75 lines
1.7 KiB
C
75 lines
1.7 KiB
C
/*
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* strlen.c -- strlen function. On at least some MIPS chips, a simple
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* strlen is faster than the 'optimized' C version.
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*
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* Copyright (c) 2001, 2002 Red Hat, Inc.
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*
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* The authors hereby grant permission to use, copy, modify, distribute,
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* and license this software and its documentation for any purpose, provided
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* that existing copyright notices are retained in all copies and that this
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* notice is included verbatim in any distributions. No written agreement,
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* license, or royalty fee is required for any of the authorized uses.
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* Modifications to this software may be copyrighted by their authors
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* and need not follow the licensing terms described here, provided that
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* the new terms are clearly indicated on the first page of each file where
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* they apply.
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*/
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#include <stddef.h>
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#include <string.h>
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/* MIPS16 needs to come first. */
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#if defined(__mips16)
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size_t
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strlen (const char *str)
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{
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const char *start = str;
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while (*str++ != '\0')
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;
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return str - start - 1;
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}
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#elif defined(__mips64)
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__asm__("" /* 64-bit MIPS targets */
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" .set noreorder\n"
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" .set nomacro\n"
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" .globl strlen\n"
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" .ent strlen\n"
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"strlen:\n"
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" daddiu $2,$4,1\n"
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"\n"
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"1: lbu $3,0($4)\n"
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" bnez $3,1b\n"
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" daddiu $4,$4,1\n"
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"\n"
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" jr $31\n"
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" dsubu $2,$4,$2\n"
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" .end strlen\n"
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" .set macro\n"
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" .set reorder\n");
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#else
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__asm__("" /* 32-bit MIPS targets */
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" .set noreorder\n"
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" .set nomacro\n"
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" .globl strlen\n"
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" .ent strlen\n"
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"strlen:\n"
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" addiu $2,$4,1\n"
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"\n"
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"1: lbu $3,0($4)\n"
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#if defined(_R3000)
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" nop \n"
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#endif
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" bnez $3,1b\n"
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" addiu $4,$4,1\n"
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"\n"
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" jr $31\n"
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" subu $2,$4,$2\n"
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" .end strlen\n"
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" .set macro\n"
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" .set reorder\n");
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#endif
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