void
insert_random_low_zero_limbs (mpf_t x, gmp_randstate_ptr rands)
{
mp_size_t max = PREC(x) - SIZ(x);
mp_size_t s;
mpz_t ds; mpz_init (ds);
mpz_urandomb (ds, rands, 32);
s = mpz_get_ui (ds) % (max + 1);
MPN_COPY_DECR (PTR(x) + s, PTR(x), SIZ(x));
MPN_ZERO (PTR(x), s);
SIZ(x) += s;
mpz_clear (ds);
}
void
mpz_mul_2exp (mpz_ptr w, mpz_srcptr u, unsigned long int cnt)
{
mp_size_t usize = u->_mp_size;
mp_size_t abs_usize = ABS (usize);
mp_size_t wsize;
mp_size_t limb_cnt;
mp_ptr wp;
mp_limb_t wlimb;
if (usize == 0)
{
w->_mp_size = 0;
return;
}
limb_cnt = cnt / GMP_NUMB_BITS;
wsize = abs_usize + limb_cnt + 1;
if (w->_mp_alloc < wsize)
_mpz_realloc (w, wsize);
wp = w->_mp_d;
wsize = abs_usize + limb_cnt;
cnt %= GMP_NUMB_BITS;
if (cnt != 0)
{
wlimb = mpn_lshift (wp + limb_cnt, u->_mp_d, abs_usize, cnt);
if (wlimb != 0)
{
wp[wsize] = wlimb;
wsize++;
}
}
else
{
MPN_COPY_DECR (wp + limb_cnt, u->_mp_d, abs_usize);
}
/* Zero all whole limbs at low end. Do it here and not before calling
mpn_lshift, not to lose for U == W. */
MPN_ZERO (wp, limb_cnt);
w->_mp_size = usize >= 0 ? wsize : -wsize;
}
void
mpi_mul_2exp( MPI w, MPI u, unsigned long cnt)
{
mpi_size_t usize, wsize, limb_cnt;
mpi_ptr_t wp;
mpi_limb_t wlimb;
int usign, wsign;
usize = u->nlimbs;
usign = u->sign;
if( !usize ) {
w->nlimbs = 0;
w->sign = 0;
return;
}
limb_cnt = cnt / BITS_PER_MPI_LIMB;
wsize = usize + limb_cnt + 1;
if( w->alloced < wsize )
mpi_resize(w, wsize );
wp = w->d;
wsize = usize + limb_cnt;
wsign = usign;
cnt %= BITS_PER_MPI_LIMB;
if( cnt ) {
wlimb = mpihelp_lshift( wp + limb_cnt, u->d, usize, cnt );
if( wlimb ) {
wp[wsize] = wlimb;
wsize++;
}
}
else {
MPN_COPY_DECR( wp + limb_cnt, u->d, usize );
}
/* Zero all whole limbs at low end. Do it here and not before calling
* mpn_lshift, not to lose for U == W. */
MPN_ZERO( wp, limb_cnt );
w->nlimbs = wsize;
w->sign = wsign;
}
int mpi_mul_2exp(MPI w, MPI u, unsigned long cnt)
{
mpi_size_t usize, wsize, limb_cnt;
mpi_ptr_t wp;
mpi_limb_t wlimb;
int usign, wsign;
usize = u->nlimbs;
usign = u->sign;
if (!usize) {
w->nlimbs = 0;
w->sign = 0;
return 0;
}
limb_cnt = cnt / BITS_PER_MPI_LIMB;
wsize = usize + limb_cnt + 1;
if (w->alloced < wsize)
if (mpi_resize(w, wsize) < 0)
return -ENOMEM;
wp = w->d;
wsize = usize + limb_cnt;
wsign = usign;
cnt %= BITS_PER_MPI_LIMB;
if (cnt) {
wlimb = mpihelp_lshift(wp + limb_cnt, u->d, usize, cnt);
if (wlimb) {
wp[wsize] = wlimb;
wsize++;
}
} else {
MPN_COPY_DECR(wp + limb_cnt, u->d, usize);
}
/*
*/
MPN_ZERO(wp, limb_cnt);
w->nlimbs = wsize;
w->sign = wsign;
return 0;
}
int
mpfr_sub1sp (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mpfr_rnd_t rnd_mode)
{
mpfr_exp_t bx,cx;
mpfr_uexp_t d;
mpfr_prec_t p, sh, cnt;
mp_size_t n;
mp_limb_t *ap, *bp, *cp;
mp_limb_t limb;
int inexact;
mp_limb_t bcp,bcp1; /* Cp and C'p+1 */
mp_limb_t bbcp = (mp_limb_t) -1, bbcp1 = (mp_limb_t) -1; /* Cp+1 and C'p+2,
gcc claims that they might be used uninitialized. We fill them with invalid
values, which should produce a failure if so. See README.dev file. */
MPFR_TMP_DECL(marker);
MPFR_TMP_MARK(marker);
MPFR_ASSERTD(MPFR_PREC(a) == MPFR_PREC(b) && MPFR_PREC(b) == MPFR_PREC(c));
MPFR_ASSERTD(MPFR_IS_PURE_FP(b));
MPFR_ASSERTD(MPFR_IS_PURE_FP(c));
/* Read prec and num of limbs */
p = MPFR_PREC (b);
n = MPFR_PREC2LIMBS (p);
/* Fast cmp of |b| and |c|*/
bx = MPFR_GET_EXP (b);
cx = MPFR_GET_EXP (c);
if (MPFR_UNLIKELY(bx == cx))
{
mp_size_t k = n - 1;
/* Check mantissa since exponent are equals */
bp = MPFR_MANT(b);
cp = MPFR_MANT(c);
while (k>=0 && MPFR_UNLIKELY(bp[k] == cp[k]))
k--;
if (MPFR_UNLIKELY(k < 0))
/* b == c ! */
{
/* Return exact number 0 */
if (rnd_mode == MPFR_RNDD)
MPFR_SET_NEG(a);
else
MPFR_SET_POS(a);
MPFR_SET_ZERO(a);
MPFR_RET(0);
}
else if (bp[k] > cp[k])
goto BGreater;
else
{
MPFR_ASSERTD(bp[k]<cp[k]);
goto CGreater;
}
}
else if (MPFR_UNLIKELY(bx < cx))
{
/* Swap b and c and set sign */
mpfr_srcptr t;
mpfr_exp_t tx;
CGreater:
MPFR_SET_OPPOSITE_SIGN(a,b);
t = b; b = c; c = t;
tx = bx; bx = cx; cx = tx;
}
else
{
/* b > c */
BGreater:
MPFR_SET_SAME_SIGN(a,b);
}
/* Now b > c */
MPFR_ASSERTD(bx >= cx);
d = (mpfr_uexp_t) bx - cx;
DEBUG (printf ("New with diff=%lu\n", (unsigned long) d));
if (MPFR_UNLIKELY(d <= 1))
{
if (MPFR_LIKELY(d < 1))
{
/* <-- b -->
<-- c --> : exact sub */
ap = MPFR_MANT(a);
mpn_sub_n (ap, MPFR_MANT(b), MPFR_MANT(c), n);
/* Normalize */
ExactNormalize:
limb = ap[n-1];
if (MPFR_LIKELY(limb))
{
/* First limb is not zero. */
count_leading_zeros(cnt, limb);
/* cnt could be == 0 <= SubD1Lose */
if (MPFR_LIKELY(cnt))
{
mpn_lshift(ap, ap, n, cnt); /* Normalize number */
bx -= cnt; /* Update final expo */
}
/* Last limb should be ok */
MPFR_ASSERTD(!(ap[0] & MPFR_LIMB_MASK((unsigned int) (-p)
% GMP_NUMB_BITS)));
}
else
{
/* First limb is zero */
mp_size_t k = n-1, len;
/* Find the first limb not equal to zero.
