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, 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 "specialize.h"
42#include "softfloat.h"
43
44float128_t
45 f128_roundToInt( float128_t a, uint_fast8_t roundingMode, bool exact )
46{
47    union ui128_f128 uA;
48    uint_fast64_t uiA64, uiA0;
49    int_fast32_t exp;
50    struct uint128 uiZ;
51    uint_fast64_t lastBitMask0, roundBitsMask;
52    bool roundNearEven;
53    uint_fast64_t lastBitMask64;
54    union ui128_f128 uZ;
55
56    /*------------------------------------------------------------------------
57    *------------------------------------------------------------------------*/
58    uA.f = a;
59    uiA64 = uA.ui.v64;
60    uiA0  = uA.ui.v0;
61    exp = expF128UI64( uiA64 );
62    /*------------------------------------------------------------------------
63    *------------------------------------------------------------------------*/
64    if ( 0x402F <= exp ) {
65        /*--------------------------------------------------------------------
66        *--------------------------------------------------------------------*/
67        if ( 0x406F <= exp ) {
68            if ( (exp == 0x7FFF) && (fracF128UI64( uiA64 ) | uiA0) ) {
69                uiZ = softfloat_propagateNaNF128UI( uiA64, uiA0, 0, 0 );
70                goto uiZ;
71            }
72            return a;
73        }
74        /*--------------------------------------------------------------------
75        *--------------------------------------------------------------------*/
76        lastBitMask0 = (uint_fast64_t) 2<<(0x406E - exp);
77        roundBitsMask = lastBitMask0 - 1;
78        uiZ.v64 = uiA64;
79        uiZ.v0  = uiA0;
80        roundNearEven = (roundingMode == softfloat_round_near_even);
81        if ( roundNearEven || (roundingMode == softfloat_round_near_maxMag) ) {
82            if ( exp == 0x402F ) {
83                if ( UINT64_C( 0x8000000000000000 ) <= uiZ.v0 ) {
84                    ++uiZ.v64;
85                    if (
86                        roundNearEven
87                            && (uiZ.v0 == UINT64_C( 0x8000000000000000 ))
88                    ) {
89                        uiZ.v64 &= ~1;
90                    }
91                }
92            } else {
93                uiZ = softfloat_add128( uiZ.v64, uiZ.v0, 0, lastBitMask0>>1 );
94                if ( roundNearEven && !(uiZ.v0 & roundBitsMask) ) {
95                    uiZ.v0 &= ~lastBitMask0;
96                }
97            }
98        } else if (
99            roundingMode
100                == (signF128UI64( uiZ.v64 ) ? softfloat_round_min
101                        : softfloat_round_max)
102        ) {
103            uiZ = softfloat_add128( uiZ.v64, uiZ.v0, 0, roundBitsMask );
104        }
105        uiZ.v0 &= ~roundBitsMask;
106        lastBitMask64 = !lastBitMask0;
107    } else {
108        /*--------------------------------------------------------------------
109        *--------------------------------------------------------------------*/
110        if ( exp < 0x3FFF ) {
111            if ( !((uiA64 & UINT64_C( 0x7FFFFFFFFFFFFFFF )) | uiA0) ) return a;
112            if ( exact ) softfloat_raiseFlags( softfloat_flag_inexact );
113            uiZ.v64 = uiA64 & packToF128UI64( 1, 0, 0 );
114            uiZ.v0  = 0;
115            switch ( roundingMode ) {
116             case softfloat_round_near_even:
117                if ( !(fracF128UI64( uiA64 ) | uiA0) ) break;
118             case softfloat_round_near_maxMag:
119                if ( exp == 0x3FFE ) uiZ.v64 |= packToF128UI64( 0, 0x3FFF, 0 );
120                break;
121             case softfloat_round_min:
122                if ( uiZ.v64 ) uiZ.v64 = packToF128UI64( 1, 0x3FFF, 0 );
123                break;
124             case softfloat_round_max:
125                if ( !uiZ.v64 ) uiZ.v64 = packToF128UI64( 0, 0x3FFF, 0 );
126                break;
127#ifdef SOFTFLOAT_ROUND_ODD
128             case softfloat_round_odd:
129                uiZ.v64 |= packToF128UI64( 0, 0x3FFF, 0 );
130                break;
131#endif
132            }
133            goto uiZ;
134        }
135        /*--------------------------------------------------------------------
136        *--------------------------------------------------------------------*/
137        uiZ.v64 = uiA64;
138        uiZ.v0  = 0;
139        lastBitMask64 = (uint_fast64_t) 1<<(0x402F - exp);
140        roundBitsMask = lastBitMask64 - 1;
141        if ( roundingMode == softfloat_round_near_maxMag ) {
142            uiZ.v64 += lastBitMask64>>1;
143        } else if ( roundingMode == softfloat_round_near_even ) {
144            uiZ.v64 += lastBitMask64>>1;
145            if ( !((uiZ.v64 & roundBitsMask) | uiA0) ) {
146                uiZ.v64 &= ~lastBitMask64;
147            }
148        } else if (
149            roundingMode
150                == (signF128UI64( uiZ.v64 ) ? softfloat_round_min
151                        : softfloat_round_max)
152        ) {
153            uiZ.v64 = (uiZ.v64 | (uiA0 != 0)) + roundBitsMask;
154        }
155        uiZ.v64 &= ~roundBitsMask;
156        lastBitMask0 = 0;
157    }
158    if ( (uiZ.v64 != uiA64) || (uiZ.v0 != uiA0) ) {
159#ifdef SOFTFLOAT_ROUND_ODD
160        if ( roundingMode == softfloat_round_odd ) {
161            uiZ.v64 |= lastBitMask64;
162            uiZ.v0  |= lastBitMask0;
163        }
164#endif
165        if ( exact ) softfloat_raiseFlags( softfloat_flag_inexact );
166    }
167 uiZ:
168    uZ.ui = uiZ;
169    return uZ.f;
170
171}
172
173