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-rw-r--r--libc/string/generic/memmove.c278
1 files changed, 278 insertions, 0 deletions
diff --git a/libc/string/generic/memmove.c b/libc/string/generic/memmove.c
new file mode 100644
index 000000000..21876ce6e
--- /dev/null
+++ b/libc/string/generic/memmove.c
@@ -0,0 +1,278 @@
+/* Copy memory to memory until the specified number of bytes
+ has been copied. Overlap is handled correctly.
+ Copyright (C) 1991, 1995, 1996, 1997, 2003 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <string.h>
+
+#include "memcopy.h"
+#include "pagecopy.h"
+
+static void _wordcopy_bwd_aligned (long int dstp, long int srcp, size_t len)
+{
+ op_t a0, a1;
+
+ switch (len % 8)
+ {
+ case 2:
+ srcp -= 2 * OPSIZ;
+ dstp -= 1 * OPSIZ;
+ a0 = ((op_t *) srcp)[1];
+ len += 6;
+ goto do1;
+ case 3:
+ srcp -= 3 * OPSIZ;
+ dstp -= 2 * OPSIZ;
+ a1 = ((op_t *) srcp)[2];
+ len += 5;
+ goto do2;
+ case 4:
+ srcp -= 4 * OPSIZ;
+ dstp -= 3 * OPSIZ;
+ a0 = ((op_t *) srcp)[3];
+ len += 4;
+ goto do3;
+ case 5:
+ srcp -= 5 * OPSIZ;
+ dstp -= 4 * OPSIZ;
+ a1 = ((op_t *) srcp)[4];
+ len += 3;
+ goto do4;
+ case 6:
+ srcp -= 6 * OPSIZ;
+ dstp -= 5 * OPSIZ;
+ a0 = ((op_t *) srcp)[5];
+ len += 2;
+ goto do5;
+ case 7:
+ srcp -= 7 * OPSIZ;
+ dstp -= 6 * OPSIZ;
+ a1 = ((op_t *) srcp)[6];
+ len += 1;
+ goto do6;
+
+ case 0:
+ if (OP_T_THRES <= 3 * OPSIZ && len == 0)
+ return;
+ srcp -= 8 * OPSIZ;
+ dstp -= 7 * OPSIZ;
+ a0 = ((op_t *) srcp)[7];
+ goto do7;
+ case 1:
+ srcp -= 9 * OPSIZ;
+ dstp -= 8 * OPSIZ;
+ a1 = ((op_t *) srcp)[8];
+ len -= 1;
+ if (OP_T_THRES <= 3 * OPSIZ && len == 0)
+ goto do0;
+ goto do8; /* No-op. */
+ }
+
+ do
+ {
+ do8:
+ a0 = ((op_t *) srcp)[7];
+ ((op_t *) dstp)[7] = a1;
+ do7:
+ a1 = ((op_t *) srcp)[6];
+ ((op_t *) dstp)[6] = a0;
+ do6:
+ a0 = ((op_t *) srcp)[5];
+ ((op_t *) dstp)[5] = a1;
+ do5:
+ a1 = ((op_t *) srcp)[4];
+ ((op_t *) dstp)[4] = a0;
+ do4:
+ a0 = ((op_t *) srcp)[3];
+ ((op_t *) dstp)[3] = a1;
+ do3:
+ a1 = ((op_t *) srcp)[2];
+ ((op_t *) dstp)[2] = a0;
+ do2:
+ a0 = ((op_t *) srcp)[1];
+ ((op_t *) dstp)[1] = a1;
+ do1:
+ a1 = ((op_t *) srcp)[0];
+ ((op_t *) dstp)[0] = a0;
+
+ srcp -= 8 * OPSIZ;
+ dstp -= 8 * OPSIZ;
+ len -= 8;
+ }
+ while (len != 0);
+
+ /* This is the right position for do0. Please don't move
+ it into the loop. */
+ do0:
+ ((op_t *) dstp)[7] = a1;
+}
+
+/* _wordcopy_bwd_dest_aligned -- Copy block finishing right
+ before SRCP to block finishing right before DSTP with LEN `op_t'
+ words (not LEN bytes!). DSTP should be aligned for memory
+ operations on `op_t', but SRCP must *not* be aligned. */
+
+static void _wordcopy_bwd_dest_aligned (long int dstp, long int srcp, size_t len)
+{
+ op_t a0, a1, a2, a3;
+ int sh_1, sh_2;
+
+ /* Calculate how to shift a word read at the memory operation
+ aligned srcp to make it aligned for copy. */
+
+ sh_1 = 8 * (srcp % OPSIZ);
+ sh_2 = 8 * OPSIZ - sh_1;
+
+ /* Make srcp aligned by rounding it down to the beginning of the op_t
+ it points in the middle of. */
+ srcp &= -OPSIZ;
+ srcp += OPSIZ;
+
+ switch (len % 4)
+ {
+ case 2:
+ srcp -= 3 * OPSIZ;
+ dstp -= 1 * OPSIZ;
+ a2 = ((op_t *) srcp)[2];
