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sortix--sortix/libc/string/memcpy.c
2021-05-30 23:48:19 +02:00

139 lines
3.7 KiB
C

/*
* Copyright (c) 2011, 2012, 2014, 2015, 2016 Jonas 'Sortie' Termansen.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* string/memcpy.c
* Copy memory between non-overlapping regions.
*/
#include <scram.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#if defined(__is_sortix_libk)
#include <libk.h>
#endif
inline static
void* memcpy_slow(void* restrict dst_ptr,
const void* restrict src_ptr,
size_t size)
{
unsigned char* restrict dst = (unsigned char* restrict) dst_ptr;
const unsigned char* restrict src = (const unsigned char* restrict) src_ptr;
for ( size_t i = 0; i < size; i++ )
dst[i] = src[i];
return dst_ptr;
}
void* memcpy(void* restrict dst_ptr,
const void* restrict src_ptr,
size_t size)
{
if ( dst_ptr == src_ptr || !size )
return dst_ptr;
void* dst_end = (char*) dst_ptr + size;
const void* src_end = (const const char*) src_ptr + size;
if ( (dst_ptr < src_ptr && src_ptr < dst_end) ||
(src_ptr < dst_ptr && dst_ptr < src_end) )
{
#if defined(__is_sortix_libk)
libk_overlapping_memcpy();
#else
struct scram_undefined_behavior info;
info.filename = __FILE__;
info.line = __LINE__;
info.column = 0;
info.violation = "overlapping memcpy";
scram(SCRAM_UNDEFINED_BEHAVIOR, &info);
#endif
}
#if 8 < __SIZEOF_LONG__
#warning "you should add support for your unexpectedly large unsigned long."
return memcpy_slow(dst_ptr, src_ptr, size);
#else
unsigned long unalign_mask = sizeof(unsigned long) - 1;
unsigned long src_unalign = (unsigned long) src_ptr & unalign_mask;
unsigned long dst_unalign = (unsigned long) dst_ptr & unalign_mask;
if ( src_unalign != dst_unalign )
return memcpy_slow(dst_ptr, src_ptr, size);
union
{
unsigned long srcval;
const unsigned char* restrict src8;
const uint16_t* restrict src16;
const uint32_t* restrict src32;
const uint64_t* restrict src64;
const unsigned long* restrict srcul;
} su;
su.srcval = (unsigned long) src_ptr;
union
{
unsigned long dstval;
unsigned char* restrict dst8;
uint16_t* restrict dst16;
uint32_t* restrict dst32;
uint64_t* restrict dst64;
unsigned long* restrict dstul;
} du;
du.dstval = (unsigned long) dst_ptr;
if ( dst_unalign )
{
if ( 1 <= size && !(du.dstval & (1-1)) && (du.dstval & (2-1)) )
*du.dst8++ = *su.src8++,
size -= 1;
if ( 2 <= size && !(du.dstval & (2-1)) && (du.dstval & (4-1)) )
*du.dst16++ = *su.src16++,
size -= 2;
#if 8 <= __SIZEOF_LONG__
if ( 4 <= size && !(du.dstval & (4-1)) && (du.dstval & (8-1)) )
*du.dst32++ = *su.src32++,
size -= 4;
#endif
}
size_t num_copies = size / sizeof(unsigned long);
for ( size_t i = 0; i < num_copies; i++ )
*du.dstul++ = *su.srcul++;
size -= num_copies * sizeof(unsigned long);
if ( size )
{
#if 8 <= __SIZEOF_LONG__
if ( 4 <= size )
*du.dst32++ = *su.src32++,
size -= 4;
#endif
if ( 2 <= size )
*du.dst16++ = *su.src16++,
size -= 2;
if ( 1 <= size )
*du.dst8++ = *su.src8++,
size -= 1;
}
return dst_ptr;
#endif
}