1
2 /*============================================================================
3
4 This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
5 Package, Release 3e, by John R. Hauser.
6
7 Copyright 2011, 2012, 2013, 2014, 2015, 2016 The Regents of the University of
8 California. All rights reserved.
9
10 Redistribution and use in source and binary forms, with or without
11 modification, 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
24 THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
25 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
26 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
27 DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
28 DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
31 ON 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
33 SOFTWARE, 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
44 extern const uint16_t softfloat_approxRecip_1k0s[];
45 extern const uint16_t softfloat_approxRecip_1k1s[];
46
f16_div(float16_t a,float16_t b)47 float16_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