// 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"

TEXT ·Equal(SB), NOSPLIT, $0-49
	MOVD a_len+8(FP), R0
	MOVD b_len+32(FP), R1
	Get R0
	Get R1
	I64Eq
	If
		Get SP
		I64Load a+0(FP)
		I64Load b+24(FP)
		Get R0
		Call memeqbody<>(SB)
		I64Store8 ret+48(FP)
	Else
		Get SP
		I64Const $0
		I64Store8 ret+48(FP)
	End
	RET

// memequal(p, q unsafe.Pointer, size uintptr) bool
TEXT runtime·memequal(SB), NOSPLIT, $0-25
	Get SP
	I64Load a+0(FP)
	I64Load b+8(FP)
	I64Load size+16(FP)
	Call memeqbody<>(SB)
	I64Store8 ret+24(FP)
	RET

// memequal_varlen(a, b unsafe.Pointer) bool
TEXT runtime·memequal_varlen(SB), NOSPLIT, $0-17
	Get SP
	I64Load a+0(FP)
	I64Load b+8(FP)
	I64Load 8(CTXT) // compiler stores size at offset 8 in the closure
	Call memeqbody<>(SB)
	I64Store8 ret+16(FP)
	RET

// params: a, b, len
// ret: 0/1
TEXT memeqbody<>(SB), NOSPLIT, $0-0
	Get R0
	Get R1
	I64Eq
	If
		I64Const $1
		Return
	End

loop:
	Loop
		Get R2
		I64Eqz
		If
			I64Const $1
			Return
		End

		Get R0
		I32WrapI64
		I64Load8U $0
		Get R1
		I32WrapI64
		I64Load8U $0
		I64Ne
		If
			I64Const $0
			Return
		End

		Get R0
		I64Const $1
		I64Add
		Set R0

		Get R1
		I64Const $1
		I64Add
		Set R1

		Get R2
		I64Const $1
		I64Sub
		Set R2

		Br loop
	End
	UNDEF
