| 1 | /******************************************************************************* |
| 2 | * |
| 3 | * Module Name: utmath - Integer math support routines |
| 4 | * |
| 5 | ******************************************************************************/ |
| 6 | |
| 7 | /* |
| 8 | * Copyright (C) 2000 - 2016, Intel Corp. |
| 9 | * All rights reserved. |
| 10 | * |
| 11 | * Redistribution and use in source and binary forms, with or without |
| 12 | * modification, are permitted provided that the following conditions |
| 13 | * are met: |
| 14 | * 1. Redistributions of source code must retain the above copyright |
| 15 | * notice, this list of conditions, and the following disclaimer, |
| 16 | * without modification. |
| 17 | * 2. Redistributions in binary form must reproduce at minimum a disclaimer |
| 18 | * substantially similar to the "NO WARRANTY" disclaimer below |
| 19 | * ("Disclaimer") and any redistribution must be conditioned upon |
| 20 | * including a substantially similar Disclaimer requirement for further |
| 21 | * binary redistribution. |
| 22 | * 3. Neither the names of the above-listed copyright holders nor the names |
| 23 | * of any contributors may be used to endorse or promote products derived |
| 24 | * from this software without specific prior written permission. |
| 25 | * |
| 26 | * Alternatively, this software may be distributed under the terms of the |
| 27 | * GNU General Public License ("GPL") version 2 as published by the Free |
| 28 | * Software Foundation. |
| 29 | * |
| 30 | * NO WARRANTY |
| 31 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 32 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 33 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR |
| 34 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 35 | * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 36 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 37 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 38 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| 39 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING |
| 40 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| 41 | * POSSIBILITY OF SUCH DAMAGES. |
| 42 | */ |
| 43 | |
| 44 | #include "acpi.h" |
| 45 | #include "accommon.h" |
| 46 | |
| 47 | |
| 48 | #define _COMPONENT ACPI_UTILITIES |
| 49 | ACPI_MODULE_NAME ("utmath" ) |
| 50 | |
| 51 | /* |
| 52 | * Optional support for 64-bit double-precision integer divide. This code |
| 53 | * is configurable and is implemented in order to support 32-bit kernel |
| 54 | * environments where a 64-bit double-precision math library is not available. |
| 55 | * |
| 56 | * Support for a more normal 64-bit divide/modulo (with check for a divide- |
| 57 | * by-zero) appears after this optional section of code. |
| 58 | */ |
| 59 | #ifndef ACPI_USE_NATIVE_DIVIDE |
| 60 | |
| 61 | /* Structures used only for 64-bit divide */ |
| 62 | |
| 63 | typedef struct uint64_struct |
| 64 | { |
| 65 | UINT32 Lo; |
| 66 | UINT32 Hi; |
| 67 | |
| 68 | } UINT64_STRUCT; |
| 69 | |
| 70 | typedef union uint64_overlay |