FIXME:It is assume it exists (since |b| > |c| and same prec)*/
do
{
MPFR_ASSERTD( k > 0 );
limb = ap[--k];
}
while (limb == 0);
MPFR_ASSERTD(limb != 0);
count_leading_zeros(cnt, limb);
k++;
len = n - k; /* Number of last limb */
MPFR_ASSERTD(k >= 0);
if (MPFR_LIKELY(cnt))
mpn_lshift(ap+len, ap, k, cnt); /* Normalize the High Limb*/
else
{
/* Must use DECR since src and dest may overlap & dest>=src*/
MPN_COPY_DECR(ap+len, ap, k);
}
MPN_ZERO(ap, len); /* Zeroing the last limbs */
bx -= cnt + len*GMP_NUMB_BITS; /* Update Expo */
/* Last limb should be ok */
MPFR_ASSERTD(!(ap[len]&MPFR_LIMB_MASK((unsigned int) (-p)
% GMP_NUMB_BITS)));
}
/* Check expo underflow */
if (MPFR_UNLIKELY(bx < __gmpfr_emin))
{
MPFR_TMP_FREE(marker);
/* inexact=0 */
DEBUG( printf("(D==0 Underflow)\n") );
if (rnd_mode == MPFR_RNDN &&
(bx < __gmpfr_emin - 1 ||
(/*inexact >= 0 &&*/ mpfr_powerof2_raw (a))))
rnd_mode = MPFR_RNDZ;
return mpfr_underflow (a, rnd_mode, MPFR_SIGN(a));
}
MPFR_SET_EXP (a, bx);
/* No rounding is necessary since the result is exact */
MPFR_ASSERTD(ap[n-1] > ~ap[n-1]);
MPFR_TMP_FREE(marker);
return 0;
}
else /* if (d == 1) */
{
/* | <-- b -->
| <-- c --> */
mp_limb_t c0, mask;
mp_size_t k;
MPFR_UNSIGNED_MINUS_MODULO(sh, p);
/* If we lose at least one bit, compute 2*b-c (Exact)
* else compute b-c/2 */
bp = MPFR_MANT(b);
cp = MPFR_MANT(c);
k = n-1;
limb = bp[k] - cp[k]/2;
if (limb > MPFR_LIMB_HIGHBIT)
{
/* We can't lose precision: compute b-c/2 */
/* Shift c in the allocated temporary block */
SubD1NoLose:
c0 = cp[0] & (MPFR_LIMB_ONE<<sh);
cp = MPFR_TMP_LIMBS_ALLOC (n);
mpn_rshift(cp, MPFR_MANT(c), n, 1);
if (MPFR_LIKELY(c0 == 0))
{
/* Result is exact: no need of rounding! */
ap = MPFR_MANT(a);
mpn_sub_n (ap, bp, cp, n);
MPFR_SET_EXP(a, bx); /* No expo overflow! */
/* No truncate or normalize is needed */
MPFR_ASSERTD(ap[n-1] > ~ap[n-1]);
/* No rounding is necessary since the result is exact */
MPFR_TMP_FREE(marker);
return 0;
}
ap = MPFR_MANT(a);
mask = ~MPFR_LIMB_MASK(sh);
cp[0] &= mask; /* Delete last bit of c */
mpn_sub_n (ap, bp, cp, n);
MPFR_SET_EXP(a, bx); /* No expo overflow! */
MPFR_ASSERTD( !(ap[0] & ~mask) ); /* Check last bits */
/* No normalize is needed */
MPFR_ASSERTD(ap[n-1] > ~ap[n-1]);
/* Rounding is necessary since c0 = 1*/
/* Cp =-1 and C'p+1=0 */
bcp = 1; bcp1 = 0;
if (MPFR_LIKELY(rnd_mode == MPFR_RNDN))
{
/* Even Rule apply: Check Ap-1 */
if (MPFR_LIKELY( (ap[0] & (MPFR_LIMB_ONE<<sh)) == 0) )
goto truncate;
else
goto sub_one_ulp;
}
MPFR_UPDATE_RND_MODE(rnd_mode, MPFR_IS_NEG(a));
if (rnd_mode == MPFR_RNDZ)
goto sub_one_ulp;
else
goto truncate;
}
else if (MPFR_LIKELY(limb < MPFR_LIMB_HIGHBIT))
{
/* We lose at least one bit of prec */
/* Calcul of 2*b-c (Exact) */
/* Shift b in the allocated temporary block */
SubD1Lose:
bp = MPFR_TMP_LIMBS_ALLOC (n);
mpn_lshift (bp, MPFR_MANT(b), n, 1);
ap = MPFR_MANT(a);
mpn_sub_n (ap, bp, cp, n);
bx--;
goto ExactNormalize;
}
else
{
/* Case: limb = 100000000000 */
/* Check while b[k] == c'[k] (C' is C shifted by 1) */
/* If b[k]<c'[k] => We lose at least one bit*/
/* If b[k]>c'[k] => We don't lose any bit */
/* If k==-1 => We don't lose any bit
AND the result is 100000000000 0000000000 00000000000 */
mp_limb_t carry;
do {
carry = cp[k]&MPFR_LIMB_ONE;
k--;
} while (k>=0 &&
bp[k]==(carry=cp[k]/2+(carry<<(GMP_NUMB_BITS-1))));
if (MPFR_UNLIKELY(k<0))
{
/*If carry then (sh==0 and Virtual c'[-1] > Virtual b[-1]) */
if (MPFR_UNLIKELY(carry)) /* carry = cp[0]&MPFR_LIMB_ONE */
{
/* FIXME: Can be faster? */
MPFR_ASSERTD(sh == 0);
goto SubD1Lose;
}
/* Result is a power of 2 */
ap = MPFR_MANT (a);
MPN_ZERO (ap, n);
ap[n-1] = MPFR_LIMB_HIGHBIT;
MPFR_SET_EXP (a, bx); /* No expo overflow! */
/* No Normalize is needed*/
/* No Rounding is needed */
MPFR_TMP_FREE (marker);
return 0;
}
/* carry = cp[k]/2+(cp[k-1]&1)<<(GMP_NUMB_BITS-1) = c'[k]*/
else if (bp[k] > carry)
goto SubD1NoLose;
else
{
MPFR_ASSERTD(bp[k]<carry);
goto SubD1Lose;
}
}
}
}
else if (MPFR_UNLIKELY(d >= p))
{
ap = MPFR_MANT(a);
MPFR_UNSIGNED_MINUS_MODULO(sh, p);
/* We can't set A before since we use cp for rounding... */
/* Perform rounding: check if a=b or a=b-ulp(b) */
if (MPFR_UNLIKELY(d == p))
{
/* cp == -1 and c'p+1 = ? */
bcp = 1;
/* We need Cp+1 later for a very improbable case. */
bbcp = (MPFR_MANT(c)[n-1] & (MPFR_LIMB_ONE<<(GMP_NUMB_BITS-2)));
/* We need also C'p+1 for an even more unprobable case... */
if (MPFR_LIKELY( bbcp ))
bcp1 = 1;
else
{
cp = MPFR_MANT(c);
if (MPFR_UNLIKELY(cp[n-1] == MPFR_LIMB_HIGHBIT))
{
mp_size_t k = n-1;
do {
k--;
} while (k>=0 && cp[k]==0);
bcp1 = (k>=0);
