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Create a branch for network fixes.

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svn path=/branches/aicom-network-fixes/; revision=34994
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Art Yerkes 2008-08-01 11:32:26 +00:00
parent 0e213bbc00
commit c501d8112c
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lib/sdk/crt/math/i386/aulldiv_asm.s Normal file
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/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* PURPOSE: Run-Time Library
* FILE: lib/rtl/i386/aulldiv_asm.S
* PROGRAMER: Alex Ionescu (alex@relsoft.net)
*
* Copyright (C) 2002 Michael Ringgaard.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES// LOSS OF USE, DATA, OR PROFITS// OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
.globl __aulldiv
.intel_syntax noprefix
/* FUNCTIONS ***************************************************************/
//
// ulldiv - unsigned long divide
//
// Purpose:
// Does a unsigned long divide of the arguments. Arguments are
// not changed.
//
// Entry:
// Arguments are passed on the stack:
// 1st pushed: divisor (QWORD)
// 2nd pushed: dividend (QWORD)
//
// Exit:
// EDX:EAX contains the quotient (dividend/divisor)
// NOTE: this routine removes the parameters from the stack.
//
// Uses:
// ECX
//
__aulldiv:
push ebx
push esi
// Set up the local stack and save the index registers. When this is done
// the stack frame will look as follows (assuming that the expression a/b will
// generate a call to uldiv(a, b)):
//
// -----------------
// | |
// |---------------|
// | |
// |--divisor (b)--|
// | |
// |---------------|
// | |
// |--dividend (a)-|
// | |
// |---------------|
// | return addr** |
// |---------------|
// | EBX |
// |---------------|
// ESP---->| ESI |
// -----------------
//
#undef DVNDLO
#undef DVNDHI
#undef DVSRLO
#undef DVSRHI
#define DVNDLO [esp + 12] // stack address of dividend (a)
#define DVNDHI [esp + 16] // stack address of dividend (a)
#define DVSRLO [esp + 20] // stack address of divisor (b)
#define DVSRHI [esp + 24] // stack address of divisor (b)
//
// Now do the divide. First look to see if the divisor is less than 4194304K.
// If so, then we can use a simple algorithm with word divides, otherwise
// things get a little more complex.
//
mov eax,DVSRHI // check to see if divisor < 4194304K
or eax,eax
jnz short ..L1 // nope, gotta do this the hard way
mov ecx,DVSRLO // load divisor
mov eax,DVNDHI // load high word of dividend
xor edx,edx
div ecx // get high order bits of quotient
mov ebx,eax // save high bits of quotient
mov eax,DVNDLO // edx:eax <- remainder:lo word of dividend
div ecx // get low order bits of quotient
mov edx,ebx // edx:eax <- quotient hi:quotient lo
jmp short ..L2 // restore stack and return
//
// Here we do it the hard way. Remember, eax contains DVSRHI
//
..L1:
mov ecx,eax // ecx:ebx <- divisor
mov ebx,DVSRLO
mov edx,DVNDHI // edx:eax <- dividend
mov eax,DVNDLO
..L3:
shr ecx,1 // shift divisor right one bit// hi bit <- 0
rcr ebx,1
shr edx,1 // shift dividend right one bit// hi bit <- 0
rcr eax,1
or ecx,ecx
jnz short ..L3 // loop until divisor < 4194304K
div ebx // now divide, ignore remainder
mov esi,eax // save quotient
//
// We may be off by one, so to check, we will multiply the quotient
// by the divisor and check the result against the orignal dividend
// Note that we must also check for overflow, which can occur if the
// dividend is close to 2**64 and the quotient is off by 1.
//
mul dword ptr DVSRHI // QUOT * DVSRHI
mov ecx,eax
mov eax,DVSRLO
mul esi // QUOT * DVSRLO
add edx,ecx // EDX:EAX = QUOT * DVSR
jc short ..L4 // carry means Quotient is off by 1
//
// do long compare here between original dividend and the result of the
// multiply in edx:eax. If original is larger or equal, we are ok, otherwise
// subtract one (1) from the quotient.
//
cmp edx,DVNDHI // compare hi words of result and original
ja short ..L4 // if result > original, do subtract
jb short ..L5 // if result < original, we are ok
cmp eax,DVNDLO // hi words are equal, compare lo words
jbe short ..L5 // if less or equal we are ok, else subtract
..L4:
dec esi // subtract 1 from quotient
..L5:
xor edx,edx // edx:eax <- quotient
mov eax,esi
//
// Just the cleanup left to do. edx:eax contains the quotient.
// Restore the saved registers and return.
//
..L2:
pop esi
pop ebx
ret 16