| 71 | { |
| 72 | UINT64 Full; |
| 73 | UINT64_STRUCT Part; |
| 74 | |
| 75 | } UINT64_OVERLAY; |
| 76 | |
| 77 | |
| 78 | /******************************************************************************* |
| 79 | * |
| 80 | * FUNCTION: AcpiUtShortDivide |
| 81 | * |
| 82 | * PARAMETERS: Dividend - 64-bit dividend |
| 83 | * Divisor - 32-bit divisor |
| 84 | * OutQuotient - Pointer to where the quotient is returned |
| 85 | * OutRemainder - Pointer to where the remainder is returned |
| 86 | * |
| 87 | * RETURN: Status (Checks for divide-by-zero) |
| 88 | * |
| 89 | * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits) |
| 90 | * divide and modulo. The result is a 64-bit quotient and a |
| 91 | * 32-bit remainder. |
| 92 | * |
| 93 | ******************************************************************************/ |
| 94 | |
| 95 | ACPI_STATUS |
| 96 | AcpiUtShortDivide ( |
| 97 | UINT64 Dividend, |
| 98 | UINT32 Divisor, |
| 99 | UINT64 *OutQuotient, |
| 100 | UINT32 *OutRemainder) |
| 101 | { |
| 102 | UINT64_OVERLAY DividendOvl; |
| 103 | UINT64_OVERLAY Quotient; |
| 104 | UINT32 Remainder32; |
| 105 | |
| 106 | |
| 107 | ACPI_FUNCTION_TRACE (UtShortDivide); |
| 108 | |
| 109 | |
| 110 | /* Always check for a zero divisor */ |
| 111 | |
| 112 | if (Divisor == 0) |
| 113 | { |
| 114 | ACPI_ERROR ((AE_INFO, "Divide by zero" )); |
| 115 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); |
| 116 | } |
| 117 | |
| 118 | DividendOvl.Full = Dividend; |
| 119 | |
| 120 | /* |
| 121 | * The quotient is 64 bits, the remainder is always 32 bits, |
| 122 | * and is generated by the second divide. |
| 123 | */ |
| 124 | ACPI_DIV_64_BY_32 (0, DividendOvl.Part.Hi, Divisor, |
| 125 | Quotient.Part.Hi, Remainder32); |
| 126 | |
| 127 | ACPI_DIV_64_BY_32 (Remainder32, DividendOvl.Part.Lo, Divisor, |
| 128 | Quotient.Part.Lo, Remainder32); |
| 129 | |
| 130 | /* Return only what was requested */ |
| 131 | |
| 132 | if (OutQuotient) |
| 133 | { |
| 134 | *OutQuotient = Quotient.Full; |
| 135 | } |
| 136 | if (OutRemainder) |
| 137 | { |
| 138 | *OutRemainder = Remainder32; |
| 139 | } |
| 140 | |
| 141 | return_ACPI_STATUS (AE_OK); |
| 142 | } |
| 143 | |
| 144 | |
| 145 | /******************************************************************************* |
| 146 | * |
| 147 | * FUNCTION: AcpiUtDivide |
| 148 | * |
| 149 | * PARAMETERS: InDividend - Dividend |
| 150 | * InDivisor - Divisor |
| 151 | * OutQuotient - Pointer to where the quotient is returned |
| 152 | * OutRemainder - Pointer to where the remainder is returned |
| 153 | * |
| 154 | * RETURN: Status (Checks for divide-by-zero) |
| 155 | * |
| 156 | * DESCRIPTION: Perform a divide and modulo. |
| 157 | * |
| 158 | ******************************************************************************/ |
| 159 | |
| 160 | ACPI_STATUS |
| 161 | AcpiUtDivide ( |
| 162 | UINT64 InDividend, |
| 163 | UINT64 InDivisor, |
| 164 | UINT64 *OutQuotient, |
| 165 | UINT64 *OutRemainder) |
| 166 | { |
| 167 | UINT64_OVERLAY Dividend; |
| 168 | UINT64_OVERLAY Divisor; |
