| /* memcopy.h -- definitions for memory copy functions. Generic C version. |
| Copyright (C) 1991-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| 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, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| /* The strategy of the memory functions is: |
| |
| 1. Copy bytes until the destination pointer is aligned. |
| |
| 2. Copy words in unrolled loops. If the source and destination |
| are not aligned in the same way, use word memory operations, |
| but shift and merge two read words before writing. |
| |
| 3. Copy the few remaining bytes. |
| |
| This is fast on processors that have at least 10 registers for |
| allocation by GCC, and that can access memory at reg+const in one |
| instruction. |
| |
| I made an "exhaustive" test of this memmove when I wrote it, |
| exhaustive in the sense that I tried all alignment and length |
| combinations, with and without overlap. */ |
| |
| #include <sysdeps/generic/memcopy.h> |
| |
| /* The macros defined in this file are: |
| |
| BYTE_COPY_FWD(dst_beg_ptr, src_beg_ptr, nbytes_to_copy) |
| |
| BYTE_COPY_BWD(dst_end_ptr, src_end_ptr, nbytes_to_copy) |
| |
| WORD_COPY_FWD(dst_beg_ptr, src_beg_ptr, nbytes_remaining, nbytes_to_copy) |
| |
| WORD_COPY_BWD(dst_end_ptr, src_end_ptr, nbytes_remaining, nbytes_to_copy) |
| |
| MERGE(old_word, sh_1, new_word, sh_2) |
| [I fail to understand. I feel stupid. --roland] |
| */ |
| |
| |
| /* Threshold value for when to enter the unrolled loops. */ |
| #undef OP_T_THRES |
| #define OP_T_THRES 16 |
| |
| /* Copy exactly NBYTES bytes from SRC_BP to DST_BP, |
| without any assumptions about alignment of the pointers. */ |
| #undef BYTE_COPY_FWD |
| #define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \ |
| do \ |
| { \ |
| size_t __nbytes = (nbytes); \ |
| if (__nbytes & 1) \ |
| { \ |
| ((byte *) dst_bp)[0] = ((byte *) src_bp)[0]; \ |
| src_bp += 1; \ |
| dst_bp += 1; \ |
| __nbytes -= 1; \ |
| } \ |
| while (__nbytes > 0) \ |
| { \ |
| byte __x = ((byte *) src_bp)[0]; \ |
| byte __y = ((byte *) src_bp)[1]; \ |
| src_bp += 2; \ |
| __nbytes -= 2; \ |
| ((byte *) dst_bp)[0] = __x; \ |
| ((byte *) dst_bp)[1] = __y; \ |
| dst_bp += 2; \ |
| } \ |
| } while (0) |
| |
| /* Copy exactly NBYTES_TO_COPY bytes from SRC_END_PTR to DST_END_PTR, |
| beginning at the bytes right before the pointers and continuing towards |
| smaller addresses. Don't assume anything about alignment of the |
| pointers. */ |
| #undef BYTE_COPY_BWD |
| #define BYTE_COPY_BWD(dst_ep, src_ep, nbytes) \ |
| do \ |
| { \ |
| size_t __nbytes = (nbytes); \ |
| if (__nbytes & 1) \ |
| { \ |
| src_ep -= 1; \ |
| dst_ep -= 1; \ |
| ((byte *) dst_ep)[0] = ((byte *) src_ep)[0]; \ |
| __nbytes -= 1; \ |
| } \ |
| while (__nbytes > 0) \ |
| { \ |
| byte __x, __y; \ |
| src_ep -= 2; \ |
| __y = ((byte *) src_ep)[1]; \ |
| __x = ((byte *) src_ep)[0]; \ |
| dst_ep -= 2; \ |
| __nbytes -= 2; \ |
| ((byte *) dst_ep)[1] = __y; \ |
| ((byte *) dst_ep)[0] = __x; \ |
| } \ |
| } while (0) |
| |
| /* The powerpc memcpy implementation is safe to use for memmove. */ |
| #undef MEMCPY_OK_FOR_FWD_MEMMOVE |
| #define MEMCPY_OK_FOR_FWD_MEMMOVE 1 |