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Demonstrate that the Rust file fits in 500 lines after stripping comments
This commit is contained in:
Peter Fidelman
parent
b0a387d5a1
commit
46061b384e
1 changed files with 500 additions and 0 deletions
500
frustration_minimal.rs
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500
frustration_minimal.rs
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@ -0,0 +1,500 @@
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// This is equivalent to frustration.rs but with comments stripped.
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// Line count: 500
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use std::convert::TryInto;
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use std::io;
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use std::io::Read;
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use std::io::Write;
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const ADDRESS_SPACE: usize = 65536;
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#[derive(Debug)]
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struct Stack<const N: usize> {
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mem: [u16; N],
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tos: usize /* top-of-stack */
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}
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impl<const N: usize> Stack<N> {
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fn push(&mut self, val: u16) {
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self.tos = (self.tos.wrapping_add(1)) & (N - 1);
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self.mem[self.tos] = val;
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}
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fn pop(&mut self) -> u16 {
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let val = self.mem[self.tos];
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self.mem[self.tos] = 0;
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self.tos = (self.tos.wrapping_sub(1)) & (N - 1);
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return val;
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}
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fn new() -> Stack<N> {
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return Stack {tos: N-1, mem: [0; N]};
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}
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}
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struct Core {
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ram: [u8; ADDRESS_SPACE],
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ip: u16,
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dstack: Stack<16>,
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rstack: Stack<32>
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}
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impl Core {
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fn new() -> Core {
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return Core {
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ram: [0; ADDRESS_SPACE],
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ip: 0,
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dstack: Stack::new(),
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rstack: Stack::new()}
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}
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fn load(&self, addr: u16) -> u16 {
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let a = addr as usize;
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return u16::from_le_bytes(self.ram[a..=a+1].try_into().unwrap());
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}
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fn store(&mut self, addr: u16, val: u16) {
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let a = addr as usize;
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self.ram[a..=a+1].copy_from_slice(&val.to_le_bytes());
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}
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fn step(&mut self) {
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let opcode = self.load(self.ip);
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self.ip = self.ip.wrapping_add(2);
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if (opcode >= 0xffe0) && (opcode & 1 == 0) {
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PRIMITIVES[((opcode - 0xffe0) >> 1) as usize](self);
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}
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else if (opcode & 1) == 1 {
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self.dstack.push(opcode >> 1);
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}
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else {
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self.rstack.push(self.ip);
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self.ip = opcode;
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}
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}
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}
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enum Op {
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RET = 0xffe0, TOR = 0xffe2, RTO = 0xffe4, LD = 0xffe6,
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ST = 0xffe8, DUP = 0xffea, SWP = 0xffec, DRP = 0xffee,
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Q = 0xfff0, ADD = 0xfff2, SFT = 0xfff4, OR = 0xfff6,
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AND = 0xfff8, INV = 0xfffa, GEQ = 0xfffc, IO = 0xfffe,
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}
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type Primitive = fn(&mut Core);
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const PRIMITIVES: [Primitive; 16] = [
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| x | {
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/* RET - Return from subroutine */
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x.ip = x.rstack.pop()
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},
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| x | {
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/* TOR - Transfer number from data stack to return stack */
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x.rstack.push(x.dstack.pop())
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},
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| x | {
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/* RTO - Transfer number from return stack to data stack */
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x.dstack.push(x.rstack.pop())
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},
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| x | {
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/* LD - Load number from memory address specified on the data stack */
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let a = x.dstack.pop();
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x.dstack.push(x.load(a));
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},
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| x | {
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/* ST - Store number to memory address specified on the data stack */
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let a = x.dstack.pop();
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let v = x.dstack.pop();
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x.store(a, v);
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},
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| x | {
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/* DUP - Duplicate the top number on the data stack */
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let v = x.dstack.pop();
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x.dstack.push(v);
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x.dstack.push(v);
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},
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| x | {
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/* SWP - Exchange the top two numbers on the data stack */
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let v1 = x.dstack.pop();
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let v2 = x.dstack.pop();
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x.dstack.push(v1);
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x.dstack.push(v2);
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},
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| x | {
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/* DRP - Discard the top number on the data stack */
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let _ = x.dstack.pop();
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},
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| x | {
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/* Q - If the top number on the data stack is zero, skip the next
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* instruction. */
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let f = x.dstack.pop();
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if f == 0 {
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x.ip = x.ip.wrapping_add(2)
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}
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},
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| x | {
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/* ADD - Sum the top two numbers on the data stack. */
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let v1 = x.dstack.pop();
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let v2 = x.dstack.pop();
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x.dstack.push(v1.wrapping_add(v2));
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},
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| x | {
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/* SFT - Bit shift number left or right by the specified amount.
