Separated math and memory functions into their own files to limit the amount of objec...
[reactos.git] / reactos / lib / rtl / i386 / allmul_asm.s
1 /*
2 * COPYRIGHT: See COPYING in the top level directory
3 * PROJECT: ReactOS kernel
4 * PURPOSE: Run-Time Library
5 * FILE: lib/rtl/i386/allmul.S
6 * PROGRAMER: Alex Ionescu (alex@relsoft.net)
7 * Eric Kohl (ekohl@rz-online.de)
8 *
9 * Copyright (C) 2002 Michael Ringgaard.
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 *
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. Neither the name of the project nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES// LOSS OF USE, DATA, OR PROFITS// OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38 .globl __allmul
39
40 /* DATA ********************************************************************/
41
42 fzero:
43 .long 0 // Floating point zero
44 .long 0 // Floating point zero
45
46 __fltused:
47 .long 0x9875
48
49 .intel_syntax noprefix
50
51 /* FUNCTIONS ***************************************************************/
52
53 //
54 // llmul - long multiply routine
55 //
56 // Purpose:
57 // Does a long multiply (same for signed/unsigned)
58 // Parameters are not changed.
59 //
60 // Entry:
61 // Parameters are passed on the stack:
62 // 1st pushed: multiplier (QWORD)
63 // 2nd pushed: multiplicand (QWORD)
64 //
65 // Exit:
66 // EDX:EAX - product of multiplier and multiplicand
67 // NOTE: parameters are removed from the stack
68 //
69 // Uses:
70 // ECX
71 //
72
73 __allmul:
74
75 #define ALO [esp + 4] // stack address of a
76 #define AHI [esp + 8] // stack address of a
77 #define BLO [esp + 12] // stack address of b
78 #define BHI [esp + 16] // stack address of b
79
80 //
81 // AHI, BHI : upper 32 bits of A and B
82 // ALO, BLO : lower 32 bits of A and B
83 //
84 // ALO * BLO
85 // ALO * BHI
86 // + BLO * AHI
87 // ---------------------
88 //
89
90 mov eax,AHI
91 mov ecx,BHI
92 or ecx,eax //test for both hiwords zero.
93 mov ecx,BLO
94 jnz short hard //both are zero, just mult ALO and BLO
95
96 mov eax,AHI
97 mul ecx
98
99 ret 16 // callee restores the stack
100
101 hard:
102 push ebx
103
104 // must redefine A and B since esp has been altered
105
106 #define A2LO [esp + 4] // stack address of a
107 #define A2HI [esp + 8] // stack address of a
108 #define B2LO [esp + 12] // stack address of b
109 #define B2HI [esp + 16] // stack address of b
110
111 mul ecx //eax has AHI, ecx has BLO, so AHI * BLO
112 mov ebx,eax //save result
113
114 mov eax,A2LO
115 mul dword ptr B2HI //ALO * BHI
116 add ebx,eax //ebx = ((ALO * BHI) + (AHI * BLO))
117
118 mov eax,A2LO //ecx = BLO
119 mul ecx //so edx:eax = ALO*BLO
120 add edx,ebx //now edx has all the LO*HI stuff
121
122 pop ebx
123
124 ret 16 // callee restores the stack
125