}
else
bcp1 = 1;
}
DEBUG( printf("(D=P) Cp=-1 Cp+1=%d C'p+1=%d \n", bbcp!=0, bcp1!=0) );
bp = MPFR_MANT (b);
/* Even if src and dest overlap, it is ok using MPN_COPY */
if (MPFR_LIKELY(rnd_mode == MPFR_RNDN))
{
if (MPFR_UNLIKELY( bcp && bcp1==0 ))
/* Cp=-1 and C'p+1=0: Even rule Apply! */
/* Check Ap-1 = Bp-1 */
if ((bp[0] & (MPFR_LIMB_ONE<<sh)) == 0)
{
MPN_COPY(ap, bp, n);
goto truncate;
}
MPN_COPY(ap, bp, n);
goto sub_one_ulp;
}
MPFR_UPDATE_RND_MODE(rnd_mode, MPFR_IS_NEG(a));
if (rnd_mode == MPFR_RNDZ)
{
MPN_COPY(ap, bp, n);
goto sub_one_ulp;
}
else
{
MPN_COPY(ap, bp, n);
goto truncate;
}
}
else
{
/* Cp=0, Cp+1=-1 if d==p+1, C'p+1=-1 */
bcp = 0; bbcp = (d==p+1); bcp1 = 1;
DEBUG( printf("(D>P) Cp=%d Cp+1=%d C'p+1=%d\n", bcp!=0,bbcp!=0,bcp1!=0) );
/* Need to compute C'p+2 if d==p+1 and if rnd_mode=NEAREST
(Because of a very improbable case) */
if (MPFR_UNLIKELY(d==p+1 && rnd_mode==MPFR_RNDN))
{
cp = MPFR_MANT(c);
if (MPFR_UNLIKELY(cp[n-1] == MPFR_LIMB_HIGHBIT))
{
mp_size_t k = n-1;
do {
k--;
} while (k>=0 && cp[k]==0);
bbcp1 = (k>=0);
}
else
bbcp1 = 1;
DEBUG( printf("(D>P) C'p+2=%d\n", bbcp1!=0) );
}
/* Copy mantissa B in A */
MPN_COPY(ap, MPFR_MANT(b), n);
/* Round */
if (MPFR_LIKELY(rnd_mode == MPFR_RNDN))
goto truncate;
MPFR_UPDATE_RND_MODE(rnd_mode, MPFR_IS_NEG(a));
if (rnd_mode == MPFR_RNDZ)
goto sub_one_ulp;
else /* rnd_mode = AWAY */
goto truncate;
}
}
else
{
mpfr_uexp_t dm;
mp_size_t m;
mp_limb_t mask;
/* General case: 2 <= d < p */
MPFR_UNSIGNED_MINUS_MODULO(sh, p);
cp = MPFR_TMP_LIMBS_ALLOC (n);
/* Shift c in temporary allocated place */
dm = d % GMP_NUMB_BITS;
m = d / GMP_NUMB_BITS;
if (MPFR_UNLIKELY(dm == 0))
{
/* dm = 0 and m > 0: Just copy */
MPFR_ASSERTD(m!=0);
MPN_COPY(cp, MPFR_MANT(c)+m, n-m);
MPN_ZERO(cp+n-m, m);
}
else if (MPFR_LIKELY(m == 0))
{
/* dm >=2 and m == 0: just shift */
MPFR_ASSERTD(dm >= 2);
mpn_rshift(cp, MPFR_MANT(c), n, dm);
}
else
{
/* dm > 0 and m > 0: shift and zero */
mpn_rshift(cp, MPFR_MANT(c)+m, n-m, dm);
MPN_ZERO(cp+n-m, m);
}
DEBUG( mpfr_print_mant_binary("Before", MPFR_MANT(c), p) );
DEBUG( mpfr_print_mant_binary("B= ", MPFR_MANT(b), p) );
DEBUG( mpfr_print_mant_binary("After ", cp, p) );
/* Compute bcp=Cp and bcp1=C'p+1 */
if (MPFR_LIKELY(sh))
{
/* Try to compute them from C' rather than C (FIXME: Faster?) */
bcp = (cp[0] & (MPFR_LIMB_ONE<<(sh-1))) ;
if (MPFR_LIKELY( cp[0] & MPFR_LIMB_MASK(sh-1) ))
bcp1 = 1;
else
{
/* We can't compute C'p+1 from C'. Compute it from C */
/* Start from bit x=p-d+sh in mantissa C
(+sh since we have already looked sh bits in C'!) */
mpfr_prec_t x = p-d+sh-1;
if (MPFR_LIKELY(x>p))
/* We are already looked at all the bits of c, so C'p+1 = 0*/
bcp1 = 0;
else
{
mp_limb_t *tp = MPFR_MANT(c);
mp_size_t kx = n-1 - (x / GMP_NUMB_BITS);
mpfr_prec_t sx = GMP_NUMB_BITS-1-(x%GMP_NUMB_BITS);
DEBUG (printf ("(First) x=%lu Kx=%ld Sx=%lu\n",
(unsigned long) x, (long) kx,
(unsigned long) sx));
/* Looks at the last bits of limb kx (if sx=0 does nothing)*/
if (tp[kx] & MPFR_LIMB_MASK(sx))
bcp1 = 1;
else
{
/*kx += (sx==0);*/
/*If sx==0, tp[kx] hasn't been checked*/
do {
kx--;
} while (kx>=0 && tp[kx]==0);
bcp1 = (kx >= 0);
}
}
}
}
else
{
/* Compute Cp and C'p+1 from C with sh=0 */
mp_limb_t *tp = MPFR_MANT(c);
/* Start from bit x=p-d in mantissa C */
mpfr_prec_t x = p-d;
mp_size_t kx = n-1 - (x / GMP_NUMB_BITS);
mpfr_prec_t sx = GMP_NUMB_BITS-1-(x%GMP_NUMB_BITS);
MPFR_ASSERTD(p >= d);
bcp = (tp[kx] & (MPFR_LIMB_ONE<<sx));
/* Looks at the last bits of limb kx (If sx=0, does nothing)*/
if (tp[kx] & MPFR_LIMB_MASK(sx))
bcp1 = 1;
else
{
/*kx += (sx==0);*/ /*If sx==0, tp[kx] hasn't been checked*/
do {
kx--;
} while (kx>=0 && tp[kx]==0);
bcp1 = (kx>=0);
}
}
DEBUG( printf("sh=%lu Cp=%d C'p+1=%d\n", sh, bcp!=0, bcp1!=0) );
/* Check if we can lose a bit, and if so compute Cp+1 and C'p+2 */
bp = MPFR_MANT(b);
if (MPFR_UNLIKELY((bp[n-1]-cp[n-1]) <= MPFR_LIMB_HIGHBIT))
{
/* We can lose a bit so we precompute Cp+1 and C'p+2 */
/* Test for trivial case: since C'p+1=0, Cp+1=0 and C'p+2 =0 */
if (MPFR_LIKELY(bcp1 == 0))
{
bbcp = 0;
bbcp1 = 0;
}
else /* bcp1 != 0 */
{
/* We can lose a bit:
compute Cp+1 and C'p+2 from mantissa C */
mp_limb_t *tp = MPFR_MANT(c);
/* Start from bit x=(p+1)-d in mantissa C */
mpfr_prec_t x = p+1-d;
mp_size_t kx = n-1 - (x/GMP_NUMB_BITS);
mpfr_prec_t sx = GMP_NUMB_BITS-1-(x%GMP_NUMB_BITS);
MPFR_ASSERTD(p > d);
DEBUG (printf ("(pre) x=%lu Kx=%ld Sx=%lu\n",
(unsigned long) x, (long) kx,
(unsigned long) sx));
bbcp = (tp[kx] & (MPFR_LIMB_ONE<<sx)) ;
/* Looks at the last bits of limb kx (If sx=0, does nothing)*/