| 169 | UINT64_OVERLAY Quotient; |
| 170 | UINT64_OVERLAY Remainder; |
| 171 | UINT64_OVERLAY NormalizedDividend; |
| 172 | UINT64_OVERLAY NormalizedDivisor; |
| 173 | UINT32 Partial1; |
| 174 | UINT64_OVERLAY Partial2; |
| 175 | UINT64_OVERLAY Partial3; |
| 176 | |
| 177 | |
| 178 | ACPI_FUNCTION_TRACE (UtDivide); |
| 179 | |
| 180 | |
| 181 | /* Always check for a zero divisor */ |
| 182 | |
| 183 | if (InDivisor == 0) |
| 184 | { |
| 185 | ACPI_ERROR ((AE_INFO, "Divide by zero" )); |
| 186 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); |
| 187 | } |
| 188 | |
| 189 | Divisor.Full = InDivisor; |
| 190 | Dividend.Full = InDividend; |
| 191 | if (Divisor.Part.Hi == 0) |
| 192 | { |
| 193 | /* |
| 194 | * 1) Simplest case is where the divisor is 32 bits, we can |
| 195 | * just do two divides |
| 196 | */ |
| 197 | Remainder.Part.Hi = 0; |
| 198 | |
| 199 | /* |
| 200 | * The quotient is 64 bits, the remainder is always 32 bits, |
| 201 | * and is generated by the second divide. |
| 202 | */ |
| 203 | ACPI_DIV_64_BY_32 (0, Dividend.Part.Hi, Divisor.Part.Lo, |
| 204 | Quotient.Part.Hi, Partial1); |
| 205 | |
| 206 | ACPI_DIV_64_BY_32 (Partial1, Dividend.Part.Lo, Divisor.Part.Lo, |
| 207 | Quotient.Part.Lo, Remainder.Part.Lo); |
| 208 | } |
| 209 | |
| 210 | else |
| 211 | { |
| 212 | /* |
| 213 | * 2) The general case where the divisor is a full 64 bits |
| 214 | * is more difficult |
| 215 | */ |
| 216 | Quotient.Part.Hi = 0; |
| 217 | NormalizedDividend = Dividend; |
| 218 | NormalizedDivisor = Divisor; |
| 219 | |
| 220 | /* Normalize the operands (shift until the divisor is < 32 bits) */ |
| 221 | |
| 222 | do |
| 223 | { |
| 224 | ACPI_SHIFT_RIGHT_64 ( |
| 225 | NormalizedDivisor.Part.Hi, NormalizedDivisor.Part.Lo); |
| 226 | ACPI_SHIFT_RIGHT_64 ( |
| 227 | NormalizedDividend.Part.Hi, NormalizedDividend.Part.Lo); |
| 228 | |
| 229 | } while (NormalizedDivisor.Part.Hi != 0); |
| 230 | |
| 231 | /* Partial divide */ |
| 232 | |
| 233 | ACPI_DIV_64_BY_32 ( |
| 234 | NormalizedDividend.Part.Hi, NormalizedDividend.Part.Lo, |
| 235 | NormalizedDivisor.Part.Lo, Quotient.Part.Lo, Partial1); |
| 236 | |
| 237 | /* |
| 238 | * The quotient is always 32 bits, and simply requires |
| 239 | * adjustment. The 64-bit remainder must be generated. |
| 240 | */ |
| 241 | Partial1 = Quotient.Part.Lo * Divisor.Part.Hi; |
| 242 | Partial2.Full = (UINT64) Quotient.Part.Lo * Divisor.Part.Lo; |
| 243 | Partial3.Full = (UINT64) Partial2.Part.Hi + Partial1; |
| 244 | |
| 245 | Remainder.Part.Hi = Partial3.Part.Lo; |
| 246 | Remainder.Part.Lo = Partial2.Part.Lo; |
| 247 | |
| 248 | if (Partial3.Part.Hi == 0) |
| 249 | { |
| 250 | if (Partial3.Part.Lo >= Dividend.Part.Hi) |
| 251 | { |
| 252 | if (Partial3.Part.Lo == Dividend.Part.Hi) |
| 253 | { |
| 254 | if (Partial2.Part.Lo > Dividend.Part.Lo) |
| 255 | { |
| 256 | Quotient.Part.Lo--; |
| 257 | Remainder.Full -= Divisor.Full; |
| 258 | } |
| 259 | } |
| 260 | else |
| 261 | { |
| 262 | Quotient.Part.Lo--; |
| 263 | Remainder.Full -= Divisor.Full; |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | Remainder.Full = Remainder.Full - Dividend.Full; |
