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/*******************************************************************************
*
* Copyright (c) 1993 Intel Corporation
*
* Intel hereby grants you permission to copy, modify, and distribute this
* software and its documentation. Intel grants this permission provided
* that the above copyright notice appears in all copies and that both the
* copyright notice and this permission notice appear in supporting
* documentation. In addition, Intel grants this permission provided that
* you prominently mark as "not part of the original" any modifications
* made to this software or documentation, and that the name of Intel
* Corporation not be used in advertising or publicity pertaining to
* distribution of the software or the documentation without specific,
* written prior permission.
*
* Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
* IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
* OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or
* representations regarding the use of, or the results of the use of,
* the software and documentation in terms of correctness, accuracy,
* reliability, currentness, or otherwise; and you rely on the software,
* documentation and results solely at your own risk.
*
* IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
* LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
* OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
* PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
*
******************************************************************************/
.file "memcpy.s"
#ifdef __PIC
.pic
#endif
#ifdef __PID
.pid
#endif
/*
* (c) copyright 1988,1993 Intel Corp., all rights reserved
*/
/*
procedure memmove (optimized assembler version for the 80960K series)
procedure memcpy (optimized assembler version for the 80960K series)
dest_addr = memmove (dest_addr, src_addr, len)
dest_addr = memcpy (dest_addr, src_addr, len)
copy len bytes pointed to by src_addr to the space pointed to by
dest_addr. Return the original dest_addr.
These routines will work even if the arrays overlap. The standard
requires this of memmove, but memcpy is allowed to fail if overlap
is present. Nevertheless, it is implemented the same as memmove
because the overhead is trifling.
Undefined behavior will occur if the end of the source array is in
the last two words of the program's allocated memory space. This
is so because the routine fetches ahead. Disallowing the fetch
ahead would impose a severe performance penalty.
Strategy:
Fetch the source array by words and store them by words to the
destination array, until there are fewer than three bytes left
to copy. Then, using the last word of the source (the one that
contains the remaining 0, 1, 2, or 3 bytes to be copied), store
a byte at a time until Ldone.
Tactics:
1) Do NOT try to fetch and store the words in a word aligned manner
because, in my judgement, the performance degradation experienced due
to non-aligned accesses does NOT outweigh the time and complexity added
by the preamble and convoluted body that would be necessary to assure
alignment. This is supported by the intuition that most source and
destination arrays (even more true of most big source arrays) will
be word aligned to begin with.
2) For non-overlapping arrays, rather than decrementing len to zero,
I calculate the address of the byte after the last byte of the
destination array, and quit when the destination byte pointer passes
that.
3) For overlapping arrays where the source starts at a lower address
than the destination the move is performed in reverse order.
4) Overlapping arrays where the source starts at a higher address
are treated like non-overlapping case. Where the two arrays exactly
coincide, the routine is short-circuited; no move is Ldone at all.
This costs only one cycle.
*/
.globl _memcpy, _memmove
.globl __memcpy, __memmove
.leafproc _memmove, __memmove
.leafproc _memcpy, __memcpy
.align 2
_memmove:
_memcpy:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__memmove:
__memcpy:
mov g14, g13 # preserve return address
cmpibge 0,g2,Lexit # exit if number of bytes to move is <= zero.
cmpo g0,g1 # does start of dest overlap end of src?
addo g2,g1,g3
be Lexit # no move necessary if src and dest are same
concmpo g3,g0
addo g2, g0, g6
bg Lbackwards # if overlap, then do move backwards
ld (g1), g7 # fetch first word of source
mov g0, g5
b Lwloop_b
Lwloop_a:
ld (g1), g7 # fetch ahead next word of source
st g4, (g5) # store word to dest
addo 4, g5, g5 # post-increment dest pointer
Lwloop_b: # word copying loop
addo 4, g1, g1 # pre-increment src pointer
cmpo g3, g1 # is len <= 3 ?
mov g7, g4 # keep a copy of the current word
bge Lwloop_a # loop if more than 3 bytes to move
cmpobe g6, g5, Lexit # quit if no more bytes to move
Lcloop_a: # character copying loop (len < 3)
stob g4, (g5) # store a byte
shro 8, g4, g4 # position next byte for storing
addo 1, g5, g5
cmpobne g6, g5, Lcloop_a # quit if no more bytes to move
Lexit:
mov 0, g14
bx (g13) # g0 = dest array address; g14 = 0
Lrett:
ret
Lwloop.a:
subo 4, g6, g6 # pre-decrement dest pointer
st g7, (g6) # store word to dest
Lbackwards: # word copying loop
subo 4, g3, g3 # pre-decrement src pointer
cmpo g1, g3 # is len <= 3?
ld (g3), g7 # fetch ahead next word of source
ble Lwloop.a # loop if more than 3 bytes to move
cmpobe g6, g0, Lexit # quit if no more bytes to move
Lcloop.a:
subo 1, g6, g6
rotate 8, g7, g7 # position byte for storing
stob g7, (g6) # store byte
cmpobne g6, g0, Lcloop.a # quit if no more bytes to move
b Lexit
/* end of memmove */
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