* Copyright (c) 1990 The Regents of the University of California.
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
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* This product includes software developed by the University of
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#if defined(LIBC_SCCS) && !defined(lint)
.asciz "@(#)bcopy.s 5.1 (Berkeley) 5/12/90"
#endif /* LIBC_SCCS and not lint */
* This is probably not the best we can do, but it is still 2-10 times
* faster than the C version in the portable gen directory.
* Things that might help:
* - unroll the longword copy loop (might not be good for a 68020)
* - longword align when possible (only on the 68020)
* - use nested DBcc instructions or use one and limit size to 64K
movl sp@(12),d1 /* check count */
jle bcdone /* <= 0, don't do anything */
movl sp@(4),a0 /* src address */
movl sp@(8),a1 /* dest address */
cmpl a1,a0 /* src after dest? */
jlt bcback /* yes, must copy backwards */
btst #0,d0 /* src address odd? */
jeq bcfeven /* no, skip alignment */
movb a0@+,a1@+ /* yes, copy a byte */
subql #1,d1 /* adjust count */
jeq bcdone /* count 0, all done */
btst #0,d0 /* dest address odd? */
jne bcfbloop /* yes, no hope for alignment, copy bytes */
movl d1,d0 /* no, both even */
lsrl #2,d0 /* convert count to longword count */
jeq bcfbloop /* count 0, skip longword loop */
movl a0@+,a1@+ /* copy a longword */
subql #1,d0 /* adjust count */
jne bcflloop /* still more, keep copying */
andl #3,d1 /* what remains */
jeq bcdone /* nothing, all done */
movb a0@+,a1@+ /* copy a byte */
subql #1,d1 /* adjust count */
jne bcfbloop /* still more, keep going */
addl d1,a0 /* src pointer to end */
addl d1,a1 /* dest pointer to end */
btst #0,d0 /* src address odd? */
jeq bcbeven /* no, skip alignment */
movb a0@-,a1@- /* yes, copy a byte */
subql #1,d1 /* adjust count */
jeq bcdone /* count 0, all done */
btst #0,d0 /* dest address odd? */
jne bcbbloop /* yes, no hope for alignment, copy bytes */
movl d1,d0 /* no, both even */
lsrl #2,d0 /* convert count to longword count */
jeq bcbbloop /* count 0, skip longword loop */
movl a0@-,a1@- /* copy a longword */
subql #1,d0 /* adjust count */
jne bcblloop /* still more, keep copying */
andl #3,d1 /* what remains */
jeq bcdone /* nothing, all done */
movb a0@-,a1@- /* copy a byte */
subql #1,d1 /* adjust count */
jne bcbbloop /* still more, keep going */
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