| 268 | Remainder.Part.Hi = (UINT32) -((INT32) Remainder.Part.Hi); |
| 269 | Remainder.Part.Lo = (UINT32) -((INT32) Remainder.Part.Lo); |
| 270 | |
| 271 | if (Remainder.Part.Lo) |
| 272 | { |
| 273 | Remainder.Part.Hi--; |
| 274 | } |
| 275 | } |
| 276 | } |
| 277 | |
| 278 | /* Return only what was requested */ |
| 279 | |
| 280 | if (OutQuotient) |
| 281 | { |
| 282 | *OutQuotient = Quotient.Full; |
| 283 | } |
| 284 | if (OutRemainder) |
| 285 | { |
| 286 | *OutRemainder = Remainder.Full; |
| 287 | } |
| 288 | |
| 289 | return_ACPI_STATUS (AE_OK); |
| 290 | } |
| 291 | |
| 292 | #else |
| 293 | |
| 294 | /******************************************************************************* |
| 295 | * |
| 296 | * FUNCTION: AcpiUtShortDivide, AcpiUtDivide |
| 297 | * |
| 298 | * PARAMETERS: See function headers above |
| 299 | * |
| 300 | * DESCRIPTION: Native versions of the UtDivide functions. Use these if either |
| 301 | * 1) The target is a 64-bit platform and therefore 64-bit |
| 302 | * integer math is supported directly by the machine. |
| 303 | * 2) The target is a 32-bit or 16-bit platform, and the |
| 304 | * double-precision integer math library is available to |
| 305 | * perform the divide. |
| 306 | * |
| 307 | ******************************************************************************/ |
| 308 | |
| 309 | ACPI_STATUS |
| 310 | AcpiUtShortDivide ( |
| 311 | UINT64 InDividend, |
| 312 | UINT32 Divisor, |
| 313 | UINT64 *OutQuotient, |
| 314 | UINT32 *OutRemainder) |
| 315 | { |
| 316 | |
| 317 | ACPI_FUNCTION_TRACE (UtShortDivide); |
| 318 | |
| 319 | |
| 320 | /* Always check for a zero divisor */ |
| 321 | |
| 322 | if (Divisor == 0) |
| 323 | { |
| 324 | ACPI_ERROR ((AE_INFO, "Divide by zero" )); |
| 325 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); |
| 326 | } |
| 327 | |
| 328 | /* Return only what was requested */ |
| 329 | |
| 330 | if (OutQuotient) |
| 331 | { |
| 332 | *OutQuotient = InDividend / Divisor; |
| 333 | } |
| 334 | if (OutRemainder) |
| 335 | { |
| 336 | *OutRemainder = (UINT32) (InDividend % Divisor); |
| 337 | } |
| 338 | |
| 339 | return_ACPI_STATUS (AE_OK); |
| 340 | } |
| 341 | |
| 342 | ACPI_STATUS |
| 343 | AcpiUtDivide ( |
| 344 | UINT64 InDividend, |
| 345 | UINT64 InDivisor, |
| 346 | UINT64 *OutQuotient, |
| 347 | UINT64 *OutRemainder) |
| 348 | { |
| 349 | ACPI_FUNCTION_TRACE (UtDivide); |
| 350 | |
| 351 | |
| 352 | /* Always check for a zero divisor */ |
| 353 | |
| 354 | if (InDivisor == 0) |
| 355 | { |
| 356 | ACPI_ERROR ((AE_INFO, "Divide by zero" )); |
| 357 | return_ACPI_STATUS (AE_AML_DIVIDE_BY_ZERO); |
| 358 | } |
| 359 | |
| 360 | |
| 361 | /* Return only what was requested */ |
| 362 | |
| 363 | if (OutQuotient) |
| 364 | { |
| 365 | *OutQuotient = InDividend / InDivisor; |
| 366 | } |
| 367 | if (OutRemainder) |
| 368 | { |
| 369 | *OutRemainder = InDividend % InDivisor; |
| 370 | } |
| 371 | |
| 372 | return_ACPI_STATUS (AE_OK); |
| 373 | } |
| 374 | |
| 375 | #endif |
| 376 | |