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d1dc791d11
libc_data_t is 8 bytes wide, so a buffer which is 4-byte but not 8-byte aligned falls back to the byte at a time loop. Add a 32-bit middle path so such buffers still handle four bytes per iteration. * Add DETECTNULL32/DETECTCHAR32, UNALIGNED4/UNALIGNED4_X, LITTLEBLOCKSIZE4/BIGBLOCKSIZE4 and TOO_SMALL4 to libs/libc/libc.h. * Take the new path in memccpy, memcmp, memcpy, memset, stpcpy, stpncpy, strcmp, strcpy, strncmp and strncpy when both pointers are 4-byte aligned but the 8-byte path can't be used. Assisted-by: Claude:claude-opus-5 Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
137 lines
3.6 KiB
C
137 lines
3.6 KiB
C
/****************************************************************************
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* libs/libc/string/lib_bsdmemset.c
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*
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* SPDX-License-Identifier: BSD
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* SPDX-FileCopyrightText: 1994-2009 Red Hat, Inc. All rights reserved
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*
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* Copyright (c) 1994-2009 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the BSD License. This program is distributed in the hope that
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* it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
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* including the implied warranties of MERCHANTABILITY or FITNESS FOR
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* A PARTICULAR PURPOSE. A copy of this license is available at
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* http://www.opensource.org/licenses. Any Red Hat trademarks that are
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* incorporated in the source code or documentation are not subject to
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* the BSD License and may only be used or replicated with the express
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* permission of Red Hat, Inc.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <string.h>
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#include "libc.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: memset
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****************************************************************************/
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#if !defined(CONFIG_LIBC_ARCH_MEMSET) && defined(LIBC_BUILD_MEMSET)
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#undef memset
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no_builtin("memset")
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FAR void *memset(FAR void *m, int c, size_t n)
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{
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FAR libc_data_t *aligned_addr;
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FAR char *s = (FAR char *)m;
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libc_data_t buffer;
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int i;
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/* To avoid sign extension, copy C to an unsigned variable. */
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while (UNALIGNED(s, 0))
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{
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if (n--)
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{
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*s++ = c;
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}
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else
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{
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return m;
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}
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}
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buffer = (uint8_t)c;
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buffer |= (buffer << 8);
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buffer |= (buffer << 16);
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for (i = 32; i < LITTLEBLOCKSIZE * 8; i <<= 1)
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{
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buffer = (buffer << i) | buffer;
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}
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if (!TOO_SMALL(n))
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{
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/* If we get this far, we know that n is large and s is word-aligned. */
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aligned_addr = (FAR libc_data_t *)s;
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/* Unroll the loop. */
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while (n >= LITTLEBLOCKSIZE * 4)
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{
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*aligned_addr++ = buffer;
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*aligned_addr++ = buffer;
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*aligned_addr++ = buffer;
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*aligned_addr++ = buffer;
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n -= 4 * LITTLEBLOCKSIZE;
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}
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while (n >= LITTLEBLOCKSIZE)
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{
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*aligned_addr++ = buffer;
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n -= LITTLEBLOCKSIZE;
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}
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/* Pick up the remainder with a bytewise loop. */
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s = (FAR char *)aligned_addr;
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}
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/* Tail: here s is libc_data_t-aligned and n < LITTLEBLOCKSIZE.
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* Fill with aligned stores of decreasing width - no unaligned access,
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* no overlap, no over-write.
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*/
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if (LITTLEBLOCKSIZE > 8 && n >= 8)
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{
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*(FAR uint64_t *)s = (uint64_t)buffer;
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s += 8;
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n -= 8;
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}
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if (n >= 4)
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{
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*(FAR uint32_t *)s = (uint32_t)buffer;
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s += 4;
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n -= 4;
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}
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if (n >= 2)
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{
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*(FAR uint16_t *)s = (uint16_t)buffer;
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s += 2;
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n -= 2;
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}
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if (n)
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{
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*s = (uint8_t)buffer;
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}
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return m;
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}
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#endif
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