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* A positive shift amount shifts left, negative shifts right. */
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let amt = x.dstack.pop();
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let val = x.dstack.pop();
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x.dstack.push(
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if amt <= 0xf {
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val << amt
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} else if amt >= 0xfff0 {
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val >> (0xffff - amt + 1)
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} else {
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0
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}
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);
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},
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| x | { // OR - Bitwise-or the top two numbers on the data stack.
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let v1 = x.dstack.pop();
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let v2 = x.dstack.pop();
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x.dstack.push(v1 | v2);
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},
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| x | { // AND - Bitwise-and the top two numbers on the data stack.
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let v1 = x.dstack.pop();
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let v2 = x.dstack.pop();
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x.dstack.push(v1 & v2);
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},
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| x | { // INV - Bitwise-invert the top number on the data stack.
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let v1 = x.dstack.pop();
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x.dstack.push(!v1);
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},
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| x | { // GEQ - Unsigned-compare the top two items on the data stack.
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let v2 = x.dstack.pop();
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let v1 = x.dstack.pop();
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x.dstack.push(if v1 >= v2 { 0xffff } else { 0 });
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},
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| x | { // IO - Write/read a number from/to input/output port.
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let port = x.dstack.pop();
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match port {
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0 => { /* Push a character from stdin onto the data stack */
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let mut buf: [u8; 1] = [0];
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let _ = io::stdin().read(&mut buf);
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x.dstack.push(buf[0] as u16);
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}
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1 => { /* Pop a character from the data stack to stdout */
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let val = x.dstack.pop();
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print!("{}", ((val & 0xff) as u8) as char);
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let _ = io::stdout().flush();
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}
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2 => { /* Dump CPU status. */
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println!("{:?} {:?}", x.ip, x.dstack);
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let _ = io::stdout().flush();
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}
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_ => {}
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}
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}
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];
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struct Dict<'a> {
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dp: u16,
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here: u16,
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c: &'a mut Core
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}
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enum Item {
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Literal(u16),
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Call(u16),
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Opcode(Op)
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}
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impl From<u16> for Item { fn from(a: u16) -> Self { Item::Call(a) } }
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impl From<Op> for Item { fn from(o: Op) -> Self { Item::Opcode(o) } }
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impl Dict<'_> {
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fn allot(&mut self, n: u16) {
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self.here = self.here.wrapping_add(n);
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}
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fn comma(&mut self, val: u16) {
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self.c.store(self.here, val);
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self.allot(2);
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}
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fn emit<T: Into<Item>>(&mut self, val: T) {
