github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/runtime/memmove_mips64x.s (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build mips64 || mips64le
     6  
     7  #include "textflag.h"
     8  
     9  // See memmove Go doc for important implementation constraints.
    10  
    11  // func memmove(to, from unsafe.Pointer, n uintptr)
    12  TEXT runtime·memmove(SB), NOSPLIT|NOFRAME, $0-24
    13  	MOVV	to+0(FP), R1
    14  	MOVV	from+8(FP), R2
    15  	MOVV	n+16(FP), R3
    16  	BNE	R3, check
    17  	RET
    18  
    19  check:
    20  	SGTU	R1, R2, R4
    21  	BNE	R4, backward
    22  
    23  	ADDV	R1, R3, R6 // end pointer
    24  
    25  	// if the two pointers are not of same alignments, do byte copying
    26  	SUBVU	R2, R1, R4
    27  	AND	$7, R4
    28  	BNE	R4, out
    29  
    30  	// if less than 8 bytes, do byte copying
    31  	SGTU	$8, R3, R4
    32  	BNE	R4, out
    33  
    34  	// do one byte at a time until 8-aligned
    35  	AND	$7, R1, R5
    36  	BEQ	R5, words
    37  	MOVB	(R2), R4
    38  	ADDV	$1, R2
    39  	MOVB	R4, (R1)
    40  	ADDV	$1, R1
    41  	JMP	-6(PC)
    42  
    43  words:
    44  	// do 8 bytes at a time if there is room
    45  	ADDV	$-7, R6, R3 // R3 is end pointer-7
    46  
    47  	SGTU	R3, R1, R5
    48  	BEQ	R5, out
    49  	MOVV	(R2), R4
    50  	ADDV	$8, R2
    51  	MOVV	R4, (R1)
    52  	ADDV	$8, R1
    53  	JMP	-6(PC)
    54  
    55  out:
    56  	BEQ	R1, R6, done
    57  	MOVB	(R2), R4
    58  	ADDV	$1, R2
    59  	MOVB	R4, (R1)
    60  	ADDV	$1, R1
    61  	JMP	-5(PC)
    62  done:
    63  	RET
    64  
    65  backward:
    66  	ADDV	R3, R2 // from-end pointer
    67  	ADDV	R1, R3, R6 // to-end pointer
    68  
    69  	// if the two pointers are not of same alignments, do byte copying
    70  	SUBVU	R6, R2, R4
    71  	AND	$7, R4
    72  	BNE	R4, out1
    73  
    74  	// if less than 8 bytes, do byte copying
    75  	SGTU	$8, R3, R4
    76  	BNE	R4, out1
    77  
    78  	// do one byte at a time until 8-aligned
    79  	AND	$7, R6, R5
    80  	BEQ	R5, words1
    81  	ADDV	$-1, R2
    82  	MOVB	(R2), R4
    83  	ADDV	$-1, R6
    84  	MOVB	R4, (R6)
    85  	JMP	-6(PC)
    86  
    87  words1:
    88  	// do 8 bytes at a time if there is room
    89  	ADDV	$7, R1, R3 // R3 is start pointer+7
    90  
    91  	SGTU	R6, R3, R5
    92  	BEQ	R5, out1
    93  	ADDV	$-8, R2
    94  	MOVV	(R2), R4
    95  	ADDV	$-8, R6
    96  	MOVV	R4, (R6)
    97  	JMP	-6(PC)
    98  
    99  out1:
   100  	BEQ	R1, R6, done1
   101  	ADDV	$-1, R2
   102  	MOVB	(R2), R4
   103  	ADDV	$-1, R6
   104  	MOVB	R4, (R6)
   105  	JMP	-5(PC)
   106  done1:
   107  	RET