220 lines
7.6 KiB
C
220 lines
7.6 KiB
C
/*#************************************************************************#*/
|
|
/*#-------------------------------------------------------------------------*/
|
|
/*# */
|
|
/*# 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. */
|
|
/*# */
|
|
/*#-------------------------------------------------------------------------*/
|
|
|
|
#include <linux/types.h>
|
|
|
|
void *memcpy(void *pdst,
|
|
const void *psrc,
|
|
size_t 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 alright, it really would need no temporaries, and no
|
|
stack space to save stuff on. */
|
|
|
|
register void *return_dst __asm__ ("r10") = pdst;
|
|
register char *dst __asm__ ("r13") = pdst;
|
|
register const char *src __asm__ ("r11") = 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. Movem is dirt cheap, so the
|
|
overheap is low enough to always use the minimum block size as the
|
|
threshold. */
|
|
if (n >= 44)
|
|
{
|
|
/* 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. */
|
|
__asm__ volatile (" \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-$r12 \n\
|
|
.err \n\
|
|
.endif \n\
|
|
\n\
|
|
;; Save the registers we'll use in the movem process \n\
|
|
\n\
|
|
;; on the stack. \n\
|
|
subq 11*4,$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() */
|