mirror of https://github.com/acidanthera/audk.git
67 lines
2.3 KiB
C
67 lines
2.3 KiB
C
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/** @file
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Calculate the quotient of a 64-bit integer by a 64-bit integer and returns
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both the quotient and the remainderSet error flag for all division functions
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Copyright (c) 2006 - 2007, Intel Corporation<BR>
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All rights reserved. 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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http://opensource.org/licenses/bsd-license.php
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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**/
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UINT64
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EFIAPI
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InternalMathDivRemU64x64 (
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IN UINT64 Dividend,
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IN UINT64 Divisor,
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OUT UINT64 *Remainder OPTIONAL
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)
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{
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_asm {
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mov edx, dword ptr [Dividend + 4]
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mov eax, dword ptr [Dividend + 0] // edx:eax <- dividend
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mov edi, edx
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mov esi, eax // edi:esi <- dividend
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mov ecx, dword ptr [Divisor + 4]
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mov ebx, dword ptr [Divisor + 0] // ecx:ebx <- divisor
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BitLoop:
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shr edx, 1
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rcr eax, 1
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shrd ebx, ecx, 1
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shr ecx, 1
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jnz BitLoop
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div ebx
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mov ebx, eax // ebx <- quotient
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mov ecx, dword ptr [Divisor + 4]
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mul dword ptr [Divisor]
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imul ecx, ebx
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add edx, ecx
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mov ecx, Remainder
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jc TooLarge // product > 2^64
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cmp edi, edx // compare high 32 bits
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ja Correct
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jb TooLarge // product > dividend
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cmp esi, eax
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jae Correct // product <= dividend
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TooLarge:
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dec ebx // adjust quotient by -1
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jecxz Return // return if Remainder == NULL
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sub eax, dword ptr [Divisor + 0]
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sbb edx, dword ptr [Divisor + 4]
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Correct:
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jecxz Return
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sub esi, eax
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sbb edi, edx // edi:esi <- remainder
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mov [ecx], esi
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mov [ecx + 4], edi
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Return:
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mov eax, ebx // eax <- quotient
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xor edx, edx
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}
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}
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