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; void memclear(const char *addr, unsigned int len)
; really does have to be an int for the length.
; this is basically bzero(), but optimized for size, not speed.
; bzero() is around 2.3x as fast as this, but it's 3.3x as
; much code.
.importzp ptr1, tmp1
.import popptr1
.export _memclear
_memclear:
stx tmp1 ; hi byte of length
tax ; lo stays in X
bne @len_ok
lda tmp1
beq @ret ; if len == 0, don't do anything (just return)
@len_ok:
jsr popptr1 ; addr arg in ptr1. leaves X alone, sets Y=0
tya ; A=0
@loop:
sta (ptr1),y
iny
bne @y_ok
inc ptr1+1
@y_ok:
dex
bne @loop
dec tmp1
bpl @loop
@ret:
rts
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