Annotation of sys/lib/libkern/arch/amd64/bcopy.S, Revision 1.1
1.1 ! nbrk 1: /*-
! 2: * Copyright (c) 1990 The Regents of the University of California.
! 3: * All rights reserved.
! 4: *
! 5: * This code is derived from locore.s.
! 6: *
! 7: * Redistribution and use in source and binary forms, with or without
! 8: * modification, are permitted provided that the following conditions
! 9: * are met:
! 10: * 1. Redistributions of source code must retain the above copyright
! 11: * notice, this list of conditions and the following disclaimer.
! 12: * 2. Redistributions in binary form must reproduce the above copyright
! 13: * notice, this list of conditions and the following disclaimer in the
! 14: * documentation and/or other materials provided with the distribution.
! 15: * 3. All advertising materials mentioning features or use of this software
! 16: * must display the following acknowledgement:
! 17: * This product includes software developed by the University of
! 18: * California, Berkeley and its contributors.
! 19: * 4. Neither the name of the University nor the names of its contributors
! 20: * may be used to endorse or promote products derived from this software
! 21: * without specific prior written permission.
! 22: *
! 23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 33: * SUCH DAMAGE.
! 34: */
! 35:
! 36: #include <machine/asm.h>
! 37:
! 38: #if defined(LIBC_SCCS)
! 39: RCSID("$NetBSD: bcopy.S,v 1.1 2001/06/19 00:22:45 fvdl Exp $")
! 40: #endif
! 41:
! 42: /*
! 43: * (ov)bcopy (src,dst,cnt)
! 44: * ws@tools.de (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
! 45: */
! 46:
! 47: #ifdef MEMCOPY
! 48: ENTRY(memcpy)
! 49: #else
! 50: #ifdef MEMMOVE
! 51: ENTRY(memmove)
! 52: #else
! 53: #ifdef OVBCOPY
! 54: ENTRY(ovbcopy)
! 55: #else
! 56: ENTRY(bcopy)
! 57: #endif
! 58: #endif
! 59: #endif
! 60: #if defined(MEMCOPY) || defined(MEMMOVE)
! 61: movq %rdi,%r11 /* save dest */
! 62: #else
! 63: xchgq %rdi,%rsi
! 64: #endif
! 65: movq %rdx,%rcx
! 66: movq %rdi,%rax
! 67: subq %rsi,%rax
! 68: cmpq %rcx,%rax /* overlapping? */
! 69: jb 1f
! 70: cld /* nope, copy forwards. */
! 71: shrq $3,%rcx /* copy by words */
! 72: rep
! 73: movsq
! 74: movq %rdx,%rcx
! 75: andq $7,%rcx /* any bytes left? */
! 76: rep
! 77: movsb
! 78: #if defined(MEMCOPY) || defined(MEMMOVE)
! 79: movq %r11,%rax
! 80: #endif
! 81: ret
! 82: 1:
! 83: addq %rcx,%rdi /* copy backwards. */
! 84: addq %rcx,%rsi
! 85: std
! 86: andq $7,%rcx /* any fractional bytes? */
! 87: decq %rdi
! 88: decq %rsi
! 89: rep
! 90: movsb
! 91: movq %rdx,%rcx /* copy remainder by words */
! 92: shrq $3,%rcx
! 93: subq $7,%rsi
! 94: subq $7,%rdi
! 95: rep
! 96: movsq
! 97: #if defined(MEMCOPY) || defined(MEMMOVE)
! 98: movq %r11,%rax
! 99: #endif
! 100: cld
! 101: ret
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