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https://github.com/torvalds/linux
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3e9f37e885
Optimise 'strnlen' to use microMIPS instructions and/or optimisations for binary size reduction. When the microMIPS ISA is not being used, the library function compiles to the original binary code. Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
46 lines
1.2 KiB
ArmAsm
46 lines
1.2 KiB
ArmAsm
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (c) 1996, 1998, 1999, 2004 by Ralf Baechle
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* Copyright (c) 1999 Silicon Graphics, Inc.
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*/
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#include <asm/asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/regdef.h>
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#define EX(insn,reg,addr,handler) \
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9: insn reg, addr; \
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.section __ex_table,"a"; \
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PTR 9b, handler; \
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.previous
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/*
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* Return the size of a string including the ending NUL character up to a
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* maximum of a1 or 0 in case of error.
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*
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* Note: for performance reasons we deliberately accept that a user may
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* make strlen_user and strnlen_user access the first few KSEG0
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* bytes. There's nothing secret there. On 64-bit accessing beyond
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* the maximum is a tad hairier ...
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*/
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LEAF(__strnlen_user_asm)
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LONG_L v0, TI_ADDR_LIMIT($28) # pointer ok?
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and v0, a0
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bnez v0, .Lfault
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FEXPORT(__strnlen_user_nocheck_asm)
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move v0, a0
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PTR_ADDU a1, a0 # stop pointer
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1: beq v0, a1, 1f # limit reached?
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EX(lb, t0, (v0), .Lfault)
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PTR_ADDIU v0, 1
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bnez t0, 1b
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1: PTR_SUBU v0, a0
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jr ra
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END(__strnlen_user_asm)
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.Lfault:
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move v0, zero
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jr ra
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