Add a readme

zforth/README.md

@@ -0,0 +1,26 @@
+# zForth for radare2
+
+zforth is a minimalistic implementation of Forth that aims to be easy
+to embed, simple and portable.
+
+This plugin exposes the forth interpreter to be used with radare2.
+
+Enter the zforth repl.
+
+```
+$ r2 -c '#!zforth' -
+```
+
+## Simple programs
+
+```
+1 3 + . 10 0 sys ( 10 0 sys is the same as printing \n char to stdout )
+```
+
+## Using the r2cmd syscall
+
+```
+s" ?E Hello World " r2cmd tell nl
+```
+
+

zforth/core.zf

@@ -14,6 +14,19 @@
 : nl 10 0 sys ; ( new line )
 : drop2 drop drop ;
 
+: place over over >r >r char+ swap chars cmove r> r> c! ;
+
+: append                         ( a1 n2 a2 --)
+   over over                  \ duplicate target and count
+   >r >r                      \ save them on the return stack
+   count chars +              \ calculate offset target
+   swap chars move            \ now move the source string
+   r> r>                      \ get target and count
+   dup >r                     \ duplicate target and save one
+   c@ +                       \ calculate new count
+   r> c!                      \ get address and store
+;
+
 
 ( dictionary access. These are shortcuts through the primitive operations are !!, @@ and ,, )