4c6134d7c8
TODO: change register usage so memcpy()/memmove() is default, put test for back-copy before memcpy() and back-copy loop after memcpy().
160 lines
2.8 KiB
ArmAsm
160 lines
2.8 KiB
ArmAsm
/* $NetBSD: memcpy.S,v 1.3 1999/03/15 07:04:04 jonathan Exp $ */
|
|
/* XXXX We need to define this in a way which supports multiple architectures */
|
|
|
|
#include <mips/asm.h>
|
|
#include <machine/endian.h>
|
|
|
|
.set push
|
|
.set noreorder
|
|
|
|
.text
|
|
/*
|
|
* memcpy(to, from, len)
|
|
*/
|
|
|
|
ALEAF(memmove)
|
|
LEAF(memcpy)
|
|
move v0, a0 # swap from and to
|
|
move a0, a1
|
|
move a1, v0
|
|
|
|
/*
|
|
* {ov}bcopy(from, to, len)
|
|
*/
|
|
ALEAF(ovbcopy)
|
|
.set noat
|
|
/*
|
|
* Make sure we can copy forwards.
|
|
*/
|
|
sltu t0,a0,a1 # t0 == a0 < a1
|
|
addu a3,a0,a2 # a3 == end of source
|
|
sltu t1,a1,a3 # t1 == a1 < a0+a2
|
|
and t2,t0,t1 # overlap -- copy backwards
|
|
bne t2,zero,backcopy
|
|
|
|
/*
|
|
* 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,a1,3 # get last 3 bits of dest
|
|
bne t1,zero,bytecopy
|
|
andi t0,a0,3 # get last 3 bits of src
|
|
bne t0,zero,destaligned
|
|
|
|
/*
|
|
* Forward aligned->aligned copy, 8*4 bytes at a time.
|
|
*/
|
|
li AT,-32
|
|
and t0,a2,AT /* count truncated to multiple of 32 */
|
|
addu a3,a0,t0 /* run fast loop up to this address */
|
|
sltu AT,a0,a3 /* any work to do? */
|
|
beq AT,zero,wordcopy
|
|
subu a2,t0
|
|
|
|
/*
|
|
* loop body
|
|
*/
|
|
cp:
|
|
lw v0,0(a0)
|
|
lw v1,4(a0)
|
|
lw t0,8(a0)
|
|
lw t1,12(a0)
|
|
addu a0,32
|
|
sw v0,0(a1)
|
|
sw v1,4(a1)
|
|
sw t0,8(a1)
|
|
sw t1,12(a1)
|
|
lw t1,-4(a0)
|
|
lw t0,-8(a0)
|
|
lw v1,-12(a0)
|
|
lw v0,-16(a0)
|
|
addu a1,32
|
|
sw t1,-4(a1)
|
|
sw t0,-8(a1)
|
|
sw v1,-12(a1)
|
|
bne a0,a3,cp
|
|
sw v0,-16(a1)
|
|
|
|
/*
|
|
* Copy a word at a time, no loop unrolling.
|
|
*/
|
|
wordcopy:
|
|
andi t2,a2,3 # get byte count / 4
|
|
subu t2,a2,t2 # t2 = number of words to copy * 4
|
|
beq t2,zero,bytecopy
|
|
addu t0,a0,t2 # stop at t0
|
|
subu a2,a2,t2
|
|
1:
|
|
lw v0,0(a0)
|
|
addu a0,4
|
|
sw v0,0(a1)
|
|
bne a0,t0,1b
|
|
addu a1,4
|
|
|
|
bytecopy:
|
|
beq a2,zero,copydone # nothing left to do?
|
|
nop
|
|
2:
|
|
lb v0,0(a0)
|
|
addu a0,1
|
|
sb v0,0(a1)
|
|
subu a2,1
|
|
bgtz a2,2b
|
|
addu a1,1
|
|
|
|
copydone:
|
|
j ra
|
|
nop
|
|
|
|
/*
|
|
* Copy from unaligned source to aligned dest.
|
|
*/
|
|
destaligned:
|
|
andi t0,a2,3 # t0 = bytecount mod 4
|
|
subu a3,a2,t0 # number of words to transfer
|
|
beq a3,zero,bytecopy
|
|
nop
|
|
move a2,t0 # this many to do after we are done
|
|
addu a3,a0,a3 # stop point
|
|
|
|
3:
|
|
LWHI v0,0(a0)
|
|
LWLO v0,3(a0)
|
|
addi a0,4
|
|
sw v0,0(a1)
|
|
bne a0,a3,3b
|
|
addi a1,4
|
|
|
|
j bytecopy
|
|
nop
|
|
|
|
/*
|
|
* Copy by bytes backwards.
|
|
*/
|
|
backcopy:
|
|
blez a2,copydone # nothing left to do?
|
|
addu t0,a0,a2 # end of source
|
|
addu t1,a1,a2 # end of destination
|
|
4:
|
|
lb v0,-1(t0)
|
|
subu t0,1
|
|
sb v0,-1(t1)
|
|
bne t0,a0,4b
|
|
subu t1,1
|
|
j ra
|
|
nop
|
|
|
|
.set at
|
|
END(memcpy)
|
|
.set pop
|