include/fpu/softfloat-types.h

   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 /* This 'flag' type must be able to hold at least 0 and 1. It should
  84  * probably be replaced with 'bool' but the uses would need to be audited
  85  * to check that they weren't accidentally relying on it being a larger type.
  86  */
  87 typedef uint8_t flag;
  88
  89 /*
  90  * Software IEC/IEEE floating-point types.
  91  */
  92
  93 typedef uint16_t float16;
  94 typedef uint32_t float32;
  95 typedef uint64_t float64;
  96 #define float16_val(x) (x)
  97 #define float32_val(x) (x)
  98 #define float64_val(x) (x)
  99 #define make_float16(x) (x)
 100 #define make_float32(x) (x)
 101 #define make_float64(x) (x)
 102 #define const_float16(x) (x)
 103 #define const_float32(x) (x)
 104 #define const_float64(x) (x)
 105 typedef struct {
 106     uint64_t low;
 107     uint16_t high;
 108 } floatx80;
 109 #define make_floatx80(exp, mant) ((floatx80) { mant, exp })
 110 #define make_floatx80_init(exp, mant) { .low = mant, .high = exp }
 111 typedef struct {
 112 #ifdef HOST_WORDS_BIGENDIAN
 113     uint64_t high, low;
 114 #else
 115     uint64_t low, high;
 116 #endif
 117 } float128;
 118 #define make_float128(high_, low_) ((float128) { .high = high_, .low = low_ })
 119 #define make_float128_init(high_, low_) { .high = high_, .low = low_ }
 120
 121 /*
 122  * Software IEC/IEEE floating-point underflow tininess-detection mode.
 123  */
 124
 125 enum {
 126     float_tininess_after_rounding  = 0,
 127     float_tininess_before_rounding = 1
 128 };
 129
 130 /*
 131  *Software IEC/IEEE floating-point rounding mode.
 132  */
 133
 134 enum {
 135     float_round_nearest_even = 0,
 136     float_round_down         = 1,
 137     float_round_up           = 2,
 138     float_round_to_zero      = 3,
 139     float_round_ties_away    = 4,
 140     /* Not an IEEE rounding mode: round to the closest odd mantissa value */
 141     float_round_to_odd       = 5,
 142 };
 143
 144 /*
 145  * Software IEC/IEEE floating-point exception flags.
 146  */
 147
 148 enum {
 149     float_flag_invalid   =  1,
 150     float_flag_divbyzero =  4,
 151     float_flag_overflow  =  8,
 152     float_flag_underflow = 16,
 153     float_flag_inexact   = 32,
 154     float_flag_input_denormal = 64,
 155     float_flag_output_denormal = 128
 156 };
 157
 158
 159 /*
 160  * Floating Point Status. Individual architectures may maintain
 161  * several versions of float_status for different functions. The
 162  * correct status for the operation is then passed by reference to
 163  * most of the softfloat functions.
 164  */
 165
 166 typedef struct float_status {
 167     signed char float_detect_tininess;
 168     signed char float_rounding_mode;
 169     uint8_t     float_exception_flags;
 170     signed char floatx80_rounding_precision;
 171     /* should denormalised results go to zero and set the inexact flag? */
 172     flag flush_to_zero;
 173     /* should denormalised inputs go to zero and set the input_denormal flag? */
 174     flag flush_inputs_to_zero;
 175     flag default_nan_mode;
 176     /* not always used -- see snan_bit_is_one() in softfloat-specialize.h */
 177     flag snan_bit_is_one;
 178 } float_status;
 179
 180 #endif /* SOFTFLOAT_TYPES_H */