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/****************************************************************
* *
* Copyright 2001 Sanchez Computer Associates, Inc. *
* *
* This source code contains the intellectual property *
* of its copyright holder(s), and is made available *
* under a license. If you do not know the terms of *
* the license, please stop and do not read further. *
* *
****************************************************************/
/* flt_mod.(u, v) = u - (v*floor.(u/v)) where x-1 < floor.x <= x ^ int.x */
#include "mdef.h"
#include "arit.h"
#include "op.h"
#include "eb_muldiv.h"
#include "promodemo.h"
#include "flt_mod.h"
LITREF mval literal_zero;
LITREF int4 ten_pwr[];
void flt_mod (mval *u, mval *v, mval *q)
{
int exp;
int4 z, x;
mval w; /* temporary mval for division result */
mval y; /* temporary mval for extended precision promotion
to prevent modifying caller's data */
mval *u_orig; /* original (caller's) value of u */
error_def(ERR_DIVZERO);
u_orig = u;
MV_FORCE_NUM(u);
MV_FORCE_NUM(v);
if ((v->mvtype & MV_INT) != 0 && v->m[1] == 0)
rts_error(VARLSTCNT(1) ERR_DIVZERO);
if ((u->mvtype & MV_INT & v->mvtype) != 0)
{
/* Both are INT's; use shortcut. */
q->mvtype = MV_NM | MV_INT;
eb_int_mod(u->m[1], v->m[1], q->m);
return;
}
else if ((u->mvtype & MV_INT) != 0)
{
/* u is INT; promote to extended precision for compatibility with v. */
y = *u;
promote(&y); /* y will be normalized, but not in canonical form */
u = &y; /* this is why we need u_orig */
}
else if ((v->mvtype & MV_INT) != 0)
{
/* v is INT; promote to extended precision for compatibility with u. */
y = *v;
promote(&y);
v = &y;
}
/* At this point, both u and v are in extended precision format. */
/* Set w = floor(u/v). */
op_div (u, v, &w);
if ((w.mvtype & MV_INT) != 0)
promote(&w);
exp = w.e;
if (exp <= MV_XBIAS)
{
/* Magnitude of w, floor(u/v), is < 1. */
if (u->sgn != v->sgn && w.m[1] != 0 && exp >= EXPLO)
{
/* Signs differ (=> floor(u/v) < 0) and (w != 0) and (no underflow) => floor(u/v) == -1 */
w.sgn = 1;
w.e = MV_XBIAS + 1;
w.m[1] = MANT_LO;
w.m[0] = 0;
}
else
{
/* Signs same (=> floor(u/v) >= 0) or (w == 0) or (underflow) => floor(u/v) == 0 */
*q = *u_orig; /* u - floor(u/v)*v == u - 0*v == u */
return;
}
}
else if (exp < EXP_IDX_BIAL)
{
z = ten_pwr[EXP_IDX_BIAL - exp];
x = (w.m[1]/z)*z;
if (u->sgn != v->sgn && (w.m[1] != x || w.m[0] != 0))
{
w.m[0] = 0;
w.m[1] = x + z;
if (w.m[1] >= MANT_HI)
{
w.m[0] = w.m[0]/10 + (w.m[1]%10)*MANT_LO;
w.m[1] /= 10;
w.e++;
}
}
else
{
w.m[0] = 0;
w.m[1] = x;
}
}
else if (exp < EXP_IDX_BIAQ)
{
z = ten_pwr[EXP_IDX_BIAQ - exp];
x = (w.m[0]/z)*z;
if (u->sgn != v->sgn && w.m[0] != x)
{
w.m[0] = x + z;
if (w.m[0] >= MANT_HI)
{
w.m[0] -= MANT_HI;
w.m[1]++;
}
}
else
{
w.m[0] = x;
}
}
op_mul (&w, v, &w); /* w = w*v = floor(u/v)*v */
op_sub (u_orig, &w, q); /* q = u - w = u - floor(u/v)*v */
}
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