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arb/arf/add_mpn.c
fredrik caf9bb7825 mp_bitcnt_t -> flint_bitcnt_t
2020-06-22 23:48:09 +02:00

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/*
Copyright (C) 2014 Fredrik Johansson
This file is part of Arb.
Arb is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version. See <http://www.gnu.org/licenses/>.
*/
#include "arf.h"
TLS_PREFIX mp_ptr __arf_add_tmp = NULL;
TLS_PREFIX slong __arf_add_alloc = 0;
void _arf_add_tmp_cleanup(void)
{
flint_free(__arf_add_tmp);
__arf_add_tmp = NULL;
__arf_add_alloc = 0;
}
/* Assumptions: top limbs of x and y nonzero. */
int
_arf_add_mpn(arf_t z, mp_srcptr xp, mp_size_t xn, int xsgnbit, const fmpz_t xexp,
mp_srcptr yp, mp_size_t yn, int ysgnbit, flint_bitcnt_t shift,
slong prec, arf_rnd_t rnd)
{
mp_size_t wn, zn, zn_original, alloc, xbase, wbase;
mp_size_t shift_limbs;
flint_bitcnt_t shift_bits;
int inexact;
slong fix;
mp_limb_t cy;
mp_ptr tmp;
ARF_ADD_TMP_DECL
/* very fast case */
if (xn == 1 && yn == 1 && shift < FLINT_BITS - 1)
{
mp_limb_t hi, lo, xhi, xlo, yhi, ylo;
xhi = xp[0];
yhi = yp[0];
xlo = xhi << (FLINT_BITS - 1);
xhi = xhi >> 1;
ylo = yhi << (FLINT_BITS - (shift + 1));
yhi = yhi >> (shift + 1);
if (xsgnbit == ysgnbit)
{
add_ssaaaa(hi, lo, xhi, xlo, yhi, ylo);
}
else
{
if (xhi > yhi)
{
sub_ddmmss(hi, lo, xhi, xlo, yhi, ylo);
}
else if (xhi < yhi)
{
sub_ddmmss(hi, lo, yhi, ylo, xhi, xlo);
xsgnbit = ysgnbit;
}
else
{
if (xlo > ylo)
{
sub_ddmmss(hi, lo, xhi, xlo, yhi, ylo);
}
else if (xlo < ylo)
{
sub_ddmmss(hi, lo, yhi, ylo, xhi, xlo);
xsgnbit = ysgnbit;
}
else
{
arf_zero(z);
return 0;
}
}
}
inexact = _arf_set_round_uiui(z, &fix, hi, lo, xsgnbit, prec, rnd);
_fmpz_add_fast(ARF_EXPREF(z), xexp, fix + 1);
return inexact;
}
/* somewhat fast case */
if (xn <= 2 && yn <= 2 && shift <= 2 * FLINT_BITS)
{
mp_limb_t t[5], xtmp[4], ytmp[4], yhi, ylo;
slong fix2;
xtmp[0] = 0;
xtmp[1] = 0;
if (xn == 1)
{
xtmp[2] = 0;
xtmp[3] = xp[0];
}
else
{
xtmp[2] = xp[0];
xtmp[3] = xp[1];
}
ytmp[0] = 0;
ytmp[1] = 0;
ytmp[2] = 0;
ytmp[3] = 0;
if (yn == 1)
{
yhi = yp[0];
ylo = 0;
}
else
{
yhi = yp[1];
ylo = yp[0];
}
shift_limbs = shift / FLINT_BITS;
shift_bits = shift % FLINT_BITS;
if (shift_bits == 0)
{
ytmp[3 - shift_limbs] = yhi;
ytmp[2 - shift_limbs] = ylo;
}
else
{
ytmp[3 - shift_limbs] = yhi >> shift_bits;
ytmp[2 - shift_limbs] = (yhi << (FLINT_BITS - shift_bits)) | (ylo >> (shift_bits));
ytmp[1 - shift_limbs] = ylo << (FLINT_BITS - shift_bits);
}
if (xsgnbit == ysgnbit)
{
t[4] = cy = mpn_add_n(t, xtmp, ytmp, 4);
