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#/*++
#
#Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
#This program and the accompanying materials
#are licensed and made available under the terms and conditions of the BSD License
#which accompanies this distribution. The full text of the license may be found at
#http://opensource.org/licenses/bsd-license.php
#
#THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
#WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
#
#Module Name:
#
# EfiCopyMem.c
#
#Abstract:
#
# This is the code that supports IA32-optimized CopyMem service
#
#--*/
#include "EfiBind.h"
#---------------------------------------------------------------------------
.686:
#.MODEL flat,C
.mmx:
.code:
#---------------------------------------------------------------------------
.globl ASM_PFX(EfiCommonLibCopyMem)
#VOID
#EfiCommonLibCopyMem (
# IN VOID *Destination,
# IN VOID *Source,
# IN UINTN Count
# )
#/*++
#
#Routine Description:
#
# Copy Length bytes from Source to Destination.
#
#Arguments:
#
# Destination - Target of copy
#
# Source - Place to copy from
#
# Length - Number of bytes to copy
#
#Returns:
#
# None
#
#--*/
ASM_PFX(EfiCommonLibCopyMem):
pushl %ebp
movl %esp, %ebp
pushl %ecx # reserve space for Scratch Local variable UINT64 MmxSave
pushl %ecx
pushl %esi
pushl %edi
movl 0x10(%ebp), %ecx # Count
movl 0xC(%ebp), %esi # Source
movl 8(%ebp), %edi # Destination
##First off, make sure we have no overlap. That is to say,
## if (Source == Destination) => do nothing
## if (Source + Count <= Destination) => regular copy
## if (Destination + Count <= Source) => regular copy
## otherwise, do a reverse copy
movl %esi, %eax
addl %ecx, %eax # Source + Count
cmpl %edi, %eax
jle _StartByteCopy
movl %edi, %eax
addl %ecx, %eax # Dest + Count
cmpl %esi, %eax
jle _StartByteCopy
cmpl %edi, %esi
je _CopyMemDone
jl _CopyOverlapped # too bad -- overlaps
# Pick up misaligned start bytes to get destination pointer 4-byte aligned
_StartByteCopy:
cmpl $0, %ecx
je _CopyMemDone # Count == 0, all done
movl %edi, %edx
andb $3, %dl # check lower 2 bits of address
testb %dl, %dl
je _CopyBlocks # already aligned?
# Copy a byte
movb (%esi), %al # get byte from Source
movb %al, (%edi) # write byte to Destination
decl %ecx
incl %edi
incl %esi
jmp _StartByteCopy # back to top of loop
_CopyBlocks:
# Compute how many 64-byte blocks we can clear
movl %ecx, %eax # get Count in eax
shrl $6, %eax # convert to 64-byte count
shll $6, %eax # convert back to bytes
subl %eax, %ecx # subtract from the original count
shrl $6, %eax # and this is how many 64-byte blocks
# If no 64-byte blocks, then skip
cmpl $0, %eax
je _CopyRemainingDWords
# Save mm0 to UINT64 MmxSave
movq %mm0, -8(%ebp)
copymmx:
movq %ds:(%esi), %mm0
movq %mm0, %ds:(%edi)
movq %ds:8(%esi), %mm0
movq %mm0, %ds:8(%edi)
movq %ds:16(%esi), %mm0
movq %mm0, %ds:16(%edi)
movq %ds:24(%esi), %mm0
movq %mm0, %ds:24(%edi)
movq %ds:32(%esi), %mm0
movq %mm0, %ds:32(%edi)
movq %ds:40(%esi), %mm0
movq %mm0, %ds:40(%edi)
movq %ds:48(%esi), %mm0
movq %mm0, %ds:48(%edi)
movq %ds:56(%esi), %mm0
movq %mm0, %ds:56(%edi)
addl $64, %edi
addl $64, %esi
decl %eax
jnz copymmx
# Restore mm0 from MmxSave
movq -8(%ebp), %mm0
emms # Exit MMX Instruction
# Copy as many DWORDS as possible
_CopyRemainingDWords:
cmpl $4, %ecx
jb _CopyRemainingBytes
movl (%esi), %eax # get data from Source
movl %eax, (%edi) # write byte to Destination
subl $4, %ecx # decrement Count
addl $4, %esi # advance Source pointer
addl $4, %edi # advance Destination pointer
jmp _CopyRemainingDWords # back to top
_CopyRemainingBytes:
cmpl $0, %ecx
je _CopyMemDone
movb (%esi), %al # get byte from Source
movb %al, (%edi) # write byte to Destination
decl %ecx
incl %esi
incl %edi # advance Destination pointer
jmp _CopyRemainingBytes # back to top of loop
#
# We do this block if the source and destination buffers overlap. To
# handle it, copy starting at the end of the source buffer and work
# your way back. Since this is the atypical case, this code has not
# been optimized, and thus simply copies bytes.
#
_CopyOverlapped:
# Move the source and destination pointers to the end of the range
addl %ecx, %esi # Source + Count
decl %esi
addl %ecx, %edi # Dest + Count
decl %edi
_CopyOverlappedLoop:
cmpl $0, %ecx
je _CopyMemDone
movb (%esi), %al # get byte from Source
movb %al, (%edi) # write byte to Destination
decl %ecx
decl %esi
decl %edi
jmp _CopyOverlappedLoop # back to top of loop
_CopyMemDone:
popl %edi
popl %esi
leave
ret
#EfiCommonLibCopyMem ENDP
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