1/*- 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8#if defined(LIBC_SCCS) && !defined(lint) 9 .asciz "@(#)memmove.s 8.1 (Berkeley) 06/04/93" 10#endif /* LIBC_SCCS and not lint */ 11 12/* 13 * void *memmove(dst, src, size) 14 * returns dst 15 * 16 * This optimises the usual case (count < 65536) at the expense 17 * of some extra memory references and branches when count >= 65536. 18 */ 19 20#include "DEFS.h" 21 22ENTRY(memmove, 0) 23 movzwl $65535,r0 /* r0 = 64K (needed below) */ 24 movq 8(ap),r1 /* r1 = src, r2 = length */ 25 movl 4(ap),r3 /* r3 = dst */ 26 cmpl r1,r3 27 bgtru 1f /* normal forward case */ 28 beql 2f /* equal, nothing to do */ 29 addl2 r2,r1 /* overlaps iff src<dst but src+len>dst */ 30 cmpl r1,r3 31 bgtru 4f /* overlapping, must move backwards */ 32 subl2 r2,r1 33 341: /* move forward */ 35 cmpl r2,r0 36 bgtru 3f /* stupid movc3 limitation */ 37 movc3 r2,(r1),(r3) /* move it all */ 382: 39 movl 4(ap),r0 /* return original dst */ 40 ret 413: 42 subl2 r0,12(ap) /* adjust length by 64K */ 43 movc3 r0,(r1),(r3) /* move 64K */ 44 movl 12(ap),r2 45 decw r0 /* from 0 to 65535 */ 46 brb 1b /* retry */ 47 484: /* move backward */ 49 addl2 r2,r3 505: 51 cmpl r2,r0 52 bgtru 6f /* stupid movc3 limitation */ 53 subl2 r2,r1 54 subl2 r2,r3 55 movc3 r2,(r1),(r3) /* move it all */ 56 movl 4(ap),r0 /* return original dst */ 57 ret 586: 59 subl2 r0,12(ap) /* adjust length by 64K */ 60 subl2 r0,r1 61 subl2 r0,r3 62 movc3 r0,(r1),(r3) /* move 64K */ 63 movl 12(ap),r2 64 decw r0 65 subl2 r0,r1 66 subl2 r0,r3 67 brb 5b 68