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match val.into() {
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Item::Call(val) => { self.comma(val) }
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Item::Opcode(val) => { self.comma(val as u16) }
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Item::Literal(val) => { assert!(val <= 0x7fff);
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self.comma((val << 1) | 1) }
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}
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}
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fn name(&mut self, n: u8, val: [u8; 3]) {
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self.comma(n as u16 | ((val[0] as u16) << 8));
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self.comma(val[1] as u16 | ((val[2] as u16) << 8));
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}
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fn entry(&mut self) {
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let here = self.here;
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self.comma(self.dp);
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self.dp = here;
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}
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}
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fn build_dictionary(c: &mut Core) {
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use Op::*;
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use Item::*;
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let mut d = Dict { dp: 0, here: 2, c: c };
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macro_rules! forth {
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($x:expr) => (d.emit($x));
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($x:expr, $($y:expr),+) => (d.emit($x); forth!($($y),+))
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}
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// key ( -- n )
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d.entry(); d.name(3, *b"key"); let key = d.here;
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forth!(Literal(0), IO, RET);
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// emit ( n -- )
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d.entry(); d.name(4, *b"emi"); let emit = d.here;
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forth!(Literal(1), IO, RET);
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// - ( a b -- a-b )
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d.entry(); d.name(1, *b"- "); let sub = d.here;
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forth!(INV, Literal(1), ADD, ADD, RET);
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let zero = d.here;
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forth!(Literal(0), RTO, DRP, RET);
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// 0= ( n -- f )
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d.entry(); d.name(2, *b"0= "); let zero_eq = d.here;
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forth!(Q, zero, Literal(0), INV, RET);
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// = ( a b -- a=b )
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d.entry(); d.name(1, *b"= "); let eq = d.here;
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forth!(sub, zero_eq, RET);
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let skip_helper = d.here;
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forth!(RTO, DRP, key, DUP, Literal(33), GEQ, Q, RET, DRP, skip_helper);
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// skipws ( -- c )
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d.entry(); d.name(6, *b"ski"); let skipws = d.here;
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forth!(skip_helper);
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// over ( a b -- a b a )
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d.entry(); d.name(4, *b"ove"); let over = d.here;
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forth!(TOR, DUP, RTO, SWP, RET);
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// 2dup ( a b -- a b a b )
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d.entry(); d.name(4, *b"2du"); let twodup = d.here;
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forth!(over, over, RET);
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let word_buf = d.here;
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d.allot(6);
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// min ( a b -- n )
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d.entry(); d.name(3, *b"min"); let min = d.here;
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forth!(twodup, GEQ, Q, SWP, DRP, RET);
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// c@ ( a -- n )
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d.entry(); d.name(2, *b"c@ "); let cld = d.here;
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forth!(LD, Literal(0xff), AND, RET);
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// c! ( n a -- )
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d.entry(); d.name(2, *b"c! "); let cst = d.here;
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forth!(DUP, LD, Literal(0xff), INV, AND, SWP, TOR, OR, RTO, ST, RET);
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// Load 1 letter into the buffer.
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let stchar = d.here;
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forth!(
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Literal(word_buf), cld, Literal(1), ADD, DUP, Literal(word_buf), cst,
