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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "textflag.h"
// See memclrNoHeapPointers Go doc for important implementation constraints.
// void runtime·memclrNoHeapPointers(void*, uintptr)
TEXT runtime·memclrNoHeapPointers<ABIInternal>(SB),NOSPLIT,$0-16
// X10 = ptr
// X11 = n
// If less than 8 bytes, do single byte zeroing.
MOV $8, X9
BLT X11, X9, check4
// Check alignment
AND $7, X10, X5
BEQZ X5, aligned
// Zero one byte at a time until we reach 8 byte alignment.
SUB X5, X9, X5
SUB X5, X11, X11
align:
SUB $1, X5
MOVB ZERO, 0(X10)
ADD $1, X10
BNEZ X5, align
aligned:
// X9 already contains $8
BLT X11, X9, check4
MOV $16, X9
BLT X11, X9, zero8
MOV $32, X9
BLT X11, X9, zero16
MOV $64, X9
BLT X11, X9, zero32
loop64:
MOV ZERO, 0(X10)
MOV ZERO, 8(X10)
MOV ZERO, 16(X10)
MOV ZERO, 24(X10)
MOV ZERO, 32(X10)
MOV ZERO, 40(X10)
MOV ZERO, 48(X10)
MOV ZERO, 56(X10)
ADD $64, X10
SUB $64, X11
BGE X11, X9, loop64
BEQZ X11, done
check32:
MOV $32, X9
BLT X11, X9, check16
zero32:
MOV ZERO, 0(X10)
MOV ZERO, 8(X10)
MOV ZERO, 16(X10)
MOV ZERO, 24(X10)
ADD $32, X10
SUB $32, X11
BEQZ X11, done
check16:
MOV $16, X9
BLT X11, X9, check8
zero16:
MOV ZERO, 0(X10)
MOV ZERO, 8(X10)
ADD $16, X10
SUB $16, X11
BEQZ X11, done
check8:
MOV $8, X9
BLT X11, X9, check4
zero8:
MOV ZERO, 0(X10)
ADD $8, X10
SUB $8, X11
BEQZ X11, done
check4:
MOV $4, X9
BLT X11, X9, loop1
zero4:
MOVB ZERO, 0(X10)
MOVB ZERO, 1(X10)
MOVB ZERO, 2(X10)
MOVB ZERO, 3(X10)
ADD $4, X10
SUB $4, X11
loop1:
BEQZ X11, done
MOVB ZERO, 0(X10)
ADD $1, X10
SUB $1, X11
JMP loop1
done:
RET
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