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authorManuel Novoa III <mjn3@codepoet.org>2004-09-02 14:39:38 +0000
committerManuel Novoa III <mjn3@codepoet.org>2004-09-02 14:39:38 +0000
commitbec90733b9de6e7d75b8bda19b3f0a7117e6b78d (patch)
tree474ca0f3b80b7990ff33e547d42c1e7dc3014e3b /libc/string/generic/memcopy.h
parentc4cedfc718426337b0215c256c184d2b4e20cd06 (diff)
Add a couple of mips-specific string funcs.
Port the generic optimized string funcs from glibc, with some tweaks to cut their size a little. The main change is making memmove call memcpy for forward copying to trim redundant code. Make use of both the generic and arch-specific speed-optimized string funcs configurable. Arch-specific take precedence over generic, and generic takes precedence over basic size-optimized uClibc funcs.
Diffstat (limited to 'libc/string/generic/memcopy.h')
-rw-r--r--libc/string/generic/memcopy.h150
1 files changed, 150 insertions, 0 deletions
diff --git a/libc/string/generic/memcopy.h b/libc/string/generic/memcopy.h
new file mode 100644
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+/* memcopy.h -- definitions for memory copy functions. Generic C version.
+ Copyright (C) 1991, 1992, 1993, 1997 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. */
+
+/* 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 <sys/cdefs.h>
+#include <endian.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]
+*/
+
+/* Type to use for aligned memory operations.
+ This should normally be the biggest type supported by a single load
+ and store. */
+#define op_t unsigned long int
+#define OPSIZ (sizeof(op_t))
+
+/* Type to use for unaligned operations. */
+typedef unsigned char byte;
+
+/* Optimal type for storing bytes in registers. */
+#define reg_char char
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) | ((w1) << (sh_2)))
+#endif
+#if __BYTE_ORDER == __BIG_ENDIAN
+#define MERGE(w0, sh_1, w1, sh_2) (((w0) << (sh_1)) | ((w1) >> (sh_2)))
+#endif
+
+/* Copy exactly NBYTES bytes from SRC_BP to DST_BP,
+ without any assumptions about alignment of the pointers. */
+#define BYTE_COPY_FWD(dst_bp, src_bp, nbytes) \
+ do \
+ { \
+ size_t __nbytes = (nbytes); \
+ while (__nbytes > 0) \
+ { \
+ byte __x = ((byte *) src_bp)[0]; \
+ src_bp += 1; \
+ __nbytes -= 1; \
+ ((byte *) dst_bp)[0] = __x; \
+ dst_bp += 1; \
+ } \
+ } 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. */
+#define BYTE_COPY_BWD(dst_ep, src_ep, nbytes) \
+ do \
+ { \
+ size_t __nbytes = (nbytes); \
+ while (__nbytes > 0) \
+ { \
+ byte __x; \
+ src_ep -= 1; \
+ __x = ((byte *) src_ep)[0]; \
+ dst_ep -= 1; \
+ __nbytes -= 1; \
+ ((byte *) dst_ep)[0] = __x; \
+ } \
+ } while (0)
+
+/* Copy *up to* NBYTES bytes from SRC_BP to DST_BP, with
+ the assumption that DST_BP is aligned on an OPSIZ multiple. If
+ not all bytes could be easily copied, store remaining number of bytes
+ in NBYTES_LEFT, otherwise store 0. */
+/* extern void _wordcopy_fwd_aligned __P ((long int, long int, size_t)); */
+/* extern void _wordcopy_fwd_dest_aligned __P ((long int, long int, size_t)); */
+#define WORD_COPY_FWD(dst_bp, src_bp, nbytes_left, nbytes) \
+ do \
+ { \
+ if (src_bp % OPSIZ == 0) \
+ _wordcopy_fwd_aligned (dst_bp, src_bp, (nbytes) / OPSIZ); \
+ else \
+ _wordcopy_fwd_dest_aligned (dst_bp, src_bp, (nbytes) / OPSIZ); \
+ src_bp += (nbytes) & -OPSIZ; \
+ dst_bp += (nbytes) & -OPSIZ; \
+ (nbytes_left) = (nbytes) % OPSIZ; \
+ } while (0)
+
+/* Copy *up to* NBYTES_TO_COPY bytes from SRC_END_PTR to DST_END_PTR,
+ beginning at the words (of type op_t) right before the pointers and
+ continuing towards smaller addresses. May take advantage of that
+ DST_END_PTR is aligned on an OPSIZ multiple. If not all bytes could be
+ easily copied, store remaining number of bytes in NBYTES_REMAINING,
+ otherwise store 0. */
+/* extern void _wordcopy_bwd_aligned __P ((long int, long int, size_t)); */
+/* extern void _wordcopy_bwd_dest_aligned __P ((long int, long int, size_t)); */
+#define WORD_COPY_BWD(dst_ep, src_ep, nbytes_left, nbytes) \
+ do \
+ { \
+ if (src_ep % OPSIZ == 0) \
+ _wordcopy_bwd_aligned (dst_ep, src_ep, (nbytes) / OPSIZ); \
+ else \
+ _wordcopy_bwd_dest_aligned (dst_ep, src_ep, (nbytes) / OPSIZ); \
+ src_ep -= (nbytes) & -OPSIZ; \
+ dst_ep -= (nbytes) & -OPSIZ; \
+ (nbytes_left) = (nbytes) % OPSIZ; \
+ } while (0)
+
+
+/* Threshold value for when to enter the unrolled loops. */
+#define OP_T_THRES 16