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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
60 lines
1.4 KiB
C
60 lines
1.4 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 "local.h"
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__attribute__((optimize("-Os")))
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int
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memcmp(const void *m1,
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const void *m2,
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size_t n)
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{
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unsigned char *s1 = (unsigned char *) m1;
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unsigned char *s2 = (unsigned char *) m2;
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unsigned long *a1;
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unsigned long *a2;
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/* If the size is too small, or either pointer is unaligned,
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then we punt to the byte compare loop. Hopefully this will
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not turn up in inner loops. */
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if (!TOO_SMALL_LITTLE_BLOCK(n) && !UNALIGNED_X_Y(s1, s2)) {
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/* Otherwise, load and compare the blocks of memory one
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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 (!TOO_SMALL_LITTLE_BLOCK(n)) {
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if (*a1 != *a2) {
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break;
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}
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a1++;
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a2++;
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n -= LITTLE_BLOCK_SIZE;
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}
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/* check m mod LITTLE_BLOCK_SIZE remaining characters */
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s1 = (unsigned char*)a1;
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s2 = (unsigned char*)a2;
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}
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while (n--) {
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if (*s1 != *s2) {
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return *s1 - *s2;
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}
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s1++;
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s2++;
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}
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return 0;
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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_memcmp_impl(void)
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{
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}
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