1 /* 2 * QEMU float support 3 * 4 * The code in this source file is derived from release 2a of the SoftFloat 5 * IEC/IEEE Floating-point Arithmetic Package. Those parts of the code (and 6 * some later contributions) are provided under that license, as detailed below. 7 * It has subsequently been modified by contributors to the QEMU Project, 8 * so some portions are provided under: 9 * the SoftFloat-2a license 10 * the BSD license 11 * GPL-v2-or-later 12 * 13 * This header holds definitions for code that might be dealing with 14 * softfloat types but not need access to the actual library functions. 15 */ 16 /* 17 =============================================================================== 18 This C header file is part of the SoftFloat IEC/IEEE Floating-point 19 Arithmetic Package, Release 2a. 20 21 Written by John R. Hauser. This work was made possible in part by the 22 International Computer Science Institute, located at Suite 600, 1947 Center 23 Street, Berkeley, California 94704. Funding was partially provided by the 24 National Science Foundation under grant MIP-9311980. The original version 25 of this code was written as part of a project to build a fixed-point vector 26 processor in collaboration with the University of California at Berkeley, 27 overseen by Profs. Nelson Morgan and John Wawrzynek. More information 28 is available through the Web page `http://HTTP.CS.Berkeley.EDU/~jhauser/ 29 arithmetic/SoftFloat.html'. 30 31 THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort 32 has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT 33 TIMES RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO 34 PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY 35 AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE. 36 37 Derivative works are acceptable, even for commercial purposes, so long as 38 (1) they include prominent notice that the work is derivative, and (2) they 39 include prominent notice akin to these four paragraphs for those parts of 40 this code that are retained. 41 42 =============================================================================== 43 */ 44 45 /* BSD licensing: 46 * Copyright (c) 2006, Fabrice Bellard 47 * All rights reserved. 48 * 49 * Redistribution and use in source and binary forms, with or without 50 * modification, are permitted provided that the following conditions are met: 51 * 52 * 1. Redistributions of source code must retain the above copyright notice, 53 * this list of conditions and the following disclaimer. 54 * 55 * 2. Redistributions in binary form must reproduce the above copyright notice, 56 * this list of conditions and the following disclaimer in the documentation 57 * and/or other materials provided with the distribution. 58 * 59 * 3. Neither the name of the copyright holder nor the names of its contributors 60 * may be used to endorse or promote products derived from this software without 61 * specific prior written permission. 62 * 63 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 64 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 65 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 66 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 67 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 68 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 69 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 70 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 71 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 72 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 73 * THE POSSIBILITY OF SUCH DAMAGE. 74 */ 75 76 /* Portions of this work are licensed under the terms of the GNU GPL, 77 * version 2 or later. See the COPYING file in the top-level directory. 78 */ 79 80 #ifndef SOFTFLOAT_TYPES_H 81 #define SOFTFLOAT_TYPES_H 82 83 /* 84 * Software IEC/IEEE floating-point types. 85 */ 86 87 typedef uint16_t float16; 88 typedef uint32_t float32; 89 typedef uint64_t float64; 90 #define float16_val(x) (x) 91 #define float32_val(x) (x) 92 #define float64_val(x) (x) 93 #define make_float16(x) (x) 94 #define make_float32(x) (x) 95 #define make_float64(x) (x) 96 #define const_float16(x) (x) 97 #define const_float32(x) (x) 98 #define const_float64(x) (x) 99 typedef struct { 100 uint64_t low; 101 uint16_t high; 102 } floatx80; 103 #define make_floatx80(exp, mant) ((floatx80) { mant, exp }) 104 #define make_floatx80_init(exp, mant) { .low = mant, .high = exp } 105 typedef struct { 106 #if HOST_BIG_ENDIAN 107 uint64_t high, low; 108 #else 109 uint64_t low, high; 110 #endif 111 } float128; 112 #define make_float128(high_, low_) ((float128) { .high = high_, .low = low_ }) 113 #define make_float128_init(high_, low_) { .high = high_, .low = low_ } 114 115 /* 116 * Software neural-network floating-point types. 