mirror of https://gitlab.com/rnger/amath
116 lines
3.8 KiB
C
116 lines
3.8 KiB
C
/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "clib.h"
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#if __GNUC__ > 2
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#pragma GCC diagnostic ignored "-Wcast-align"
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#endif
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/**
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*
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* sizeof(word) MUST BE A POWER OF TWO
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* SO THAT wmask BELOW IS ALL ONES
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*/
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typedef int word; // "word" used for optimal copy speed
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/**
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*
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* Macros: loop-t-times; and loop-t-times, t>0
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*/
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#define TLOOP(s) if (t) TLOOP1(s)
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#define TLOOP1(s) do { s; } while (--t)
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/**
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* @brief Copy a block of memory, handling overlap.
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*
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* Original file can be found at:
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* https://svnweb.freebsd.org/base/release/9.0.0/lib/libc/string/bcopy.c?revision=229286
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*
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*/
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void MemCopy(void *destination, const void *source, unsigned int length)
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{
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char *dst = (char*) destination;
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const char *src = (const char*) source;
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unsigned int t;
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if (length == 0 || dst == src) // nothing to do
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return;
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if ((unsigned long)dst < (unsigned long)src) {
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// Copy forward
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t = (unsigned long)src; // only need low bits
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if ((t | (unsigned long)dst) & wmask) {
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// Try to align operands. This cannot be done unless the low bits match.
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if ((t ^ (unsigned long)dst) & wmask || length < wsize)
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t = length;
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else
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t = wsize - (t & wmask);
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length -= t;
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TLOOP1(*dst++ = *src++);
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}
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// Copy whole words, then mop up any trailing bytes.
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t = length / wsize;
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TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
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t = length & wmask;
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TLOOP(*dst++ = *src++);
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} else {
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// Copy backwards. Otherwise essentially the same.
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// Alignment works as before, except that it takes
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// (t&wmask) bytes to align, not wsize-(t&wmask).
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src += length;
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dst += length;
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t = (unsigned long)src;
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if ((t | (unsigned long)dst) & wmask) {
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if ((t ^ (unsigned long)dst) & wmask || length <= wsize)
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t = length;
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else
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t &= wmask;
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length -= t;
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TLOOP1(*--dst = *--src);
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}
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t = length / wsize;
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TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src);
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t = length & wmask;
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TLOOP(*--dst = *--src);
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}
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}
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