| /* bzero -- set a block of memory to zero. For Intel 80x86, x>=3. |
| This file is part of the GNU C Library. |
| Copyright (C) 1991,92,93,97,98,99, 05 Free Software Foundation, Inc. |
| Contributed by Torbjorn Granlund (tege@sics.se). |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <string.h> |
| #include <memcopy.h> |
| |
| #undef bzero |
| #undef __bzero |
| |
| #ifdef __GNUC__ |
| |
| void |
| __bzero (dstpp, len) |
| void *dstpp; |
| size_t len; |
| { |
| /* N.B.: This code is almost verbatim from memset.c. */ |
| int d0; |
| unsigned long int dstp = (unsigned long int) dstpp; |
| |
| /* This explicit register allocation |
| improves code very much indeed. */ |
| register op_t x asm ("ax"); |
| |
| x = 0; |
| |
| /* Clear the direction flag, so filling will move forward. */ |
| asm volatile ("cld"); |
| |
| /* This threshold value is optimal. */ |
| if (len >= 12) |
| { |
| /* Adjust LEN for the bytes handled in the first loop. */ |
| len -= (-dstp) % OPSIZ; |
| |
| /* There are at least some bytes to set. |
| No need to test for LEN == 0 in this alignment loop. */ |
| |
| /* Fill bytes until DSTP is aligned on a longword boundary. */ |
| asm volatile ("rep\n" |
| "stosb" /* %0, %2, %3 */ : |
| "=D" (dstp), "=c" (d0) : |
| "0" (dstp), "1" ((-dstp) % OPSIZ), "a" (x) : |
| "memory"); |
| |
| /* Fill longwords. */ |
| asm volatile ("rep\n" |
| "stosl" /* %0, %2, %3 */ : |
| "=D" (dstp), "=c" (d0) : |
| "0" (dstp), "1" (len / OPSIZ), "a" (x) : |
| "memory"); |
| len %= OPSIZ; |
| } |
| |
| /* Write the last few bytes. */ |
| asm volatile ("rep\n" |
| "stosb" /* %0, %2, %3 */ : |
| "=D" (dstp), "=c" (d0) : |
| "0" (dstp), "c" (len), "a" (x) : |
| "memory"); |
| } |
| weak_alias (__bzero, bzero) |
| |
| #else |
| #include <string/bzero.c> |
| #endif |