diff options
Diffstat (limited to 'libc/string/generic/memcpy.c')
| -rw-r--r-- | libc/string/generic/memcpy.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/libc/string/generic/memcpy.c b/libc/string/generic/memcpy.c new file mode 100644 index 000000000..9851fdea6 --- /dev/null +++ b/libc/string/generic/memcpy.c @@ -0,0 +1,246 @@ +/* Copy memory to memory until the specified number of bytes + has been copied. Overlap is NOT handled correctly. + Copyright (C) 1991, 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" + +#undef memcpy + +/* _wordcopy_fwd_aligned -- Copy block beginning at SRCP to + block beginning at DSTP with LEN `op_t' words (not LEN bytes!). + Both SRCP and DSTP should be aligned for memory operations on `op_t's. */ + +static void _wordcopy_fwd_aligned (long int dstp, long int srcp, size_t len) +{ + op_t a0, a1; + + switch (len % 8) + { + case 2: + a0 = ((op_t *) srcp)[0]; + srcp -= 6 * OPSIZ; + dstp -= 7 * OPSIZ; + len += 6; + goto do1; + case 3: + a1 = ((op_t *) srcp)[0]; + srcp -= 5 * OPSIZ; + dstp -= 6 * OPSIZ; + len += 5; + goto do2; + case 4: + a0 = ((op_t *) srcp)[0]; + srcp -= 4 * OPSIZ; + dstp -= 5 * OPSIZ; + len += 4; + goto do3; + case 5: + a1 = ((op_t *) srcp)[0]; + srcp -= 3 * OPSIZ; + dstp -= 4 * OPSIZ; + len += 3; + goto do4; + case 6: + a0 = ((op_t *) srcp)[0]; + srcp -= 2 * OPSIZ; + dstp -= 3 * OPSIZ; + len += 2; + goto do5; + case 7: + a1 = ((op_t *) srcp)[0]; + srcp -= 1 * OPSIZ; + dstp -= 2 * OPSIZ; + len += 1; + goto do6; + + case 0: + if (OP_T_THRES <= 3 * OPSIZ && len == 0) + return; + a0 = ((op_t *) srcp)[0]; + srcp -= 0 * OPSIZ; + dstp -= 1 * OPSIZ; + goto do7; + case 1: + a1 = ((op_t *) srcp)[0]; + srcp -=-1 * OPSIZ; + dstp -= 0 * OPSIZ; + len -= 1; + if (OP_T_THRES <= 3 * OPSIZ && len == 0) + goto do0; + goto do8; /* No-op. */ + } + + do + { + do8: + a0 = ((op_t *) srcp)[0]; + ((op_t *) dstp)[0] = a1; + do7: + a1 = ((op_t *) srcp)[1]; + ((op_t *) dstp)[1] = a0; + do6: + a0 = ((op_t *) srcp)[2]; + ((op_t *) dstp)[2] = a1; + do5: + a1 = ((op_t *) srcp)[3]; + ((op_t *) dstp)[3] = a0; + do4: + a0 = ((op_t *) srcp)[4]; + ((op_t *) dstp)[4] = a1; + do3: + a1 = ((op_t *) srcp)[5]; + ((op_t *) dstp)[5] = a0; + do2: + a0 = ((op_t *) srcp)[6]; + ((op_t *) dstp)[6] = a1; + do1: + a1 = ((op_t *) srcp)[7]; + ((op_t *) dstp)[7] = 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)[0] = a1; +} + +/* _wordcopy_fwd_dest_aligned -- Copy block beginning at SRCP to + block beginning at DSTP with LEN `op_t' words (not LEN bytes!). + DSTP should be aligned for memory operations on `op_t's, but SRCP must + *not* be aligned. */ + +static void _wordcopy_fwd_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; + + switch (len % 4) + { + case 2: + a1 = ((op_t *) srcp)[0]; + a2 = ((op_t *) srcp)[1]; + srcp -= 1 * OPSIZ; + dstp -= 3 * OPSIZ; + len += 2; + goto do1; + case 3: + a0 = ((op_t *) srcp)[0]; + a1 = ((op_t *) srcp)[1]; + srcp -= 0 * OPSIZ; + dstp -= 2 * OPSIZ; + len += 1; + goto do2; + case 0: + if (OP_T_THRES <= 3 * OPSIZ && len == 0) + return; + a3 = ((op_t *) srcp)[0]; + a0 = ((op_t *) srcp)[1]; + srcp -=-1 * OPSIZ; + dstp -= 1 * OPSIZ; + len += 0; + goto do3; + case 1: + a2 = ((op_t *) srcp)[0]; + a3 = ((op_t *) srcp)[1]; + srcp -=-2 * OPSIZ; + dstp -= 0 * OPSIZ; + len -= 1; + if (OP_T_THRES <= 3 * OPSIZ && len == 0) + goto do0; + goto do4; /* No-op. */ + } + + do + { + do4: + a0 = ((op_t *) srcp)[0]; + ((op_t *) dstp)[0] = MERGE (a2, sh_1, a3, sh_2); + do3: + a1 = ((op_t *) srcp)[1]; + ((op_t *) dstp)[1] = MERGE (a3, sh_1, a0, sh_2); + do2: + a2 = ((op_t *) srcp)[2]; + ((op_t *) dstp)[2] = MERGE (a0, sh_1, a1, sh_2); + do1: + a3 = ((op_t *) srcp)[3]; + ((op_t *) dstp)[3] = 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)[0] = MERGE (a2, sh_1, a3, sh_2); +} + +void *memcpy (void *dstpp, const void *srcpp, size_t len) +{ + unsigned long int dstp = (long int) dstpp; + unsigned long int srcp = (long int) srcpp; + + /* 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); + + return dstpp; +} |