/* If Cp+1=0, since C'p+1!=0, C'p+2=1 ! */
if (MPFR_LIKELY(bbcp==0 || (tp[kx]&MPFR_LIMB_MASK(sx))))
bbcp1 = 1;
else
{
/*kx += (sx==0);*/ /*If sx==0, tp[kx] hasn't been checked*/
do {
kx--;
} while (kx>=0 && tp[kx]==0);
bbcp1 = (kx>=0);
DEBUG (printf ("(Pre) Scan done for %ld\n", (long) kx));
}
} /*End of Bcp1 != 0*/
DEBUG( printf("(Pre) Cp+1=%d C'p+2=%d\n", bbcp!=0, bbcp1!=0) );
} /* End of "can lose a bit" */
/* Clean shifted C' */
mask = ~MPFR_LIMB_MASK (sh);
cp[0] &= mask;
/* Subtract the mantissa c from b in a */
ap = MPFR_MANT(a);
mpn_sub_n (ap, bp, cp, n);
DEBUG( mpfr_print_mant_binary("Sub= ", ap, p) );
/* Normalize: we lose at max one bit*/
if (MPFR_UNLIKELY(MPFR_LIMB_MSB(ap[n-1]) == 0))
{
/* High bit is not set and we have to fix it! */
/* Ap >= 010000xxx001 */
mpn_lshift(ap, ap, n, 1);
/* Ap >= 100000xxx010 */
if (MPFR_UNLIKELY(bcp!=0)) /* Check if Cp = -1 */
/* Since Cp == -1, we have to substract one more */
{
mpn_sub_1(ap, ap, n, MPFR_LIMB_ONE<<sh);
MPFR_ASSERTD(MPFR_LIMB_MSB(ap[n-1]) != 0);
}
/* Ap >= 10000xxx001 */
/* Final exponent -1 since we have shifted the mantissa */
bx--;
/* Update bcp and bcp1 */
MPFR_ASSERTN(bbcp != (mp_limb_t) -1);
MPFR_ASSERTN(bbcp1 != (mp_limb_t) -1);
bcp = bbcp;
bcp1 = bbcp1;
/* We dont't have anymore a valid Cp+1!
But since Ap >= 100000xxx001, the final sub can't unnormalize!*/
}
MPFR_ASSERTD( !(ap[0] & ~mask) );
/* Rounding */
if (MPFR_LIKELY(rnd_mode == MPFR_RNDN))
{
if (MPFR_LIKELY(bcp==0))
goto truncate;
else if ((bcp1) || ((ap[0] & (MPFR_LIMB_ONE<<sh)) != 0))
goto sub_one_ulp;
else
goto truncate;
}
/* Update rounding mode */
MPFR_UPDATE_RND_MODE(rnd_mode, MPFR_IS_NEG(a));
if (rnd_mode == MPFR_RNDZ && (MPFR_LIKELY(bcp || bcp1)))
goto sub_one_ulp;
goto truncate;
}
MPFR_RET_NEVER_GO_HERE ();
/* Sub one ulp to the result */
sub_one_ulp:
mpn_sub_1 (ap, ap, n, MPFR_LIMB_ONE << sh);
/* Result should be smaller than exact value: inexact=-1 */
inexact = -1;
/* Check normalisation */
if (MPFR_UNLIKELY(MPFR_LIMB_MSB(ap[n-1]) == 0))
{
/* ap was a power of 2, and we lose a bit */
/* Now it is 0111111111111111111[00000 */
mpn_lshift(ap, ap, n, 1);
bx--;
/* And the lost bit x depends on Cp+1, and Cp */
/* Compute Cp+1 if it isn't already compute (ie d==1) */
/* FIXME: Is this case possible? */
if (MPFR_UNLIKELY(d == 1))
bbcp = 0;
DEBUG( printf("(SubOneUlp)Cp=%d, Cp+1=%d C'p+1=%d\n", bcp!=0,bbcp!=0,bcp1!=0));
/* Compute the last bit (Since we have shifted the mantissa)
we need one more bit!*/
MPFR_ASSERTN(bbcp != (mp_limb_t) -1);
if ( (rnd_mode == MPFR_RNDZ && bcp==0)
|| (rnd_mode==MPFR_RNDN && bbcp==0)
|| (bcp && bcp1==0) ) /*Exact result*/
{
ap[0] |= MPFR_LIMB_ONE<<sh;
if (rnd_mode == MPFR_RNDN)
inexact = 1;
DEBUG( printf("(SubOneUlp) Last bit set\n") );
}
/* Result could be exact if C'p+1 = 0 and rnd == Zero
since we have had one more bit to the result */
/* Fixme: rnd_mode == MPFR_RNDZ needed ? */
if (bcp1==0 && rnd_mode==MPFR_RNDZ)
{
DEBUG( printf("(SubOneUlp) Exact result\n") );
inexact = 0;
}
}
goto end_of_sub;
truncate:
/* Check if the result is an exact power of 2: 100000000000
in which cases, we could have to do sub_one_ulp due to some nasty reasons:
If Result is a Power of 2:
+ If rnd = AWAY,
| If Cp=-1 and C'p+1 = 0, SubOneUlp and the result is EXACT.
If Cp=-1 and C'p+1 =-1, SubOneUlp and the result is above.
Otherwise truncate
+ If rnd = NEAREST,
If Cp= 0 and Cp+1 =-1 and C'p+2=-1, SubOneUlp and the result is above
If cp=-1 and C'p+1 = 0, SubOneUlp and the result is exact.
Otherwise truncate.
X bit should always be set if SubOneUlp*/
if (MPFR_UNLIKELY(ap[n-1] == MPFR_LIMB_HIGHBIT))
{
mp_size_t k = n-1;
do {
k--;
} while (k>=0 && ap[k]==0);
if (MPFR_UNLIKELY(k<0))
{
/* It is a power of 2! */
/* Compute Cp+1 if it isn't already compute (ie d==1) */
/* FIXME: Is this case possible? */
if (d == 1)
bbcp=0;
DEBUG( printf("(Truncate) Cp=%d, Cp+1=%d C'p+1=%d C'p+2=%d\n", \
bcp!=0, bbcp!=0, bcp1!=0, bbcp1!=0) );
MPFR_ASSERTN(bbcp != (mp_limb_t) -1);
MPFR_ASSERTN((rnd_mode != MPFR_RNDN) || (bcp != 0) || (bbcp == 0) || (bbcp1 != (mp_limb_t) -1));
if (((rnd_mode != MPFR_RNDZ) && bcp)
||
((rnd_mode == MPFR_RNDN) && (bcp == 0) && (bbcp) && (bbcp1)))
{
DEBUG( printf("(Truncate) Do sub\n") );
mpn_sub_1 (ap, ap, n, MPFR_LIMB_ONE << sh);
mpn_lshift(ap, ap, n, 1);
ap[0] |= MPFR_LIMB_ONE<<sh;
bx--;
/* FIXME: Explain why it works (or why not)... */
inexact = (bcp1 == 0) ? 0 : (rnd_mode==MPFR_RNDN) ? -1 : 1;
goto end_of_sub;
}
}
}
/* Calcul of Inexact flag.*/
inexact = MPFR_LIKELY(bcp || bcp1) ? 1 : 0;
end_of_sub:
/* Update Expo */
/* FIXME: Is this test really useful?
