| 1 | /* mpf_get_si -- mpf to long conversion */ |
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| 2 | |
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| 3 | /* |
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| 4 | Copyright 2001, 2002 Free Software Foundation, Inc. |
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| 5 | |
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| 6 | This file is part of the GNU MP Library. |
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| 7 | |
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| 8 | The GNU MP Library is free software; you can redistribute it and/or modify |
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| 9 | it under the terms of the GNU Lesser General Public License as published by |
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| 10 | the Free Software Foundation; either version 2.1 of the License, or (at your |
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| 11 | option) any later version. |
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| 12 | |
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| 13 | The GNU MP Library is distributed in the hope that it will be useful, but |
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| 14 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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| 15 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
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| 16 | License for more details. |
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| 17 | |
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| 18 | You should have received a copy of the GNU Lesser General Public License |
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| 19 | along with the GNU MP Library; see the file COPYING.LIB. If not, write to |
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| 20 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
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| 21 | MA 02111-1307, USA. |
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| 22 | */ |
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| 23 | |
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| 24 | #include "gmp.h" |
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| 25 | #include "gmp-impl.h" |
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| 26 | |
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| 27 | |
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| 28 | /* Any fraction bits are truncated, meaning simply discarded. |
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| 29 | |
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| 30 | For values bigger than a long, the low bits are returned, like |
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| 31 | mpz_get_si, but this isn't documented. |
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| 32 | |
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| 33 | Notice this is equivalent to mpz_set_f + mpz_get_si. */ |
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| 34 | |
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| 35 | long |
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| 36 | mpf_get_si (mpf_srcptr f) |
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| 37 | { |
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| 38 | mp_exp_t exp; |
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| 39 | mp_size_t size, abs_size; |
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| 40 | mp_ptr fp; |
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| 41 | mp_limb_t fl; |
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| 42 | |
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| 43 | size = SIZ (f); |
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| 44 | if (size == 0) |
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| 45 | return 0L; |
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| 46 | |
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| 47 | /* fraction alone truncates to zero */ |
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| 48 | exp = EXP (f); |
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| 49 | if (exp <= 0) |
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| 50 | return 0L; |
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| 51 | |
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| 52 | /* exponent bigger than available data means low limb zero */ |
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| 53 | abs_size = ABS (size); |
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| 54 | if (exp > abs_size) |
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| 55 | return 0L; |
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| 56 | |
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| 57 | fp = PTR(f); |
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| 58 | fl = fp[abs_size - exp]; |
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| 59 | |
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| 60 | #if GMP_NAIL_BITS != 0 |
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| 61 | if (ULONG_MAX > GMP_NUMB_MAX != 0 && exp > 1) |
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| 62 | fl |= fp[abs_size - exp + 1] << GMP_NUMB_BITS; |
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| 63 | #endif |
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| 64 | |
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| 65 | if (size > 0) |
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| 66 | return fl & LONG_MAX; |
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| 67 | else |
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| 68 | /* this form necessary to correctly handle -0x80..00 */ |
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| 69 | return ~ ((fl - 1) & LONG_MAX); |
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| 70 | } |
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