// Copyright 2018 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 "go_asm.h"
#include "textflag.h"
// memequal(a, b unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal(SB),NOSPLIT|NOFRAME,$0-13
MOVW a+0(FP), R0
MOVW b+4(FP), R2
CMP R0, R2
B.EQ eq
MOVW size+8(FP), R1
CMP $0, R1
B.EQ eq // short path to handle 0-byte case
MOVW $ret+12(FP), R7
B memeqbody<>(SB)
eq:
MOVW $1, R0
MOVB R0, ret+12(FP)
RET
// memequal_varlen(a, b unsafe.Pointer) bool
TEXT runtime·memequal_varlen(SB),NOSPLIT|NOFRAME,$0-9
MOVW a+0(FP), R0
MOVW b+4(FP), R2
CMP R0, R2
B.EQ eq
MOVW 4(R7), R1 // compiler stores size at offset 4 in the closure
CMP $0, R1
B.EQ eq // short path to handle 0-byte case
MOVW $ret+8(FP), R7
B memeqbody<>(SB)
eq:
MOVW $1, R0
MOVB R0, ret+8(FP)
RET
// Input:
// R0: data of a
// R1: length
// R2: data of b
// R7: points to return value
//
// On exit:
// R4, R5 and R6 are clobbered
TEXT memeqbody<>(SB),NOSPLIT|NOFRAME,$0-0
CMP $1, R1
B.EQ one // 1-byte special case for better performance
CMP $4, R1
ADD R0, R1 // R1 is the end of the range to compare
B.LT byte_loop // length < 4
AND $3, R0, R6
CMP $0, R6
B.NE byte_loop // unaligned a, use byte-wise compare (TODO: try to align a)
AND $3, R2, R6
CMP $0, R6
B.NE byte_loop // unaligned b, use byte-wise compare
AND $0xfffffffc, R1, R6
// length >= 4
chunk4_loop:
MOVW.P 4(R0), R4
MOVW.P 4(R2), R5
CMP R4, R5
B.NE notequal
CMP R0, R6
B.NE chunk4_loop
CMP R0, R1
B.EQ equal // reached the end
byte_loop:
MOVBU.P 1(R0), R4
MOVBU.P 1(R2), R5
CMP R4, R5
B.NE notequal
CMP R0, R1
B.NE byte_loop
equal:
MOVW $1, R0
MOVB R0, (R7)
RET
one:
MOVBU (R0), R4
MOVBU (R2), R5
CMP R4, R5
B.EQ equal
notequal:
MOVW $0, R0
MOVB R0, (R7)
RET
