mirror of https://go.googlesource.com/go
105 lines
1.8 KiB
ArmAsm
105 lines
1.8 KiB
ArmAsm
// Copyright 2022 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "textflag.h"
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// See memmove Go doc for important implementation constraints.
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// func memmove(to, from unsafe.Pointer, n uintptr)
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TEXT runtime·memmove<ABIInternal>(SB), NOSPLIT|NOFRAME, $0-24
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BNE R6, check
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RET
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check:
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SGTU R4, R5, R7
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BNE R7, backward
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ADDV R4, R6, R9 // end pointer
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// if the two pointers are not of same alignments, do byte copying
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SUBVU R5, R4, R7
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AND $7, R7
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BNE R7, out
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// if less than 8 bytes, do byte copying
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SGTU $8, R6, R7
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BNE R7, out
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// do one byte at a time until 8-aligned
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AND $7, R4, R8
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BEQ R8, words
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MOVB (R5), R7
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ADDV $1, R5
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MOVB R7, (R4)
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ADDV $1, R4
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JMP -6(PC)
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words:
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// do 8 bytes at a time if there is room
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ADDV $-7, R9, R6 // R6 is end pointer-7
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PCALIGN $16
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SGTU R6, R4, R8
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BEQ R8, out
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MOVV (R5), R7
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ADDV $8, R5
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MOVV R7, (R4)
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ADDV $8, R4
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JMP -6(PC)
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out:
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BEQ R4, R9, done
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MOVB (R5), R7
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ADDV $1, R5
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MOVB R7, (R4)
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ADDV $1, R4
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JMP -5(PC)
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done:
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RET
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backward:
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ADDV R6, R5 // from-end pointer
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ADDV R4, R6, R9 // to-end pointer
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// if the two pointers are not of same alignments, do byte copying
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SUBVU R9, R5, R7
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AND $7, R7
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BNE R7, out1
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// if less than 8 bytes, do byte copying
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SGTU $8, R6, R7
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BNE R7, out1
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// do one byte at a time until 8-aligned
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AND $7, R9, R8
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BEQ R8, words1
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ADDV $-1, R5
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MOVB (R5), R7
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ADDV $-1, R9
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MOVB R7, (R9)
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JMP -6(PC)
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words1:
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// do 8 bytes at a time if there is room
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ADDV $7, R4, R6 // R6 is start pointer+7
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PCALIGN $16
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SGTU R9, R6, R8
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BEQ R8, out1
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ADDV $-8, R5
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MOVV (R5), R7
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ADDV $-8, R9
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MOVV R7, (R9)
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JMP -6(PC)
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out1:
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BEQ R4, R9, done1
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ADDV $-1, R5
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MOVB (R5), R7
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ADDV $-1, R9
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MOVB R7, (R9)
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JMP -5(PC)
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done1:
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RET
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