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;*************************************************************************
;*************************************************************************
;** **
;** (C)Copyright 1985-2009, American Megatrends, Inc. **
;** **
;** All Rights Reserved. **
;** **
;** 5555 Oakbrook Parkway, Suite 200, Norcross, GA 30093 **
;** **
;** Phone: (770)-246-8600 **
;** **
;*************************************************************************
;*************************************************************************
;*************************************************************************
; $Header: /Alaska/SOURCE/Core/Modules/x64Core/x64AsmLib/MemCpy.asm 2 3/09/11 1:58p Felixp $
;
; $Revision: 2 $
;
; $Date: 3/09/11 1:58p $
;*************************************************************************
; Revision History
; ----------------
; $Log: /Alaska/SOURCE/Core/Modules/x64Core/x64AsmLib/MemCpy.asm $
;
; 2 3/09/11 1:58p Felixp
; MemCpy is updated to copy 8 bytes at a time (used to be 4)
;
; 1 10/01/10 5:07p Felixp
;
; 1 8/24/06 12:57p Felixp
;
;*************************************************************************
;<AMI_FHDR_START>
;
; Name:
;
; Description:
;
;<AMI_FHDR_END>
;*************************************************************************
.code
;*************************************************************************
;<AMI_PHDR_START>
;
; Name: MemCpy
;
; Description:
; VOID MemCpy(OUT VOID *pDestination, IN VOID *pSource, IN UINTN Count)
; copies Count bytes of memory from Source to Destination.
;
; Input:
; OUT VOID *pDestination
; Memory address where data shall be copied. User is responsible for
; allocating the necessary memory resources.
;
; IN VOID *pSource
; Memory address from where data shall be copied.
;
; IN UINTN Count
; Number of bytes to copy from pSource.
;
; Output:
; VOID.
;
; Modified:
;
; Referrals:
;
; Notes:
; This function checks for overlapping of source and destination and
; selects copy direction that prevents memory corruption.
;
;<AMI_PHDR_END>
;*************************************************************************
public memcpy
memcpy:
MemCpy proc
push rdi
push rsi
push rbx
pushf
mov rsi, rdx ; pSource
mov rdi, rcx ; pDestination
mov rcx, r8 ; Count
mov dl, 0
; if pSource > pDestination CopyForward
mov rax, rsi
sub rax, rdi ; rax = pSource-pDestination
jnb CopyForward; if pSource-pDestination > 0 CopyForward
; if pSource+Count < pDestination then CopyForward
lea rbx, [rsi+rcx] ; rbx = pSource + Count
neg rax ; rax = pDestination - pSource
cmp rbx, rdi
jb CopyForward ; if (pSource + Count < pDestination ) CopyForward
; Copy Backward
mov rsi, rbx; rsi = pSource + Count
lea rdi, [rdi+rcx]; rdi = pDestination + Count
mov dl, 1; Flag to indicate that we are copying backward
std; set direction flag to copy backward
CopyForward:
cmp rcx, 8 ; if (Counter<8) copy byte by byte
jb m8
cmp rax, 8 ; if (pDestination - pSource < 8) copy byte by byte
jb m8
; if pSource and pDestination are not 8 byte aligned
; Calculate 8-(Buffer%8), which is a number of bytes we have to copy to align the buffer
; if this number if the same for source and destinations
; copy several bytes to align them
; otherwise proceed to QWORD copy
mov rax, rsi
mov rbx, rdi
and rax, 7
and rbx, 7
test dl, dl
jz skip1
dec rsi
dec rdi
skip1:
cmp rax, rbx
jne m64
test rax, rax
jz m64
test dl, dl
jnz skip_nz1
neg rax
add rax, 8
skip_nz1:
xchg rax, rcx
sub rax, rcx
rep movsb
mov rcx, rax
m64:
test dl, dl
jz skip2
sub rsi, 7
sub rdi, 7
skip2:
mov rax, rcx
shr rcx, 3
rep movsq
and rax, 7
jz MemCpuEnd
test dl, dl
jz skip3
add rsi, 8
add rdi, 8
skip3:
mov rcx, rax
m8:
test dl, dl
jz skip4
dec rsi
dec rdi
skip4:
rep movsb
MemCpuEnd:
popf
pop rbx
pop rsi
pop rdi
ret
MemCpy endp
END
;*************************************************************************
;*************************************************************************
;** **
;** (C)Copyright 1985-2009, American Megatrends, Inc. **
;** **
;** All Rights Reserved. **
;** **
;** 5555 Oakbrook Parkway, Suite 200, Norcross, GA 30093 **
;** **
;** Phone: (770)-246-8600 **
;** **
;*************************************************************************
|
