1
2/*============================================================================
3
4This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
5Package, Release 3e, by John R. Hauser.
6
7Copyright 2011, 2012, 2013, 2014, 2015, 2017 The Regents of the University of
8California.  All rights reserved.
9
10Redistribution and use in source and binary forms, with or without
11modification, are permitted provided that the following conditions are met:
12
13 1. Redistributions of source code must retain the above copyright notice,
14    this list of conditions, and the following disclaimer.
15
16 2. Redistributions in binary form must reproduce the above copyright notice,
17    this list of conditions, and the following disclaimer in the documentation
18    and/or other materials provided with the distribution.
19
20 3. Neither the name of the University nor the names of its contributors may
21    be used to endorse or promote products derived from this software without
22    specific prior written permission.
23
24THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
25EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
26WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
27DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
28DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34
35=============================================================================*/
36
37#include <stdbool.h>
38#include <stdint.h>
39#include "platform.h"
40#include "internals.h"
41#include "softfloat.h"
42
43extFloat80_t
44 softfloat_roundPackToExtF80(
45     bool sign,
46     int_fast32_t exp,
47     uint_fast64_t sig,
48     uint_fast64_t sigExtra,
49     uint_fast8_t roundingPrecision
50 )
51{
52    uint_fast8_t roundingMode;
53    bool roundNearEven;
54    uint_fast64_t roundIncrement, roundMask, roundBits;
55    bool isTiny, doIncrement;
56    struct uint64_extra sig64Extra;
57    union { struct extFloat80M s; extFloat80_t f; } uZ;
58
59    /*------------------------------------------------------------------------
60    *------------------------------------------------------------------------*/
61    roundingMode = softfloat_roundingMode;
62    roundNearEven = (roundingMode == softfloat_round_near_even);
63    if ( roundingPrecision == 80 ) goto precision80;
64    if ( roundingPrecision == 64 ) {
65        roundIncrement = UINT64_C( 0x0000000000000400 );
66        roundMask = UINT64_C( 0x00000000000007FF );
67    } else if ( roundingPrecision == 32 ) {
68        roundIncrement = UINT64_C( 0x0000008000000000 );
69        roundMask = UINT64_C( 0x000000FFFFFFFFFF );
70    } else {
71        goto precision80;
72    }
73    sig |= (sigExtra != 0);
74    if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
75        roundIncrement =
76            (roundingMode
77                 == (sign ? softfloat_round_min : softfloat_round_max))
78                ? roundMask
79                : 0;
80    }
81    roundBits = sig & roundMask;
82    /*------------------------------------------------------------------------
83    *------------------------------------------------------------------------*/
84    if ( 0x7FFD <= (uint32_t) (exp - 1) ) {
85        if ( exp <= 0 ) {
86            /*----------------------------------------------------------------
87            *----------------------------------------------------------------*/
88            isTiny =
89                   (softfloat_detectTininess
90                        == softfloat_tininess_beforeRounding)
91                || (exp < 0)
92                || (sig <= (uint64_t) (sig + roundIncrement));
93            sig = softfloat_shiftRightJam64( sig, 1 - exp );
94            roundBits = sig & roundMask;
95            if ( roundBits ) {
96                if ( isTiny ) softfloat_raiseFlags( softfloat_flag_underflow );
97                softfloat_raiseFlags( softfloat_flag_inexact );
98#ifdef SOFTFLOAT_ROUND_ODD
99                if ( roundingMode == softfloat_round_odd ) {
100                    sig |= roundMask + 1;
101                }
102#endif
103            }
104            sig += roundIncrement;
105            exp = ((sig & UINT64_C( 0x8000000000000000 )) != 0);
106            roundIncrement = roundMask + 1;
107            if ( roundNearEven && (roundBits<<1 == roundIncrement) ) {
108                roundMask |= roundIncrement;
109            }
110            sig &= ~roundMask;
111            goto packReturn;
112        }
113        if (
114               (0x7FFE < exp)
115            || ((exp == 0x7FFE) && ((uint64_t) (sig + roundIncrement) < sig))
116        ) {
117            goto overflow;
118        }
119    }
120    /*------------------------------------------------------------------------
121    *------------------------------------------------------------------------*/
122    if ( roundBits ) {
123        softfloat_raiseFlags( softfloat_flag_inexact );
124#ifdef SOFTFLOAT_ROUND_ODD
125        if ( roundingMode == softfloat_round_odd ) {
126            sig = (sig & ~roundMask) | (roundMask + 1);
127            goto packReturn;
