130 lines
3.6 KiB
C++
130 lines
3.6 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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string/memcpy.cpp
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Copy memory between non-overlapping regions.
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*******************************************************************************/
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#include <stdint.h>
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#include <string.h>
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#if 8 < __SIZEOF_LONG__
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#error unsigned long is bigger than expected, please add support to this file.
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#endif
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inline static void* memcpy_slow(void* restrict dstptr,
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const void* restrict srcptr, size_t length)
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{
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uint8_t* restrict dst = (uint8_t* restrict) dstptr;
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const uint8_t* restrict src = (const uint8_t* restrict) srcptr;
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for ( size_t i = 0; i < length; i += sizeof(uint8_t) )
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dst[i] = src[i];
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return dstptr;
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}
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extern "C" void* memcpy(void* restrict dstptr, const void* restrict srcptr,
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size_t length)
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{
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const unsigned long unalignmask = sizeof(unsigned long) - 1;
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const unsigned long srcunalign = (unsigned long) srcptr & unalignmask;
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const unsigned long dstunalign = (unsigned long) dstptr & unalignmask;
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if ( srcunalign != dstunalign )
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return memcpy_slow(dstptr, srcptr, length);
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union
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{
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unsigned long srcval;
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const uint8_t* restrict src8;
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const uint16_t* restrict src16;
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const uint32_t* restrict src32;
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const uint64_t* restrict src64;
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const unsigned long* restrict srcul;
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};
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srcval = (unsigned long) srcptr;
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union
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{
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unsigned long dstval;
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uint8_t* restrict dst8;
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uint16_t* restrict dst16;
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uint32_t* restrict dst32;
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uint64_t* restrict dst64;
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unsigned long* restrict dstul;
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};
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dstval = (unsigned long) dstptr;
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if ( dstunalign )
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{
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if ( 1 <= length && !(dstval & (1-1)) && (dstval & (2-1)) )
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*dst8++ = *src8++,
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length -= 1;
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if ( 2 <= length && !(dstval & (2-1)) && (dstval & (4-1)) )
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*dst16++ = *src16++,
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length -= 2;
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#if 8 <= __SIZEOF_LONG__
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if ( 4 <= length && !(dstval & (4-1)) && (dstval & (8-1)) )
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*dst32++ = *src32++,
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length -= 4;
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#endif
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}
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size_t numcopies = length / sizeof(unsigned long);
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#if 0
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#if defined(__x86_64__) || defined(__i386__)
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unsigned long zeroed_numcopies;
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#if defined(__x86_64__)
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asm volatile ("rep movsq" : "=c"(zeroed_numcopies), "=S"(srcul), "=D"(dstul)
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: "c"(numcopies), "S"(srcul), "D"(dstul)
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: "memory");
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#elif defined(__i386__)
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asm volatile ("rep movsd" : "=c"(zeroed_numcopies), "=S"(srcul), "=D"(dstul)
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: "c"(numcopies), "S"(srcul), "D"(dstul)
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: "memory");
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#endif
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#endif
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#else
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for ( size_t i = 0; i < numcopies; i++ )
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*dstul++ = *srcul++;
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#endif
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length -= numcopies * sizeof(unsigned long);
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if ( length )
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{
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#if 8 <= __SIZEOF_LONG__
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if ( 4 <= length )
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*dst32++ = *src32++,
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length -= 4;
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#endif
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if ( 2 <= length )
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*dst16++ = *src16++,
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length -= 2;
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if ( 1 <= length )
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*dst8++ = *src8++,
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length -= 1;
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}
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return dstptr;
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}
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