117 */ 118 typedef uint16_t bfloat16; 119 120 /* 121 * Software IEC/IEEE floating-point underflow tininess-detection mode. 122 */ 123 124 #define float_tininess_after_rounding false 125 #define float_tininess_before_rounding true 126 127 /* 128 *Software IEC/IEEE floating-point rounding mode. 129 */ 130 131 typedef enum __attribute__((__packed__)) { 132 float_round_nearest_even = 0, 133 float_round_down = 1, 134 float_round_up = 2, 135 float_round_to_zero = 3, 136 float_round_ties_away = 4, 137 /* Not an IEEE rounding mode: round to closest odd, overflow to max */ 138 float_round_to_odd = 5, 139 /* Not an IEEE rounding mode: round to closest odd, overflow to inf */ 140 float_round_to_odd_inf = 6, 141 } FloatRoundMode; 142 143 /* 144 * Software IEC/IEEE floating-point exception flags. 145 */ 146 147 enum { 148 float_flag_invalid = 0x0001, 149 float_flag_divbyzero = 0x0002, 150 float_flag_overflow = 0x0004, 151 float_flag_underflow = 0x0008, 152 float_flag_inexact = 0x0010, 153 float_flag_input_denormal = 0x0020, 154 float_flag_output_denormal = 0x0040, 155 float_flag_invalid_isi = 0x0080, /* inf - inf */ 156 float_flag_invalid_imz = 0x0100, /* inf * 0 */ 157 float_flag_invalid_idi = 0x0200, /* inf / inf */ 158 float_flag_invalid_zdz = 0x0400, /* 0 / 0 */ 159 float_flag_invalid_sqrt = 0x0800, /* sqrt(-x) */ 160 float_flag_invalid_cvti = 0x1000, /* non-nan to integer */ 161 float_flag_invalid_snan = 0x2000, /* any operand was snan */ 162 }; 163 164 /* 165 * Rounding precision for floatx80. 166 */ 167 typedef enum __attribute__((__packed__)) { 168 floatx80_precision_x, 169 floatx80_precision_d, 170 floatx80_precision_s, 171 } FloatX80RoundPrec; 172 173 /* 174 * 2-input NaN propagation rule. Individual architectures have 175 * different rules for which input NaN is propagated to the output 176 * when there is more than one NaN on the input. 177 * 178 * If default_nan_mode is enabled then it is valid not to set a 179 * NaN propagation rule, because the softfloat code guarantees 180 * not to try to pick a NaN to propagate in default NaN mode. 181 * When not in default-NaN mode, it is an error for the target 182 * not to set the rule in float_status, and we will assert if 183 * we need to handle an input NaN and no rule was selected. 184 */ 185 typedef enum __attribute__((__packed__)) { 186 /* No propagation rule specified */ 187 float_2nan_prop_none = 0, 188 /* Prefer SNaN over QNaN, then operand A over B */ 189 float_2nan_prop_s_ab, 190 /* Prefer SNaN over QNaN, then operand B over A */ 191 float_2nan_prop_s_ba, 192 /* Prefer A over B regardless of SNaN vs QNaN */ 193 float_2nan_prop_ab, 194 /* Prefer B over A regardless of SNaN vs QNaN */ 195 float_2nan_prop_ba, 196 /* 197 * This implements x87 NaN propagation rules: 198 * SNaN + QNaN => return the QNaN 199 * two SNaNs => return the one with the larger significand, silenced 200 * two QNaNs => return the one with the larger significand 201 * SNaN and a non-NaN => return the SNaN, silenced 202 * QNaN and a non-NaN => return the QNaN 203 * 204 * If we get down to comparing significands and they are the same, 205 * return the NaN with the positive sign bit (if any). 206 */ 207 float_2nan_prop_x87, 208 } Float2NaNPropRule; 209 210 /* 211 * Floating Point Status. Individual architectures may maintain 212 * several versions of float_status for different functions. The 213 * correct status for the operation is then passed by reference to 214 * most of the softfloat functions. 215 */ 216 217 typedef struct float_status { 218 uint16_t float_exception_flags; 219 FloatRoundMode float_rounding_mode; 220 FloatX80RoundPrec floatx80_rounding_precision; 221 Float2NaNPropRule float_2nan_prop_rule; 222 bool tininess_before_rounding; 223 /* should denormalised results go to zero and set the inexact flag? */ 224 bool flush_to_zero; 225 /* should denormalised inputs go to zero and set the input_denormal flag? */ 226 bool flush_inputs_to_zero; 227 bool default_nan_mode; 228 /* 229 * The flags below are not used on all specializations and may 230 * constant fold away (see snan_bit_is_one()/no_signalling_nans() in 231 * softfloat-specialize.inc.c) 232 */ 233 bool snan_bit_is_one; 234 bool use_first_nan; 235 bool no_signaling_nans; 236 /* should overflowed results subtract re_bias to its exponent? */ 237 bool rebias_overflow; 238 /* should underflowed results add re_bias to its exponent? */ 239 bool rebias_underflow; 240 } float_status; 241 242 #endif /* SOFTFLOAT_TYPES_H */ 243