1/*- 2 * Copyright (c) 1990 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * the Systems Programming Group of the University of Utah Computer 7 * Science Department. 8 * 9 * %sccs.include.redist.c% 10 */ 11 12#if defined(LIBC_SCCS) && !defined(lint) 13 .asciz "@(#)bcopy.s 5.1 (Berkeley) 05/12/90" 14#endif /* LIBC_SCCS and not lint */ 15 16#include "DEFS.h" 17 18/* 19 * This is probably not the best we can do, but it is still 2-10 times 20 * faster than the C version in the portable gen directory. 21 * 22 * Things that might help: 23 * - unroll the longword copy loop (might not be good for a 68020) 24 * - longword align when possible (only on the 68020) 25 * - use nested DBcc instructions or use one and limit size to 64K 26 */ 27ENTRY(bcopy) 28 movl sp@(12),d1 /* check count */ 29 jle bcdone /* <= 0, don't do anything */ 30 movl sp@(4),a0 /* src address */ 31 movl sp@(8),a1 /* dest address */ 32 cmpl a1,a0 /* src after dest? */ 33 jlt bcback /* yes, must copy backwards */ 34 movl a0,d0 35 btst #0,d0 /* src address odd? */ 36 jeq bcfeven /* no, skip alignment */ 37 movb a0@+,a1@+ /* yes, copy a byte */ 38 subql #1,d1 /* adjust count */ 39 jeq bcdone /* count 0, all done */ 40bcfeven: 41 movl a1,d0 42 btst #0,d0 /* dest address odd? */ 43 jne bcfbloop /* yes, no hope for alignment, copy bytes */ 44 movl d1,d0 /* no, both even */ 45 lsrl #2,d0 /* convert count to longword count */ 46 jeq bcfbloop /* count 0, skip longword loop */ 47bcflloop: 48 movl a0@+,a1@+ /* copy a longword */ 49 subql #1,d0 /* adjust count */ 50 jne bcflloop /* still more, keep copying */ 51 andl #3,d1 /* what remains */ 52 jeq bcdone /* nothing, all done */ 53bcfbloop: 54 movb a0@+,a1@+ /* copy a byte */ 55 subql #1,d1 /* adjust count */ 56 jne bcfbloop /* still more, keep going */ 57bcdone: 58 rts 59bcback: 60 addl d1,a0 /* src pointer to end */ 61 addl d1,a1 /* dest pointer to end */ 62 movl a0,d0 63 btst #0,d0 /* src address odd? */ 64 jeq bcbeven /* no, skip alignment */ 65 movb a0@-,a1@- /* yes, copy a byte */ 66 subql #1,d1 /* adjust count */ 67 jeq bcdone /* count 0, all done */ 68bcbeven: 69 movl a1,d0 70 btst #0,d0 /* dest address odd? */ 71 jne bcbbloop /* yes, no hope for alignment, copy bytes */ 72 movl d1,d0 /* no, both even */ 73 lsrl #2,d0 /* convert count to longword count */ 74 jeq bcbbloop /* count 0, skip longword loop */ 75bcblloop: 76 movl a0@-,a1@- /* copy a longword */ 77 subql #1,d0 /* adjust count */ 78 jne bcblloop /* still more, keep copying */ 79 andl #3,d1 /* what remains */ 80 jeq bcdone /* nothing, all done */ 81bcbbloop: 82 movb a0@-,a1@- /* copy a byte */ 83 subql #1,d1 /* adjust count */ 84 jne bcbbloop /* still more, keep going */ 85 rts 86 87