1 /* Simple data type for positive real numbers for the GNU compiler.
2 Copyright (C) 2002-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /* This library supports positive real numbers and 0;
21 inf and nan are NOT supported.
22 It is written to be simple and fast.
28 (for < 64-bit machines sig = sig_lo + sig_hi * 2 ^ SREAL_PART_BITS)
31 One uint64_t is used for the significant.
32 Only a half of significant bits is used (in normalized sreals) so that we do
33 not have problems with overflow, for example when c->sig = a->sig * b->sig.
34 So the precision is 32-bit.
36 Invariant: The numbers are normalized before and after each call of sreal_*.
39 All numbers (except zero) meet following conditions:
40 SREAL_MIN_SIG <= sig && sig <= SREAL_MAX_SIG
41 -SREAL_MAX_EXP <= exp && exp <= SREAL_MAX_EXP
43 If the number would be too large, it is set to upper bounds of these
46 If the number is zero or would be too small it meets following conditions:
47 sig == 0 && exp == -SREAL_MAX_EXP
52 #include "coretypes.h"
55 /* Print the content of struct sreal. */
58 sreal::dump (FILE *file
) const
60 fprintf (file
, "(%" PRIu64
" * 2^%d)", m_sig
, m_exp
);
75 fprintf (stderr
, "<nil>\n");
78 /* Shift this right by S bits. Needed: 0 < S <= SREAL_BITS.
79 When the most significant bit shifted out is 1, add 1 to this (rounding).
83 sreal::shift_right (int s
)
86 gcc_assert (s
<= SREAL_BITS
);
87 /* Exponent should never be so large because shift_right is used only by
88 sreal_add and sreal_sub ant thus the number cannot be shifted out from
90 gcc_assert (m_exp
+ s
<= SREAL_MAX_EXP
);
94 m_sig
+= (uint64_t) 1 << (s
- 1);
98 /* Normalize *this. */
105 m_exp
= -SREAL_MAX_EXP
;
107 else if (m_sig
< SREAL_MIN_SIG
)
114 while (m_sig
< SREAL_MIN_SIG
);
116 /* Check underflow. */
117 if (m_exp
< -SREAL_MAX_EXP
)
119 m_exp
= -SREAL_MAX_EXP
;
123 else if (m_sig
> SREAL_MAX_SIG
)
128 last_bit
= m_sig
& 1;
132 while (m_sig
> SREAL_MAX_SIG
);
134 /* Round the number. */
136 if (m_sig
> SREAL_MAX_SIG
)
142 /* Check overflow. */
143 if (m_exp
> SREAL_MAX_EXP
)
145 m_exp
= SREAL_MAX_EXP
;
146 m_sig
= SREAL_MAX_SIG
;
151 /* Return integer value of *this. */
154 sreal::to_int () const
156 if (m_exp
<= -SREAL_BITS
)
158 if (m_exp
>= SREAL_PART_BITS
)
161 return m_sig
<< m_exp
;
163 return m_sig
>> -m_exp
;
167 /* Return *this + other. */
170 sreal::operator+ (const sreal
&other
) const
174 const sreal
*a_p
= this, *b_p
= &other
, *bb
;
184 dexp
= a_p
->m_exp
- b_p
->m_exp
;
185 r
.m_exp
= a_p
->m_exp
;
186 if (dexp
> SREAL_BITS
)
188 r
.m_sig
= a_p
->m_sig
;
197 tmp
.shift_right (dexp
);
201 r
.m_sig
= a_p
->m_sig
+ bb
->m_sig
;
206 /* Return *this - other. */
209 sreal::operator- (const sreal
&other
) const
215 gcc_assert (*this >= other
);
217 dexp
= m_exp
- other
.m_exp
;
219 if (dexp
> SREAL_BITS
)
229 tmp
.shift_right (dexp
);
233 r
.m_sig
= m_sig
- bb
->m_sig
;
238 /* Return *this * other. */
241 sreal::operator* (const sreal
&other
) const
244 if (m_sig
< SREAL_MIN_SIG
|| other
.m_sig
< SREAL_MIN_SIG
)
247 r
.m_exp
= -SREAL_MAX_EXP
;
251 r
.m_sig
= m_sig
* other
.m_sig
;
252 r
.m_exp
= m_exp
+ other
.m_exp
;
258 /* Return *this / other. */
261 sreal::operator/ (const sreal
&other
) const
263 gcc_assert (other
.m_sig
!= 0);
265 r
.m_sig
= (m_sig
<< SREAL_PART_BITS
) / other
.m_sig
;
266 r
.m_exp
= m_exp
- other
.m_exp
- SREAL_PART_BITS
;