If d==0 : Exact case. This is never called.
if 1 < d < p : bx=MPFR_EXP(b) or MPFR_EXP(b)-1 > MPFR_EXP(c) > emin
if d == 1 : bx=MPFR_EXP(b). If we could lose any bits, the exact
normalisation is called.
if d >= p : bx=MPFR_EXP(b) >= MPFR_EXP(c) + p > emin
After SubOneUlp, we could have one bit less.
if 1 < d < p : bx >= MPFR_EXP(b)-2 >= MPFR_EXP(c) > emin
if d == 1 : bx >= MPFR_EXP(b)-1 = MPFR_EXP(c) > emin.
if d >= p : bx >= MPFR_EXP(b)-1 > emin since p>=2.
*/
MPFR_ASSERTD( bx >= __gmpfr_emin);
/*
if (MPFR_UNLIKELY(bx < __gmpfr_emin))
{
DEBUG( printf("(Final Underflow)\n") );
if (rnd_mode == MPFR_RNDN &&
(bx < __gmpfr_emin - 1 ||
(inexact >= 0 && mpfr_powerof2_raw (a))))
rnd_mode = MPFR_RNDZ;
MPFR_TMP_FREE(marker);
return mpfr_underflow (a, rnd_mode, MPFR_SIGN(a));
}
*/
MPFR_SET_EXP (a, bx);
MPFR_TMP_FREE(marker);
MPFR_RET (inexact * MPFR_INT_SIGN (a));
}
int
mpfr_set_uj_2exp (mpfr_t x, uintmax_t j, intmax_t e, mp_rnd_t rnd)
{
unsigned int cnt, i;
mp_size_t k, len;
mp_limb_t limb;
mp_limb_t yp[sizeof(uintmax_t) / sizeof(mp_limb_t)];
mpfr_t y;
unsigned long uintmax_bit_size = sizeof(uintmax_t) * CHAR_BIT;
unsigned long bpml = BITS_PER_MP_LIMB % uintmax_bit_size;
/* Special case */
if (j == 0)
{
MPFR_SET_POS(x);
MPFR_SET_ZERO(x);
MPFR_RET(0);
}
MPFR_ASSERTN (sizeof(uintmax_t) % sizeof(mp_limb_t) == 0);
/* Create an auxillary var */
MPFR_TMP_INIT1 (yp, y, uintmax_bit_size);
k = numberof (yp);
if (k == 1)
limb = yp[0] = j;
else
{
/* Note: either BITS_PER_MP_LIMB = uintmax_bit_size, then k = 1 the
shift j >>= bpml is never done, or BITS_PER_MP_LIMB < uintmax_bit_size
and bpml = BITS_PER_MP_LIMB. */
for (i = 0; i < k; i++, j >>= bpml)
yp[i] = j; /* Only the low bits are copied */
/* Find the first limb not equal to zero. */
do
{
MPFR_ASSERTD (k > 0);
limb = yp[--k];
}
while (limb == 0);
k++;
}
count_leading_zeros(cnt, limb);
len = numberof (yp) - k;
/* Normalize it: len = number of last 0 limb, k number of non-zero limbs */
if (MPFR_LIKELY(cnt))
mpn_lshift (yp+len, yp, k, cnt); /* Normalize the High Limb*/
else if (len != 0)
MPN_COPY_DECR (yp+len, yp, k); /* Must use DECR */
if (len != 0)
/* Note: when numberof(yp)==1, len is constant and null, so the compiler
can optimize out this code. */
{
if (len == 1)
yp[0] = (mp_limb_t) 0;
else
MPN_ZERO (yp, len); /* Zeroing the last limbs */
}
e += k * BITS_PER_MP_LIMB - cnt; /* Update Expo */
MPFR_ASSERTD (MPFR_LIMB_MSB(yp[numberof (yp) - 1]) != 0);
/* Check expo underflow / overflow (can't use mpfr_check_range) */
if (MPFR_UNLIKELY(e < __gmpfr_emin))
{
/* The following test is necessary because in the rounding to the
* nearest mode, mpfr_underflow always rounds away from 0. In
* this rounding mode, we need to round to 0 if:
* _ |x| < 2^(emin-2), or
* _ |x| = 2^(emin-2) and the absolute value of the exact
* result is <= 2^(emin-2). */
if (rnd == GMP_RNDN && (e+1 < __gmpfr_emin || mpfr_powerof2_raw(y)))
rnd = GMP_RNDZ;
return mpfr_underflow (x, rnd, MPFR_SIGN_POS);
}
if (MPFR_UNLIKELY(e > __gmpfr_emax))
return mpfr_overflow (x, rnd, MPFR_SIGN_POS);
MPFR_SET_EXP (y, e);
/* Final: set x to y (rounding if necessary) */
return mpfr_set (x, y, rnd);
}
int
mpfr_round_raw_generic(
#if flag == 0
mp_limb_t *yp,
#endif
const mp_limb_t *xp, mpfr_prec_t xprec,
int neg, mpfr_prec_t yprec, mpfr_rnd_t rnd_mode
#if use_inexp != 0
, int *inexp
#endif
)
{
mp_size_t xsize, nw;
mp_limb_t himask, lomask, sb;
int rw;
#if flag == 0
int carry;
#endif
#if use_inexp == 0
int *inexp;
#endif
if (use_inexp)
MPFR_ASSERTD(inexp != ((int*) 0));
MPFR_ASSERTD(neg == 0 || neg == 1);
if (flag && !use_inexp &&
(xprec <= yprec || MPFR_IS_LIKE_RNDZ (rnd_mode, neg)))
return 0;
xsize = MPFR_PREC2LIMBS (xprec);
nw = yprec / GMP_NUMB_BITS;
rw = yprec & (GMP_NUMB_BITS - 1);
if (MPFR_UNLIKELY(xprec <= yprec))
{ /* No rounding is necessary. */
/* if yp=xp, maybe an overlap: MPN_COPY_DECR is OK when src <= dst */
if (MPFR_LIKELY(rw))
nw++;
MPFR_ASSERTD(nw >= 1);
MPFR_ASSERTD(nw >= xsize);
if (use_inexp)
*inexp = 0;
#if flag == 0
MPN_COPY_DECR(yp + (nw - xsize), xp, xsize);
MPN_ZERO(yp, nw - xsize);
#endif
return 0;
}
if (use_inexp || !MPFR_IS_LIKE_RNDZ(rnd_mode, neg))
{
mp_size_t k = xsize - nw - 1;
if (MPFR_LIKELY(rw))
{
nw++;
lomask = MPFR_LIMB_MASK (GMP_NUMB_BITS - rw);
himask = ~lomask;
}
else
{
lomask = MPFR_LIMB_MAX;
himask = MPFR_LIMB_MAX;
}
MPFR_ASSERTD(k >= 0);
sb = xp[k] & lomask; /* First non-significant bits */
/* Rounding to nearest? */
if (MPFR_LIKELY (rnd_mode == MPFR_RNDN || rnd_mode == MPFR_RNDNA))
{
/* Rounding to nearest */
mp_limb_t rbmask = MPFR_LIMB_ONE << (GMP_NUMB_BITS - 1 - rw);
if ((sb & rbmask) == 0) /* rounding bit = 0 ? */
goto rnd_RNDZ; /* yes, behave like rounding toward zero */
/* Rounding to nearest with rounding bit = 1 */
if (MPFR_UNLIKELY (rnd_mode == MPFR_RNDNA))
/* FIXME: *inexp is not set. First, add a testcase that
triggers the bug (at least with a sanitizer). */
goto rnd_RNDN_add_one_ulp; /* like rounding away from zero */
sb &= ~rbmask; /* first bits after the rounding bit */
while (MPFR_UNLIKELY(sb == 0) && k > 0)
sb = xp[--k];
if (MPFR_UNLIKELY(sb == 0)) /* Even rounding. */
{
/* sb == 0 && rnd_mode == MPFR_RNDN */
sb = xp[xsize - nw] & (himask ^ (himask << 1));
if (sb == 0)
{
if (use_inexp)
*inexp = 2*MPFR_EVEN_INEX*neg-MPFR_EVEN_INEX;
/* ((neg!=0)^(sb!=0)) ? MPFR_EVEN_INEX : -MPFR_EVEN_INEX */
/* since neg = 0 or 1 and sb = 0 */
#if flag == 0
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
#endif
return 0; /* sb != 0 && rnd_mode != MPFR_RNDZ */
}
else
{
/* sb != 0 && rnd_mode == MPFR_RNDN */
if (use_inexp)
*inexp = MPFR_EVEN_INEX-2*MPFR_EVEN_INEX*neg;
/* ((neg!=0)^(sb!=0)) ? MPFR_EVEN_INEX : -MPFR_EVEN_INEX */
/* since neg = 0 or 1 and sb != 0 */
goto rnd_RNDN_add_one_ulp;
}
}
else /* sb != 0 && rnd_mode == MPFR_RNDN */
{
if (use_inexp)
*inexp = 1-2*neg; /* neg == 0 ? 1 : -1 */
rnd_RNDN_add_one_ulp:
#if flag == 1
return 1; /* sb != 0 && rnd_mode != MPFR_RNDZ */
#else
carry = mpn_add_1 (yp, xp + xsize - nw, nw,
rw ?