128        }
129#endif
130    }
131    sig = (uint64_t) (sig + roundIncrement);
132    if ( sig < roundIncrement ) {
133        ++exp;
134        sig = UINT64_C( 0x8000000000000000 );
135    }
136    roundIncrement = roundMask + 1;
137    if ( roundNearEven && (roundBits<<1 == roundIncrement) ) {
138        roundMask |= roundIncrement;
139    }
140    sig &= ~roundMask;
141    goto packReturn;
142    /*------------------------------------------------------------------------
143    *------------------------------------------------------------------------*/
144 precision80:
145    doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
146    if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
147        doIncrement =
148            (roundingMode
149                 == (sign ? softfloat_round_min : softfloat_round_max))
150                && sigExtra;
151    }
152    /*------------------------------------------------------------------------
153    *------------------------------------------------------------------------*/
154    if ( 0x7FFD <= (uint32_t) (exp - 1) ) {
155        if ( exp <= 0 ) {
156            /*----------------------------------------------------------------
157            *----------------------------------------------------------------*/
158            isTiny =
159                   (softfloat_detectTininess
160                        == softfloat_tininess_beforeRounding)
161                || (exp < 0)
162                || ! doIncrement
163                || (sig < UINT64_C( 0xFFFFFFFFFFFFFFFF ));
164            sig64Extra =
165                softfloat_shiftRightJam64Extra( sig, sigExtra, 1 - exp );
166            exp = 0;
167            sig = sig64Extra.v;
168            sigExtra = sig64Extra.extra;
169            if ( sigExtra ) {
170                if ( isTiny ) softfloat_raiseFlags( softfloat_flag_underflow );
171                softfloat_raiseFlags( softfloat_flag_inexact );
172#ifdef SOFTFLOAT_ROUND_ODD
173                if ( roundingMode == softfloat_round_odd ) {
174                    sig |= 1;
175                    goto packReturn;
176                }
177#endif
178            }
179            doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
180            if (
181                ! roundNearEven
182                    && (roundingMode != softfloat_round_near_maxMag)
183            ) {
184                doIncrement =
185                    (roundingMode
186                         == (sign ? softfloat_round_min : softfloat_round_max))
187                        && sigExtra;
188            }
189            if ( doIncrement ) {
190                ++sig;
191                sig &=
192                    ~(uint_fast64_t)
193                         (! (sigExtra & UINT64_C( 0x7FFFFFFFFFFFFFFF ))
194                              & roundNearEven);
195                exp = ((sig & UINT64_C( 0x8000000000000000 )) != 0);
196            }
197            goto packReturn;
198        }
199        if (
200               (0x7FFE < exp)
201            || ((exp == 0x7FFE) && (sig == UINT64_C( 0xFFFFFFFFFFFFFFFF ))
202                    && doIncrement)
203        ) {
204            /*----------------------------------------------------------------
205            *----------------------------------------------------------------*/
206            roundMask = 0;
207 overflow:
208            softfloat_raiseFlags(
209                softfloat_flag_overflow | softfloat_flag_inexact );
210            if (
211                   roundNearEven
212                || (roundingMode == softfloat_round_near_maxMag)
213                || (roundingMode
214                        == (sign ? softfloat_round_min : softfloat_round_max))
215            ) {
216                exp = 0x7FFF;
217                sig = UINT64_C( 0x8000000000000000 );
218            } else {
219                exp = 0x7FFE;
220                sig = ~roundMask;
221            }
222            goto packReturn;
223        }
224    }
225    /*------------------------------------------------------------------------
226    *------------------------------------------------------------------------*/
227    if ( sigExtra ) {
228        softfloat_raiseFlags( softfloat_flag_inexact );
229#ifdef SOFTFLOAT_ROUND_ODD
230        if ( roundingMode == softfloat_round_odd ) {
231            sig |= 1;
232            goto packReturn;
233        }
234#endif
235    }
236    if ( doIncrement ) {
237        ++sig;
238        if ( ! sig ) {
239            ++exp;
240            sig = UINT64_C( 0x8000000000000000 );
241        } else {
242            sig &=
243                ~(uint_fast64_t)
244                     (! (sigExtra & UINT64_C( 0x7FFFFFFFFFFFFFFF ))
245                          & roundNearEven);
246        }
247    }
248    /*------------------------------------------------------------------------
249    *------------------------------------------------------------------------*/
250 packReturn:
251    uZ.s.signExp = packToExtF80UI64( sign, exp );
252    uZ.s.signif = sig;
253    return uZ.f;
254
255}
256
257