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/** @file
Implementation of the InternalMemCopyMem routine. This function is broken
out into its own source file so that it can be excluded from a build for a
particular platform easily if an optimized version is desired.
Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2012 - 2013, ARM Ltd. All rights reserved.<BR>
Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#include "MemLibInternals.h"
/**
Copy Length bytes from Source to Destination.
@param DestinationBuffer The target of the copy request.
@param SourceBuffer The place to copy from.
@param Length The number of bytes to copy.
@return Destination
**/
VOID *
EFIAPI
InternalMemCopyMem (
OUT VOID *DestinationBuffer,
IN CONST VOID *SourceBuffer,
IN UINTN Length
)
{
//
// Declare the local variables that actually move the data elements as
// volatile to prevent the optimizer from replacing this function with
// the intrinsic memcpy()
//
volatile UINT8 *Destination8;
CONST UINT8 *Source8;
volatile UINT32 *Destination32;
CONST UINT32 *Source32;
volatile UINT64 *Destination64;
CONST UINT64 *Source64;
UINTN Alignment;
if ((((UINTN)DestinationBuffer & 0x7) == 0) && (((UINTN)SourceBuffer & 0x7) == 0) && (Length >= 8)) {
if (SourceBuffer > DestinationBuffer) {
Destination64 = (UINT64 *)DestinationBuffer;
Source64 = (CONST UINT64 *)SourceBuffer;
while (Length >= 8) {
*(Destination64++) = *(Source64++);
Length -= 8;
}
// Finish if there are still some bytes to copy
Destination8 = (UINT8 *)Destination64;
Source8 = (CONST UINT8 *)Source64;
while (Length-- != 0) {
*(Destination8++) = *(Source8++);
}
} else if (SourceBuffer < DestinationBuffer) {
Destination64 = (UINT64 *)((UINTN)DestinationBuffer + Length);
Source64 = (CONST UINT64 *)((UINTN)SourceBuffer + Length);
// Destination64 and Source64 were aligned on a 64-bit boundary
// but if length is not a multiple of 8 bytes then they won't be
// anymore.
Alignment = Length & 0x7;
if (Alignment != 0) {
Destination8 = (UINT8 *)Destination64;
Source8 = (CONST UINT8 *)Source64;
while (Alignment-- != 0) {
*(--Destination8) = *(--Source8);
--Length;
}
Destination64 = (UINT64 *)Destination8;
Source64 = (CONST UINT64 *)Source8;
}
while (Length > 0) {
*(--Destination64) = *(--Source64);
Length -= 8;
}
}
} else if ((((UINTN)DestinationBuffer & 0x3) == 0) && (((UINTN)SourceBuffer & 0x3) == 0) && (Length >= 4)) {
if (SourceBuffer > DestinationBuffer) {
Destination32 = (UINT32 *)DestinationBuffer;
Source32 = (CONST UINT32 *)SourceBuffer;
while (Length >= 4) {
*(Destination32++) = *(Source32++);
Length -= 4;
}
// Finish if there are still some bytes to copy
Destination8 = (UINT8 *)Destination32;
Source8 = (CONST UINT8 *)Source32;
while (Length-- != 0) {
*(Destination8++) = *(Source8++);
}
} else if (SourceBuffer < DestinationBuffer) {
Destination32 = (UINT32 *)((UINTN)DestinationBuffer + Length);
Source32 = (CONST UINT32 *)((UINTN)SourceBuffer + Length);
// Destination32 and Source32 were aligned on a 32-bit boundary
// but if length is not a multiple of 4 bytes then they won't be
// anymore.
Alignment = Length & 0x3;
if (Alignment != 0) {
Destination8 = (UINT8 *)Destination32;
Source8 = (CONST UINT8 *)Source32;
while (Alignment-- != 0) {
*(--Destination8) = *(--Source8);
--Length;
}
Destination32 = (UINT32 *)Destination8;
Source32 = (CONST UINT32 *)Source8;
}
while (Length > 0) {
*(--Destination32) = *(--Source32);
Length -= 4;
}
}
} else {
if (SourceBuffer > DestinationBuffer) {
Destination8 = (UINT8 *)DestinationBuffer;
Source8 = (CONST UINT8 *)SourceBuffer;
while (Length-- != 0) {
*(Destination8++) = *(Source8++);
}
} else if (SourceBuffer < DestinationBuffer) {
Destination8 = (UINT8 *)DestinationBuffer + (Length - 1);
Source8 = (CONST UINT8 *)SourceBuffer + (Length - 1);
while (Length-- != 0) {
*(Destination8--) = *(Source8--);
}
}
}
return DestinationBuffer;
}
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