116 lines
2.3 KiB
C
116 lines
2.3 KiB
C
|
// Emacs style mode select -*- C++ -*-
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
//
|
||
|
|
// $Id:$
|
||
|
|
//
|
||
|
|
// Copyright (C) 1993-1996 by id Software, Inc.
|
||
|
|
//
|
||
|
|
// This source is available for distribution and/or modification
|
||
|
|
// only under the terms of the DOOM Source Code License as
|
||
|
|
// published by id Software. All rights reserved.
|
||
|
|
//
|
||
|
|
// The source is distributed in the hope that it will be useful,
|
||
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code License
|
||
|
|
// for more details.
|
||
|
|
//
|
||
|
|
// $Log:$
|
||
|
|
//
|
||
|
|
// DESCRIPTION:
|
||
|
|
// Fixed point implementation.
|
||
|
|
//
|
||
|
|
//-----------------------------------------------------------------------------
|
||
|
|
|
||
|
|
|
||
|
|
//static const char
|
||
|
|
|
||
|
|
#include "os.h"
|
||
|
|
|
||
|
|
#include "doomtype.h"
|
||
|
|
#include "i_system.h"
|
||
|
|
|
||
|
|
#ifdef __GNUG__
|
||
|
|
#pragma implementation "m_fixed.h"
|
||
|
|
#endif
|
||
|
|
#include "m_fixed.h"
|
||
|
|
|
||
|
|
|
||
|
|
// Fixme. __USE_C_FIXED__ or something.
|
||
|
|
//CGD: Bastl impl of int*int=>int64 , (int64 >>16) => int
|
||
|
|
fixed_t FixedMul( fixed_t a, fixed_t b )
|
||
|
|
{
|
||
|
|
int iResult;
|
||
|
|
unsigned int iNegative = (a<0) != (b <0);
|
||
|
|
unsigned int iMask = 1;
|
||
|
|
unsigned int iResLo = 0;
|
||
|
|
unsigned int iResHi = 0;
|
||
|
|
unsigned int iaHi = 0;
|
||
|
|
unsigned int ua = abs(a);
|
||
|
|
unsigned int ub = abs(b);
|
||
|
|
if(ua<ub) //swap
|
||
|
|
{
|
||
|
|
unsigned int uc = ua;
|
||
|
|
ua = ub;
|
||
|
|
ub = uc;
|
||
|
|
}
|
||
|
|
ASSERT((ub & 0x80000000)==0);
|
||
|
|
while(ub)
|
||
|
|
{
|
||
|
|
if(ub & iMask)
|
||
|
|
{
|
||
|
|
unsigned int iLo = iResLo + ua;
|
||
|
|
if(iLo < iResLo)
|
||
|
|
{
|
||
|
|
iResHi ++;
|
||
|
|
}
|
||
|
|
iResLo = iLo;
|
||
|
|
iResHi += iaHi;
|
||
|
|
ub &= ~iMask;
|
||
|
|
}
|
||
|
|
iMask <<= 1;
|
||
|
|
iaHi <<= 1;
|
||
|
|
if(ua & 0x80000000)
|
||
|
|
{
|
||
|
|
iaHi |= 1;
|
||
|
|
}
|
||
|
|
ua <<= 1;
|
||
|
|
}
|
||
|
|
iResLo >>= FRACBITS;
|
||
|
|
iResHi <<= FRACBITS;
|
||
|
|
iResult = iResHi | iResLo;
|
||
|
|
if(iNegative) iResult= -iResult;
|
||
|
|
return iResult;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
//
|
||
|
|
// FixedDiv, C version.
|
||
|
|
//
|
||
|
|
|
||
|
|
unsigned int FixedDivU(unsigned int ua, unsigned int ub )
|
||
|
|
{
|
||
|
|
unsigned int uRes = 0;
|
||
|
|
int i;
|
||
|
|
for(i=0;i<FRACBITS;i++)
|
||
|
|
{
|
||
|
|
unsigned int uDiv = ua / ub;
|
||
|
|
ua = ua % ub;
|
||
|
|
uRes += uDiv;
|
||
|
|
uRes <<= 1;
|
||
|
|
ua <<= 1;
|
||
|
|
}
|
||
|
|
return uRes;
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
fixed_t FixedDiv( fixed_t a, fixed_t b )
|
||
|
|
{
|
||
|
|
int iResult;
|
||
|
|
int iNegative = (a < 0) != (b<0);
|
||
|
|
if ( (abs(a)>>14) >= abs(b))
|
||
|
|
return iNegative ? MININT : MAXINT;
|
||
|
|
iResult = FixedDivU(abs(a),abs(b));
|
||
|
|
if(iNegative) iResult = -iResult;
|
||
|
|
return iResult;
|
||
|
|
}
|