From: Jonas Hvid <mail@johv.dk>
Date: Fri, 6 Dec 2019 12:37:07 +0000 (+0100)
Subject: Implement ','
X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=06d7dcb24315373eebf8f1e8082bb39e33b3fcad;p=rrq%2Fjonasforth.git

Implement ','
---

diff --git a/main.asm b/main.asm
index cbf8a13..8af0955 100644
--- a/main.asm
+++ b/main.asm
@@ -366,6 +366,23 @@ forth_asm GET, '@'
   push rax
   next
 
+;; Add two integers on the stack.
+forth_asm PLUS, '+'
+  pop rax
+  pop rbx
+  add rax, rbx
+  push rax
+  next
+
+;; Calculate difference between two integers on the stack. The second number is
+;; subtracted from the first.
+forth_asm MINUS, '-'
+  pop rax
+  pop rbx
+  sub rbx, rax
+  push rbx
+  next
+
 ;; Get the location of the STATE variable. It can be set with '!' and read with
 ;; '@'.
 forth STATE, 'STATE'
@@ -385,6 +402,12 @@ forth HERE, 'HERE'
   dq LIT, here
   dq EXIT
 
+forth COMMA, ','
+  dq HERE, GET, PUT             ; Set the memory at the address pointed to by HERE
+  dq HERE, GET, LIT, 8, PLUS    ; Calculate new address for HERE to point to
+  dq HERE, PUT                  ; Update HERE to point to the new address
+  dq EXIT
+
 forth MAIN, 'MAIN'
   dq HELLO
   dq INTERPRET