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| Current File : //compat/linux/proc/self/root/usr/src/lib/libc/mips/string/bcopy.S |
/* $NetBSD: bcopy.S,v 1.3 2009/12/14 00:39:00 matt Exp $ */
/*
* Mach Operating System
* Copyright (c) 1993 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* File: mips_bcopy.s
* Author: Chris Maeda
* Date: June 1993
*
* Fast copy routine. Derived from aligned_block_copy.
*/
#include <machine/asm.h>
__FBSDID("$FreeBSD: release/9.1.0/lib/libc/mips/string/bcopy.S 209231 2010-06-16 12:55:14Z jchandra $");
#define _LOCORE /* XXX not really, just assembly-code source */
#include <machine/endian.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
ASMSTR("from: @(#)mips_bcopy.s 2.2 CMU 18/06/93")
#else
ASMSTR("$NetBSD: bcopy.S,v 1.3 2009/12/14 00:39:00 matt Exp $")
#endif
#endif /* LIBC_SCCS and not lint */
#ifdef __ABICALLS__
.abicalls
#endif
/*
* bcopy(caddr_t src, caddr_t dst, unsigned int len)
*
* a0 src address
* a1 dst address
* a2 length
*/
#if defined(MEMCOPY) || defined(MEMMOVE)
#ifdef MEMCOPY
#define FUNCTION memcpy
#else
#define FUNCTION memmove
#endif
#define SRCREG a1
#define DSTREG a0
#else
#define FUNCTION bcopy
#define SRCREG a0
#define DSTREG a1
#endif
#define SIZEREG a2
LEAF(FUNCTION)
.set noat
.set noreorder
#if defined(MEMCOPY) || defined(MEMMOVE)
/* set up return value, while we still can */
move v0,DSTREG
#endif
/*
* Make sure we can copy forwards.
*/
sltu t0,SRCREG,DSTREG # t0 == SRCREG < DSTREG
bne t0,zero,6f # copy backwards
/*
* There are four alignment cases (with frequency)
* (Based on measurements taken with a DECstation 5000/200
* inside a Mach kernel.)
*
* aligned -> aligned (mostly)
* unaligned -> aligned (sometimes)
* aligned,unaligned -> unaligned (almost never)
*
* Note that we could add another case that checks if
* the destination and source are unaligned but the
* copy is alignable. eg if src and dest are both
* on a halfword boundary.
*/
andi t1,DSTREG,(SZREG-1) # get last bits of dest
bne t1,zero,3f # dest unaligned
andi t0,SRCREG,(SZREG-1) # get last bits of src
bne t0,zero,5f
/*
* Forward aligned->aligned copy, 8 words at a time.
*/
98:
li AT,-(SZREG*8)
and t0,SIZEREG,AT # count truncated to multiples
PTR_ADDU a3,SRCREG,t0 # run fast loop up to this addr
sltu AT,SRCREG,a3 # any work to do?
beq AT,zero,2f
PTR_SUBU SIZEREG,t0
/*
* loop body
*/
1: # cp
REG_L t3,(0*SZREG)(SRCREG)
REG_L v1,(1*SZREG)(SRCREG)
REG_L t0,(2*SZREG)(SRCREG)
REG_L t1,(3*SZREG)(SRCREG)
PTR_ADDU SRCREG,SZREG*8
REG_S t3,(0*SZREG)(DSTREG)
REG_S v1,(1*SZREG)(DSTREG)
REG_S t0,(2*SZREG)(DSTREG)
REG_S t1,(3*SZREG)(DSTREG)
REG_L t1,(-1*SZREG)(SRCREG)
REG_L t0,(-2*SZREG)(SRCREG)
REG_L v1,(-3*SZREG)(SRCREG)
REG_L t3,(-4*SZREG)(SRCREG)
PTR_ADDU DSTREG,SZREG*8
REG_S t1,(-1*SZREG)(DSTREG)
REG_S t0,(-2*SZREG)(DSTREG)
REG_S v1,(-3*SZREG)(DSTREG)
bne SRCREG,a3,1b
REG_S t3,(-4*SZREG)(DSTREG)
/*
* Copy a word at a time, no loop unrolling.
*/
2: # wordcopy
andi t2,SIZEREG,(SZREG-1) # get byte count / SZREG
PTR_SUBU t2,SIZEREG,t2 # t2 = words to copy * SZREG
beq t2,zero,3f
PTR_ADDU t0,SRCREG,t2 # stop at t0
PTR_SUBU SIZEREG,SIZEREG,t2
1:
REG_L t3,0(SRCREG)
PTR_ADDU SRCREG,SZREG
REG_S t3,0(DSTREG)
bne SRCREG,t0,1b
PTR_ADDU DSTREG,SZREG
3: # bytecopy
beq SIZEREG,zero,4f # nothing left to do?
nop
1:
lb t3,0(SRCREG)
PTR_ADDU SRCREG,1
sb t3,0(DSTREG)
PTR_SUBU SIZEREG,1
bgtz SIZEREG,1b
PTR_ADDU DSTREG,1
4: # copydone
j ra
nop
/*
* Copy from unaligned source to aligned dest.
