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https://github.com/freebsd/freebsd-src
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e5dd4df84c
PR: 73111 Submitted by: Ville-Pertti Keinonen <will@iki.fi> (taken from NetBSD) MFC after: 3 weeks
74 lines
1.1 KiB
ArmAsm
74 lines
1.1 KiB
ArmAsm
/*
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* Written by J.T. Conklin <jtc@acorntoolworks.com>
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* Public domain.
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*/
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#include <machine/asm.h>
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__FBSDID("$FreeBSD$");
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#if 0
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RCSID("$NetBSD: strcmp.S,v 1.3 2004/07/19 20:04:41 drochner Exp $")
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#endif
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ENTRY(strcmp)
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/*
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* Align s1 to word boundary.
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* Consider unrolling loop?
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*/
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.Ls1align:
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testb $7,%dil
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je .Ls1aligned
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movb (%rdi),%al
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incq %rdi
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movb (%rsi),%dl
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incq %rsi
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testb %al,%al
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je .Ldone
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cmpb %al,%dl
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je .Ls1align
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jmp .Ldone
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/*
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* Check whether s2 is aligned to a word boundry. If it is, we
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* can compare by words. Otherwise we have to compare by bytes.
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*/
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.Ls1aligned:
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testb $7,%sil
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jne .Lbyte_loop
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movabsq $0x0101010101010101,%r8
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subq $8,%rdi
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movabsq $0x8080808080808080,%r9
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subq $8,%rsi
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.align 4
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.Lword_loop:
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movq 8(%rdi),%rax
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addq $8,%rdi
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movq 8(%rsi),%rdx
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addq $8,%rsi
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cmpq %rax,%rdx
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jne .Lbyte_loop
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subq %r8,%rdx
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notq %rax
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andq %rax,%rdx
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testq %r9,%rdx
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je .Lword_loop
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.align 4
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.Lbyte_loop:
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movb (%rdi),%al
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incq %rdi
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movb (%rsi),%dl
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incq %rsi
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testb %al,%al
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je .Ldone
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cmpb %al,%dl
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je .Lbyte_loop
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.Ldone:
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movzbq %al,%rax
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movzbq %dl,%rdx
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subq %rdx,%rax
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ret
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