fix2 = cy * FLINT_BITS;
zn = 4 + cy;
while (t[zn - 1] == 0)
{
zn--;
fix2 -= FLINT_BITS;
}
}
else
{
#if 1
cy = mpn_sub_n(t, xtmp, ytmp, 4);
if (cy)
{
mpn_neg_n(t, t, 4);
xsgnbit = ysgnbit;
}
zn = 4;
fix2 = 0;
while (t[zn - 1] == 0)
{
zn--;
fix2 -= FLINT_BITS;
if (zn == 0)
{
arf_zero(z);
return 0;
}
}
#else
int cmp;
cmp = mpn_cmp(xtmp, ytmp, 4);
if (cmp > 0)
{
mpn_sub_n(t, xtmp, ytmp, 4);
}
else if (cmp < 0)
{
mpn_sub_n(t, ytmp, xtmp, 4);
xsgnbit = ysgnbit;
}
else
{
arf_zero(z);
return 0;
}
fix2 = 0;
zn = 4;
while (t[zn - 1] == 0)
{
zn--;
fix2 -= FLINT_BITS;
}
#endif
}
inexact = _arf_set_round_mpn(z, &fix, t, zn, xsgnbit, prec, rnd);
_fmpz_add_fast(ARF_EXPREF(z), xexp, fix + fix2);
return inexact;
}
/* x +/- eps */
if (shift > prec + FLINT_BITS + 1 &&
prec != ARF_PREC_EXACT &&
shift > (xn + 1) * FLINT_BITS)
{
zn = (prec + FLINT_BITS - 1) / FLINT_BITS;
zn_original = zn = FLINT_MAX(zn, xn) + 2;
shift_limbs = zn - xn;
alloc = zn + 1;
ARF_ADD_TMP_ALLOC(tmp, alloc)
flint_mpn_zero(tmp, shift_limbs);
flint_mpn_copyi(tmp + shift_limbs, xp, xn);
if (xsgnbit == ysgnbit)
{
tmp[0] = 1;
}
else
{
mpn_sub_1(tmp, tmp, zn, 1);
while (tmp[zn-1] == 0)
zn--;
}
_arf_set_round_mpn(z, &fix, tmp, zn, xsgnbit, prec, rnd);
fix += (zn - zn_original) * FLINT_BITS;
_fmpz_add_fast(ARF_EXPREF(z), xexp, fix);
ARF_ADD_TMP_FREE(tmp, alloc)
return 1;
}
shift_limbs = shift / FLINT_BITS;
shift_bits = shift % FLINT_BITS;
/* TODO: shift == 0 optimization! (common case) */
/* w = y shifted */
wn = yn + (shift_bits != 0);
/* Size of sum (possibly one more limb than this for carry). */
zn_original = zn = FLINT_MAX(xn, wn + shift_limbs);
alloc = zn + 1;
ARF_ADD_TMP_ALLOC(tmp, alloc)
/* Low limbs of both operands */
xbase = zn - xn;
wbase = zn - shift_limbs - wn;
/* Shift y to its correct offset in the sum. */
if (shift_bits == 0)
flint_mpn_copyi(tmp + wbase, yp, yn);
else
tmp[wbase] = cy = mpn_rshift(tmp + wbase + 1, yp, yn, shift_bits);
if (xsgnbit == ysgnbit)
{
if (shift_limbs >= xn)
{
/* XXXXXX
WWWWWWW */
flint_mpn_zero(tmp + wn, zn - xn - wn);
flint_mpn_copyi(tmp + zn - xn, xp, xn);
cy = 0;
}
else if (shift_limbs == 0)
{
/* XXXXXX or XXXXX
WWWW WWWWWWW */
if (wn < xn)
{
flint_mpn_copyi(tmp, xp, xn - wn);
cy = mpn_add_n(tmp + wbase, xp + wbase, tmp + wbase, wn);
}
else
{
cy = mpn_add_n(tmp + xbase, xp, tmp + xbase, xn);
}
}
else if (xbase >= wbase)
{
/* XXXXXX or XXXXXX
WWWWWWW WWWW */
cy = mpn_add_n(tmp + xbase, tmp + xbase, xp, wn - xbase);
cy = mpn_add_1(tmp + wn, xp + wn - xbase, zn - wn, cy);
}
else
{
/* XXXXXXXX todo: merge with above?