*/
5: # destaligned
andi t0,SIZEREG,(SZREG-1) # t0 = bytecount mod SZREG
PTR_SUBU a3,SIZEREG,t0 # number of words to transfer
beq a3,zero,3b
nop
move SIZEREG,t0 # this many to do after we are done
PTR_ADDU a3,SRCREG,a3 # stop point
1:
REG_LHI t3,0(SRCREG)
REG_LLO t3,SZREG-1(SRCREG)
PTR_ADDI SRCREG,SZREG
REG_S t3,0(DSTREG)
bne SRCREG,a3,1b
PTR_ADDI DSTREG,SZREG
b 3b
nop
6: # backcopy -- based on above
PTR_ADDU SRCREG,SIZEREG
PTR_ADDU DSTREG,SIZEREG
andi t1,DSTREG,SZREG-1 # get last 3 bits of dest
bne t1,zero,3f
andi t0,SRCREG,SZREG-1 # get last 3 bits of src
bne t0,zero,5f
/*
* Forward aligned->aligned copy, 8*4 bytes at a time.
*/
li AT,(-8*SZREG)
and t0,SIZEREG,AT # count truncated to multiple of 32
beq t0,zero,2f # any work to do?
PTR_SUBU SIZEREG,t0
PTR_SUBU a3,SRCREG,t0
/*
* loop body
*/
1: # cp
REG_L t3,(-4*SZREG)(SRCREG)
REG_L v1,(-3*SZREG)(SRCREG)
REG_L t0,(-2*SZREG)(SRCREG)
REG_L t1,(-1*SZREG)(SRCREG)
PTR_SUBU SRCREG,8*SZREG
REG_S t3,(-4*SZREG)(DSTREG)
REG_S v1,(-3*SZREG)(DSTREG)
REG_S t0,(-2*SZREG)(DSTREG)
REG_S t1,(-1*SZREG)(DSTREG)
REG_L t1,(3*SZREG)(SRCREG)
REG_L t0,(2*SZREG)(SRCREG)
REG_L v1,(1*SZREG)(SRCREG)
REG_L t3,(0*SZREG)(SRCREG)
PTR_SUBU DSTREG,8*SZREG
REG_S t1,(3*SZREG)(DSTREG)
REG_S t0,(2*SZREG)(DSTREG)
REG_S v1,(1*SZREG)(DSTREG)
bne SRCREG,a3,1b
REG_S t3,(0*SZREG)(DSTREG)
/*
* Copy a word at a time, no loop unrolling.
*/
2: # wordcopy
andi t2,SIZEREG,SZREG-1 # get byte count / 4
PTR_SUBU t2,SIZEREG,t2 # t2 = number of words to copy
beq t2,zero,3f
PTR_SUBU t0,SRCREG,t2 # stop at t0
PTR_SUBU SIZEREG,SIZEREG,t2
1:
REG_L t3,-SZREG(SRCREG)
PTR_SUBU SRCREG,SZREG
REG_S t3,-SZREG(DSTREG)
bne SRCREG,t0,1b
PTR_SUBU DSTREG,SZREG
3: # bytecopy
beq SIZEREG,zero,4f # nothing left to do?
nop
1:
lb t3,-1(SRCREG)
PTR_SUBU SRCREG,1
sb t3,-1(DSTREG)
PTR_SUBU SIZEREG,1
bgtz SIZEREG,1b
PTR_SUBU DSTREG,1
4: # copydone
j ra
nop
/*
* Copy from unaligned source to aligned dest.
*/
5: # destaligned
andi t0,SIZEREG,SZREG-1 # t0 = bytecount mod 4
PTR_SUBU a3,SIZEREG,t0 # number of words to transfer
beq a3,zero,3b
nop
move SIZEREG,t0 # this many to do after we are done
PTR_SUBU a3,SRCREG,a3 # stop point
1:
REG_LHI t3,-SZREG(SRCREG)
REG_LLO t3,-1(SRCREG)
PTR_SUBU SRCREG,SZREG
REG_S t3,-SZREG(DSTREG)
bne SRCREG,a3,1b
PTR_SUBU DSTREG,SZREG
b 3b
nop
.set reorder
.set at
END(FUNCTION)