MPFR_LIMB_ONE << (GMP_NUMB_BITS - rw)
: MPFR_LIMB_ONE);
yp[0] &= himask;
return carry;
#endif
}
}
/* Rounding toward zero? */
else if (MPFR_IS_LIKE_RNDZ(rnd_mode, neg))
{
/* rnd_mode == MPFR_RNDZ */
rnd_RNDZ:
while (MPFR_UNLIKELY(sb == 0) && k > 0)
sb = xp[--k];
if (use_inexp)
/* rnd_mode == MPFR_RNDZ and neg = 0 or 1 */
/* ((neg != 0) ^ (rnd_mode != MPFR_RNDZ)) ? 1 : -1 */
*inexp = MPFR_UNLIKELY(sb == 0) ? 0 : (2*neg-1);
#if flag == 0
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
#endif
return 0; /* sb != 0 && rnd_mode != MPFR_RNDZ */
}
else
{
/* Rounding away from zero */
while (MPFR_UNLIKELY(sb == 0) && k > 0)
sb = xp[--k];
if (MPFR_UNLIKELY(sb == 0))
{
/* sb = 0 && rnd_mode != MPFR_RNDZ */
if (use_inexp)
/* ((neg != 0) ^ (rnd_mode != MPFR_RNDZ)) ? 1 : -1 */
*inexp = 0;
#if flag == 0
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
#endif
return 0;
}
else
{
/* sb != 0 && rnd_mode != MPFR_RNDZ */
if (use_inexp)
*inexp = 1-2*neg; /* neg == 0 ? 1 : -1 */
#if flag == 1
return 1;
#else
carry = mpn_add_1(yp, xp + xsize - nw, nw,
rw ? MPFR_LIMB_ONE << (GMP_NUMB_BITS - rw)
: 1);
yp[0] &= himask;
return carry;
#endif
}
}
}
else
{
/* Rounding toward zero / no inexact flag */
#if flag == 0
if (MPFR_LIKELY(rw))
{
nw++;
himask = ~MPFR_LIMB_MASK (GMP_NUMB_BITS - rw);
}
else
himask = MPFR_LIMB_MAX;
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
#endif
return 0;
}
}
mp_limb_t
mpn_divrem (mp_ptr qp, mp_size_t qextra_limbs,
mp_ptr np, mp_size_t nsize,
mp_srcptr dp, mp_size_t dsize)
{
mp_limb_t most_significant_q_limb = 0;
switch (dsize)
{
case 0:
/* We are asked to divide by zero, so go ahead and do it! (To make
the compiler not remove this statement, return the value.) */
return 1 / dsize;
case 1:
{
mp_size_t i;
mp_limb_t n1;
mp_limb_t d;
d = dp[0];
n1 = np[nsize - 1];
if (n1 >= d)
{
n1 -= d;
most_significant_q_limb = 1;
}
qp += qextra_limbs;
for (i = nsize - 2; i >= 0; i--)
udiv_qrnnd (qp[i], n1, n1, np[i], d);
qp -= qextra_limbs;
for (i = qextra_limbs - 1; i >= 0; i--)
udiv_qrnnd (qp[i], n1, n1, 0, d);
np[0] = n1;
}
break;
case 2:
{
mp_size_t i;
mp_limb_t n1, n0, n2;
mp_limb_t d1, d0;
np += nsize - 2;
d1 = dp[1];
d0 = dp[0];
n1 = np[1];
n0 = np[0];
if (n1 >= d1 && (n1 > d1 || n0 >= d0))
{
sub_ddmmss (n1, n0, n1, n0, d1, d0);
most_significant_q_limb = 1;
}
for (i = qextra_limbs + nsize - 2 - 1; i >= 0; i--)
{
mp_limb_t q;
mp_limb_t r;
if (i >= qextra_limbs)
np--;
else
np[0] = 0;
if (n1 == d1)
{
/* Q should be either 111..111 or 111..110. Need special
treatment of this rare case as normal division would
give overflow. */
q = ~(mp_limb_t) 0;
r = n0 + d1;
if (r < d1) /* Carry in the addition? */
{
add_ssaaaa (n1, n0, r - d0, np[0], 0, d0);
qp[i] = q;
continue;
}
n1 = d0 - (d0 != 0);
n0 = -d0;
}
else
{
udiv_qrnnd (q, r, n1, n0, d1);
umul_ppmm (n1, n0, d0, q);
}
n2 = np[0];
q_test:
if (n1 > r || (n1 == r && n0 > n2))
{
/* The estimated Q was too large. */
q--;
sub_ddmmss (n1, n0, n1, n0, 0, d0);
r += d1;
if (r >= d1) /* If not carry, test Q again. */
goto q_test;
}
qp[i] = q;
sub_ddmmss (n1, n0, r, n2, n1, n0);
}
np[1] = n1;
np[0] = n0;
}
break;
default:
{
mp_size_t i;
mp_limb_t dX, d1, n0;
np += nsize - dsize;
dX = dp[dsize - 1];
d1 = dp[dsize - 2];
n0 = np[dsize - 1];
if (n0 >= dX)
{
if (n0 > dX || mpn_cmp (np, dp, dsize - 1) >= 0)
{
mpn_sub_n (np, np, dp, dsize);
n0 = np[dsize - 1];
most_significant_q_limb = 1;
}
}
for (i = qextra_limbs + nsize - dsize - 1; i >= 0; i--)
{
mp_limb_t q;
mp_limb_t n1, n2;
mp_limb_t cy_limb;
if (i >= qextra_limbs)
{
np--;
n2 = np[dsize];
}
else
{
n2 = np[dsize - 1];
MPN_COPY_DECR (np + 1, np, dsize);
np[0] = 0;
}
if (n0 == dX)
/* This might over-estimate q, but it's probably not worth
the extra code here to find out. */
q = ~(mp_limb_t) 0;
else
{
mp_limb_t r;
udiv_qrnnd (q, r, n0, np[dsize - 1], dX);
umul_ppmm (n1, n0, d1, q);
while (n1 > r || (n1 == r && n0 > np[dsize - 2]))
{
q--;
r += dX;
if (r < dX) /* I.e. "carry in previous addition?" */
break;
n1 -= n0 < d1;
n0 -= d1;
}
}
/* Possible optimization: We already have (q * n0) and (1 * n1)
after the calculation of q. Taking advantage of that, we
could make this loop make two iterations less. */
cy_limb = mpn_submul_1 (np, dp, dsize, q);
if (n2 != cy_limb)
{
mpn_add_n (np, np, dp, dsize);
q--;
}
qp[i] = q;
n0 = np[dsize - 1];
}
}
}
return most_significant_q_limb;
}
void mpn_copyd(mp_ptr rp,mp_srcptr sp,mp_size_t n)
{
MPN_COPY_DECR(rp,sp,n);
return;
}
int
mpfr_frac (mpfr_ptr r, mpfr_srcptr u, mp_rnd_t rnd_mode)
{
mp_exp_t re, ue;
mp_prec_t uq, fq;
mp_size_t un, tn, t0;
mp_limb_t *up, *tp, k;
int sh;
mpfr_t tmp;
mpfr_ptr t;
/* Special cases */
if (MPFR_UNLIKELY(MPFR_IS_NAN(u)))
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
