// Copyright 2019 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.

//go:build mips64 || mips64le

#include "go_asm.h"

#include "textflag.h"

TEXT ·Compare(SB),NOSPLIT,$0-56

MOVV a_base+0(FP), R3

MOVV b_base+24(FP), R4

MOVV a_len+8(FP), R1

MOVV b_len+32(FP), R2

MOVV $ret+48(FP), R9

JMP cmpbody<>(SB)

TEXT runtime·cmpstring(SB),NOSPLIT,$0-40

MOVV a_base+0(FP), R3

MOVV b_base+16(FP), R4

MOVV a_len+8(FP), R1

MOVV b_len+24(FP), R2

MOVV $ret+32(FP), R9

JMP cmpbody<>(SB)

// On entry:

// R1 length of a

// R2 length of b

// R3 points to the start of a

// R4 points to the start of b

// R9 points to the return value (-1/0/1)

TEXT cmpbody<>(SB),NOSPLIT|NOFRAME,$0

BEQ R3, R4, samebytes // same start of a and b

SGTU R1, R2, R7

BNE R0, R7, r2_lt_r1

MOVV R1, R10

JMP entry

r2_lt_r1:

MOVV R2, R10 // R10 is min(R1, R2)

entry:

ADDV R3, R10, R8 // R3 start of a, R8 end of a

BEQ R3, R8, samebytes // length is 0

SRLV $4, R10 // R10 is number of chunks

BEQ R0, R10, byte_loop

// make sure both a and b are aligned.

OR R3, R4, R11

AND $7, R11

BNE R0, R11, byte_loop

chunk16_loop:

BEQ R0, R10, byte_loop

MOVV (R3), R6

MOVV (R4), R7

BNE R6, R7, byte_loop

MOVV 8(R3), R13

MOVV 8(R4), R14

ADDV $16, R3

ADDV $16, R4

SUBVU $1, R10

BEQ R13, R14, chunk16_loop

SUBV $8, R3

SUBV $8, R4

byte_loop:

BEQ R3, R8, samebytes

MOVBU (R3), R6

ADDVU $1, R3

MOVBU (R4), R7

ADDVU $1, R4

BEQ R6, R7, byte_loop

byte_cmp:

SGTU R6, R7, R8 // R8 = 1 if (R6 > R7)

BNE R0, R8, ret

MOVV $-1, R8

JMP ret

samebytes:

SGTU R1, R2, R6

SGTU R2, R1, R7

SUBV R7, R6, R8

ret:

MOVV R8, (R9)

RET