From 009df2d6b56cce9f0f9ace86209678c6be958eea Mon Sep 17 00:00:00 2001
From: cuz <cuz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Sat, 18 May 2002 21:18:45 +0000
Subject: [PATCH] New entry points for bzero and _bzero

git-svn-id: svn://svn.cc65.org/cc65/trunk@1277 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 libsrc/common/memset.s | 51 +++++++++++++++++++++++++++++-------------
 1 file changed, 36 insertions(+), 15 deletions(-)

diff --git a/libsrc/common/memset.s b/libsrc/common/memset.s
index 18fc9966e..f9a1ecd08 100644
--- a/libsrc/common/memset.s
+++ b/libsrc/common/memset.s
@@ -1,27 +1,50 @@
 ;
 ; void* memset (void* ptr, int c, size_t n);
+; void* _bzero (void* ptr, size_t n);
+; void bzero (void* ptr, size_t n);
 ;
 ; Ullrich von Bassewitz, 29.05.1998
+;
+; NOTE: bzero will return it's first argument as memset does. It is no problem
+;       to declare the return value as void, since it may be ignored. _bzero
+;       (note the leading underscore) is declared with the proper return type,
+;       because the compiler will replace memset by _bzero if the fill value
+;       is zero, and the optimizer looks at the return type to see if the value
+;       in a/x is of any use.
 ;
 
- 	.export		_memset
+ 	.export		_memset, _bzero, __bzero
 	.import		popax
-	.importzp	ptr1, ptr2, tmp1, tmp2, tmp3
+       	.importzp	sp, ptr1, ptr2, ptr3, tmp1
+
+_bzero:
+__bzero:
+        sta     ptr3
+        stx     ptr3+1          ; Save n
+        lda     #0
+        sta     tmp1            ; fill with zeros
+        beq     common
 
 _memset:
- 	sta	tmp1		; Save n
- 	stx	tmp2
+ 	sta	ptr3		; Save n
+ 	stx	ptr3+1
  	jsr	popax  	 	; Get c
- 	sta	tmp3		; Save c
- 	jsr	popax  	 	; Get ptr
+       	sta	tmp1		; Save c
+
+; Common stuff for memset and bzero from here
+
+common:
+        ldy     #1
+        lda     (sp),y
+        tax
+        dey
+        lda     (sp),y          ; Get ptr
  	sta	ptr1
  	stx	ptr1+1 		; Save work copy
-	sta	ptr2
-	stx	ptr2+1		; Save a copy for the function result
-       	lda	tmp3
 
+       	lda	tmp1            ; Load fill value
 	ldy	#0
-	ldx	tmp2		; Get high byte of n
+	ldx	ptr3+1  	; Get high byte of n
        	beq    	L2		; Jump if zero
 
 ; Set 256 byte blocks
@@ -36,8 +59,8 @@ L1:	sta	(ptr1),y	; Set one byte
 	bne	L1		; Repeat if any
 
 ; Set the remaining bytes if any
-					       
-L2:    	ldx	tmp1		; Get the low byte of n
+
+L2:    	ldx	ptr3		; Get the low byte of n
   	beq	L9		; Low byte is zero
 
 L3:    	sta    	(ptr1),y       	; Set one byte
@@ -45,8 +68,6 @@ L3:    	sta    	(ptr1),y       	; Set one byte
        	dex			; Done?
   	bne	L3
 
-L9:	lda	ptr2		; Load function result
-	ldx	ptr2+1
-   	rts
+L9:    	jmp     popax           ; Pop ptr and return as result
 
 
-- 
2.39.5