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compare_mipsx.s
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// 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.
//go:build mips || mipsle
#include "go_asm.h"
#include "textflag.h"
TEXT ·Compare(SB),NOSPLIT,$0-28
MOVW a_base+0(FP), R3
MOVW b_base+12(FP), R4
MOVW a_len+4(FP), R1
MOVW b_len+16(FP), R2
BEQ R3, R4, samebytes
SGTU R1, R2, R7
MOVW R1, R8
CMOVN R7, R2, R8 // R8 is min(R1, R2)
ADDU R3, R8 // R3 is current byte in a, R8 is last byte in a to compare
loop:
BEQ R3, R8, samebytes
MOVBU (R3), R6
ADDU $1, R3
MOVBU (R4), R7
ADDU $1, R4
BEQ R6, R7 , loop
SGTU R6, R7, R8
MOVW $-1, R6
CMOVZ R8, R6, R8
JMP cmp_ret
samebytes:
SGTU R1, R2, R6
SGTU R2, R1, R7
SUBU R7, R6, R8
cmp_ret:
MOVW R8, ret+24(FP)
RET
TEXT runtime·cmpstring(SB),NOSPLIT,$0-20
MOVW a_base+0(FP), R3
MOVW a_len+4(FP), R1
MOVW b_base+8(FP), R4
MOVW b_len+12(FP), R2
BEQ R3, R4, samebytes
SGTU R1, R2, R7
MOVW R1, R8
CMOVN R7, R2, R8 // R8 is min(R1, R2)
ADDU R3, R8 // R3 is current byte in a, R8 is last byte in a to compare
loop:
BEQ R3, R8, samebytes // all compared bytes were the same; compare lengths
MOVBU (R3), R6
ADDU $1, R3
MOVBU (R4), R7
ADDU $1, R4
BEQ R6, R7 , loop
// bytes differed
SGTU R6, R7, R8
MOVW $-1, R6
CMOVZ R8, R6, R8
JMP cmp_ret
samebytes:
SGTU R1, R2, R6
SGTU R2, R1, R7
SUBU R7, R6, R8
cmp_ret:
MOVW R8, ret+16(FP)
RET