/*
* Copyright (C) 2008 Gunnar von Boehn, IBM Corp.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
*
* memcpy (and copy_4K_page) routine optimized for CELL-BE-PPC
*
* The CELL PPC core has 1 integerunit and 1 load/store unit
* CELL: 1st level data cache = 32K - 2nd level data cache = 512K
* - 3rd level data cache = 0K
* To improve copy performance we need to prefetch source data
* far ahead to hide this latency
* For best performance instruction forms ending in "." like "andi."
* should be avoided as they are implemented in microcode on CELL.
*
* The below code is loop unrolled for the CELL cache line of 128 bytes.
*/
#include <asm/processor.h>
#include <asm/ppc_asm.h>
#define PREFETCH_AHEAD 6
#define ZERO_AHEAD 4
.align 7
_GLOBAL(memcpy)
dcbt 0,r4 /* Prefetch ONE SRC cacheline */
cmpldi cr1,r5,16 /* is size < 16 ? */
mr r6,r3
blt+ cr1,.Lshortcopy
.Lbigcopy:
neg r8,r3 /* LS 3 bits = # bytes to 8-byte dest bdry */
clrldi r8,r8,64-4 /* aling to 16byte boundary */
sub r7,r4,r3
cmpldi cr0,r8,0
beq+ .Ldst_aligned
.Ldst_unaligned:
mtcrf 0x01,r8 /* put #bytes to boundary into cr7 */
subf r5,r8,r5
bf cr7*4+3,1f
lbzx r0,r7,r6 /* copy 1 byte */
stb r0,0(r6)
addi r6,r6,1
1: bf cr7*4+2,2f
lhzx r0,r7,r6 /* copy 2 byte */
sth r0,0(r6)
addi r6,r6,2
2: bf cr7*4+1,4f
lwzx r0,r7,r6 /* copy 4 byte */
stw r0,0(r6)
addi r6,r6,4
4: bf cr7*4+0,8f
ldx r0,r7,r6 /* copy 8 byte */
std r0,0(r6)
addi r6,r6,8
8:
add r4,r7,r6
.Ldst_aligned:
cmpdi cr5,r5,128-1
neg r7,r6
addi r6,r6,-8 /* prepare for stdu */
addi r4,r4,-8 /* prepare for ldu */
clrldi r7,r7,64-7 /* align to cacheline boundary */
ble+ cr5,.Llessthancacheline
cmpldi cr6,r7,0
subf r5,r7,r5
srdi r7,r7,4 /* divide size by 16 */
srdi r10,r5,7 /* number of cache lines to copy */
cmpldi r10,0
li r11,0 /* number cachelines to copy with
prefetch */
beq .Lnocacheprefetch
cmpldi r10,PREFETCH_AHEAD
li r12,128+8 /* prefetch distance*/
ble .Llessthanmaxprefetch
subi r11,r10,PREFETCH_AHEAD
li r10,PREFETCH_AHEAD
.Llessthanmaxprefetch:
mtctr r10
.LprefetchSRC:
dcbt r12,r4
addi r12,r12,128
bdnz .LprefetchSRC
.Lnocacheprefetch:
mtctr r7
cmpldi cr1,r5,128
clrldi r5,r5,64-7
beq cr6,.Lcachelinealigned /* */
.Laligntocacheline:
ld r9,0x08(r4)
ldu r7,0x10(r4)
std r9,0x08(r6)
stdu r7,0x10(r6)
bdnz .Laligntocacheline
.Lcachelinealigned: /* copy while cache lines */
blt- cr1,.Llessthancacheline /* size <128 */
.Louterloop:
cmpdi r11,0
mtctr r11
beq- .Lendloop
li r11,128*ZERO_AHEAD +8 /* DCBZ dist */
.align 4
/* Copy whole cachelines, optimized by prefetching SRC cacheline */
.Lloop: /* Copy aligned body */
dcbt r12,r4 /* PREFETCH SOURCE some cache lines
ahead*/
ld r9, 0x08(r4)
dcbz r11,r6
ld r7, 0x10(r4) /* 4 register stride copy */
ld r8, 0x18(r4) /* 4 are optimal to hide 1st level
cache lantency*/
ld r0, 0x20(r4)
std r9, 0x08(r6)
std r7, 0x10(r6)
std r8, 0x18(r6)
std r0, 0x20(r6)
ld r9, 0x28(r4)
ld r7, 0x30(r4)
ld r8, 0x38(r4)
ld r0, 0x40(r4)
std r9, 0x28(r6)
std r7, 0x30(r6)
std r8, 0x38(r6)
std r0, 0x40(r6)
ld r9, 0x48(r4)
ld r7, 0x50(r4)
ld r8, 0x58(r4)
ld r0, 0x60(r4)
std r9, 0x48(r6)
std r7, 0x50(r6)
std r8, 0x58(r6)
std r0, 0x60(r6)
ld r9, 0x68(r4)
ld r7, 0x70(r4)
ld r8, 0x78(r4)
ldu r0, 0x80(r4)
std r9, 0x68(r6)
std r7, 0x70(r6)
std r8, 0x78(r6)
stdu r0, 0x80(r6)
bdnz .Lloop
.Lendloop:
cmpdi r10,0
sldi r10,r10,2 /* adjust from 128 to 32 byte stride */
beq- .Lendloop2
mtctr r10
.Lloop2: /* Copy aligned body */
ld r9, 0x08(r4)
ld r7, 0x10(r4)
ld r8, 0x18(r4)
ldu r0, 0x20(r4)
std r9, 0x08(r6)
std r7, 0x10(r6)
std r8, 0x18(r6)
stdu r0, 0x20(r6)
bdnz .Lloop2
.Lendloop2:
.Llessthancacheline: /* less than cache to do ? */
cmpldi cr0,r5,16
srdi r7,r5,4 /* divide size by 16 */
blt- .Ldo_lt16
mtctr r7
.Lcopy_remaining:
ld r8,0x08(r4)
ldu r7,0x10(r4)
std r8,0x08(r6)
stdu r7,0x10(r6)
bdnz .Lcopy_remaining
.Ldo_lt16: /* less than 16 ? */
cmpldi cr0,r5,0 /* copy remaining bytes (0-15) */
beqlr+ /* no rest to copy */
addi r4,r4,8
addi r6,r6,8
.Lshortcopy: /* SIMPLE COPY to handle size =< 15 bytes */
mtcrf 0x01,r5
sub r7,r4,r6
bf- cr7*4+0,8f
ldx r0,r7,r6 /* copy 8 byte */
std r0,0(r6)
addi r6,r6,8
8:
bf cr7*4+1,4f
lwzx r0,r7,r6 /* copy 4 byte */
stw r0,0(r6)
addi r6,r6,4
4:
bf cr7*4+2,2f
lhzx r0,r7,r6 /* copy 2 byte */
sth r0,0(r6)
addi r6,r6,2
2:
bf cr7*4+3,1f
lbzx r0,r7,r6 /* copy 1 byte */
stb r0,0(r6)
1: blr
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