[OpenBIOS] [PATCHv2 1/3] rstack.fs: add pseudo r-stack implementation for interpret mode

[Mark Cave-Ayland]

The OS 9 boot loader uses the r-stack outside of a word in interpret mode.
Provide an r-stack implementation which allows r-stack accesses in
interpret mode using a separate pseudo stack.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland at ilande.co.uk>
---
 forth/lib/build.xml |    1 +
 forth/lib/rstack.fs |   21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 forth/lib/rstack.fs

diff --git a/forth/lib/build.xml b/forth/lib/build.xml
index 34eee40..f1c9a45 100644
--- a/forth/lib/build.xml
+++ b/forth/lib/build.xml
@@ -8,6 +8,7 @@
   -->
  
  <dictionary name="openbios" target="forth">
+  <object source="rstack.fs"/>
   <object source="vocabulary.fs"/>
   <object source="string.fs"/>
   <object source="preprocessor.fs"/>
diff --git a/forth/lib/rstack.fs b/forth/lib/rstack.fs
new file mode 100644
index 0000000..c095a9e
--- /dev/null
+++ b/forth/lib/rstack.fs
@@ -0,0 +1,21 @@
+\ tag: pseudo r-stack implementation for openbios
+\ 
+\ Copyright (C) 2016 Mark Cave-Ayland
+\ 
+\ See the file "COPYING" for further information about
+\ the copyright and warranty status of this work.
+\ 
+
+\
+\ Pseudo r-stack implementation for interpret mode
+\
+
+create prstack h# 20 cells allot
+variable #prstack 0 #prstack !
+
+: prstack-push  prstack #prstack @ cells + ! 1 #prstack +! ;
+: prstack-pop   -1 #prstack +! prstack #prstack @ cells + @ ;
+
+: >r state @ if ['] >r , exit then r> swap prstack-push >r ; immediate
+: r> state @ if ['] r> , exit then r> prstack-pop swap >r ; immediate
+: r@ state @ if ['] r@ , exit then r> prstack-pop dup prstack-push swap >r ; immediate
-- 
1.7.10.4