This is mp_sl3todivul3.c in view mode; [Download] [Up]
#define ulong unsigned long
#define shift1BitRight(h,l) \
(l = l >> 1 , (h & 1 ? l = l | (1 << (WORD_SIZE -1)) : 0), h = h >> 1)
#define shift2BitRight(h,l) \
(l = l >> 2 , (h & 3 ? l = l | ((h & 3) << (WORD_SIZE -2)) : 0), h = h >> 2)
#define addll(x,y) \
(Xtx=(x),Xty=(y), Xtres = Xtx+Xty, \
(Xtres < Xtx ? overflow = 1 :0), Xtres)
/* the following defines divul3 in terms of divsl3.
*/
#define WORD_SIZE 32
divul3(x, y, hi)
ulong x, y, *hi;
{
ulong q = 0,Xtx,Xty,Xtres,addy,overflow;
ulong h = *hi, l = x, hibit;
ulong dd;
/* if (y<=h) printf("error: the quotient will be more than 32 bits"); */
if ((int) y > 0) {
dd = y >> 1;
if (dd <= h) {
unsigned int ll = l;
shift1BitRight(h, ll);
q = divsl3(ll, y, &h);
h = h + h + (l & 1);
q = q + q;
if (h >= y) {
q++;
h -= y;
}
*hi = h;
return q;
} else {
return divsl3(x, y, hi);
}
}
/* negative */
{
ulong ll;
ulong rem;
ll = l;
shift2BitRight(h, ll);
dd = y >> 1;
q = divsl3(ll, dd, &h);
rem = h + h;
overflow = 0;
rem = addll(rem, rem);
rem += l & 3;
q = q + q;
addy = 0;
if (y & 1) {
if (overflow==0 && rem < q)
{ addy = 1;
rem = addll(rem, y);
if (overflow==0 && rem < q)
{ addy = 2;
rem +=y;
}
}
rem -= q;
}
if (addy > 0)
{ q -= addy; }
else
{ if (overflow || (rem >= y))
{ rem -= y;
q++;
}
}
*hi = rem;
return q;
}
}
/*
;;- Local variables:
;;- mode:c
;;- version-control:t
;;- End:
*/
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