Duh, a stack machine without swap; implement GNU compatible 'r'

(swap) operator. Prompted by Michael Knudsen <e at molioner dot dk>

4 files changed, 32 insertions, 6 deletions

diff --git a/usr.bin/dc/bcode.c b/usr.bin/dc/bcode.c
index d4a9d68d063..630a5ee4c04 100644
--- a/usr.bin/dc/bcode.c
+++ b/usr.bin/dc/bcode.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bcode.c,v 1.12 2003/10/22 14:58:32 otto Exp $	*/
+/*	$OpenBSD: bcode.c,v 1.13 2003/11/04 08:10:06 otto Exp $	*/
 
 /*
  * Copyright (c) 2003, Otto Moerbeek <otto@drijf.net>
@@ -17,7 +17,7 @@
  */
 
 #ifndef lint
-static const char rcsid[] = "$OpenBSD: bcode.c,v 1.12 2003/10/22 14:58:32 otto Exp $";
+static const char rcsid[] = "$OpenBSD: bcode.c,v 1.13 2003/11/04 08:10:06 otto Exp $";
 #endif /* not lint */
 
 #include <ssl/ssl.h>
@@ -69,6 +69,7 @@ static __inline void	print_tos(void);
 static __inline void	pop_print(void);
 static __inline void	print_stack();
 static __inline void	dup(void);
+static void		swap(void);
 
 static void		get_scale(void);
 static void		set_scale(void);
@@ -158,6 +159,7 @@ static const struct jump_entry jump_table_data[] = {
 	{ 'l',	load		},
 	{ 'L',	load_stack	},
 	{ 'd',	dup		},
+	{ 'r',	swap		},
 	{ 'p',	print_tos	},
 	{ 'P',	pop_print	},
 	{ 'f',	print_stack	},
@@ -479,6 +481,12 @@ dup(void)
 }
 
 static void
+swap(void)
+{
+	stack_swap(&bmachine.stack);
+}
+
+static void
 get_scale(void)
 {
 	struct number	*n;
diff --git a/usr.bin/dc/dc.1 b/usr.bin/dc/dc.1
index 18cffca76e0..f276f74618d 100644
--- a/usr.bin/dc/dc.1
+++ b/usr.bin/dc/dc.1
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: dc.1,v 1.13 2003/10/23 09:01:42 jmc Exp $
+.\"	$OpenBSD: dc.1,v 1.14 2003/11/04 08:10:06 otto Exp $
 .\"
 .\" Copyright (C) Caldera International Inc.  2001-2002.
 .\" All rights reserved.
@@ -214,6 +214,9 @@ by that value.
 Exits the program.
 If executing a string, the recursion level is
 popped by two.
+.It Ic r
+The top two values on the stack are reversed (swapped).
+This is a non-portable extension.
 .It Ic S Ns Ar x
 Register
 .Ar x
diff --git a/usr.bin/dc/extern.h b/usr.bin/dc/extern.h
index 3c0dc8de205..386b3bc7c51 100644
--- a/usr.bin/dc/extern.h
+++ b/usr.bin/dc/extern.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: extern.h,v 1.1 2003/09/19 17:58:25 otto Exp $	*/
+/*	$OpenBSD: extern.h,v 1.2 2003/11/04 08:10:06 otto Exp $	*/
 
 /*
  * Copyright (c) 2003, Otto Moerbeek <otto@drijf.net>
@@ -43,6 +43,7 @@ void		bn_checkp(const void *);
 void		stack_init(struct stack *);
 void		stack_free_value(struct value *);
 struct value	*stack_dup_value(const struct value *, struct value *);
+void		stack_swap(struct stack *);
 int		stack_size(const struct stack *);
 void		stack_dup(struct stack *);
 void		stack_pushnumber(struct stack *, struct number *);
diff --git a/usr.bin/dc/stack.c b/usr.bin/dc/stack.c
index d700b787677..03e2f771369 100644
--- a/usr.bin/dc/stack.c
+++ b/usr.bin/dc/stack.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: stack.c,v 1.4 2003/10/18 20:34:26 otto Exp $	*/
+/*	$OpenBSD: stack.c,v 1.5 2003/11/04 08:10:06 otto Exp $	*/
 
 /*
  * Copyright (c) 2003, Otto Moerbeek <otto@drijf.net>
@@ -17,7 +17,7 @@
  */
 
 #ifndef lint
-static const char rcsid[] = "$OpenBSD: stack.c,v 1.4 2003/10/18 20:34:26 otto Exp $";
+static const char rcsid[] = "$OpenBSD: stack.c,v 1.5 2003/11/04 08:10:06 otto Exp $";
 #endif /* not lint */
 
 #include <err.h>
@@ -116,6 +116,20 @@ stack_dup(struct stack *stack)
 	stack_push(stack, stack_dup_value(value, &copy));
 }
 
+void
+stack_swap(struct stack *stack)
+{
+	struct value	copy;
+
+	if (stack->sp < 1) {
+		warnx("stack empty");
+		return;
+	}
+	copy = stack->stack[stack->sp];
+	stack->stack[stack->sp] = stack->stack[stack->sp-1];
+	stack->stack[stack->sp-1] = copy;
+}
+
 static void
 stack_grow(struct stack *stack)
 {