[41604] | 1 | ; $Id: __U4D.asm 98103 2023-01-17 14:15:46Z vboxsync $
|
---|
| 2 | ;; @file
|
---|
| 3 | ; Compiler support routines.
|
---|
| 4 | ;
|
---|
| 5 |
|
---|
| 6 | ;
|
---|
[98103] | 7 | ; Copyright (C) 2012-2023 Oracle and/or its affiliates.
|
---|
[41604] | 8 | ;
|
---|
[96407] | 9 | ; This file is part of VirtualBox base platform packages, as
|
---|
| 10 | ; available from https://www.virtualbox.org.
|
---|
[41604] | 11 | ;
|
---|
[96407] | 12 | ; This program is free software; you can redistribute it and/or
|
---|
| 13 | ; modify it under the terms of the GNU General Public License
|
---|
| 14 | ; as published by the Free Software Foundation, in version 3 of the
|
---|
| 15 | ; License.
|
---|
| 16 | ;
|
---|
| 17 | ; This program is distributed in the hope that it will be useful, but
|
---|
| 18 | ; WITHOUT ANY WARRANTY; without even the implied warranty of
|
---|
| 19 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
---|
| 20 | ; General Public License for more details.
|
---|
| 21 | ;
|
---|
| 22 | ; You should have received a copy of the GNU General Public License
|
---|
| 23 | ; along with this program; if not, see <https://www.gnu.org/licenses>.
|
---|
| 24 | ;
|
---|
| 25 | ; SPDX-License-Identifier: GPL-3.0-only
|
---|
| 26 | ;
|
---|
[41604] | 27 |
|
---|
| 28 |
|
---|
| 29 | ;*******************************************************************************
|
---|
| 30 | ;* Exported Symbols *
|
---|
| 31 | ;*******************************************************************************
|
---|
| 32 | public __U4D
|
---|
| 33 |
|
---|
[86686] | 34 | ; MASM (ML.EXE) is used for PXE and no longer understands the .8086 directive.
|
---|
| 35 | ; WASM is used for the BIOS and understands it just fine.
|
---|
| 36 | ifdef __WASM__
|
---|
[60484] | 37 | .8086
|
---|
[86686] | 38 | endif
|
---|
[41604] | 39 |
|
---|
[86686] | 40 |
|
---|
[60484] | 41 | if VBOX_BIOS_CPU lt 80386
|
---|
| 42 | extrn _DoUInt32Div:near
|
---|
| 43 | endif
|
---|
[41604] | 44 |
|
---|
| 45 |
|
---|
| 46 | _TEXT segment public 'CODE' use16
|
---|
| 47 | assume cs:_TEXT
|
---|
| 48 |
|
---|
| 49 |
|
---|
| 50 | ;;
|
---|
| 51 | ; 32-bit unsigned division.
|
---|
| 52 | ;
|
---|
| 53 | ; @param dx:ax Dividend.
|
---|
| 54 | ; @param cx:bx Divisor.
|
---|
| 55 | ; @returns dx:ax Quotient.
|
---|
[58723] | 56 | ; cx:bx Remainder.
|
---|
[41604] | 57 | ;
|
---|
| 58 | __U4D:
|
---|
| 59 | pushf
|
---|
[60484] | 60 | if VBOX_BIOS_CPU ge 80386
|
---|
| 61 | .386
|
---|
[41604] | 62 | push eax
|
---|
| 63 | push edx
|
---|
| 64 | push ecx
|
---|
| 65 |
|
---|
| 66 | rol eax, 16
|
---|
| 67 | mov ax, dx
|
---|
| 68 | ror eax, 16
|
---|
| 69 | xor edx, edx
|
---|
| 70 |
|
---|
| 71 | shr ecx, 16
|
---|
| 72 | mov cx, bx
|
---|
| 73 |
|
---|
[58723] | 74 | div ecx ; eax:edx / ecx -> eax=quotient, edx=remainder.
|
---|
[41604] | 75 |
|
---|
| 76 | mov bx, dx
|
---|
| 77 | pop ecx
|
---|
| 78 | shr edx, 16
|
---|
| 79 | mov cx, dx
|
---|
| 80 |
|
---|
| 81 | pop edx
|
---|
| 82 | ror eax, 16
|
---|
| 83 | mov dx, ax
|
---|
| 84 | add sp, 2
|
---|
| 85 | pop ax
|
---|
| 86 | rol eax, 16
|
---|
[86686] | 87 | ifdef __WASM__
|
---|
[60484] | 88 | .8086
|
---|
[86686] | 89 | endif
|
---|
[60484] | 90 | else
|
---|
[75248] | 91 | ;
|
---|
| 92 | ; If the divisor is only 16-bit, use a fast path
|
---|
| 93 | ;
|
---|
| 94 | test cx, cx
|
---|
| 95 | jnz do_it_the_hard_way
|
---|
[75263] | 96 |
|
---|
[75248] | 97 | div bx ; dx:ax / bx -> ax=quotient, dx=remainder
|
---|
[41604] | 98 |
|
---|
[75248] | 99 | mov bx, dx ; remainder in cx:bx, and we know cx=0
|
---|
| 100 |
|
---|
| 101 | xor dx, dx ; quotient in dx:ax, dx must be zero
|
---|
| 102 |
|
---|
| 103 | popf
|
---|
| 104 | ret
|
---|
| 105 |
|
---|
| 106 | do_it_the_hard_way:
|
---|
[60484] | 107 | ; Call C function do this.
|
---|
| 108 | push ds
|
---|
| 109 | push es
|
---|
[41604] | 110 |
|
---|
[60484] | 111 | ;
|
---|
| 112 | ; Convert to a C __cdecl call - not doing this in assembly.
|
---|
| 113 | ;
|
---|
[41604] | 114 |
|
---|
[60530] | 115 | ; Set up a frame of sorts, allocating 4 bytes for the result buffer.
|
---|
[60484] | 116 | push bp
|
---|
[60530] | 117 | sub sp, 04h
|
---|
[60484] | 118 | mov bp, sp
|
---|
[42059] | 119 |
|
---|
[60484] | 120 | ; Pointer to the return buffer.
|
---|
| 121 | push ss
|
---|
| 122 | push bp
|
---|
[60530] | 123 | add bp, 04h ; Correct bp.
|
---|
[42059] | 124 |
|
---|
[60484] | 125 | ; The divisor.
|
---|
| 126 | push cx
|
---|
| 127 | push bx
|
---|
[42059] | 128 |
|
---|
[60484] | 129 | ; The dividend.
|
---|
| 130 | push dx
|
---|
| 131 | push ax
|
---|
[42059] | 132 |
|
---|
[60484] | 133 | call _DoUInt32Div
|
---|
[42059] | 134 |
|
---|
[60530] | 135 | ; Load the remainder.
|
---|
| 136 | mov cx, [bp - 02h]
|
---|
| 137 | mov bx, [bp - 04h]
|
---|
[42059] | 138 |
|
---|
[60530] | 139 | ; The quotient is already in dx:ax
|
---|
[42059] | 140 |
|
---|
[60484] | 141 | mov sp, bp
|
---|
| 142 | pop bp
|
---|
| 143 | pop es
|
---|
| 144 | pop ds
|
---|
| 145 | endif
|
---|
[41604] | 146 | popf
|
---|
| 147 | ret
|
---|
| 148 |
|
---|
| 149 | _TEXT ends
|
---|
| 150 | end
|
---|
| 151 |
|
---|