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)
8 * Copyright (C) 2002 Michael Ringgaard.
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12 * modification, are permitted provided that the following conditions
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16 * notice, this list of conditions and the following disclaimer.
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20 * 3. Neither the name of the project nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
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37 #include <reactos/asm.h>
41 /* FUNCTIONS ***************************************************************/
45 // llmul - long multiply routine
48 // Does a long multiply (same for signed/unsigned)
49 // Parameters are not changed.
52 // Parameters are passed on the stack:
53 // 1st pushed: multiplier (QWORD)
54 // 2nd pushed: multiplicand (QWORD)
57 // EDX:EAX - product of multiplier and multiplicand
58 // NOTE: parameters are removed from the stack
66 #define ALO [esp + 4] // stack address of a
67 #define AHI [esp + 8] // stack address of a
68 #define BLO [esp + 12] // stack address of b
69 #define BHI [esp + 16] // stack address of b
72 // AHI, BHI : upper 32 bits of A and B
73 // ALO, BLO : lower 32 bits of A and B
78 // ---------------------
83 or ecx,eax //test for both hiwords zero.
85 jnz short hard //both are zero, just mult ALO and BLO
90 ret 16 // callee restores the stack
95 // must redefine A and B since esp has been altered
97 #define A2LO [esp + 8] // stack address of a
98 #define A2HI [esp + 12] // stack address of a
99 #define B2LO [esp + 16] // stack address of b
100 #define B2HI [esp + 20] // stack address of b
102 mul ecx //eax has AHI, ecx has BLO, so AHI * BLO
103 mov ebx,eax //save result
106 mul dword ptr B2HI //ALO * BHI
107 add ebx,eax //ebx = ((ALO * BHI) + (AHI * BLO))
109 mov eax,A2LO //ecx = BLO
110 mul ecx //so edx:eax = ALO*BLO
111 add edx,ebx //now edx has all the LO*HI stuff
115 ret 16 // callee restores the stack