| // SPDX-License-Identifier: BSD-3-Clause |
| /* |
| * Copyright (c) 1994-2009 Red Hat, Inc. |
| * All rights reserved. |
| * |
| * 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 of the copyright holder 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 HOLDER 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. |
| */ |
| |
| /* |
| FUNCTION |
| <<memset>>---set an area of memory |
| |
| INDEX |
| memset |
| |
| ANSI_SYNOPSIS |
| #include <string.h> |
| void *memset(void *<[dst]>, int <[c]>, size_t <[length]>); |
| |
| TRAD_SYNOPSIS |
| #include <string.h> |
| void *memset(<[dst]>, <[c]>, <[length]>) |
| void *<[dst]>; |
| int <[c]>; |
| size_t <[length]>; |
| |
| DESCRIPTION |
| This function converts the argument <[c]> into an unsigned |
| char and fills the first <[length]> characters of the array |
| pointed to by <[dst]> to the value. |
| |
| RETURNS |
| <<memset>> returns the value of <[dst]>. |
| |
| PORTABILITY |
| <<memset>> is ANSI C. |
| |
| <<memset>> requires no supporting OS subroutines. |
| |
| QUICKREF |
| memset ansi pure |
| */ |
| |
| #include "_ansi.h" |
| #include <string.h> |
| |
| #define LBLOCKSIZE (sizeof(long)) |
| #define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1)) |
| #define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE) |
| |
| _PTR _DEFUN(memset, (m, c, n), _PTR m _AND int c _AND size_t n) |
| { |
| char *s = (char *)m; |
| |
| #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) |
| int i; |
| unsigned long buffer; |
| unsigned long *aligned_addr; |
| unsigned int d = c & 0xff; /* To avoid sign extension, copy C to an |
| unsigned variable. */ |
| |
| while (UNALIGNED(s)) { |
| if (n--) |
| *s++ = (char)c; |
| else |
| return m; |
| } |
| |
| if (!TOO_SMALL(n)) { |
| /* |
| * If we get this far, we know that n is large and s is |
| * word-aligned. |
| */ |
| aligned_addr = (unsigned long *)s; |
| |
| /* Store D into each char sized location in BUFFER so that |
| we can set large blocks quickly. */ |
| buffer = (d << 8) | d; |
| buffer |= (buffer << 16); |
| for (i = 32; i < LBLOCKSIZE * 8; i <<= 1) |
| buffer = (buffer << i) | buffer; |
| |
| /* Unroll the loop. */ |
| while (n >= LBLOCKSIZE * 4) { |
| *aligned_addr++ = buffer; |
| *aligned_addr++ = buffer; |
| *aligned_addr++ = buffer; |
| *aligned_addr++ = buffer; |
| n -= 4 * LBLOCKSIZE; |
| } |
| |
| while (n >= LBLOCKSIZE) { |
| *aligned_addr++ = buffer; |
| n -= LBLOCKSIZE; |
| } |
| /* Pick up the remainder with a bytewise loop. */ |
| s = (char *)aligned_addr; |
| } |
| #endif /* not PREFER_SIZE_OVER_SPEED */ |
| |
| while (n--) |
| *s++ = (char)c; |
| |
| return m; |
| } |