else if (MPFR_UNLIKELY(MPFR_IS_INF(u) || mpfr_integer_p (u)))
{
MPFR_CLEAR_FLAGS(r);
MPFR_SET_SAME_SIGN(r, u);
MPFR_SET_ZERO(r);
MPFR_RET(0); /* zero is exact */
}
ue = MPFR_GET_EXP (u);
if (ue <= 0) /* |u| < 1 */
return mpfr_set (r, u, rnd_mode);
uq = MPFR_PREC(u);
un = (uq - 1) / BITS_PER_MP_LIMB; /* index of most significant limb */
un -= (mp_size_t) (ue / BITS_PER_MP_LIMB);
/* now the index of the MSL containing bits of the fractional part */
up = MPFR_MANT(u);
sh = ue % BITS_PER_MP_LIMB;
k = up[un] << sh;
/* the first bit of the fractional part is the MSB of k */
if (k != 0)
{
int cnt;
count_leading_zeros(cnt, k);
/* first bit 1 of the fractional part -> MSB of the number */
re = -cnt;
sh += cnt;
MPFR_ASSERTN (sh < BITS_PER_MP_LIMB);
k <<= cnt;
}
else
{
re = sh - BITS_PER_MP_LIMB;
/* searching for the first bit 1 (exists since u isn't an integer) */
while (up[--un] == 0)
re -= BITS_PER_MP_LIMB;
MPFR_ASSERTN(un >= 0);
k = up[un];
count_leading_zeros(sh, k);
re -= sh;
k <<= sh;
}
/* The exponent of r will be re */
/* un: index of the limb of u that contains the first bit 1 of the FP */
ue -= re; /* number of bits of u to discard */
fq = uq - ue; /* number of bits of the fractional part of u */
/* Temporary fix */
t = /* fq > MPFR_PREC(r) */
(mp_size_t) (MPFR_PREC(r) - 1) / BITS_PER_MP_LIMB < un ?
(mpfr_init2 (tmp, (un + 1) * BITS_PER_MP_LIMB), tmp) : r;
/* t has enough precision to contain the fractional part of u */
/* If we use a temporary variable, we take the non-significant bits
of u into account, because of the mpn_lshift below. */
MPFR_CLEAR_FLAGS(t);
MPFR_SET_SAME_SIGN(t, u);
MPFR_SET_EXP (t, re);
/* Put the fractional part of u into t */
tn = (MPFR_PREC(t) - 1) / BITS_PER_MP_LIMB;
MPFR_ASSERTN(tn >= un);
t0 = tn - un;
tp = MPFR_MANT(t);
if (sh == 0)
MPN_COPY_DECR(tp + t0, up, un + 1);
else /* warning: un may be 0 here */
tp[tn] = k | ((un) ? mpn_lshift (tp + t0, up, un, sh) : (mp_limb_t) 0);
if (t0 > 0)
MPN_ZERO(tp, t0);
if (t != r)
{ /* t is tmp */
int inex;
inex = mpfr_set (r, t, rnd_mode);
mpfr_clear (t);
return inex;
}
else
MPFR_RET(0);
}
int
mpfr_round_raw_generic(
#if flag == 0
mp_limb_t *yp,
#endif
const mp_limb_t *xp, mpfr_prec_t xprec,
int neg, mpfr_prec_t yprec, mpfr_rnd_t rnd_mode
#if use_inexp != 0
, int *inexp
#endif
)
{
mp_size_t xsize, nw;
mp_limb_t himask, lomask, sb;
int rw;
#if flag == 0
int carry;
#endif
#if use_inexp == 0
int *inexp;
#endif
if (use_inexp)
MPFR_ASSERTD(inexp != ((int*) 0));
MPFR_ASSERTD(neg == 0 || neg == 1);
if (flag && !use_inexp &&
(xprec <= yprec || MPFR_IS_LIKE_RNDZ (rnd_mode, neg)))
return 0;
xsize = (xprec-1)/GMP_NUMB_BITS + 1;
nw = yprec / GMP_NUMB_BITS;
rw = yprec & (GMP_NUMB_BITS - 1);
if (MPFR_UNLIKELY(xprec <= yprec))
{ /* No rounding is necessary. */
/* if yp=xp, maybe an overlap: MPN_COPY_DECR is ok when src <= dst */
if (MPFR_LIKELY(rw))
nw++;
MPFR_ASSERTD(nw >= 1);
MPFR_ASSERTD(nw >= xsize);
if (use_inexp)
*inexp = 0;
#if flag == 0
MPN_COPY_DECR(yp + (nw - xsize), xp, xsize);
MPN_ZERO(yp, nw - xsize);
#endif
return 0;
}
if (use_inexp || !MPFR_IS_LIKE_RNDZ(rnd_mode, neg))
{
mp_size_t k = xsize - nw - 1;
if (MPFR_LIKELY(rw))
{
nw++;
lomask = MPFR_LIMB_MASK (GMP_NUMB_BITS - rw);
himask = ~lomask;
}
else
{
lomask = ~(mp_limb_t) 0;
himask = ~(mp_limb_t) 0;
}
MPFR_ASSERTD(k >= 0);
sb = xp[k] & lomask; /* First non-significant bits */
/* Rounding to nearest ? */
if (MPFR_LIKELY( rnd_mode == MPFR_RNDN) )
{
/* Rounding to nearest */
mp_limb_t rbmask = MPFR_LIMB_ONE << (GMP_NUMB_BITS - 1 - rw);
if (sb & rbmask) /* rounding bit */
sb &= ~rbmask; /* it is 1, clear it */
else
{
/* Rounding bit is 0, behave like rounding to 0 */
goto rnd_RNDZ;
}
while (MPFR_UNLIKELY(sb == 0) && k > 0)
sb = xp[--k];
/* rounding to nearest, with rounding bit = 1 */
if (MPFR_UNLIKELY(sb == 0)) /* Even rounding. */
{
/* sb == 0 && rnd_mode == MPFR_RNDN */
sb = xp[xsize - nw] & (himask ^ (himask << 1));
if (sb == 0)
{
if (use_inexp)
*inexp = 2*MPFR_EVEN_INEX*neg-MPFR_EVEN_INEX;
/* ((neg!=0)^(sb!=0)) ? MPFR_EVEN_INEX : -MPFR_EVEN_INEX;*/
/* Since neg = 0 or 1 and sb=0*/
#if flag == 1
return 0 /*sb != 0 && rnd_mode != MPFR_RNDZ */;
#else
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
return 0;
#endif
}
else
{
/* sb != 0 && rnd_mode == MPFR_RNDN */
if (use_inexp)
*inexp = MPFR_EVEN_INEX-2*MPFR_EVEN_INEX*neg;
/*((neg!=0)^(sb!=0))? MPFR_EVEN_INEX : -MPFR_EVEN_INEX; */
/*Since neg= 0 or 1 and sb != 0 */
goto rnd_RNDN_add_one_ulp;
}
}
else /* sb != 0 && rnd_mode == MPFR_RNDN*/
{
if (use_inexp)
/* *inexp = (neg == 0) ? 1 : -1; but since neg = 0 or 1 */
*inexp = 1-2*neg;
rnd_RNDN_add_one_ulp:
#if flag == 1
return 1; /*sb != 0 && rnd_mode != MPFR_RNDZ;*/
#else
carry = mpn_add_1 (yp, xp + xsize - nw, nw,
rw ?
