From dce8ad424dac64b8221d12d5850a8212ba118948 Mon Sep 17 00:00:00 2001
From: Kartik Agaram <vc@akkartik.com>
Date: Mon, 15 Jun 2020 18:12:45 -0700
Subject: 6532 - arith: REPL converting ints to hex

I'm using one character of lookahead, inspired by Crenshaw's "let's build
a compiler".
---
 apps/arith.mu | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/apps/arith.mu b/apps/arith.mu
index 6d0307ee..43aa404c 100644
--- a/apps/arith.mu
+++ b/apps/arith.mu
@@ -1,16 +1,28 @@
 fn main -> exit-status/ebx: int {
-  var val/eax: int <- num
-  print-int32-to-screen val
-  print-string "\n"
+  {
+    var c/eax: byte <- read-key
+    # if (c == 0) break
+    compare c, 0
+    break-if-=
+    # parse an int from screen and print it out
+    var n/eax: int <- num c
+    print-int32-to-screen n
+    print-string "\n"
+    loop
+  }
   exit-status <- copy 0
 }
 
-fn num -> result/eax: int {
+fn num firstc: byte -> result/eax: int {
   var out/edi: int <- copy 0
+  {
+    var first-digit/eax: int <- to-decimal-digit firstc
+    out <- copy first-digit
+  }
   {
     var c/eax: byte <- read-key
-    # if (c == EOF) break
-    compare c, 0xffffffff  # EOF marker
+    # if (c == 0) break
+    compare c, 0
     break-if-=
     # if (c == ' ') break
     compare c, 0x20  # space
-- 
cgit 1.4.1-2-gfad0