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/* Copyright (C) 2001, 2003 Free Software Foundation, Inc.
Copyright (C) 1994, 1995, 2000 Axis Communications AB.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
/*#************************************************************************#*/
/*#-------------------------------------------------------------------------*/
/*# */
/*# FUNCTION NAME: memcpy() */
/*# */
/*# PARAMETERS: void* dst; Destination address. */
/*# void* src; Source address. */
/*# int len; Number of bytes to copy. */
/*# */
/*# RETURNS: dst. */
/*# */
/*# DESCRIPTION: Copies len bytes of memory from src to dst. No guarantees */
/*# about copying of overlapping memory areas. This routine is */
/*# very sensitive to compiler changes in register allocation. */
/*# Should really be rewritten to avoid this problem. */
/*# */
/*#-------------------------------------------------------------------------*/
/*# */
/*# HISTORY */
/*# */
/*# DATE NAME CHANGES */
/*# ---- ---- ------- */
/*# 941007 Kenny R Creation */
/*# 941011 Kenny R Lots of optimizations and inlining. */
/*# 941129 Ulf A Adapted for use in libc. */
/*# 950216 HP N==0 forgotten if non-aligned src/dst. */
/*# Added some optimizations. */
/*# 001025 HP Make src and dst char *. Align dst to */
/*# dword, not just word-if-both-src-and-dst- */
/*# are-misaligned. */
/*# 070806 RW Modified for uClibc */
/*# (__arch_v32 -> __CONFIG_CRISV32__, */
/*# include features.h to reach it.) */
/*# */
/*#-------------------------------------------------------------------------*/
#include <features.h>
#ifdef __CONFIG_CRISV32__
/* For CRISv32, movem is very cheap. */
#define MEMCPY_BLOCK_THRESHOLD (44)
#else
/* Break even between movem and move16 is at 38.7*2, but modulo 44. */
#define MEMCPY_BLOCK_THRESHOLD (44*2)
#endif
void *memcpy(void *, const void *, unsigned int);
libc_hidden_proto(memcpy)
void *memcpy(void *pdst,
const void *psrc,
unsigned int pn)
{
/* Ok. Now we want the parameters put in special registers.
Make sure the compiler is able to make something useful of this.
As it is now: r10 -> r13; r11 -> r11 (nop); r12 -> r12 (nop).
If gcc was allright, it really would need no temporaries, and no
stack space to save stuff on. */
#ifndef MEMPCPY
register void *return_dst __asm__ ("r10") = pdst;
#else
/* FIXME: Use R10 for something. */
# define return_dst dst
#endif
register char *dst __asm__ ("r13") = pdst;
register char *src __asm__ ("r11") = (char *) psrc;
register int n __asm__ ("r12") = pn;
/* When src is aligned but not dst, this makes a few extra needless
cycles. I believe it would take as many to check that the
re-alignment was unnecessary. */
if (((unsigned long) dst & 3) != 0
/* Don't align if we wouldn't copy more than a few bytes; so we
don't have to check further for overflows. */
&& n >= 3)
{
if ((unsigned long) dst & 1)
{
n--;
*(char*)dst = *(char*)src;
src++;
dst++;
}
if ((unsigned long) dst & 2)
{
n -= 2;
*(short*)dst = *(short*)src;
src += 2;
dst += 2;
}
}
/* Decide which copying method to use. */
if (n >= MEMCPY_BLOCK_THRESHOLD)
{
/* For large copies we use 'movem' */
/* It is not optimal to tell the compiler about clobbering any
registers; that will move the saving/restoring of those registers
to the function prologue/epilogue, and make non-movem sizes
suboptimal.
This method is not foolproof; it assumes that the "register asm"
declarations at the beginning of the function really are used
here (beware: they may be moved to temporary registers).
This way, we do not have to save/move the registers around into
temporaries; we can safely use them straight away. */
__asm__ volatile ("\
.syntax no_register_prefix \n\
\n\
;; Check that the register asm declaration got right. \n\
;; The GCC manual explicitly says TRT will happen. \n\
.ifnc %0-%1-%2,$r13-$r11-$r12 \n\
.err \n\
.endif \n\
\n\
;; Save the registers we'll use in the movem process \n\
;; on the stack. \n\
subq 11*4,sp \n\
movem r10,[sp] \n\
\n\
;; Now we've got this: \n\
;; r11 - src \n\
;; r13 - dst \n\
;; r12 - n \n\
\n\
;; Update n for the first loop \n\
subq 44,r12 \n\
0: \n\
movem [r11+],r10 \n\
subq 44,r12 \n\
bge 0b \n\
movem r10,[r13+] \n\
\n\
addq 44,r12 ;; compensate for last loop underflowing n \n\
\n\
;; Restore registers from stack \n\
movem [sp+],r10"
/* Outputs */ : "=r" (dst), "=r" (src), "=r" (n)
/* Inputs */ : "0" (dst), "1" (src), "2" (n));
}
/* Either we directly starts copying, using dword copying
in a loop, or we copy as much as possible with 'movem'
and then the last block (<44 bytes) is copied here.
This will work since 'movem' will have updated src,dst,n. */
while ( n >= 16 )
{
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
n -= 16;
}
/* A switch() is definitely the fastest although it takes a LOT of code.
* Particularly if you inline code this.
*/
switch (n)
{
case 0:
break;
case 1:
*((char*)dst)++ = *((char*)src)++;
break;
case 2:
*((short*)dst)++ = *((short*)src)++;
break;
case 3:
*((short*)dst)++ = *((short*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
case 4:
*((long*)dst)++ = *((long*)src)++;
break;
case 5:
*((long*)dst)++ = *((long*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
case 6:
*((long*)dst)++ = *((long*)src)++;
*((short*)dst)++ = *((short*)src)++;
break;
case 7:
*((long*)dst)++ = *((long*)src)++;
*((short*)dst)++ = *((short*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
case 8:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
break;
case 9:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
case 10:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((short*)dst)++ = *((short*)src)++;
break;
case 11:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((short*)dst)++ = *((short*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
case 12:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
break;
case 13:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
case 14:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((short*)dst)++ = *((short*)src)++;
break;
case 15:
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((long*)dst)++ = *((long*)src)++;
*((short*)dst)++ = *((short*)src)++;
*((char*)dst)++ = *((char*)src)++;
break;
}
return return_dst; /* destination pointer. */
} /* memcpy() */
libc_hidden_def(memcpy)
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