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
44extern const uint16_t softfloat_approxRecip_1k0s[];
45extern const uint16_t softfloat_approxRecip_1k1s[];
46
47float16_t f16_div( float16_t a, float16_t b )
48{
49    union ui16_f16 uA;
50    uint_fast16_t uiA;
51    bool signA;
52    int_fast8_t expA;
53    uint_fast16_t sigA;
54    union ui16_f16 uB;
55    uint_fast16_t uiB;
56    bool signB;
57    int_fast8_t expB;
58    uint_fast16_t sigB;
59    bool signZ;
60    struct exp8_sig16 normExpSig;
61    int_fast8_t expZ;
62#ifdef SOFTFLOAT_FAST_DIV32TO16
63    uint_fast32_t sig32A;
64    uint_fast16_t sigZ;
65#else
66    int index;
67    uint16_t r0;
68    uint_fast16_t sigZ, rem;
69#endif
70    uint_fast16_t uiZ;
71    union ui16_f16 uZ;
72
73    /*------------------------------------------------------------------------
74    *------------------------------------------------------------------------*/
75    uA.f = a;
76    uiA = uA.ui;
77    signA = signF16UI( uiA );
78    expA  = expF16UI( uiA );
79    sigA  = fracF16UI( uiA );
80    uB.f = b;
81    uiB = uB.ui;
82    signB = signF16UI( uiB );
83    expB  = expF16UI( uiB );
84    sigB  = fracF16UI( uiB );
85    signZ = signA ^ signB;
86    /*------------------------------------------------------------------------
87    *------------------------------------------------------------------------*/
88    if ( expA == 0x1F ) {
89        if ( sigA ) goto propagateNaN;
90        if ( expB == 0x1F ) {
91            if ( sigB ) goto propagateNaN;
92            goto invalid;
93        }
94        goto infinity;
95    }
96    if ( expB == 0x1F ) {
97        if ( sigB ) goto propagateNaN;
98        goto zero;
99    }
100    /*------------------------------------------------------------------------
101    *------------------------------------------------------------------------*/
102    if ( ! expB ) {
103        if ( ! sigB ) {
104            if ( ! (expA | sigA) ) goto invalid;
105            softfloat_raiseFlags( softfloat_flag_infinite );
106            goto infinity;
107        }
108        normExpSig = softfloat_normSubnormalF16Sig( sigB );
109        expB = normExpSig.exp;
110        sigB = normExpSig.sig;
111    }
112    if ( ! expA ) {
113        if ( ! sigA ) goto zero;
114        normExpSig = softfloat_normSubnormalF16Sig( sigA );
115        expA = normExpSig.exp;
116        sigA = normExpSig.sig;
117    }
118    /*------------------------------------------------------------------------
119    *------------------------------------------------------------------------*/
120    expZ = expA - expB + 0xE;
121    sigA |= 0x0400;
122    sigB |= 0x0400;
123#ifdef SOFTFLOAT_FAST_DIV32TO16
124    if ( sigA < sigB ) {
125        --expZ;
126        sig32A = (uint_fast32_t) sigA<<15;
127    } else {
128        sig32A = (uint_fast32_t) sigA<<14;
129    }
130    sigZ = sig32A / sigB;
131    if ( ! (sigZ & 7) ) sigZ |= ((uint_fast32_t) sigB * sigZ != sig32A);
132#else
133    if ( sigA < sigB ) {
134        --expZ;
135        sigA <<= 5;
136    } else {
137        sigA <<= 4;
138    }
139    index = sigB>>6 & 0xF;
140    r0 = softfloat_approxRecip_1k0s[index]
141             - (((uint_fast32_t) softfloat_approxRecip_1k1s[index]
142                     * (sigB & 0x3F))
143                    >>10);
144    sigZ = ((uint_fast32_t) sigA * r0)>>16;
145    rem = (sigA<<10) - sigZ * sigB;
146    sigZ += (rem * (uint_fast32_t) r0)>>26;
147    /*------------------------------------------------------------------------
148    *------------------------------------------------------------------------*/
149    ++sigZ;
150    if ( ! (sigZ & 7) ) {
151        sigZ &= ~1;
152        rem = (sigA<<10) - sigZ * sigB;
153        if ( rem & 0x8000 ) {
154            sigZ -= 2;
155        } else {
156            if ( rem ) sigZ |= 1;
157        }
158    }
159#endif
160    return softfloat_roundPackToF16( signZ, expZ, sigZ );
161    /*------------------------------------------------------------------------
162    *------------------------------------------------------------------------*/
163 propagateNaN:
164    uiZ = softfloat_propagateNaNF16UI( uiA, uiB );
165    goto uiZ;
166    /*------------------------------------------------------------------------
167    *------------------------------------------------------------------------*/
168 invalid:
169    softfloat_raiseFlags( softfloat_flag_invalid );
170    uiZ = defaultNaNF16UI;
171    goto uiZ;
172    /*------------------------------------------------------------------------
173    *------------------------------------------------------------------------*/
174 infinity:
175    uiZ = packToF16UI( signZ, 0x1F, 0 );
176    goto uiZ;
177    /*------------------------------------------------------------------------
178    *------------------------------------------------------------------------*/
179 zero:
180    uiZ = packToF16UI( signZ, 0, 0 );
181 uiZ:
182    uZ.ui = uiZ;
183    return uZ.f;
184
185}
186
187