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Slightly improved memset function by Christian Krüger.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4923 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2011-01-26 22:07:59 +00:00
parent b4c237b2b1
commit f79473f53a
1 changed files with 7 additions and 9 deletions
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16
libsrc/common/memset.s
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@ -5,7 +5,7 @@
;
; Ullrich von Bassewitz, 29.05.1998
; Performance increase (about 20%) by
; Christian Krueger, 12.09.2009
; Christian Krueger, 12.09.2009, slightly improved 12.01.2011
;
; 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
@ -81,15 +81,13 @@ L1: .repeat 2 ; Unroll this a bit to make it faster
; Set the remaining bytes if any
L2: ldy ptr3 ; Get the low byte of n
bne L3 ; something to set?
jmp popax ; no -> Pop ptr and return as result
beq leave ; something to set? No -> leave
L3a: sta (ptr1),y ; set bytes in low
sta (ptr2),y ; and high section
L3: dey
bne L3a
sta (ptr1),y ; Set remaining byte(s)
sta (ptr2),y
L3: dey
sta (ptr1),y ; set bytes in low
sta (ptr2),y ; and high section
bne L3 ; flags still up to date from dey!
leave:
jmp popax ; Pop ptr and return as result