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
44float16_t
45 softfloat_mulAddF16(
46     uint_fast16_t uiA, uint_fast16_t uiB, uint_fast16_t uiC, uint_fast8_t op )
47{
48    bool signA;
49    int_fast8_t expA;
50    uint_fast16_t sigA;
51    bool signB;
52    int_fast8_t expB;
53    uint_fast16_t sigB;
54    bool signC;
55    int_fast8_t expC;
56    uint_fast16_t sigC;
57    bool signProd;
58    uint_fast16_t magBits, uiZ;
59    struct exp8_sig16 normExpSig;
60    int_fast8_t expProd;
61    uint_fast32_t sigProd;
62    bool signZ;
63    int_fast8_t expZ;
64    uint_fast16_t sigZ;
65    int_fast8_t expDiff;
66    uint_fast32_t sig32Z, sig32C;
67    int_fast8_t shiftDist;
68    union ui16_f16 uZ;
69
70    /*------------------------------------------------------------------------
71    *------------------------------------------------------------------------*/
72    signA = signF16UI( uiA );
73    expA  = expF16UI( uiA );
74    sigA  = fracF16UI( uiA );
75    signB = signF16UI( uiB );
76    expB  = expF16UI( uiB );
77    sigB  = fracF16UI( uiB );
78    signC = signF16UI( uiC ) ^ (op == softfloat_mulAdd_subC);
79    expC  = expF16UI( uiC );
80    sigC  = fracF16UI( uiC );
81    signProd = signA ^ signB ^ (op == softfloat_mulAdd_subProd);
82    /*------------------------------------------------------------------------
83    *------------------------------------------------------------------------*/
84    if ( expA == 0x1F ) {
85        if ( sigA || ((expB == 0x1F) && sigB) ) goto propagateNaN_ABC;
86        magBits = expB | sigB;
87        goto infProdArg;
88    }
89    if ( expB == 0x1F ) {
90        if ( sigB ) goto propagateNaN_ABC;
91        magBits = expA | sigA;
92        goto infProdArg;
93    }
94    if ( expC == 0x1F ) {
95        if ( sigC ) {
96            uiZ = 0;
97            goto propagateNaN_ZC;
98        }
99        uiZ = uiC;
100        goto uiZ;
101    }
102    /*------------------------------------------------------------------------
103    *------------------------------------------------------------------------*/
104    if ( ! expA ) {
105        if ( ! sigA ) goto zeroProd;
106        normExpSig = softfloat_normSubnormalF16Sig( sigA );
107        expA = normExpSig.exp;
108        sigA = normExpSig.sig;
109    }
110    if ( ! expB ) {
111        if ( ! sigB ) goto zeroProd;
112        normExpSig = softfloat_normSubnormalF16Sig( sigB );
113        expB = normExpSig.exp;
114        sigB = normExpSig.sig;
115    }
116    /*------------------------------------------------------------------------
117    *------------------------------------------------------------------------*/
118    expProd = expA + expB - 0xE;
119    sigA = (sigA | 0x0400)<<4;
120    sigB = (sigB | 0x0400)<<4;
121    sigProd = (uint_fast32_t) sigA * sigB;
122    if ( sigProd < 0x20000000 ) {
123        --expProd;
124        sigProd <<= 1;
125    }
126    signZ = signProd;
127    if ( ! expC ) {
128        if ( ! sigC ) {
129            expZ = expProd - 1;
130            sigZ = sigProd>>15 | ((sigProd & 0x7FFF) != 0);
131            goto roundPack;
132        }
133        normExpSig = softfloat_normSubnormalF16Sig( sigC );
134        expC = normExpSig.exp;
135        sigC = normExpSig.sig;
136    }
137    sigC = (sigC | 0x0400)<<3;
138    /*------------------------------------------------------------------------
139    *------------------------------------------------------------------------*/
140    expDiff = expProd - expC;
141    if ( signProd == signC ) {
142        /*--------------------------------------------------------------------
143        *--------------------------------------------------------------------*/
144        if ( expDiff <= 0 ) {
145            expZ = expC;
146            sigZ = sigC + softfloat_shiftRightJam32( sigProd, 16 - expDiff );
147        } else {
148            expZ = expProd;
149            sig32Z =
150                sigProd
151                    + softfloat_shiftRightJam32(
152                          (uint_fast32_t) sigC<<16, expDiff );
153            sigZ = sig32Z>>16 | ((sig32Z & 0xFFFF) != 0 );
154        }
155        if ( sigZ < 0x4000 ) {
156            --expZ;
157            sigZ <<= 1;
158        }
159    } else {
160        /*--------------------------------------------------------------------
161        *--------------------------------------------------------------------*/
162        sig32C = (uint_fast32_t) sigC<<16;
163        if ( expDiff < 0 ) {
164            signZ = signC;
165            expZ = expC;
166            sig32Z = sig32C - softfloat_shiftRightJam32( sigProd, -expDiff );
167        } else if ( ! expDiff ) {
168            expZ = expProd;
169            sig32Z = sigProd - sig32C;
170            if ( ! sig32Z ) goto completeCancellation;
171            if ( sig32Z & 0x80000000 ) {
172                signZ = ! signZ;
173                sig32Z = -sig32Z;
174            }
175        } else {
176            expZ = expProd;
177            sig32Z = sigProd - softfloat_shiftRightJam32( sig32C, expDiff );
178        }
179        shiftDist = softfloat_countLeadingZeros32( sig32Z ) - 1;
180        expZ -= shiftDist;
181        shiftDist -= 16;
182        if ( shiftDist < 0 ) {
183            sigZ =
184                sig32Z>>(-shiftDist)
185                    | ((uint32_t) (sig32Z<<(shiftDist & 31)) != 0);
186        } else {
187            sigZ = (uint_fast16_t) sig32Z<<shiftDist;
188        }
189    }
190 roundPack:
191    return softfloat_roundPackToF16( signZ, expZ, sigZ );
192    /*------------------------------------------------------------------------
193    *------------------------------------------------------------------------*/
194 propagateNaN_ABC:
195    uiZ = softfloat_propagateNaNF16UI( uiA, uiB );
196    goto propagateNaN_ZC;
197    /*------------------------------------------------------------------------
198    *------------------------------------------------------------------------*/
199 infProdArg:
200    if ( magBits ) {
201        uiZ = packToF16UI( signProd, 0x1F, 0 );
202        if ( expC != 0x1F ) goto uiZ;
203        if ( sigC ) goto propagateNaN_ZC;
204        if ( signProd == signC ) goto uiZ;
205    }
206    softfloat_raiseFlags( softfloat_flag_invalid );
207    uiZ = defaultNaNF16UI;
208 propagateNaN_ZC:
209    uiZ = softfloat_propagateNaNF16UI( uiZ, uiC );
210    goto uiZ;
211    /*------------------------------------------------------------------------
212    *------------------------------------------------------------------------*/
213 zeroProd:
214    uiZ = uiC;
215    if ( ! (expC | sigC) && (signProd != signC) ) {
216 completeCancellation:
217        uiZ =
218            packToF16UI(
219                (softfloat_roundingMode == softfloat_round_min), 0, 0 );
220    }
221 uiZ:
222    uZ.ui = uiZ;
223    return uZ.f;
224
225}
226
227