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Literal(5), min, Literal(word_buf), ADD, cst, RET);
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let getcs_helper = d.here;
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forth!(RTO, DRP, stchar, key, DUP, Literal(32), SWP, GEQ, Q, RET,
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getcs_helper);
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// getcs ( -- c )
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d.entry(); d.name(5, *b"get"); let getcs = d.here;
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forth!(getcs_helper, RET);
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// word ( -- )
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d.entry(); d.name(4, *b"wor"); let word = d.here;
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forth!(Literal(word_buf),
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DUP, Literal(2), ADD,
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Literal(0x2020), SWP, ST,
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Literal(0x2000), SWP, ST,
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skipws, getcs, DRP, RET);
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// latest ( -- a )
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let latest_ptr = d.here; d.allot(2);
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d.entry(); d.name(6, *b"lat"); let latest = d.here;
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forth!(Literal(latest_ptr), RET);
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// Helper word ( a -- f )
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let matches = d.here;
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forth!(Literal(2), ADD, TOR,
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Literal(word_buf), DUP, Literal(2), ADD, LD, SWP, LD,
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RTO, DUP, TOR, LD, Literal(0x0080), INV, AND, eq,
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SWP, RTO, Literal(2), ADD, LD, eq, AND, RET);
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// Helper word ( a -- a' )
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let matched = d.here;
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forth!(Literal(6), ADD, RTO, DRP, RET);
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let find_helper = d.here;
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forth!(RTO, DRP,
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DUP, Literal(0), eq, Q, RET, /* No match - return 0 */
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DUP, matches, Q, matched, /* Match - return the code address */
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LD, find_helper); /* Try the next one */
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// find ( -- xt|0 )
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d.entry(); d.name(4, *b"fin"); let find = d.here;
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forth!(latest, LD, find_helper);
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// ' ( -- xt|0 )
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d.entry(); d.name(1, *b"' "); let quote = d.here;
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forth!(word, find, RET);
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// here ( -- a )
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let here_ptr = d.here; d.allot(2);
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d.entry(); d.name(4, *b"her"); let here = d.here;
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forth!(Literal(here_ptr), RET);
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// state ( -- a )
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let state_ptr = d.here; d.allot(2);
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d.entry(); d.name(5, *b"sta"); let state = d.here;
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forth!(Literal(state_ptr), RET);
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let word_addr = d.here;
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forth!(Literal(latest_ptr), LD, Literal(2), ADD, RET);
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// immediate ( -- )
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d.entry(); d.name(9, *b"imm");
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forth!(word_addr, DUP, LD, Literal(0x0080), OR, SWP, ST, RET);
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// [ ( -- )
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d.entry(); d.name(1 | 0x80, *b"[ ");
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let lbracket = d.here;
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forth!(Literal(0), INV, state, ST, RET);
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// ] ( -- )
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d.entry(); d.name(1 | 0x80, *b"] "); let rbracket = d.here;
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forth!(Literal(0), state, ST, RET);
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// smudge ( -- )
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d.entry(); d.name(6 | 0x80, *b"smu"); let smudge = d.here;
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forth!(word_addr, DUP, LD, Literal(0x0040), OR, SWP, ST, RET);
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// unsmudge ( -- )
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d.entry(); d.name(8 | 0x80, *b"uns"); let unsmudge = d.here;
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forth!(word_addr, DUP, LD, Literal(0x0040), INV, AND, SWP, ST, RET);