+ a1 = ((op_t *) srcp)[1];
+ len += 2;
+ goto do1;
+ case 3:
+ srcp -= 4 * OPSIZ;
+ dstp -= 2 * OPSIZ;
+ a3 = ((op_t *) srcp)[3];
+ a2 = ((op_t *) srcp)[2];
+ len += 1;
+ goto do2;
+ case 0:
+ if (OP_T_THRES <= 3 * OPSIZ && len == 0)
+ return;
+ srcp -= 5 * OPSIZ;
+ dstp -= 3 * OPSIZ;
+ a0 = ((op_t *) srcp)[4];
+ a3 = ((op_t *) srcp)[3];
+ goto do3;
+ case 1:
+ srcp -= 6 * OPSIZ;
+ dstp -= 4 * OPSIZ;
+ a1 = ((op_t *) srcp)[5];
+ a0 = ((op_t *) srcp)[4];
+ len -= 1;
+ if (OP_T_THRES <= 3 * OPSIZ && len == 0)
+ goto do0;
+ goto do4; /* No-op. */
+ }
+
+ do
+ {
+ do4:
+ a3 = ((op_t *) srcp)[3];
+ ((op_t *) dstp)[3] = MERGE (a0, sh_1, a1, sh_2);
+ do3:
+ a2 = ((op_t *) srcp)[2];
+ ((op_t *) dstp)[2] = MERGE (a3, sh_1, a0, sh_2);
+ do2:
+ a1 = ((op_t *) srcp)[1];
+ ((op_t *) dstp)[1] = MERGE (a2, sh_1, a3, sh_2);
+ do1:
+ a0 = ((op_t *) srcp)[0];
+ ((op_t *) dstp)[0] = MERGE (a1, sh_1, a2, sh_2);
+
+ srcp -= 4 * OPSIZ;
+ dstp -= 4 * OPSIZ;
+ len -= 4;
+ }
+ while (len != 0);
+
+ /* This is the right position for do0. Please don't move
+ it into the loop. */
+ do0:
+ ((op_t *) dstp)[3] = MERGE (a0, sh_1, a1, sh_2);
+}
+
+void *memmove (void *dest, const void *src, size_t len)
+{
+ unsigned long int dstp = (long int) dest;
+ unsigned long int srcp = (long int) src;
+
+ /* This test makes the forward copying code be used whenever possible.
+ Reduces the working set. */
+ if (dstp - srcp >= len) /* *Unsigned* compare! */
+ {
+#if 1
+#warning REMINDER: generic-opt memmove assumes memcpy does forward copying!
+ memcpy(dest, src, len);
+#else
+ /* Copy from the beginning to the end. */
+
+ /* If there not too few bytes to copy, use word copy. */
+ if (len >= OP_T_THRES)
+ {
+ /* Copy just a few bytes to make DSTP aligned. */
+ len -= (-dstp) % OPSIZ;
+ BYTE_COPY_FWD (dstp, srcp, (-dstp) % OPSIZ);
+
+ /* Copy whole pages from SRCP to DSTP by virtual address
+ manipulation, as much as possible. */
+
+ PAGE_COPY_FWD_MAYBE (dstp, srcp, len, len);
+
+ /* Copy from SRCP to DSTP taking advantage of the known
+ alignment of DSTP. Number of bytes remaining is put
+ in the third argument, i.e. in LEN. This number may
+ vary from machine to machine. */
+
+ WORD_COPY_FWD (dstp, srcp, len, len);
+
+ /* Fall out and copy the tail. */
+ }
+
+ /* There are just a few bytes to copy. Use byte memory operations. */
+ BYTE_COPY_FWD (dstp, srcp, len);
+#endif
+ }
+ else
+ {
+ /* Copy from the end to the beginning. */
+ srcp += len;
+ dstp += len;
+
+ /* If there not too few bytes to copy, use word copy. */
+ if (len >= OP_T_THRES)
+ {
+ /* Copy just a few bytes to make DSTP aligned. */
+ len -= dstp % OPSIZ;
+ BYTE_COPY_BWD (dstp, srcp, dstp % OPSIZ);
+
+ /* Copy from SRCP to DSTP taking advantage of the known
+ alignment of DSTP. Number of bytes remaining is put
+ in the third argument, i.e. in LEN. This number may
+ vary from machine to machine. */
+
+ WORD_COPY_BWD (dstp, srcp, len, len);
+
+ /* Fall out and copy the tail. */
+ }
+
+ /* There are just a few bytes to copy. Use byte memory operations. */
+ BYTE_COPY_BWD (dstp, srcp, len);
+ }
+
+ return (dest);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-27 19:58:57 +0000