2012-11-10 17:06:01 +01:00
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/****************************************************************************
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2018-05-29 21:21:26 +02:00
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* libs/libc/string/lib_memset.c
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2012-11-10 17:06:01 +01:00
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*
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2021-03-02 15:54:21 +01:00
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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2012-11-10 17:06:01 +01:00
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*
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2021-03-02 15:54:21 +01:00
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* http://www.apache.org/licenses/LICENSE-2.0
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2012-11-10 17:06:01 +01:00
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*
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2021-03-02 15:54:21 +01:00
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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2012-11-10 17:06:01 +01:00
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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 <stdint.h>
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#include <string.h>
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#include <assert.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* Can't support CONFIG_MEMSET_64BIT if the platform does not have 64-bit
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* integer types.
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*/
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#ifndef CONFIG_HAVE_LONG_LONG
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# undef CONFIG_MEMSET_64BIT
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#endif
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/****************************************************************************
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2015-10-03 00:30:35 +02:00
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* Public Functions
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2012-11-10 17:06:01 +01:00
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****************************************************************************/
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2017-01-20 16:30:07 +01:00
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#ifndef CONFIG_LIBC_ARCH_MEMSET
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2015-10-12 15:45:02 +02:00
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FAR void *memset(FAR void *s, int c, size_t n)
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2012-11-10 17:06:01 +01:00
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{
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#ifdef CONFIG_MEMSET_OPTSPEED
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/* This version is optimized for speed (you could do better
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* still by exploiting processor caching or memory burst
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* knowledge.)
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*/
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uintptr_t addr = (uintptr_t)s;
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uint16_t val16 = ((uint16_t)c << 8) | (uint16_t)c;
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uint32_t val32 = ((uint32_t)val16 << 16) | (uint32_t)val16;
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#ifdef CONFIG_MEMSET_64BIT
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uint64_t val64 = ((uint64_t)val32 << 32) | (uint64_t)val32;
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#endif
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/* Make sure that there is something to be cleared */
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if (n > 0)
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{
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/* Align to a 16-bit boundary */
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if ((addr & 1) != 0)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint8_t *)addr = (uint8_t)c;
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2012-11-10 17:06:01 +01:00
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addr += 1;
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n -= 1;
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}
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/* Check if there are at least 16-bits left to be written */
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if (n >= 2)
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{
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/* Align to a 32-bit boundary (we know that the destination
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* address is already aligned to at least a 16-bit boundary).
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*/
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if ((addr & 3) != 0)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint16_t *)addr = val16;
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2012-11-10 17:06:01 +01:00
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addr += 2;
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n -= 2;
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}
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#ifndef CONFIG_MEMSET_64BIT
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/* Loop while there are at least 32-bits left to be written */
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while (n >= 4)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint32_t *)addr = val32;
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2012-11-10 17:06:01 +01:00
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addr += 4;
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n -= 4;
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}
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#else
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/* Check if there are at least 32-bits left to be written */
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if (n >= 4)
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{
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/* Align to a 64-bit boundary (we know that the destination
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* address is already aligned to at least a 32-bit boundary).
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*/
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if ((addr & 7) != 0)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint32_t *)addr = val32;
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2012-11-10 17:06:01 +01:00
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addr += 4;
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n -= 4;
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}
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/* Loop while there are at least 64-bits left to be written */
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while (n >= 8)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint64_t *)addr = val64;
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2012-11-10 17:06:01 +01:00
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addr += 8;
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n -= 8;
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}
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}
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#endif
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}
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#ifdef CONFIG_MEMSET_64BIT
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/* We may get here with n in the range 0..7. If n >= 4, then we should
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* have 64-bit alignment.
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*/
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if (n >= 4)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint32_t *)addr = val32;
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2012-11-10 17:06:01 +01:00
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addr += 4;
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n -= 4;
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}
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#endif
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/* We may get here under the following conditions:
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*
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* n = 0, addr may or may not be aligned
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* n = 1, addr is aligned to at least a 16-bit boundary
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* n = 2, addr is aligned to a 32-bit boundary
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* n = 3, addr is aligned to a 32-bit boundary
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*/
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if (n >= 2)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint16_t *)addr = val16;
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2012-11-10 17:06:01 +01:00
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addr += 2;
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n -= 2;
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}
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if (n >= 1)
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{
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2015-10-12 15:45:02 +02:00
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*(FAR uint8_t *)addr = (uint8_t)c;
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2012-11-10 17:06:01 +01:00
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}
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}
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#else
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/* This version is optimized for size */
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2021-03-02 14:33:27 +01:00
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FAR unsigned char *p = (FAR unsigned char *)s;
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2012-11-10 17:06:01 +01:00
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while (n-- > 0) *p++ = c;
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#endif
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return s;
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}
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#endif
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