add DUPLICATE to ALLOCATE and copy a string or other data

startup.4th

@@ -1421,6 +1421,11 @@ VARIABLE TOTAL
    ( S: obj-addr1 obj-addr2 copy-size R: obj-addr1 obj-addr2 )
    CMOVE R> R> FREE ;
 
+\ Allocate memory to hold a copy of the data describe by c-addr and u
+\ This can be used to duplicate strings
+: DUPLICATE ( c-addr u -- obj-addr u )
+   DUP ALLOCATE >R >R 2R@ CMOVE 2R> ;
+
 >>SYSTEM
 
 \ Execute the closure captured at a-addr

test/allocate.4th

@@ -30,6 +30,12 @@
    0 ALLOCATE "Result: " TYPE U. EOL
 
    "Free a NULL pointer" HEADING
-   0 FREE ;
+   0 FREE
+
+   "Duplicate a string" HEADING
+   "test string" 2DUP DUPLICATE
+   "original  (" TYPE 2SWAP DUP U. " chars): " TYPE TYPE EOL
+   "duplicate (" TYPE DUP U. " chars): " TYPE 2DUP TYPE EOL
+   DROP FREE ;
 
 TEST

test/allocate.exp

@@ -5,4 +5,7 @@
 * Allocate 0 bytes
 Result: 0
 * Free a NULL pointer
+* Duplicate a string
+original  (11 chars): test string
+duplicate (11 chars): test string
 exit-code: 0