diff options
| -rw-r--r-- | examples/bf.rs | 47 |
1 files changed, 25 insertions, 22 deletions
diff --git a/examples/bf.rs b/examples/bf.rs index ce2a682..f288178 100644 --- a/examples/bf.rs +++ b/examples/bf.rs @@ -21,6 +21,8 @@ use juicebox_asm::insn::*; use juicebox_asm::Runtime; use juicebox_asm::{Asm, Imm64, Imm8, Label, MemOp, MemOp8, Reg64, Reg8}; +// -- BRAINFUCK INTERPRETER ---------------------------------------------------- + struct BrainfuckInterp { pc: usize, imem: Vec<char>, @@ -31,8 +33,9 @@ struct BrainfuckInterp { impl BrainfuckInterp { fn new(prog: &str) -> Result<Self, String> { - // Do a first pass over the bf program to filter whitespace and detect invalid tokens. - // Additionally validate all conditional branches, and compute their branch target. + // Do a first pass over the bf program to filter whitespace and detect + // invalid tokens. Additionally validate all conditional branches, and + // compute their branch target. let (imem, branches) = { // Instruction memory holding the final bf program. let mut imem = Vec::new(); @@ -130,7 +133,7 @@ fn run_interp(prog: &str) { } } -// -- BRAINFUCK JIT -------------------------------------------------------------- +// -- BRAINFUCK JIT ------------------------------------------------------------ #[cfg(not(any(target_arch = "x86_64", target_os = "linux")))] compile_error!("Only supported on x86_64 with SystemV abi"); @@ -142,7 +145,8 @@ struct BrainfuckJit { impl BrainfuckJit { fn new(prog: &str) -> Result<Self, String> { - // Do a first pass over the bf program to filter whitespace and detect invalid tokens. + // Do a first pass over the bf program to filter whitespace and detect + // invalid tokens. let imem = prog .chars() .filter(|c| !c.is_whitespace()) @@ -168,20 +172,19 @@ extern "C" fn putchar(c: u8) { fn run_jit(prog: &str) { let mut vm = BrainfuckJit::new(prog).unwrap(); - // Use callee saved registers to hold vm state, such that we don't - // need to save any state before calling out to putchar. + // Use callee saved registers to hold vm state, such that we don't need to + // save any state before calling out to putchar. let dmem_base = Reg64::rbx; let dmem_idx = Reg64::r12; let mut asm = Asm::new(); - // Move data memory pointer (argument on jit entry) into correct - // register. + // Move data memory pointer (argument on jit entry) into correct register. asm.mov(dmem_base, Reg64::rdi); // Clear data memory index. asm.xor(dmem_idx, dmem_idx); - // A stack of label pairs, used to link up forward and backward - // jumps for a given '[]' pair. + // A stack of label pairs, used to link up forward and backward jumps for a + // given '[]' pair. let mut label_stack = Vec::new(); // Generate code for each instruction in the bf program. @@ -202,12 +205,11 @@ fn run_jit(prog: &str) { asm.dec(MemOp8::from(MemOp::IndirectBaseIndex(dmem_base, dmem_idx))); } '.' => { - // Load data memory from active cell into di register, - // which is the first argument register according to - // the SystemV abi, then call into putchar. Since we - // stored all out vm state in callee saved registers - // we don't need to save any registers before the - // call. + // Load data memory from active cell into di register, which is + // the first argument register according to the SystemV abi, + // then call into putchar. Since we stored all out vm state in + // callee saved registers we don't need to save any registers + // before the call. asm.mov(Reg8::dil, MemOp::IndirectBaseIndex(dmem_base, dmem_idx)); asm.mov(Reg64::rax, Imm64::from(putchar as usize)); asm.call(Reg64::rax); @@ -229,8 +231,8 @@ fn run_jit(prog: &str) { ); asm.jz(&mut label_pair.0); - // Bind label_pair.1 after the jump instruction, which - // will be the branch target for the matching ']'. + // Bind label_pair.1 after the jump instruction, which will be + // the branch target for the matching ']'. asm.bind(&mut label_pair.1); } ']' => { @@ -238,8 +240,7 @@ fn run_jit(prog: &str) { .pop() .expect("encountered un-balanced brackets, found ']' without matching '['"); - // Goto label_pair.1 if data memory at active cell is - // not 0. + // Goto label_pair.1 if data memory at active cell is not 0. // if vm.dmem[vm.dptr] != 0 goto label_pair.1 asm.cmp( MemOp::IndirectBaseIndex(dmem_base, dmem_idx), @@ -247,8 +248,8 @@ fn run_jit(prog: &str) { ); asm.jnz(&mut label_pair.1); - // Bind label_pair.0 after the jump instruction, which - // is the branch target for the matching '['. + // Bind label_pair.0 after the jump instruction, which is the + // branch target for the matching '['. asm.bind(&mut label_pair.0); } _ => unreachable!(), @@ -268,6 +269,8 @@ fn run_jit(prog: &str) { bf_entry(&mut vm.dmem as *mut u8); } +// -- MAIN --------------------------------------------------------------------- + fn main() { // https://en.wikipedia.org/wiki/Brainfuck#Adding_two_values //let inp = "++>+++++ [<+>-] ++++++++[<++++++>-]<."; |