X-Git-Url: https://git.rrq.au/?a=blobdiff_plain;f=jonesforth.S;h=b7990e8cb9d0c8e12943320503f846bf8f226ad1;hb=e8aaec0eb1676422d1cda0338405c0cae8bd42a7;hp=5c1249c13ebc5d472464427fdd88cd1b0acc83e1;hpb=f288aec7ec596e7da9a0390c66517bd03ad837fd;p=rrq%2Fjonesforth.git

diff --git a/jonesforth.S b/jonesforth.S
index 5c1249c..b7990e8 100644
--- a/jonesforth.S
+++ b/jonesforth.S
@@ -1,11 +1,11 @@
 /*	A sometimes minimal FORTH compiler and tutorial for Linux / i386 systems. -*- asm -*-
 	By Richard W.M. Jones <rich@annexia.org> http://annexia.org/forth
 	This is PUBLIC DOMAIN (see public domain release statement below).
-	$Id: jonesforth.S,v 1.36 2007-09-27 23:09:39 rich Exp $
+	$Id: jonesforth.S,v 1.38 2007-09-28 19:39:21 rich Exp $
 
 	gcc -m32 -nostdlib -static -Wl,-Ttext,0 -o jonesforth jonesforth.S
 */
-	.set JONES_VERSION,36
+	.set JONES_VERSION,38
 /*
 	INTRODUCTION ----------------------------------------------------------------------
 
@@ -757,6 +757,14 @@ code_\label :			// assembler code follows
 	push %ecx
 	NEXT
 
+	defcode "?DUP",4,,QDUP	// duplicate top of stack if non-zero
+	pop %eax
+	test %eax,%eax
+	jz 1f
+	push %eax
+1:	push %eax
+	NEXT
+
 	defcode "1+",2,,INCR
 	incl (%esp)		// increment top of stack
 	NEXT
@@ -1924,10 +1932,13 @@ _COMMA:
 	NEXT
 
 /*
-	PRINTING STRINGS ----------------------------------------------------------------------
+	LITERAL STRINGS ----------------------------------------------------------------------
+
+	LITSTRING is a primitive used to implement the ." and S" operators (which are written in
+	FORTH).  See the definition of those operators later.
 
-	LITSTRING and EMITSTRING are primitives used to implement the ." and S" operators
-	(which are written in FORTH).  See the definition of those operators below.
+	TELL just prints a string.  It's more efficient to define this in assembly because we
+	can make it a single Linux syscall.
 */
 
 	defcode "LITSTRING",9,,LITSTRING
@@ -1939,7 +1950,7 @@ _COMMA:
 	andl $~3,%esi
 	NEXT
 
-	defcode "EMITSTRING",10,,EMITSTRING
+	defcode "TELL",4,,TELL
 	mov $1,%ebx		// 1st param: stdout
 	pop %edx		// 3rd param: length of string
 	pop %ecx		// 2nd param: address of string