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https://github.com/espressif/esp-idf.git
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ec68cb3300
This option replaces implementations of functions from ROM: - memcpy - memcmp - memmove - str[n]cpy - str[n]cmp The functions used in the firmware will be better optimized for misaligned memory. Here are some measurements in CPU cycles for 4096-byte buffers: memcpy: 28676 -> 4128 memcmp: 49147 -> 14259 memmove: 33896 -> 8086 strcpy: 32771 -> 17313 strcmp: 32775 -> 13191
64 lines
1.5 KiB
C
64 lines
1.5 KiB
C
/*
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* SPDX-FileCopyrightText: 1994-2009 Red Hat, Inc.
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*
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD AND Apache-2.0
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*
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* SPDX-FileContributor: 2025 Espressif Systems (Shanghai) CO LTD
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*/
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#include <string.h>
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#include <limits.h>
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#include "local.h"
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__attribute__((optimize("-Os")))
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int
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strncmp(const char *s1,
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const char *s2,
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size_t n)
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{
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unsigned long *a1;
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unsigned long *a2;
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if (n == 0) {
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return 0;
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}
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/* If s1 or s2 are unaligned, then compare bytes. */
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if (!UNALIGNED_X_Y(s1, s2)) {
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/* If s1 and s2 are word-aligned, compare them a word at a time. */
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a1 = (unsigned long*)s1;
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a2 = (unsigned long*)s2;
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while (n >= sizeof(long) && *a1 == *a2) {
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n -= sizeof(long);
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/* If we've run out of bytes or hit a null, return zero
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since we already know *a1 == *a2. */
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if (n == 0 || DETECT_NULL(*a1)) {
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return 0;
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}
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a1++;
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a2++;
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}
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/* A difference was detected in last few bytes of s1, so search bytewise */
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s1 = (char*)a1;
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s2 = (char*)a2;
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}
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while (n-- > 0 && *s1 == *s2) {
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/* If we've run out of bytes or hit a null, return zero
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since we already know *s1 == *s2. */
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if (n == 0 || *s1 == '\0') {
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return 0;
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}
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s1++;
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s2++;
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}
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return (*(unsigned char *) s1) - (*(unsigned char *) s2);
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}
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// Hook to force the linker to include this file
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void esp_libc_include_strncmp_impl(void)
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{
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}
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