1 /* mpfr_set_uj -- set a MPFR number from a huge machine unsigned integer
2
3 Copyright 2004-2023 Free Software Foundation, Inc.
4 Contributed by the AriC and Caramba projects, INRIA.
5
6 This file is part of the GNU MPFR Library.
7
8 The GNU MPFR Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or (at your
11 option) any later version.
12
13 The GNU MPFR Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16 License for more details.
17
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
20 https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
22
23 #define MPFR_NEED_LONGLONG_H
24 #define MPFR_NEED_INTMAX_H
25 #include "mpfr-impl.h"
26
27 #ifdef _MPFR_H_HAVE_INTMAX_T
28
29 #define uintmaxpml (sizeof(uintmax_t) / sizeof(mp_limb_t))
30
31 int
mpfr_set_uj(mpfr_ptr x,uintmax_t j,mpfr_rnd_t rnd)32 mpfr_set_uj (mpfr_ptr x, uintmax_t j, mpfr_rnd_t rnd)
33 {
34 return mpfr_set_uj_2exp (x, j, 0, rnd);
35 }
36
37 int
mpfr_set_uj_2exp(mpfr_ptr x,uintmax_t j,intmax_t e,mpfr_rnd_t rnd)38 mpfr_set_uj_2exp (mpfr_ptr x, uintmax_t j, intmax_t e, mpfr_rnd_t rnd)
39 {
40 int cnt, inex;
41 mp_size_t i, k;
42 mp_limb_t limb;
43 mp_limb_t yp[uintmaxpml];
44 mpfr_t y;
45 unsigned long uintmax_bit_size = sizeof(uintmax_t) * CHAR_BIT;
46 unsigned long bpml = GMP_NUMB_BITS % uintmax_bit_size;
47
48 /* Special case */
49 if (j == 0)
50 {
51 MPFR_SET_POS(x);
52 MPFR_SET_ZERO(x);
53 MPFR_RET(0);
54 }
55
56 /* early overflow detection to avoid a possible integer overflow below */
57 if (MPFR_UNLIKELY(e >= __gmpfr_emax))
58 return mpfr_overflow (x, rnd, MPFR_SIGN_POS);
59
60 MPFR_ASSERTN (sizeof(uintmax_t) % sizeof(mp_limb_t) == 0);
61
62 /* Create an auxiliary var */
63 MPFR_TMP_INIT1 (yp, y, uintmax_bit_size);
64 /* The compiler will optimize the code by removing the useless branch. */
65 k = uintmaxpml;
66 if (uintmaxpml == 1)
67 {
68 limb = j;
69 count_leading_zeros(cnt, limb);
70 /* Normalize the most significant limb */
71 yp[0] = limb << cnt;
72 }
73 else
74 {
75 mp_size_t len;
76 /* Note: either GMP_NUMB_BITS = uintmax_bit_size, then k = 1 the
77 shift j >>= bpml is never done, or GMP_NUMB_BITS < uintmax_bit_size
78 and bpml = GMP_NUMB_BITS. */
79 for (i = 0; i < k; i++, j >>= bpml)
80 yp[i] = j; /* Only the low bits are copied */
81
82 /* Find the first limb not equal to zero. */
83 do
84 {
85 MPFR_ASSERTD (k > 0);
86 limb = yp[--k];
87 }
88 while (limb == 0);
89 k++;
90 len = numberof (yp) - k;
91 count_leading_zeros(cnt, limb);
92
93 /* Normalize it: len = number of last zero limbs,
94 k = number of previous limbs */
95 if (MPFR_LIKELY (cnt != 0))
96 mpn_lshift (yp+len, yp, k, cnt); /* Normalize the high limb */
97 else if (len != 0)
98 mpn_copyd (yp+len, yp, k); /* Must use copyd */
99 if (len != 0)
100 {
101 if (len == 1)
102 yp[0] = MPFR_LIMB_ZERO;
103 else
104 MPN_ZERO (yp, len); /* Zero the last limbs */
105 }
106 }
107 e += k * GMP_NUMB_BITS - cnt; /* Update Expo */
108 MPFR_ASSERTD (MPFR_LIMB_MSB(yp[numberof (yp) - 1]) != 0);
109
110 MPFR_RNDRAW (inex, x, yp, uintmax_bit_size, rnd, MPFR_SIGN_POS, e++);
111
112 /* Check expo underflow / overflow */
113 if (MPFR_UNLIKELY(e < __gmpfr_emin))
114 {
115 /* The following test is necessary because in the rounding to the
116 * nearest mode, mpfr_underflow always rounds away from 0. In
117 * this rounding mode, we need to round to 0 if:
118 * _ |x| < 2^(emin-2), or
119 * _ |x| = 2^(emin-2) and the absolute value of the exact
120 * result is <= 2^(emin-2). */
121 if (rnd == MPFR_RNDN &&
122 (e + 1 < __gmpfr_emin ||
123 (mpfr_powerof2_raw (x) && inex >= 0)))
124 rnd = MPFR_RNDZ;
125 return mpfr_underflow (x, rnd, MPFR_SIGN_POS);
126 }
127 if (MPFR_UNLIKELY(e > __gmpfr_emax))
128 return mpfr_overflow (x, rnd, MPFR_SIGN_POS);
129
130 MPFR_SET_SIGN (x, MPFR_SIGN_POS);
131 MPFR_SET_EXP (x, e);
132 MPFR_RET (inex);
133 }
134
135 #endif
136