WWW */
flint_mpn_copyi(tmp, xp, wbase);
cy = mpn_add_n(tmp + wbase, tmp + wbase, xp + wbase, wn);
cy = mpn_add_1(tmp + zn - shift_limbs, xp + xn - shift_limbs, shift_limbs, cy);
}
/* There could be a carry. */
tmp[zn] = cy;
zn += cy;
}
else
{
if (shift_limbs >= xn)
{
/* XXXXXX
WWWWWWW */
mpn_neg(tmp, tmp, wn);
flint_mpn_store(tmp + wn, zn - xn - wn, -LIMB_ONE);
mpn_sub_1(tmp + zn - xn, xp, xn, 1);
}
else if (shift_limbs == 0)
{
/* XXXXXX (1) or XXXXX (2)
WWWW WWWWWWW */
if (wn <= xn) /* (1) */
{
if (mpn_cmp(xp + wbase, tmp + wbase, wn) >= 0)
{
flint_mpn_copyi(tmp, xp, wbase);
mpn_sub_n(tmp + wbase, xp + wbase, tmp + wbase, wn);
}
else
{
xsgnbit = ysgnbit;
mpn_sub_n(tmp + wbase, tmp + wbase, xp + wbase, wn);
if (wbase != 0)
{
cy = mpn_neg_n(tmp, xp, wbase);
mpn_sub_1(tmp + wbase, tmp + wbase, wn, cy);
}
}
}
else /* (2) */
{
if (mpn_cmp(tmp + xbase, xp, xn) >= 0)
{
xsgnbit = ysgnbit;
mpn_sub_n(tmp + xbase, tmp + xbase, xp, xn);
}
else
{
cy = mpn_neg(tmp, tmp, xbase);
mpn_sub_n(tmp + xbase, xp, tmp + xbase, xn);
mpn_sub_1(tmp + xbase, tmp + xbase, xn, cy);
}
}
}
else if (xbase >= wbase)
{
/* XXXXXX or XXXXXX
WWWWWWW WWWW */
if (xbase > 0)
{
cy = mpn_sub_n(tmp + xbase, xp, tmp + xbase, wn - xbase);
cy = mpn_sub_1(tmp + wn, xp + xn - shift_limbs, shift_limbs, cy);
cy = mpn_neg(tmp, tmp, xbase);
mpn_sub_1(tmp + xbase, tmp + xbase, xn, cy);
}
else
{
cy = mpn_sub_n(tmp, xp, tmp, wn);
cy = mpn_sub_1(tmp + wn, xp + wn, xn - wn, cy);
}
}
else
{
/* XXXXXXXX
WWW */
flint_mpn_copyi(tmp, xp, wbase);
cy = mpn_sub_n(tmp + wbase, xp + wbase, tmp + wbase, wn);
mpn_sub_1(tmp + zn - shift_limbs, xp + xn - shift_limbs, shift_limbs, cy);
}
/* There could be cancellation. */
while (zn > 0 && tmp[zn - 1] == 0)
zn--;
}
if (zn == 0)
{
arf_zero(z);
inexact = 0;
}
else
{
inexact = _arf_set_round_mpn(z, &fix, tmp, zn, xsgnbit, prec, rnd);
fix += (zn - zn_original) * FLINT_BITS;
_fmpz_add_fast(ARF_EXPREF(z), xexp, fix);
}
ARF_ADD_TMP_FREE(tmp, alloc)
return inexact;
}
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