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source: vbox/trunk/src/libs/softfloat-3e/source/s_roundPackToF128.c@ 99863

Last change on this file since 99863 was 94558, checked in by vboxsync, 3 years ago

VMM/IEM,libs/softfloat: Don't use global variables in SoftFloat, pass in a state pointer to (almost) all functions instead. Started on fsqrt instruction implementation. bugref:9898

  • Property svn:eol-style set to native
File size: 6.6 KB
Line 
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
43float128_t
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 SOFTFLOAT_STATE_DECL_COMMA
51 )
52{
53 uint_fast8_t roundingMode;
54 bool roundNearEven, doIncrement, isTiny;
55 struct uint128_extra sig128Extra;
56 uint_fast64_t uiZ64, uiZ0;
57 struct uint128 sig128;
58 union ui128_f128 uZ;
59
60 /*------------------------------------------------------------------------
61 *------------------------------------------------------------------------*/
62 roundingMode = softfloat_roundingMode;
63 roundNearEven = (roundingMode == softfloat_round_near_even);
64 doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
65 if ( ! roundNearEven && (roundingMode != softfloat_round_near_maxMag) ) {
66 doIncrement =
67 (roundingMode
68 == (sign ? softfloat_round_min : softfloat_round_max))
69 && sigExtra;
70 }
71 /*------------------------------------------------------------------------
72 *------------------------------------------------------------------------*/
73 if ( 0x7FFD <= (uint32_t) exp ) {
74 if ( exp < 0 ) {
75 /*----------------------------------------------------------------
76 *----------------------------------------------------------------*/
77 isTiny =
78 (softfloat_detectTininess
79 == softfloat_tininess_beforeRounding)
80 || (exp < -1)
81 || ! doIncrement
82 || softfloat_lt128(
83 sig64,
84 sig0,
85 UINT64_C( 0x0001FFFFFFFFFFFF ),
86 UINT64_C( 0xFFFFFFFFFFFFFFFF )
87 );
88 sig128Extra =
89 softfloat_shiftRightJam128Extra( sig64, sig0, sigExtra, -exp );
90 sig64 = sig128Extra.v.v64;
91 sig0 = sig128Extra.v.v0;
92 sigExtra = sig128Extra.extra;
93 exp = 0;
94 if ( isTiny && sigExtra ) {
95 softfloat_raiseFlags( softfloat_flag_underflow SOFTFLOAT_STATE_ARG_COMMA );
96 }
97 doIncrement = (UINT64_C( 0x8000000000000000 ) <= sigExtra);
98 if (
99 ! roundNearEven
100 && (roundingMode != softfloat_round_near_maxMag)
101 ) {
102 doIncrement =
103 (roundingMode
104 == (sign ? softfloat_round_min : softfloat_round_max))
105 && sigExtra;
106 }
107 } else if (
108 (0x7FFD < exp)
109 || ((exp == 0x7FFD)
110 && softfloat_eq128(
111 sig64,
112 sig0,
113 UINT64_C( 0x0001FFFFFFFFFFFF ),
114 UINT64_C( 0xFFFFFFFFFFFFFFFF )
115 )
116 && doIncrement)
117 ) {
118 /*----------------------------------------------------------------
119 *----------------------------------------------------------------*/
120 softfloat_raiseFlags(
121 softfloat_flag_overflow | softfloat_flag_inexact
122 SOFTFLOAT_STATE_ARG_COMMA );
123 if (
124 roundNearEven
125 || (roundingMode == softfloat_round_near_maxMag)
126 || (roundingMode
127 == (sign ? softfloat_round_min : softfloat_round_max))
128 ) {
129 uiZ64 = packToF128UI64( sign, 0x7FFF, 0 );
130 uiZ0 = 0;
131 } else {
132 uiZ64 =
133 packToF128UI64(
134 sign, 0x7FFE, UINT64_C( 0x0000FFFFFFFFFFFF ) );
135 uiZ0 = UINT64_C( 0xFFFFFFFFFFFFFFFF );
136 }
137 goto uiZ;
138 }
139 }
140 /*------------------------------------------------------------------------
141 *------------------------------------------------------------------------*/
142 if ( sigExtra ) {
143 softfloat_exceptionFlags |= softfloat_flag_inexact;
144#ifdef SOFTFLOAT_ROUND_ODD
145 if ( roundingMode == softfloat_round_odd ) {
146 sig0 |= 1;
147 goto packReturn;
148 }
149#endif
150 }
151 if ( doIncrement ) {
152 sig128 = softfloat_add128( sig64, sig0, 0, 1 );
153 sig64 = sig128.v64;
154 sig0 =
155 sig128.v0
156 & ~(uint64_t)
157 (! (sigExtra & UINT64_C( 0x7FFFFFFFFFFFFFFF ))
158 & roundNearEven);
159 } else {
160 if ( ! (sig64 | sig0) ) exp = 0;
161 }
162 /*------------------------------------------------------------------------
163 *------------------------------------------------------------------------*/
164 packReturn:
165 uiZ64 = packToF128UI64( sign, exp, sig64 );
166 uiZ0 = sig0;
167 uiZ:
168 uZ.ui.v64 = uiZ64;
169 uZ.ui.v0 = uiZ0;
170 return uZ.f;
171
172}
173
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