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/*
Copyright (C) 1994 W. Schelter
This file is part of GNU Common Lisp, herein referred to as GCL
GCL is free software; you can redistribute it and/or modify it under
the terms of the GNU LIBRARY GENERAL PUBLIC LICENSE as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GCL is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
License for more details.
*/
/* author: William F. Schelter
The following is an implementation of extended_div in C suitable
for a machine which can do 32 bit arithmetic.
The assembler output could be optimized, so that carry tests
were read from the condition codes
*/
#include "arith.h"
/* #define ESTIMATE_LOG_QUOTIENT(x,l,d) estimate_logq(x,l,d) */
#define ESTIMATE_LOG_QUOTIENT(x,l,d) 31
/*
int
estimate_logq(x,l,div)
unsigned int x,div,l;
{ unsigned int logq,w;
if (x==0) {w=0;x=l;} else {w=WSIZ;}
for(logq=0; logq < WSIZ ; logq+=1)
if ((div << logq) >= x)
break;
return 31;
return logq+w;}
*/
extended_div(divisor,dh,dl,q,r)
unsigned int dh,dl , divisor, *q, *r;
{ unsigned int Rh,Rl,temph,templ;
unsigned int Q;
int iter;
#ifdef DEBUG
char *op;
#endif
Rh=dh;
Rl=dl;
/* if (dh) printf("\n(di %d %d %d ",divisor,dh,dl); */
NORMALIZE(Rh,Rl);
Q=0;
if (dh==0)
{*q=dl/divisor; *r=dl%divisor;
return;}
#ifdef DEBUG
printf("\n%d (Q %d %d) (R %d %d) %s" , -1,0,Q,Rh,Rl,"begin");
#endif
for (iter=ESTIMATE_LOG_QUOTIENT(dh,dl,divisor); iter >=0 ; iter-= 1)
{
/* assert(Q*divisor+R ==dividend); */
lshift(divisor,iter,temph,templ);
if ((int)Rh>=0)
{lsub(temph,templ,Rh,Rl);
#ifdef DEBUG
op="add";
#endif
/* lshift(1,iter,temph,templ);
ladd(temph,templ,Qh,Ql);
*/
/* ladd(0,(1<<iter),Qh,Ql); */
Q=Q+ (1<<iter);
}
else
{
#ifdef DEBUG
op="sub";
#endif
ladd(temph,templ,Rh,Rl);
/* lshift(1,iter,temph,templ);
lsub(temph,templ,Qh,Ql);
*/
/* lsub(0,(1<<iter),Qh,Ql); */
Q=Q- (1<<iter);
}
#ifdef DEBUG
printf("\n%d (Q %d %d) (R %d %d) %s" , iter,0,Q,Rh,Rl,op);
#endif
}
/* if (((int)Rl)< 0) {Ql--;Rl=Rl+divisor;} */
if (((int)Rl)< 0) {Q--;Rl=Rl+divisor;}
KCLNORMALIZE(Rh,Rl);
*q=Q;
/* *q=Ql; */
*r=Rl;
/* printf("%d %d)",*q,*r);
fflush(stdout); */
}
#ifndef VSSIZE
try(h,d, h1,l1, qp, rp)
unsigned int d, h, h1,l1,*qp, *rp;
{
extended_div (l1,h,d,qp,rp);
}
#endif
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