1 /* Copyright (C) 1995-2013 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
24 /* Convert a `__float128' in IEEE854 quad-precision format to a
25 multi-precision integer representing the significand scaled up by its
26 number of bits (113 for long double) and an integral power of two
30 mpn_extract_flt128 (mp_ptr res_ptr
, mp_size_t size
,
31 int *expt
, int *is_neg
,
37 *is_neg
= u
.ieee
.negative
;
38 *expt
= (int) u
.ieee
.exponent
- IEEE854_FLOAT128_BIAS
;
40 #if BITS_PER_MP_LIMB == 32
41 res_ptr
[0] = u
.ieee
.mant_low
; /* Low-order 32 bits of fraction. */
42 res_ptr
[1] = (u
.ieee
.mant_low
>> 32);
43 res_ptr
[2] = u
.ieee
.mant_high
;
44 res_ptr
[3] = (u
.ieee
.mant_high
>> 32); /* High-order 32 bits. */
46 #elif BITS_PER_MP_LIMB == 64
47 res_ptr
[0] = u
.ieee
.mant_low
;
48 res_ptr
[1] = u
.ieee
.mant_high
;
51 #error "mp_limb size " BITS_PER_MP_LIMB "not accounted for"
53 /* The format does not fill the last limb. There are some zeros. */
54 #define NUM_LEADING_ZEROS (BITS_PER_MP_LIMB \
55 - (FLT128_MANT_DIG - ((N - 1) * BITS_PER_MP_LIMB)))
57 if (u
.ieee
.exponent
== 0)
59 /* A biased exponent of zero is a special case.
60 Either it is a zero or it is a denormal number. */
61 if (res_ptr
[0] == 0 && res_ptr
[1] == 0
62 && res_ptr
[N
- 2] == 0 && res_ptr
[N
- 1] == 0) /* Assumes N<=4. */
67 /* It is a denormal number, meaning it has no implicit leading
68 one bit, and its exponent is in fact the format minimum. */
72 if (res_ptr
[N
- 1] != 0)
74 count_leading_zeros (cnt
, res_ptr
[N
- 1]);
75 cnt
-= NUM_LEADING_ZEROS
;
76 res_ptr
[N
- 1] = res_ptr
[N
- 1] << cnt
77 | (res_ptr
[0] >> (BITS_PER_MP_LIMB
- cnt
));
79 *expt
= FLT128_MIN_EXP
- 1 - cnt
;
83 count_leading_zeros (cnt
, res_ptr
[0]);
84 if (cnt
>= NUM_LEADING_ZEROS
)
86 res_ptr
[N
- 1] = res_ptr
[0] << (cnt
- NUM_LEADING_ZEROS
);
91 res_ptr
[N
- 1] = res_ptr
[0] >> (NUM_LEADING_ZEROS
- cnt
);
92 res_ptr
[0] <<= BITS_PER_MP_LIMB
- (NUM_LEADING_ZEROS
- cnt
);
94 *expt
= FLT128_MIN_EXP
- 1
95 - (BITS_PER_MP_LIMB
- NUM_LEADING_ZEROS
) - cnt
;
100 for (j
= N
- 1; j
> 0; j
--)
104 count_leading_zeros (cnt
, res_ptr
[j
]);
105 cnt
-= NUM_LEADING_ZEROS
;
109 cnt
+= BITS_PER_MP_LIMB
;
113 for (k
= N
- 1; k
>= l
; k
--)
114 res_ptr
[k
] = res_ptr
[k
-l
];
117 for (k
= N
- 1; k
> l
; k
--)
118 res_ptr
[k
] = res_ptr
[k
-l
] << cnt
119 | res_ptr
[k
-l
-1] >> (BITS_PER_MP_LIMB
- cnt
);
120 res_ptr
[k
--] = res_ptr
[0] << cnt
;
125 *expt
= FLT128_MIN_EXP
- 1 - l
* BITS_PER_MP_LIMB
- cnt
;
130 /* Add the implicit leading one bit for a normalized number. */
131 res_ptr
[N
- 1] |= (mp_limb_t
) 1 << (FLT128_MANT_DIG
- 1
132 - ((N
- 1) * BITS_PER_MP_LIMB
));