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 The Regents of the University of California.
8All 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
44extFloat80_t extF80_div( extFloat80_t a, extFloat80_t b )
45{
46    union { struct extFloat80M s; extFloat80_t f; } uA;
47    uint_fast16_t uiA64;
48    uint_fast64_t uiA0;
49    bool signA;
50    int_fast32_t expA;
51    uint_fast64_t sigA;
52    union { struct extFloat80M s; extFloat80_t f; } uB;
53    uint_fast16_t uiB64;
54    uint_fast64_t uiB0;
55    bool signB;
56    int_fast32_t expB;
57    uint_fast64_t sigB;
58    bool signZ;
59    struct exp32_sig64 normExpSig;
60    int_fast32_t expZ;
61    struct uint128 rem;
62    uint_fast32_t recip32;
63    uint_fast64_t sigZ;
64    int ix;
65    uint_fast64_t q64;
66    uint_fast32_t q;
67    struct uint128 term;
68    uint_fast64_t sigZExtra;
69    struct uint128 uiZ;
70    uint_fast16_t uiZ64;
71    uint_fast64_t uiZ0;
72    union { struct extFloat80M s; extFloat80_t f; } uZ;
73
74    /*------------------------------------------------------------------------
75    *------------------------------------------------------------------------*/
76    uA.f = a;
77    uiA64 = uA.s.signExp;
78    uiA0  = uA.s.signif;
79    signA = signExtF80UI64( uiA64 );
80    expA  = expExtF80UI64( uiA64 );
81    sigA  = uiA0;
82    uB.f = b;
83    uiB64 = uB.s.signExp;
84    uiB0  = uB.s.signif;
85    signB = signExtF80UI64( uiB64 );
86    expB  = expExtF80UI64( uiB64 );
87    sigB  = uiB0;
88    signZ = signA ^ signB;
89    /*------------------------------------------------------------------------
90    *------------------------------------------------------------------------*/
91    if ( expA == 0x7FFF ) {
92        if ( sigA & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) goto propagateNaN;
93        if ( expB == 0x7FFF ) {
94            if ( sigB & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) goto propagateNaN;
95            goto invalid;
96        }
97        goto infinity;
98    }
99    if ( expB == 0x7FFF ) {
100        if ( sigB & UINT64_C( 0x7FFFFFFFFFFFFFFF ) ) goto propagateNaN;
101        goto zero;
102    }
103    /*------------------------------------------------------------------------
104    *------------------------------------------------------------------------*/
105    if ( ! expB ) expB = 1;
106    if ( ! (sigB & UINT64_C( 0x8000000000000000 )) ) {
107        if ( ! sigB ) {
108            if ( ! sigA ) goto invalid;
109            softfloat_raiseFlags( softfloat_flag_infinite );
110            goto infinity;
111        }
112        normExpSig = softfloat_normSubnormalExtF80Sig( sigB );
113        expB += normExpSig.exp;
114        sigB = normExpSig.sig;
115    }
116    if ( ! expA ) expA = 1;
117    if ( ! (sigA & UINT64_C( 0x8000000000000000 )) ) {
118        if ( ! sigA ) goto zero;
119        normExpSig = softfloat_normSubnormalExtF80Sig( sigA );
120        expA += normExpSig.exp;
121        sigA = normExpSig.sig;
122    }
123    /*------------------------------------------------------------------------
124    *------------------------------------------------------------------------*/
125    expZ = expA - expB + 0x3FFF;
126    if ( sigA < sigB ) {
127        --expZ;
128        rem = softfloat_shortShiftLeft128( 0, sigA, 32 );
129    } else {
130        rem = softfloat_shortShiftLeft128( 0, sigA, 31 );
131    }
132    recip32 = softfloat_approxRecip32_1( sigB>>32 );
133    sigZ = 0;
134    ix = 2;
135    for (;;) {
136        q64 = (uint_fast64_t) (uint32_t) (rem.v64>>2) * recip32;
137        q = (q64 + 0x80000000)>>32;
138        --ix;
139        if ( ix < 0 ) break;
140        rem = softfloat_shortShiftLeft128( rem.v64, rem.v0, 29 );
141        term = softfloat_mul64ByShifted32To128( sigB, q );
142        rem = softfloat_sub128( rem.v64, rem.v0, term.v64, term.v0 );
143        if ( rem.v64 & UINT64_C( 0x8000000000000000 ) ) {
144            --q;
145            rem = softfloat_add128( rem.v64, rem.v0, sigB>>32, sigB<<32 );
146        }
147        sigZ = (sigZ<<29) + q;
148    }
149    /*------------------------------------------------------------------------
150    *------------------------------------------------------------------------*/
151    if ( ((q + 1) & 0x3FFFFF) < 2 ) {
152        rem = softfloat_shortShiftLeft128( rem.v64, rem.v0, 29 );
153        term = softfloat_mul64ByShifted32To128( sigB, q );
154        rem = softfloat_sub128( rem.v64, rem.v0, term.v64, term.v0 );
155        term = softfloat_shortShiftLeft128( 0, sigB, 32 );
156        if ( rem.v64 & UINT64_C( 0x8000000000000000 ) ) {
157            --q;
158            rem = softfloat_add128( rem.v64, rem.v0, term.v64, term.v0 );
159        } else if ( softfloat_le128( term.v64, term.v0, rem.v64, rem.v0 ) ) {
160            ++q;
161            rem = softfloat_sub128( rem.v64, rem.v0, term.v64, term.v0 );
162        }
163        if ( rem.v64 | rem.v0 ) q |= 1;
164    }
165    /*------------------------------------------------------------------------
166    *------------------------------------------------------------------------*/
167    sigZ = (sigZ<<6) + (q>>23);
168    sigZExtra = (uint64_t) ((uint_fast64_t) q<<41);
169    return
170        softfloat_roundPackToExtF80(
171            signZ, expZ, sigZ, sigZExtra, extF80_roundingPrecision );
172    /*------------------------------------------------------------------------
173    *------------------------------------------------------------------------*/
174 propagateNaN:
175    uiZ = softfloat_propagateNaNExtF80UI( uiA64, uiA0, uiB64, uiB0 );
176    uiZ64 = uiZ.v64;
177    uiZ0  = uiZ.v0;
178    goto uiZ;
179    /*------------------------------------------------------------------------
180    *------------------------------------------------------------------------*/
181 invalid:
182    softfloat_raiseFlags( softfloat_flag_invalid );
183    uiZ64 = defaultNaNExtF80UI64;
184    uiZ0  = defaultNaNExtF80UI0;
185    goto uiZ;
186    /*------------------------------------------------------------------------
187    *------------------------------------------------------------------------*/
188 infinity:
189    uiZ64 = packToExtF80UI64( signZ, 0x7FFF );
190    uiZ0  = UINT64_C( 0x8000000000000000 );
191    goto uiZ;
192    /*------------------------------------------------------------------------
193    *------------------------------------------------------------------------*/
194 zero:
195    uiZ64 = packToExtF80UI64( signZ, 0 );
196    uiZ0  = 0;
197 uiZ:
198    uZ.s.signExp = uiZ64;
199    uZ.s.signif  = uiZ0;
200    return uZ.f;
201
202}
203
204