movq %r12, {}\n", outaddr));
} else {
state.output.push_str(&format!(" movq {}(%rbx), %rax\n", offset * 8));
state.output.push_str(&format!(" movq %rax, {}\n", outaddr));
}
if add > 0 {
state.output.push_str(&format!(" addb ${}, {}\n", add, outaddr));
} else if add < 0 {
state.output.push_str(&format!(" subb ${}, {}\n", -add, outaddr));
}
outbuffpos += 1;
}
LoadOutSet(value) => {
let outaddr = format!("(strbuff+{})", outbuffpos);
state.output.push_str(&format!(" movq ${}, {}\n", value, outaddr));
outbuffpos += 1;
}
Output => {
state.output.push_str(&format!(concat!(" movq $1, %rax\n",
" movq $1, %rdi\n",
" movq $strbuff, %rsi\n",
" movq ${}, %rdx\n",
" syscall\n\n"),
outbuffpos));
if state.outbuffsize < outbuffpos + 8 {
state.outbuffsize = outbuffpos + 8;
}
outbuffpos = 0;
}
}
}
}
pub fn compile(tokens: Vec<Token>, tape_size: i32) -> String {
let mut state = CompileState::default();
compile_iter(&mut state, tokens);
format!(concat!(".section .bss\n",
" .lcomm strbuff, {outbuffsize}\n",
" .lcomm mem, {}\n",
" .set startidx, mem + {}\n",
".section .text\n",
".global _start\n",
"_start:\n",
" xor %r12, %r12\n",
" movq $startidx, %rbx\n\n",
"{}\n",
// Exit syscall
" movq $60, %rax\n",
" movq $0, %rdi\n",
" syscall\n"),
tape_size,
tape_size / 2,
state.output,
outbuffsize = state.outbuffsize)
}