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// , ( n -- )
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d.entry(); d.name(1, *b", "); let comma = d.here;
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forth!(here, LD, ST,
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here, LD, Literal(2), ADD, here, ST, RET);
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// x10 ( n -- n*10 )
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d.entry(); d.name(3, *b"x10"); let x10 = d.here;
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forth!(DUP, DUP, Literal(3), SFT, ADD, ADD, RET);
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let end_num = d.here;
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forth!(DRP, RTO, DRP, RET);
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let bad_num = d.here;
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forth!(DRP, DRP, DRP, Literal(0), INV, RTO, DRP, RET);
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// Helper function ( 0 1 -- n|-1 )
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let number_helper = d.here;
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forth!(RTO, DRP,
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DUP, Literal(word_buf), ADD, cld,
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Literal(48), sub, DUP, Literal(10), GEQ, Q, bad_num,
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SWP, TOR, SWP, x10, ADD, RTO,
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DUP, Literal(word_buf), cld, GEQ, Q, end_num,
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Literal(1), ADD, number_helper);
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// number ( -- n|-1 )
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d.entry(); d.name(6, *b"num"); let number = d.here;
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forth!(Literal(0), Literal(1), number_helper);
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// lit ( n -- )
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d.entry(); d.name(3, *b"lit"); let lit = d.here;
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forth!(DUP, ADD, Literal(1), ADD, comma, RET);
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// Helper function to compile a number ( n -- n? )
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let try_compile_lit = d.here;
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forth!(state, LD, Q, RET, lit, RTO, DRP, RET);
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// Helper function to compile a call ( xt -- xt? )
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let try_compile_call = d.here;
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forth!(
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DUP, Literal(4), sub, LD, Literal(0x0080), AND, state, LD, OR, Q, RET,
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comma, RTO, DRP, RET);
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// execute ( xt -- )
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d.entry(); d.name(7, *b"exe"); let execute = d.here;
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forth!(TOR, RET);
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// Helper function to compile or execute a word ( xt -- )
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let do_word = d.here;
|
||||
forth!(RTO, DRP, try_compile_call, execute, RET);
|
||||
|
||||
let bad = d.here;
|
||||
forth!(DRP, Literal(63), emit, RTO, DRP, RET);
|
||||
|
||||
// dispatch ( xt -- )
|
||||
d.entry(); d.name(9, *b"int"); let dispatch = d.here;
|
||||
forth!(DUP, Q, do_word,
|
||||
DRP, number, DUP, Literal(1), ADD, zero_eq, Q, bad,
|
||||
try_compile_lit, RET);
|
||||
|
||||
// quit ( -- )
|
||||
d.entry(); d.name(4, *b"qui"); let quit = d.here;
|
||||
forth!(quote, dispatch, quit);
|
||||
|
||||
// create ( -- )
|
||||
d.entry(); d.name(6, *b"cre"); let create = d.here;
|
||||
forth!(
|
||||
here, LD, latest, LD, comma, latest, ST, word,
|
||||
Literal(word_buf), DUP, LD, comma, Literal(2), ADD, LD, comma, RET);
|
||||
|
||||
// : ( -- )
|
||||
d.entry(); d.name(1, *b": ");
|
||||
forth!(create, smudge, rbracket, RET);
|
||||
|
||||
// ; ( -- )
|
||||
d.entry(); d.name(1 | 0x80, *b"; ");
|
||||
forth!(Literal(!(RET as u16)), INV, comma, unsmudge, lbracket, RET);
|
||||
|
||||
d.entry(); d.name(3, *b"ret"); forth!(RTO, DRP, RET);
|
||||
d.entry(); d.name(2, *b">r "); forth!(RTO, SWP, TOR, TOR, RET);
|
||||
d.entry(); d.name(2, *b"r> "); forth!(RTO, RTO, SWP, TOR, RET);
|
||||
d.entry(); d.name(1, *b"@ "); forth!(LD, RET);
|
||||
d.entry(); d.name(1, *b"! "); forth!(ST, RET);
|
||||
d.entry(); d.name(3, *b"dup"); forth!(DUP, RET);
|
||||
d.entry(); d.name(4, *b"swa"); forth!(SWP, RET);
|
||||
d.entry(); d.name(4, *b"dro"); forth!(DRP, RET);
|
||||
d.entry(); d.name(1 | 0x80, *b"? "); /* This one only works in-line. */
|
||||
forth!(Literal(!(Q as u16)), INV, comma, RET);
|
||||
d.entry(); d.name(1, *b"+ "); forth!(ADD, RET);
|
||||
d.entry(); d.name(5, *b"shi"); forth!(SFT, RET);
|
||||
d.entry(); d.name(2, *b"or "); forth!(OR, RET);
|
||||
d.entry(); d.name(3, *b"and"); forth!(AND, RET);
|
||||
d.entry(); d.name(3, *b"inv"); forth!(INV, RET);
|
||||
d.entry(); d.name(3, *b"u>="); forth!(GEQ, RET);
|
||||
d.entry(); d.name(2, *b"io "); forth!(IO, RET);
|
||||
|
||||
d.c.store(latest_ptr, d.dp);
|
||||
d.c.store(here_ptr, d.here);
|
||||
d.c.store(state_ptr, 0xffff);
|
||||
d.c.store(0, quit);
|
||||
}
|
||||
|
||||
fn main() {
|
||||
let mut c = Core::new();
|
||||
build_dictionary(&mut c);
|
||||
c.ip = 0;
|
||||
loop { c.step(); }
|
||||
}
|
||||
Loading…
Reference in a new issue