From 72dae5a249027471a288e361f593abfad287a33b Mon Sep 17 00:00:00 2001
From: psf <psf@phone>
Date: Sun, 27 Mar 2022 00:44:04 -0700
Subject: [PATCH] user-callable return-stack juggling words that work correctly

---
 frustration.rs | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/frustration.rs b/frustration.rs
index 63d87ba..0597579 100644
--- a/frustration.rs
+++ b/frustration.rs
@@ -1,5 +1,5 @@
 use std::io;
-//use std::process;
+use std::process;
 use std::convert::TryInto;
 
 //const CORE_SIZE: usize = 65408
@@ -56,7 +56,7 @@ struct TableEntry {
     immediate: bool
 }
 
-const PRIMITIVES: [TableEntry; 21] = [
+const PRIMITIVES: [TableEntry; 24] = [
     TableEntry {f: ret     , name: None, immediate: false},
     TableEntry {f: lit     , name: None, immediate: false},
     TableEntry {f: add     , name: Some(ShortName {bytes: *b"+  ", length: 1}), immediate: false},
@@ -68,15 +68,18 @@ const PRIMITIVES: [TableEntry; 21] = [
     TableEntry {f: drop    , name: Some(ShortName {bytes: *b"dro", length: 4}), immediate: false},
     TableEntry {f: dup     , name: Some(ShortName {bytes: *b"dup", length: 3}), immediate: false},
     TableEntry {f: dump    , name: Some(ShortName {bytes: *b"dum", length: 4}), immediate: false},
+    TableEntry {f: from_r_ , name: Some(ShortName {bytes: *b"r> ", length: 2}), immediate: false},
     TableEntry {f: immediate,name: Some(ShortName {bytes: *b"imm", length: 9}), immediate: false},
     TableEntry {f: lbracket, name: Some(ShortName {bytes: *b"[  ", length: 1}), immediate: true},
     TableEntry {f: load    , name: Some(ShortName {bytes: *b"@  ", length: 1}), immediate: false},
     TableEntry {f: mul     , name: Some(ShortName {bytes: *b"*  ", length: 1}), immediate: false},
+    TableEntry {f: ret_    , name: Some(ShortName {bytes: *b"ret", length: 3}), immediate: false},
     TableEntry {f: rbracket, name: Some(ShortName {bytes: *b"]  ", length: 1}), immediate: false},
     TableEntry {f: store   , name: Some(ShortName {bytes: *b"!  ", length: 1}), immediate: false},
     TableEntry {f: sub     , name: Some(ShortName {bytes: *b"-  ", length: 1}), immediate: false},
     TableEntry {f: swap    , name: Some(ShortName {bytes: *b"swa", length: 4}), immediate: false},
     TableEntry {f: tick    , name: Some(ShortName {bytes: *b"'  ", length: 1}), immediate: false},
+    TableEntry {f: to_r_ , name: Some(ShortName {bytes: *b">r ", length: 2}), immediate: false},
     TableEntry {f: word    , name: Some(ShortName {bytes: *b"wor", length: 4}), immediate: false}
 ];
 
@@ -237,11 +240,25 @@ fn to_r(c: &mut Core, val: u16) {
     c.trs += 1;
 }
 
+fn to_r_(c: &mut Core) {
+    let r1 = from_r(c);
+    let r2 = pop(c);
+    to_r(c, r2);
+    to_r(c, r1);
+}
+
 fn from_r(c: &mut Core) -> u16 {
     c.trs -= 1;
     return c.rstack[c.trs];
 }
 
+fn from_r_(c: &mut Core) {
+    let r1 = from_r(c);
+    let r2 = from_r(c);
+    to_r(c, r1);
+    push(c, r2);
+}
+
 fn call(c: &mut Core) {
     to_r(c, c.ip);
     c.ip = pop(c);
@@ -249,9 +266,17 @@ fn call(c: &mut Core) {
 
 // note: this is an inline primitive, not a dict entry
 fn ret(c: &mut Core) {
+    if c.trs == 0 {
+        std::process::exit(0);
+    }
     c.ip = from_r(c);
 }
 
+fn ret_(c: &mut Core) {
+    _ = from_r(c);
+    ret(c);
+}
+
 // --- Inner interpreter ---
 
 fn fetch(c: &mut Core) -> u16 {