/* memset -- set a block of memory to some byte value. For Intel 80x86, x>=3. Copyright (C) 1991, 1992, 1993 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 Library General Public License as published by the Free Software Foundation; either version 2 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 Library General Public License for more details. You should have received a copy of the GNU Library General Public License along with the GNU C Library; see the file COPYING.LIB. If not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include <ansidecl.h> #include <string.h> #include <memcopy.h> #ifdef __GNUC__ PTR DEFUN(memset, (dstpp, c, len), PTR dstpp AND int c AND size_t len) { unsigned long int dstp = (unsigned long int) dstpp; /* This explicit register allocation improves code very much indeed. */ register op_t x asm("ax"); x = (unsigned char) c; /* Clear the direction flag, so filling will move forward. */ asm volatile("cld"); /* This threshold value is optimal. */ if (len >= 12) { /* Fill X with four copies of the char we want to fill with. */ x |= (x << 8); x |= (x << 16); /* 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) : "0" (dstp), "c" ((-dstp) % OPSIZ), "a" (x) : "cx"); /* Fill longwords. */ asm volatile("rep\n" "stosl" /* %0, %2, %3 */ : "=D" (dstp) : "0" (dstp), "c" (len / OPSIZ), "a" (x) : "cx"); len %= OPSIZ; } /* Write the last few bytes. */ asm volatile("rep\n" "stosb" /* %0, %2, %3 */ : "=D" (dstp) : "0" (dstp), "c" (len), "a" (x) : "cx"); return dstpp; } #else #include <sysdeps/generic/memset.c> #endif