From 6e5fdbc8a46131da418591ba1bd4ae55ef011d6a Mon Sep 17 00:00:00 2001
From: hellerve <veit@veitheller.de>
Date: Sun, 4 Jun 2017 15:27:29 -0400
Subject: [PATCH] exec: implemented; still doesnt work

---
 src/main.rs | 97 ++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 82 insertions(+), 15 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index f5b3d3c..9e83062 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -55,13 +55,23 @@ fn get_contents(fname: String) -> Result<String, io::Error> {
     Ok(contents)
 }
 
-fn parse(contents: String, opcodes: HashMap<&'static str, (i64, i32)>) -> Vec<i64> {
+fn parse(contents: String, opcodes: HashMap<&'static str, (i64, i32)>) -> (Vec<i64>, usize) {
     let mut code = Vec::new();
+    let mut ip = 0;
     for line in contents.split("\n") {
         if line.is_empty() { continue }
         let tmp = line.split(" ").map(String::from).collect::<Vec<String>>();
         let (op, args) = tmp.split_first().expect("malformatted line!");
         let opcode: &str = &op.to_lowercase()[..];
+
+        // Special case: ENTRY
+        if opcode == "entry" {
+            if let Ok(_ip) = args[0].parse::<usize>() {
+                ip = _ip;
+            }
+            continue;
+        }
+
         if let Some(v) = opcodes.get(opcode) {
             code.push(v.0);
             if args.len() as i32 != v.1 {
@@ -74,7 +84,7 @@ fn parse(contents: String, opcodes: HashMap<&'static str, (i64, i32)>) -> Vec<i6
             }
         }
     }
-    return code
+    return (code, ip)
 }
 
 fn binop<F>(stack: &mut Vec<i64>, fun: F) where F: Fn(i64, i64) -> i64 {
@@ -87,11 +97,13 @@ fn binop<F>(stack: &mut Vec<i64>, fun: F) where F: Fn(i64, i64) -> i64 {
     panic!("pop needs at least two elements on the stack");
 }
 
-fn exec(instructions: Vec<i64>) -> i64 {
+/* Casting abound. You have been warned. */
+fn exec(instructions: Vec<i64>, _ip: usize) -> i64 {
     let mut stack: Vec<i64> = Vec::new();
     let mut data: Vec<i64> = Vec::new();
     let ilen = instructions.len();
-    let mut ip = 0;
+    let mut ip: usize = _ip;
+    let mut fp: usize = 0;
     while ip < ilen {
         match instructions[ip] {
             /* ENT */ 0 => (),
@@ -103,17 +115,47 @@ fn exec(instructions: Vec<i64>) -> i64 {
             /* LT  */ 6 => binop(&mut stack, |x, y| (x < y) as i64),
             /* EQ  */ 7 => binop(&mut stack, |x, y| (x == y) as i64),
             /* GT  */ 8 => binop(&mut stack, |x, y| (x > y) as i64),
-            /* BR  */ 9 => (),
-            /* BRT */ 10 => (),
-            /* BRF */ 11 => (),
+            /* BR  */ 9 => {
+                ip = instructions[ip+1] as usize;
+            },
+            /* BRT */ 10 => {
+                ip += 1;
+                let addr = instructions[ip];
+                if let Some(x) = stack.pop() {
+                    if x != 0 { ip = addr as usize; }
+                }
+            },
+            /* BRF */ 11 => {
+                ip += 1;
+                let addr = instructions[ip];
+                if let Some(x) = stack.pop() {
+                    if x == 0 { ip = addr as usize; }
+                }
+            },
             /* CST */ 12 => {
                 ip += 1;
                 stack.push(instructions[ip])
             },
-            /* LD  */ 13 => (),
-            /* GLD */ 14 => (),
-            /* ST  */ 15 => (),
-            /* GST */ 16 => (),
+            /* LD  */ 13 => {
+                ip += 1;
+                stack.push(instructions[ip+fp])
+            },
+            /* GLD */ 14 => {
+                ip += 1;
+                stack.push(data[instructions[ip] as usize]);
+            },
+            /* ST  */ 15 => {
+                ip += 1;
+                if let Some(x) = stack.pop() {
+                    stack[fp+instructions[ip] as usize] = x;
+                }
+            },
+            /* GST */ 16 => {
+                ip += 1;
+                if let Some(x) = stack.pop() {
+                    data[instructions[ip] as usize] = x;
+                }
+            },
             /* PRN */ 17 => {
                 if let Some(x) = stack.last() {
                     if let Some(x) = char::from_digit(*x as u32, 10) {
@@ -128,8 +170,33 @@ fn exec(instructions: Vec<i64>) -> i64 {
             /* HLT */ 19 => break,
             /* LEQ */ 20 => binop(&mut stack, |x, y| (x <= y) as i64),
             /* GEQ */ 21 => binop(&mut stack, |x, y| (x >= y) as i64),
-            /* CAL */ 22 => (),
-            /* RET */ 23 => (),
+            /* CAL */ 22 => {
+                let addr  = instructions[ip+1];
+                let nargs = instructions[ip+2];
+                stack.push(nargs);
+                stack.push(fp as i64);
+                stack.push((ip+2) as i64);
+                fp = stack.len() as usize;
+                ip = addr as usize;
+            },
+            /* RET */ 23 => {
+                if let Some(addr) = stack.pop() {
+                    let mut nargs = 0;
+                    stack.truncate(addr as usize);
+                    if let Some(_ip) = stack.pop() {
+                        ip = _ip as usize;
+                    }
+                    if let Some(_fp) = stack.pop() {
+                        fp = _fp as usize;
+                    }
+                    if let Some(_nargs) = stack.pop() {
+                        nargs = _nargs;
+                    }
+                    let stl = stack.len();
+                    stack.truncate(stl-nargs as usize);
+                    stack.push(addr);
+                }
+            },
             /* IPR */ 24 => {
                 if let Some(x) = stack.last() {
                     print!("{}", x);
@@ -174,7 +241,7 @@ fn main() {
         }
     };
 
-    let parsed = parse(contents, opcodes);
+    let (parsed, ip) = parse(contents, opcodes);
 
-    println!("{}", exec(parsed));
+    println!("{}", exec(parsed, ip));
 }