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source: vbox/trunk/src/libs/softfloat-3e/source/s_subMagsF64.c

Last change on this file was 94558, checked in by vboxsync, 2 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: 5.5 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, 2016 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
44float64_t
45 softfloat_subMagsF64( uint_fast64_t uiA, uint_fast64_t uiB, bool signZ SOFTFLOAT_STATE_DECL_COMMA )
46{
47 int_fast16_t expA;
48 uint_fast64_t sigA;
49 int_fast16_t expB;
50 uint_fast64_t sigB;
51 int_fast16_t expDiff;
52 uint_fast64_t uiZ;
53 int_fast64_t sigDiff;
54 int_fast8_t shiftDist;
55 int_fast16_t expZ;
56 uint_fast64_t sigZ;
57 union ui64_f64 uZ;
58
59 /*------------------------------------------------------------------------
60 *------------------------------------------------------------------------*/
61 expA = expF64UI( uiA );
62 sigA = fracF64UI( uiA );
63 expB = expF64UI( uiB );
64 sigB = fracF64UI( uiB );
65 /*------------------------------------------------------------------------
66 *------------------------------------------------------------------------*/
67 expDiff = expA - expB;
68 if ( ! expDiff ) {
69 /*--------------------------------------------------------------------
70 *--------------------------------------------------------------------*/
71 if ( expA == 0x7FF ) {
72 if ( sigA | sigB ) goto propagateNaN;
73 softfloat_raiseFlags( softfloat_flag_invalid SOFTFLOAT_STATE_ARG_COMMA );
74 uiZ = defaultNaNF64UI;
75 goto uiZ;
76 }
77 sigDiff = sigA - sigB;
78 if ( ! sigDiff ) {
79 uiZ =
80 packToF64UI(
81 (softfloat_roundingMode == softfloat_round_min), 0, 0 );
82 goto uiZ;
83 }
84 if ( expA ) --expA;
85 if ( sigDiff < 0 ) {
86 signZ = ! signZ;
87 sigDiff = -sigDiff;
88 }
89 shiftDist = softfloat_countLeadingZeros64( sigDiff ) - 11;
90 expZ = expA - shiftDist;
91 if ( expZ < 0 ) {
92 shiftDist = expA;
93 expZ = 0;
94 }
95 uiZ = packToF64UI( signZ, expZ, sigDiff<<shiftDist );
96 goto uiZ;
97 } else {
98 /*--------------------------------------------------------------------
99 *--------------------------------------------------------------------*/
100 sigA <<= 10;
101 sigB <<= 10;
102 if ( expDiff < 0 ) {
103 /*----------------------------------------------------------------
104 *----------------------------------------------------------------*/
105 signZ = ! signZ;
106 if ( expB == 0x7FF ) {
107 if ( sigB ) goto propagateNaN;
108 uiZ = packToF64UI( signZ, 0x7FF, 0 );
109 goto uiZ;
110 }
111 sigA += expA ? UINT64_C( 0x4000000000000000 ) : sigA;
112 sigA = softfloat_shiftRightJam64( sigA, -expDiff );
113 sigB |= UINT64_C( 0x4000000000000000 );
114 expZ = expB;
115 sigZ = sigB - sigA;
116 } else {
117 /*----------------------------------------------------------------
118 *----------------------------------------------------------------*/
119 if ( expA == 0x7FF ) {
120 if ( sigA ) goto propagateNaN;
121 uiZ = uiA;
122 goto uiZ;
123 }
124 sigB += expB ? UINT64_C( 0x4000000000000000 ) : sigB;
125 sigB = softfloat_shiftRightJam64( sigB, expDiff );
126 sigA |= UINT64_C( 0x4000000000000000 );
127 expZ = expA;
128 sigZ = sigA - sigB;
129 }
130 return softfloat_normRoundPackToF64( signZ, expZ - 1, sigZ SOFTFLOAT_STATE_ARG_COMMA );
131 }
132 /*------------------------------------------------------------------------
133 *------------------------------------------------------------------------*/
134 propagateNaN:
135 uiZ = softfloat_propagateNaNF64UI( uiA, uiB SOFTFLOAT_STATE_ARG_COMMA );
136 uiZ:
137 uZ.ui = uiZ;
138 return uZ.f;
139
140}
141
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