sysdeps/generic/pagecopy.h

   1 /* Macros for copying by pages; used in memcpy, memmove.
   2    Copyright (C) 1995-2024 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