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Diffstat (limited to 'nuttx/libc/string/lib_memset.c')
| -rw-r--r-- | nuttx/libc/string/lib_memset.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/nuttx/libc/string/lib_memset.c b/nuttx/libc/string/lib_memset.c new file mode 100644 index 000000000..0b98ebf96 --- /dev/null +++ b/nuttx/libc/string/lib_memset.c @@ -0,0 +1,188 @@ + +/**************************************************************************** + * libc/string/lib_memset.c + * + * Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ****************************************************************************/ + + +/**************************************************************************** + * Included Files + ****************************************************************************/ + +#include <nuttx/config.h> + +#include <sys/types.h> + +#include <stdint.h> +#include <string.h> +#include <assert.h> + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +/* Can't support CONFIG_MEMSET_64BIT if the platform does not have 64-bit + * integer types. + */ + +#ifndef CONFIG_HAVE_LONG_LONG +# undef CONFIG_MEMSET_64BIT +#endif + +/**************************************************************************** + * Global Functions + ****************************************************************************/ + +#ifndef CONFIG_ARCH_MEMSET +void *memset(void *s, int c, size_t n) +{ +#ifdef CONFIG_MEMSET_OPTSPEED + /* This version is optimized for speed (you could do better + * still by exploiting processor caching or memory burst + * knowledge.) + */ + + uintptr_t addr = (uintptr_t)s; + uint16_t val16 = ((uint16_t)c << 8) | (uint16_t)c; + uint32_t val32 = ((uint32_t)val16 << 16) | (uint32_t)val16; +#ifdef CONFIG_MEMSET_64BIT + uint64_t val64 = ((uint64_t)val32 << 32) | (uint64_t)val32; +#endif + + /* Make sure that there is something to be cleared */ + + if (n > 0) + { + /* Align to a 16-bit boundary */ + + if ((addr & 1) != 0) + { + *(uint8_t*)addr = (uint8_t)c; + addr += 1; + n -= 1; + } + + /* Check if there are at least 16-bits left to be written */ + + if (n >= 2) + { + /* Align to a 32-bit boundary (we know that the destination + * address is already aligned to at least a 16-bit boundary). + */ + + if ((addr & 3) != 0) + { + *(uint16_t*)addr = val16; + addr += 2; + n -= 2; + } + +#ifndef CONFIG_MEMSET_64BIT + /* Loop while there are at least 32-bits left to be written */ + + while (n >= 4) + { + *(uint32_t*)addr = val32; + addr += 4; + n -= 4; + } +#else + /* Check if there are at least 32-bits left to be written */ + + if (n >= 4) + { + /* Align to a 64-bit boundary (we know that the destination + * address is already aligned to at least a 32-bit boundary). + */ + + if ((addr & 7) != 0) + { + *(uint32_t*)addr = val32; + addr += 4; + n -= 4; + } + + /* Loop while there are at least 64-bits left to be written */ + + while (n >= 8) + { + *(uint64_t*)addr = val64; + addr += 8; + n -= 8; + } + } +#endif + } + +#ifdef CONFIG_MEMSET_64BIT + /* We may get here with n in the range 0..7. If n >= 4, then we should + * have 64-bit alignment. + */ + + if (n >= 4) + { + *(uint32_t*)addr = val32; + addr += 4; + n -= 4; + } +#endif + + /* We may get here under the following conditions: + * + * n = 0, addr may or may not be aligned + * n = 1, addr is aligned to at least a 16-bit boundary + * n = 2, addr is aligned to a 32-bit boundary + * n = 3, addr is aligned to a 32-bit boundary + */ + + if (n >= 2) + { + *(uint16_t*)addr = val16; + addr += 2; + n -= 2; + } + + if (n >= 1) + { + *(uint8_t*)addr = (uint8_t)c; + } + } +#else + /* This version is optimized for size */ + + unsigned char *p = (unsigned char*)s; + while (n-- > 0) *p++ = c; +#endif + return s; +} +#endif |