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// vm/primitives.rs — Kernel primitive word implementations
//
// These are the minimum words a Forth needs: stack manipulation,
// arithmetic, memory access, I/O, and debugging.
use crate::types::{Cell, Instruction};
use std::io::{self, Read};
impl super::VM {
// -----------------------------------------------------------------------
pub(crate) fn prim_dup(&mut self) {
if let Some(&val) = self.stack.last() {
self.stack.push(val);
} else {
eprintln!("stack underflow");
}
}
pub(crate) fn prim_drop(&mut self) {
self.pop();
}
pub(crate) fn prim_swap(&mut self) {
let len = self.stack.len();
if len < 2 {
eprintln!("stack underflow");
return;
}
self.stack.swap(len - 1, len - 2);
}
pub(crate) fn prim_over(&mut self) {
let len = self.stack.len();
if len < 2 {
eprintln!("stack underflow");
return;
}
self.stack.push(self.stack[len - 2]);
}
pub(crate) fn prim_rot(&mut self) {
let len = self.stack.len();
if len < 3 {
eprintln!("stack underflow");
return;
}
let val = self.stack.remove(len - 3);
self.stack.push(val);
}
// -----------------------------------------------------------------------
// Memory
// -----------------------------------------------------------------------
pub(crate) fn prim_fetch(&mut self) {
let addr = self.pop() as usize;
if addr < self.memory.len() {
self.stack.push(self.memory[addr]);
} else {
eprintln!("invalid address: {}", addr);
self.stack.push(0);
}
}
pub(crate) fn prim_store(&mut self) {
let addr = self.pop() as usize;
let val = self.pop();
if addr < self.memory.len() {
self.memory[addr] = val;
} else {
eprintln!("invalid address: {}", addr);
}
}
// -----------------------------------------------------------------------
// Arithmetic
// -----------------------------------------------------------------------
pub(crate) fn prim_add(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(a.wrapping_add(b));
}
pub(crate) fn prim_sub(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(a.wrapping_sub(b));
}
pub(crate) fn prim_mul(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(a.wrapping_mul(b));
}
pub(crate) fn prim_div(&mut self) {
let b = self.pop();
let a = self.pop();
if b == 0 {
self.emit_str("error: division by zero\n");
self.stack.push(0);
} else {
self.stack.push(a / b);
}
}
pub(crate) fn prim_mod(&mut self) {
let b = self.pop();
let a = self.pop();
if b == 0 {
self.emit_str("error: division by zero\n");
self.stack.push(0);
} else {
self.stack.push(a % b);
}
}
// -----------------------------------------------------------------------
// Comparison (Forth convention: -1 = true, 0 = false)
// -----------------------------------------------------------------------
pub(crate) fn prim_eq(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(if a == b { -1 } else { 0 });
}
pub(crate) fn prim_lt(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(if a < b { -1 } else { 0 });
}
pub(crate) fn prim_gt(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(if a > b { -1 } else { 0 });
}
// -----------------------------------------------------------------------
// Logic
// -----------------------------------------------------------------------
pub(crate) fn prim_and(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(a & b);
}
pub(crate) fn prim_or(&mut self) {
let b = self.pop();
let a = self.pop();
self.stack.push(a | b);
}
pub(crate) fn prim_not(&mut self) {
let a = self.pop();
self.stack.push(if a == 0 { -1 } else { 0 });
}
// -----------------------------------------------------------------------
// I/O
// -----------------------------------------------------------------------
pub(crate) fn prim_emit(&mut self) {
let code = self.pop();
if let Some(ch) = char::from_u32(code as u32) {
self.emit_char(ch);
}
}
pub(crate) fn prim_key(&mut self) {
let stdin = io::stdin();
let mut buf = [0u8; 1];
if stdin.lock().read_exact(&mut buf).is_ok() {
self.stack.push(buf[0] as Cell);
} else {
self.stack.push(-1);
}
}
pub(crate) fn prim_cr(&mut self) {
self.emit_str("\n");
}
pub(crate) fn prim_dot(&mut self) {
let val = self.pop();
self.emit_str(&format!("{} ", val));
}
pub(crate) fn prim_dot_s(&mut self) {
let s = format!("<{}> ", self.stack.len());
self.emit_str(&s);
let vals: Vec<String> = self.stack.iter().map(|v| format!("{} ", v)).collect();
for v in &vals {
self.emit_str(v);
}
}
// -----------------------------------------------------------------------
// Introspection
// -----------------------------------------------------------------------
pub(crate) fn prim_words(&mut self) {
let names: Vec<String> = self
.dictionary
.iter()
.rev()
.filter(|e| !e.hidden)
.map(|e| e.name.clone())
.collect();
let mut count = 0;
for name in &names {
self.emit_str(&format!("{} ", name));
count += 1;
if count % 12 == 0 {
self.emit_str("\n");
}
}
self.emit_str("\n");
}
pub(crate) fn prim_see(&mut self) {
if let Some(name) = self.next_word() {
let upper = name.to_uppercase();
if let Some(idx) = self.find_word(&upper) {
// Collect the entire decompilation into a string first
// to avoid borrow conflicts with emit_str.
let entry = &self.dictionary[idx];
let mut out = format!(": {} ", entry.name);
for instr in &entry.body {
match instr {
Instruction::Primitive(id) => {
let pname = self
.primitive_names
.iter()
.find(|(_, pid)| pid == id)
.map(|(n, _)| n.as_str())
.unwrap_or("?PRIM");
out.push_str(&format!("{} ", pname));
}
Instruction::Literal(val) => out.push_str(&format!("LIT({}) ", val)),
Instruction::Call(cidx) => {
if *cidx < self.dictionary.len() {
out.push_str(&format!("{} ", self.dictionary[*cidx].name));
} else {
out.push_str(&format!("CALL({}) ", cidx));
}
}
Instruction::StringLit(s) => out.push_str(&format!(".\" {}\" ", s)),
Instruction::Branch(off) => out.push_str(&format!("BRANCH({}) ", off)),
Instruction::BranchIfZero(off) => {
out.push_str(&format!("0BRANCH({}) ", off))
}
}
}
out.push_str(";\n");
self.emit_str(&out);
} else {
self.emit_str(&format!("{}?\n", upper));
}
} else {
self.emit_str("expected word name after SEE\n");
}
}
// -----------------------------------------------------------------------
// REPL control
// -----------------------------------------------------------------------
pub(crate) fn prim_recurse(&mut self) {
// Immediate: compile a self-call to the word currently being defined.
if let Some(ref mut def) = self.current_def {
let target = self.dictionary.len(); // where this def will land
def.body.push(Instruction::Call(target));
}
}
pub(crate) fn prim_quit(&mut self) {
self.running = false;
}
pub(crate) fn prim_bye(&mut self) {
// Auto-save on graceful shutdown.
if self.auto_save_enabled {
if let Some(id) = self.node_id_cache {
let snap = self.make_snapshot();
let data = crate::persist::serialize_snapshot(&snap);
let _ = crate::persist::save_state(&id, &data);
}
}
self.running = false;
}
}