From 9474cb786427bf2a5987efac13c4e3d73d774f6e Mon Sep 17 00:00:00 2001
From: CrazyEttin <>
Date: Wed, 3 Aug 2022 20:04:50 +0300
Subject: [PATCH] Add looping and ability to correct input to the adder

---
 examples/adder.asm | 76 ++++++++++++++++++++++++++++------------------
 1 file changed, 46 insertions(+), 30 deletions(-)

diff --git a/examples/adder.asm b/examples/adder.asm
index 05aac70..2bacdc8 100644
--- a/examples/adder.asm
+++ b/examples/adder.asm
@@ -1,23 +1,12 @@
         ;Two-digit hexadecimal adder
 
         ;Print a prompt
-        load    r0, prompt
+start:  load    r0, prompt
         store   ffff, r0
 
-        ;Read and convert the first argument and load it to r2
-        ;First digit
-        load    r0, ffff
-        cleq    r0, r0, hex2n
-        xor     r2, r2
-        xor     r2, r0
-        shl     r2
-        shl     r2
-        shl     r2
-        shl     r2
-        ;Second digit
-        load    r0, ffff
-        cleq    r0, r0, hex2n
-        or      r2, r0
+        ;Read and convert the first argument and store it to arg1
+        cleq    r0, r0, rarg
+        store   arg1, r0
 
         ;Print a newline
         cleq    r0, r0, newln
@@ -26,20 +15,13 @@
         load    r0, plus
         store   ffff, r0
 
-        ;Read and convert the second argument and load it to r0
-        ;First digit
-        load    r0, ffff
-        cleq    r0, r0, hex2n
-        xor     r3, r3
-        xor     r3, r0
-        shl     r3
-        shl     r3
-        shl     r3
-        shl     r3
-        ;Second digit
-        load    r0, ffff
-        cleq    r0, r0, hex2n
-        or      r0, r3
+        ;Read and convert the second argument and load it to r2
+        cleq    r0, r0, rarg
+        xor     r2, r2
+        xor     r2, r0
+
+        ;Reload the first argument to r0
+        load    r0, arg1
 
         ;Print a newline
         cleq    r0, r0, newln
@@ -74,8 +56,38 @@
         ;Print a newline
         cleq    r0, r0, newln
 
-        ;Halt
+        ;Loop
+        breq    r0, r0, start
+
+        ;Read and convert an argument and load it to r0
+        ;First digit
+rarg:   load    r0, ffff
+        cleq    r0, r0, hex2n
+        xor     r2, r2
+        xor     r2, r0
+        shl     r2
+        shl     r2
+        shl     r2
+        shl     r2
+        ;Second digit
+rarg2:  load    r0, ffff
+        load    r1, backsp
+        breq    r0, r1, rarg
+        cleq    r0, r0, hex2n
+        ;Confirm
+        load    r3, ffff
+        load    r1, backsp
+        breq    r3, r1, rarg2
+        load    r1, cr
+        breq    r3, r1, rarg3
+        load    r0, qmark
+        store   ffff, r0
+        cleq    r0, r0, newln
         halt
+        ;Combine the digits
+rarg3:  or      r0, r2
+        ;Return
+        ret
 
         ;Print a newline
 newln:  load    r1, cr
@@ -265,6 +277,7 @@ prompt: data    3e
 plus:   data    2b
 equals: data    3d
 qmark:  data    3f
+backsp: data     8
 cr:     data     d
 lf:     data     a
 
@@ -319,3 +332,6 @@ tbl28:  data    e
 tbl29:  data    65
 tbl2a:  data    f
 tbl2b:  data    66
+
+        ;First argument
+arg1:   data     0