1 
2 /*============================================================================
3 
4 This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
5 Package, Release 3a, by John R. Hauser.
6 
7 Copyright 2011, 2012, 2013, 2014, 2015 The Regents of the University of
8 California.  All rights reserved.
9 
10 Redistribution and use in source and binary forms, with or without
11 modification, 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 
24 THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
25 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
26 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
27 DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
28 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31 ON 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
33 SOFTWARE, 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 
43 float128_t
softfloat_roundPackToF128(bool sign,int_fast32_t exp,uint_fast64_t sig64,uint_fast64_t sig0,uint_fast64_t sigExtra)44  softfloat_roundPackToF128(
45      bool sign,
46      int_fast32_t exp,
47      uint_fast64_t sig64,
48      uint_fast64_t sig0,
49      uint_fast64_t sigExtra
50  )
51 {
52     uint_fast8_t roundingMode;
53     bool roundNearEven, doIncrement, isTiny;
54     struct uint128_extra sig128Extra;
55     uint_fast64_t uiZ64, uiZ0;
56     struct uint128 sig128;
57     union ui128_f128 uZ;
58 
59     roundingMode = softfloat_roundingMode;
60     roundNearEven = (roundingMode == softfloat_round_near_even);
61     doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
62     if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
63         doIncrement =
64             (roundingMode
65                  == (sign ? softfloat_round_min : softfloat_round_max))
66                 && sigExtra;
67     }
68     if ( 0x7FFD <= (uint32_t) exp ) {
69         if ( exp < 0 ) {
70             isTiny =
71                    (softfloat_detectTininess
72                         == softfloat_tininess_beforeRounding)
73                 || (exp < -1)
74                 || ! doIncrement
75                 || softfloat_lt128(
76                        sig64,
77                        sig0,
78                        UINT64_C( 0x0001FFFFFFFFFFFF ),
79                        UINT64_C( 0xFFFFFFFFFFFFFFFF )
80                    );
81             sig128Extra =
82                 softfloat_shiftRightJam128Extra( sig64, sig0, sigExtra, -exp );
83             sig64 = sig128Extra.v.v64;
84             sig0  = sig128Extra.v.v0;
85             sigExtra = sig128Extra.extra;
86             exp = 0;
87             if ( isTiny && sigExtra ) {
88                 softfloat_raiseFlags( softfloat_flag_underflow );
89             }
90             doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
91             if (
92                    ! roundNearEven
93                 && (roundingMode != softfloat_round_near_maxMag)
94             ) {
95                 doIncrement =
96                     (roundingMode
97                          == (sign ? softfloat_round_min : softfloat_round_max))
98                         && sigExtra;
99             }
100         } else if (
101                (0x7FFD < exp)
102             || ((exp == 0x7FFD)
103                     && softfloat_eq128(
104                            sig64,
105                            sig0,
106                            UINT64_C( 0x0001FFFFFFFFFFFF ),
107                            UINT64_C( 0xFFFFFFFFFFFFFFFF )
108                        )
109                     && doIncrement)
110         ) {
111             softfloat_raiseFlags(
112                 softfloat_flag_overflow | softfloat_flag_inexact );
113             if (
114                    roundNearEven
115                 || (roundingMode == softfloat_round_near_maxMag)
116                 || (roundingMode
117                         == (sign ? softfloat_round_min : softfloat_round_max))
118             ) {
119                 uiZ64 = packToF128UI64( sign, 0x7FFF, 0 );
120                 uiZ0  = 0;
121             } else {
122                 uiZ64 =
123                     packToF128UI64(
124                         sign, 0x7FFE, UINT64_C( 0x0000FFFFFFFFFFFF ) );
125                 uiZ0 = UINT64_C( 0xFFFFFFFFFFFFFFFF );
126             }
127             goto uiZ;
128         }
129     }
130     if ( sigExtra ) softfloat_exceptionFlags |= softfloat_flag_inexact;
131     if ( doIncrement ) {
132         sig128 = softfloat_add128( sig64, sig0, 0, 1 );
133         sig64 = sig128.v64;
134         sig0 =
135             sig128.v0
136                 & ~(uint64_t)
137                        (! (sigExtra & UINT64_C( 0x7FFFFFFFFFFFFFFF ))
138                             & roundNearEven);
139     } else {
140         if ( ! (sig64 | sig0) ) exp = 0;
141     }
142     uiZ64 = packToF128UI64( sign, exp, sig64 );
143     uiZ0  = sig0;
144  uiZ:
145     uZ.ui.v64 = uiZ64;
146     uZ.ui.v0  = uiZ0;
147     return uZ.f;
148 
149 }
150 
151