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.nasm
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    SECTION .text
24
25extern ASM_PFX(InternalMathDivRemU64x32)
26
27;------------------------------------------------------------------------------
28; UINT64
29; EFIAPI
30; InternalMathDivRemU64x64 (
31;   IN      UINT64                    Dividend,
32;   IN      UINT64                    Divisor,
33;   OUT     UINT64                    *Remainder    OPTIONAL
34;   );
35;------------------------------------------------------------------------------
36global ASM_PFX(InternalMathDivRemU64x64)
37ASM_PFX(InternalMathDivRemU64x64):
38    mov     ecx, [esp + 16]             ; ecx <- divisor[32..63]
39    test    ecx, ecx
40    jnz     _@DivRemU64x64              ; call _@DivRemU64x64 if Divisor > 2^32
41    mov     ecx, [esp + 20]
42    jecxz   .0
43    and     dword [ecx + 4], 0      ; zero high dword of remainder
44    mov     [esp + 16], ecx             ; set up stack frame to match DivRemU64x32
45.0:
46    jmp     ASM_PFX(InternalMathDivRemU64x32)
47
48_@DivRemU64x64:
49    push    ebx
50    push    esi
51    push    edi
52    mov     edx, dword [esp + 20]
53    mov     eax, dword [esp + 16]   ; edx:eax <- dividend
54    mov     edi, edx
55    mov     esi, eax                    ; edi:esi <- dividend
56    mov     ebx, dword [esp + 24]   ; ecx:ebx <- divisor
57.1:
58    shr     edx, 1
59    rcr     eax, 1
60    shrd    ebx, ecx, 1
61    shr     ecx, 1
62    jnz     .1
63    div     ebx
64    mov     ebx, eax                    ; ebx <- quotient
65    mov     ecx, [esp + 28]             ; ecx <- high dword of divisor
66    mul     dword [esp + 24]        ; edx:eax <- quotient * divisor[0..31]
67    imul    ecx, ebx                    ; ecx <- quotient * divisor[32..63]
68    add     edx, ecx                    ; edx <- (quotient * divisor)[32..63]
69    mov     ecx, dword [esp + 32]   ; ecx <- addr for Remainder
70    jc      @TooLarge                   ; product > 2^64
71    cmp     edi, edx                    ; compare high 32 bits
72    ja      @Correct
73    jb      @TooLarge                   ; product > dividend
74    cmp     esi, eax
75    jae     @Correct                    ; product <= dividend
76@TooLarge:
77    dec     ebx                         ; adjust quotient by -1
78    jecxz   @Return                     ; return if Remainder == NULL
79    sub     eax, dword [esp + 24]
80    sbb     edx, dword [esp + 28]   ; edx:eax <- (quotient - 1) * divisor
81@Correct:
82    jecxz   @Return
83    sub     esi, eax
84    sbb     edi, edx                    ; edi:esi <- remainder
85    mov     [ecx], esi
86    mov     [ecx + 4], edi
87@Return:
88    mov     eax, ebx                    ; eax <- quotient
89    xor     edx, edx                    ; quotient is 32 bits long
90    pop     edi
91    pop     esi
92    pop     ebx
93    ret
94
95