MdePkg/BaseMemoryLib: widen aligned accesses to 32 or 64 bits
Since the default BaseMemoryLib should be callable from any context, including ones where unaligned accesses are not allowed, it implements InternalCopyMem() and InternalSetMem() using byte accesses only. However, especially in a context where the MMU is off, such narrow accesses may be disproportionately costly, and so if the size and alignment of the access allow it, use 32-bit or even 64-bit loads and stores (the latter may be beneficial even on a 32-bit architectures like ARM, which has load pair/store pair instructions) Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Liming Gao <liming.gao@intel.com>
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@@ -5,6 +5,9 @@
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is desired.
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Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
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Copyright (c) 2012 - 2013, ARM Ltd. All rights reserved.<BR>
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Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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@@ -43,11 +46,42 @@ InternalMemSetMem (
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// volatile to prevent the optimizer from replacing this function with
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// the intrinsic memset()
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//
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volatile UINT8 *Pointer;
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volatile UINT8 *Pointer8;
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volatile UINT32 *Pointer32;
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volatile UINT64 *Pointer64;
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UINT32 Value32;
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UINT64 Value64;
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Pointer = (UINT8*)Buffer;
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if ((((UINTN)Buffer & 0x7) == 0) && (Length >= 8)) {
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// Generate the 64bit value
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Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
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Value64 = LShiftU64 (Value32, 32) | Value32;
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Pointer64 = (UINT64*)Buffer;
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while (Length >= 8) {
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*(Pointer64++) = Value64;
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Length -= 8;
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}
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// Finish with bytes if needed
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Pointer8 = (UINT8*)Pointer64;
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} else if ((((UINTN)Buffer & 0x3) == 0) && (Length >= 4)) {
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// Generate the 32bit value
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Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
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Pointer32 = (UINT32*)Buffer;
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while (Length >= 4) {
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*(Pointer32++) = Value32;
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Length -= 4;
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}
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// Finish with bytes if needed
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Pointer8 = (UINT8*)Pointer32;
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} else {
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Pointer8 = (UINT8*)Buffer;
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}
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while (Length-- > 0) {
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*(Pointer++) = Value;
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*(Pointer8++) = Value;
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}
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return Buffer;
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}
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