1/* $NetBSD: amdgpu_custom_float.c,v 1.2 2021/12/18 23:45:01 riastradh Exp $ */ 2 3/* 4 * Copyright 2017 Advanced Micro Devices, Inc. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a 7 * copy of this software and associated documentation files (the "Software"), 8 * to deal in the Software without restriction, including without limitation 9 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 10 * and/or sell copies of the Software, and to permit persons to whom the 11 * Software is furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 22 * OTHER DEALINGS IN THE SOFTWARE. 23 * 24 * Authors: AMD 25 * 26 */ 27#include <sys/cdefs.h> 28__KERNEL_RCSID(0, "$NetBSD: amdgpu_custom_float.c,v 1.2 2021/12/18 23:45:01 riastradh Exp $"); 29 30#include "dm_services.h" 31#include "custom_float.h" 32 33 34static bool build_custom_float( 35 struct fixed31_32 value, 36 const struct custom_float_format *format, 37 bool *negative, 38 uint32_t *mantissa, 39 uint32_t *exponenta) 40{ 41 uint32_t exp_offset = (1 << (format->exponenta_bits - 1)) - 1; 42 43 const struct fixed31_32 mantissa_constant_plus_max_fraction = 44 dc_fixpt_from_fraction( 45 (1LL << (format->mantissa_bits + 1)) - 1, 46 1LL << format->mantissa_bits); 47 48 struct fixed31_32 mantiss; 49 50 if (dc_fixpt_eq( 51 value, 52 dc_fixpt_zero)) { 53 *negative = false; 54 *mantissa = 0; 55 *exponenta = 0; 56 return true; 57 } 58 59 if (dc_fixpt_lt( 60 value, 61 dc_fixpt_zero)) { 62 *negative = format->sign; 63 value = dc_fixpt_neg(value); 64 } else { 65 *negative = false; 66 } 67 68 if (dc_fixpt_lt( 69 value, 70 dc_fixpt_one)) { 71 uint32_t i = 1; 72 73 do { 74 value = dc_fixpt_shl(value, 1); 75 ++i; 76 } while (dc_fixpt_lt( 77 value, 78 dc_fixpt_one)); 79 80 --i; 81 82 if (exp_offset <= i) { 83 *mantissa = 0; 84 *exponenta = 0; 85 return true; 86 } 87 88 *exponenta = exp_offset - i; 89 } else if (dc_fixpt_le( 90 mantissa_constant_plus_max_fraction, 91 value)) { 92 uint32_t i = 1; 93 94 do { 95 value = dc_fixpt_shr(value, 1); 96 ++i; 97 } while (dc_fixpt_lt( 98 mantissa_constant_plus_max_fraction, 99 value)); 100 101 *exponenta = exp_offset + i - 1; 102 } else { 103 *exponenta = exp_offset; 104 } 105 106 mantiss = dc_fixpt_sub( 107 value, 108 dc_fixpt_one); 109 110 if (dc_fixpt_lt( 111 mantiss, 112 dc_fixpt_zero) || 113 dc_fixpt_lt( 114 dc_fixpt_one, 115 mantiss)) 116 mantiss = dc_fixpt_zero; 117 else 118 mantiss = dc_fixpt_shl( 119 mantiss, 120 format->mantissa_bits); 121 122 *mantissa = dc_fixpt_floor(mantiss); 123 124 return true; 125} 126 127static bool setup_custom_float( 128 const struct custom_float_format *format, 129 bool negative, 130 uint32_t mantissa, 131 uint32_t exponenta, 132 uint32_t *result) 133{ 134 uint32_t i = 0; 135 uint32_t j = 0; 136 137 uint32_t value = 0; 138 139 /* verification code: 140 * once calculation is ok we can remove it 141 */ 142 143 const uint32_t mantissa_mask = 144 (1 << (format->mantissa_bits + 1)) - 1; 145 146 const uint32_t exponenta_mask = 147 (1 << (format->exponenta_bits + 1)) - 1; 148 149 if (mantissa & ~mantissa_mask) { 150 BREAK_TO_DEBUGGER(); 151 mantissa = mantissa_mask; 152 } 153 154 if (exponenta & ~exponenta_mask) { 155 BREAK_TO_DEBUGGER(); 156 exponenta = exponenta_mask; 157 } 158 159 /* end of verification code */ 160 161 while (i < format->mantissa_bits) { 162 uint32_t mask = 1 << i; 163 164 if (mantissa & mask) 165 value |= mask; 166 167 ++i; 168 } 169 170 while (j < format->exponenta_bits) { 171 uint32_t mask = 1 << j; 172 173 if (exponenta & mask) 174 value |= mask << i; 175 176 ++j; 177 } 178 179 if (negative && format->sign) 180 value |= 1 << (i + j); 181 182 *result = value; 183 184 return true; 185} 186 187bool convert_to_custom_float_format( 188 struct fixed31_32 value, 189 const struct custom_float_format *format, 190 uint32_t *result) 191{ 192 uint32_t mantissa; 193 uint32_t exponenta; 194 bool negative; 195 196 return build_custom_float( 197 value, format, &negative, &mantissa, &exponenta) && 198 setup_custom_float( 199 format, negative, mantissa, exponenta, result); 200} 201 202 203