1 /* Macros for copying by pages; used in memcpy, memmove. 2 Copyright (C) 1995-2021 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 /* The macro PAGE_COPY_FWD_MAYBE defined in memcopy.h is used in memmove if the 20 PAGE_COPY_THRESHOLD macro is set to a non-zero value. The default is 0, 21 that is copying by pages is not implemented. 22 23 System-specific pagecopy.h files that want to support page copying should 24 define these macros: 25 26 PAGE_COPY_THRESHOLD 27 -- A non-zero minimum size for which virtual copying by pages is worthwhile. 28 29 PAGE_SIZE 30 -- Size of a page. 31 32 PAGE_COPY_FWD (dstp, srcp, nbytes_left, nbytes) 33 -- Macro to perform the virtual copy operation. 34 The pointers will be aligned to PAGE_SIZE bytes. 35 */ 36 37 #define PAGE_COPY_THRESHOLD 0 38