1;------------------------------------------------------------------------------
2;
3; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
4; This program and the accompanying materials
5; are licensed and made available under the terms and conditions of the BSD License
6; which accompanies this distribution.  The full text of the license may be found at
7; http://opensource.org/licenses/bsd-license.php.
8;
9; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
10; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
11;
12; Module Name:
13;
14;   DivU64x64Remainder.asm
15;
16; Abstract:
17;
18;   Calculate the quotient of a 64-bit integer by a 64-bit integer and returns
19;   both the quotient and the remainder
20;
21;------------------------------------------------------------------------------
22
23    .386
24    .model  flat,C
25    .code
26
27EXTERN  InternalMathDivRemU64x32:PROC
28
29;------------------------------------------------------------------------------
30; UINT64
31; EFIAPI
32; InternalMathDivRemU64x64 (
33;   IN      UINT64                    Dividend,
34;   IN      UINT64                    Divisor,
35;   OUT     UINT64                    *Remainder    OPTIONAL
36;   );
37;------------------------------------------------------------------------------
38InternalMathDivRemU64x64    PROC
39    mov     ecx, [esp + 16]             ; ecx <- divisor[32..63]
40    test    ecx, ecx
41    jnz     _@DivRemU64x64              ; call _@DivRemU64x64 if Divisor > 2^32
42    mov     ecx, [esp + 20]
43    jecxz   @F
44    and     dword ptr [ecx + 4], 0      ; zero high dword of remainder
45    mov     [esp + 16], ecx             ; set up stack frame to match DivRemU64x32
46@@:
47    jmp     InternalMathDivRemU64x32
48InternalMathDivRemU64x64    ENDP
49
50_@DivRemU64x64  PROC    USES    ebx esi edi
51    mov     edx, dword ptr [esp + 20]
52    mov     eax, dword ptr [esp + 16]   ; edx:eax <- dividend
53    mov     edi, edx
54    mov     esi, eax                    ; edi:esi <- dividend
55    mov     ebx, dword ptr [esp + 24]   ; ecx:ebx <- divisor
56@@:
57    shr     edx, 1
58    rcr     eax, 1
59    shrd    ebx, ecx, 1
60    shr     ecx, 1
61    jnz     @B
62    div     ebx
63    mov     ebx, eax                    ; ebx <- quotient
64    mov     ecx, [esp + 28]             ; ecx <- high dword of divisor
65    mul     dword ptr [esp + 24]        ; edx:eax <- quotient * divisor[0..31]
66    imul    ecx, ebx                    ; ecx <- quotient * divisor[32..63]
67    add     edx, ecx                    ; edx <- (quotient * divisor)[32..63]
68    mov     ecx, dword ptr [esp + 32]   ; ecx <- addr for Remainder
69    jc      @TooLarge                   ; product > 2^64
70    cmp     edi, edx                    ; compare high 32 bits
71    ja      @Correct
72    jb      @TooLarge                   ; product > dividend
73    cmp     esi, eax
74    jae     @Correct                    ; product <= dividend
75@TooLarge:
76    dec     ebx                         ; adjust quotient by -1
77    jecxz   @Return                     ; return if Remainder == NULL
78    sub     eax, dword ptr [esp + 24]
79    sbb     edx, dword ptr [esp + 28]   ; edx:eax <- (quotient - 1) * divisor
80@Correct:
81    jecxz   @Return
82    sub     esi, eax
83    sbb     edi, edx                    ; edi:esi <- remainder
84    mov     [ecx], esi
85    mov     [ecx + 4], edi
86@Return:
87    mov     eax, ebx                    ; eax <- quotient
88    xor     edx, edx                    ; quotient is 32 bits long
89    ret
90_@DivRemU64x64  ENDP
91
92    END
93