MPFR_LIMB_ONE << (GMP_NUMB_BITS - rw)
: MPFR_LIMB_ONE);
yp[0] &= himask;
return carry;
#endif
}
}
/* Rounding to Zero ? */
else if (MPFR_IS_LIKE_RNDZ(rnd_mode, neg))
{
/* rnd_mode == MPFR_RNDZ */
rnd_RNDZ:
while (MPFR_UNLIKELY(sb == 0) && k > 0)
sb = xp[--k];
if (use_inexp)
/* rnd_mode == MPFR_RNDZ and neg = 0 or 1 */
/* (neg != 0) ^ (rnd_mode != MPFR_RNDZ)) ? 1 : -1);*/
*inexp = MPFR_UNLIKELY(sb == 0) ? 0 : (2*neg-1);
#if flag == 1
return 0; /*sb != 0 && rnd_mode != MPFR_RNDZ;*/
#else
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
return 0;
#endif
}
else
{
/* rnd_mode = Away */
while (MPFR_UNLIKELY(sb == 0) && k > 0)
sb = xp[--k];
if (MPFR_UNLIKELY(sb == 0))
{
/* sb = 0 && rnd_mode != MPFR_RNDZ */
if (use_inexp)
/* (neg != 0) ^ (rnd_mode != MPFR_RNDZ)) ? 1 : -1);*/
*inexp = 0;
#if flag == 1
return 0;
#else
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
return 0;
#endif
}
else
{
/* sb != 0 && rnd_mode != MPFR_RNDZ */
if (use_inexp)
/* (neg != 0) ^ (rnd_mode != MPFR_RNDZ)) ? 1 : -1);*/
*inexp = 1-2*neg;
#if flag == 1
return 1;
#else
carry = mpn_add_1(yp, xp + xsize - nw, nw,
rw ? MPFR_LIMB_ONE << (GMP_NUMB_BITS - rw)
: 1);
yp[0] &= himask;
return carry;
#endif
}
}
}
else
{
/* Roundind mode = Zero / No inexact flag */
#if flag == 1
return 0 /*sb != 0 && rnd_mode != MPFR_RNDZ*/;
#else
if (MPFR_LIKELY(rw))
{
nw++;
himask = ~MPFR_LIMB_MASK (GMP_NUMB_BITS - rw);
}
else
himask = ~(mp_limb_t) 0;
MPN_COPY_INCR(yp, xp + xsize - nw, nw);
yp[0] &= himask;
return 0;
#endif
}
}
int
mpfr_frac (mpfr_ptr r, mpfr_srcptr u, mpfr_rnd_t rnd_mode)
{
mpfr_exp_t re, ue;
mpfr_prec_t uq;
mp_size_t un, tn, t0;
mp_limb_t *up, *tp, k;
int sh;
mpfr_t tmp;
mpfr_ptr t;
int inex;
MPFR_SAVE_EXPO_DECL (expo);
/* Special cases */
if (MPFR_UNLIKELY(MPFR_IS_NAN(u)))
{
MPFR_SET_NAN(r);
MPFR_RET_NAN;
}
else if (MPFR_UNLIKELY(MPFR_IS_INF(u) || mpfr_integer_p (u)))
{
MPFR_SET_SAME_SIGN(r, u);
MPFR_SET_ZERO(r);
MPFR_RET(0); /* zero is exact */
}
ue = MPFR_GET_EXP (u);
if (ue <= 0) /* |u| < 1 */
return mpfr_set (r, u, rnd_mode);
/* Now |u| >= 1, meaning that an overflow is not possible. */
uq = MPFR_PREC(u);
un = (uq - 1) / GMP_NUMB_BITS; /* index of most significant limb */
un -= (mp_size_t) (ue / GMP_NUMB_BITS);
/* now the index of the MSL containing bits of the fractional part */
up = MPFR_MANT(u);
sh = ue % GMP_NUMB_BITS;
k = up[un] << sh;
/* the first bit of the fractional part is the MSB of k */
if (k != 0)
{
int cnt;
count_leading_zeros(cnt, k);
/* first bit 1 of the fractional part -> MSB of the number */
re = -cnt;
sh += cnt;
MPFR_ASSERTN (sh < GMP_NUMB_BITS);
k <<= cnt;
}
else
{
re = sh - GMP_NUMB_BITS;
/* searching for the first bit 1 (exists since u isn't an integer) */
while (up[--un] == 0)
re -= GMP_NUMB_BITS;
MPFR_ASSERTN(un >= 0);
k = up[un];
count_leading_zeros(sh, k);
re -= sh;
k <<= sh;
}
/* The exponent of r will be re */
/* un: index of the limb of u that contains the first bit 1 of the FP */
t = (mp_size_t) (MPFR_PREC(r) - 1) / GMP_NUMB_BITS < un ?
(mpfr_init2 (tmp, (un + 1) * GMP_NUMB_BITS), tmp) : r;
/* t has enough precision to contain the fractional part of u */
/* If we use a temporary variable, we take the non-significant bits
of u into account, because of the mpn_lshift below. */
MPFR_SET_SAME_SIGN(t, u);
/* Put the fractional part of u into t */
tn = (MPFR_PREC(t) - 1) / GMP_NUMB_BITS;
MPFR_ASSERTN(tn >= un);
t0 = tn - un;
tp = MPFR_MANT(t);
if (sh == 0)
MPN_COPY_DECR(tp + t0, up, un + 1);
else /* warning: un may be 0 here */
tp[tn] = k | ((un) ? mpn_lshift (tp + t0, up, un, sh) : (mp_limb_t) 0);
if (t0 > 0)
MPN_ZERO(tp, t0);
MPFR_SAVE_EXPO_MARK (expo);
if (t != r)
{ /* t is tmp */
MPFR_EXP (t) = 0; /* should be re, but not necessarily in the range */
inex = mpfr_set (r, t, rnd_mode); /* no underflow */
mpfr_clear (t);
MPFR_EXP (r) += re;
}
else
{ /* There may be remaining non-significant bits in t (= r). */
int carry;
MPFR_EXP (r) = re;
carry = mpfr_round_raw (tp, tp,
(mpfr_prec_t) (tn + 1) * GMP_NUMB_BITS,
MPFR_IS_NEG (r), MPFR_PREC (r), rnd_mode,
&inex);
if (carry)
{
tp[tn] = MPFR_LIMB_HIGHBIT;
MPFR_EXP (r) ++;
}
}
MPFR_SAVE_EXPO_FREE (expo);
return mpfr_check_range (r, inex, rnd_mode);
}
