drivers/acpi/acpica/utmath.c

   1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
   2 /*******************************************************************************
   3  *
   4  * Module Name: utmath - Integer math support routines
   5  *
   6  ******************************************************************************/
   7
   8 #include <acpi/acpi.h>
   9 #include "accommon.h"
  10
  11 #define _COMPONENT          ACPI_UTILITIES
  12 ACPI_MODULE_NAME("utmath")
  13
  14 /* Structures used only for 64-bit divide */
  15 typedef struct uint64_struct {
  16         u32 lo;
  17         u32 hi;
  18
  19 } uint64_struct;
  20
  21 typedef union uint64_overlay {
  22         u64 full;
  23         struct uint64_struct part;
  24
  25 } uint64_overlay;
  26
  27 /*
  28  * Optional support for 64-bit double-precision integer multiply and shift.
  29  * This code is configurable and is implemented in order to support 32-bit
  30  * kernel environments where a 64-bit double-precision math library is not
  31  * available.
  32  */
  33 #ifndef ACPI_USE_NATIVE_MATH64
  34
  35 /*******************************************************************************
  36  *
  37  * FUNCTION:    acpi_ut_short_multiply
  38  *
  39  * PARAMETERS:  multiplicand        - 64-bit multiplicand
  40  *              multiplier          - 32-bit multiplier
  41  *              out_product         - Pointer to where the product is returned
  42  *
  43  * DESCRIPTION: Perform a short multiply.
  44  *
  45  ******************************************************************************/
  46
  47 acpi_status
  48 acpi_ut_short_multiply(u64 multiplicand, u32 multiplier, u64 *out_product)
  49 {
  50         union uint64_overlay multiplicand_ovl;
  51         union uint64_overlay product;
  52         u32 carry32;
  53
  54         ACPI_FUNCTION_TRACE(ut_short_multiply);
  55
  56         multiplicand_ovl.full = multiplicand;
  57
  58         /*
  59          * The Product is 64 bits, the carry is always 32 bits,
  60          * and is generated by the second multiply.
  61          */
  62         ACPI_MUL_64_BY_32(0, multiplicand_ovl.part.hi, multiplier,
  63                           product.part.hi, carry32);
  64
  65         ACPI_MUL_64_BY_32(0, multiplicand_ovl.part.lo, multiplier,
  66                           product.part.lo, carry32);
  67
  68         product.part.hi += carry32;
  69
  70         /* Return only what was requested */
  71
  72         if (out_product) {
  73                 *out_product = product.full;
  74         }
  75
  76         return_ACPI_STATUS(AE_OK);
  77 }
  78
  79 /*******************************************************************************
  80  *
  81  * FUNCTION:    acpi_ut_short_shift_left
  82  *
  83  * PARAMETERS:  operand             - 64-bit shift operand
  84  *              count               - 32-bit shift count
  85  *              out_result          - Pointer to where the result is returned
  86  *
  87  * DESCRIPTION: Perform a short left shift.
  88  *
  89  ******************************************************************************/
  90
  91 acpi_status acpi_ut_short_shift_left(u64 operand, u32 count, u64 *out_result)
  92 {
  93         union uint64_overlay operand_ovl;
  94
  95         ACPI_FUNCTION_TRACE(ut_short_shift_left);
  96
  97         operand_ovl.full = operand;
  98
  99         if ((count & 63) >= 32) {
 100                 operand_ovl.part.hi = operand_ovl.part.lo;
 101                 operand_ovl.part.lo = 0;
 102                 count = (count & 63) - 32;
 103         }
 104         ACPI_SHIFT_LEFT_64_BY_32(operand_ovl.part.hi,
 105                                  operand_ovl.part.lo, count);
 106
 107         /* Return only what was requested */
 108
 109         if (out_result) {
 110                 *out_result = operand_ovl.full;
 111         }
 112
 113         return_ACPI_STATUS(AE_OK);
 114 }
 115
 116 /*******************************************************************************
 117  *
 118  * FUNCTION:    acpi_ut_short_shift_right
 119  *
 120  * PARAMETERS:  operand             - 64-bit shift operand
 121  *              count               - 32-bit shift count
 122  *              out_result          - Pointer to where the result is returned
 123  *
 124  * DESCRIPTION: Perform a short right shift.
 125  *
 126  ******************************************************************************/
 127
 128 acpi_status acpi_ut_short_shift_right(u64 operand, u32 count, u64 *out_result)
 129 {
 130         union uint64_overlay operand_ovl;
 131
 132         ACPI_FUNCTION_TRACE(ut_short_shift_right);
 133
 134         operand_ovl.full = operand;
 135
 136         if ((count & 63) >= 32) {
 137                 operand_ovl.part.lo = operand_ovl.part.hi;
 138                 operand_ovl.part.hi = 0;
 139                 count = (count & 63) - 32;
 140         }
 141         ACPI_SHIFT_RIGHT_64_BY_32(operand_ovl.part.hi,
 142                                   operand_ovl.part.lo, count);
 143
 144         /* Return only what was requested */
 145
 146         if (out_result) {
 147                 *out_result = operand_ovl.full;
 148         }
 149
 150         return_ACPI_STATUS(AE_OK);
 151 }
 152 #else
 153
 154 /*******************************************************************************
 155  *
 156  * FUNCTION:    acpi_ut_short_multiply
 157  *
 158  * PARAMETERS:  See function headers above
 159  *
 160  * DESCRIPTION: Native version of the ut_short_multiply function.
 161  *
 162  ******************************************************************************/
 163
 164 acpi_status
 165 acpi_ut_short_multiply(u64 multiplicand, u32 multiplier, u64 *out_product)
 166 {
 167
 168         ACPI_FUNCTION_TRACE(ut_short_multiply);
 169
 170         /* Return only what was requested */
 171
 172         if (out_product) {
 173                 *out_product = multiplicand * multiplier;
 174         }
 175
 176         return_ACPI_STATUS(AE_OK);
 177 }
 178
 179 /*******************************************************************************
 180  *
 181  * FUNCTION:    acpi_ut_short_shift_left
 182  *
 183  * PARAMETERS:  See function headers above
 184  *
 185  * DESCRIPTION: Native version of the ut_short_shift_left function.
 186  *
 187  ******************************************************************************/
 188
 189 acpi_status acpi_ut_short_shift_left(u64 operand, u32 count, u64 *out_result)
 190 {
 191
 192         ACPI_FUNCTION_TRACE(ut_short_shift_left);
 193
 194         /* Return only what was requested */
 195
 196         if (out_result) {
 197                 *out_result = operand << count;
 198         }
 199
 200         return_ACPI_STATUS(AE_OK);
 201 }
 202
 203 /*******************************************************************************
 204  *
 205  * FUNCTION:    acpi_ut_short_shift_right
 206  *
 207  * PARAMETERS:  See function headers above
 208  *
 209  * DESCRIPTION: Native version of the ut_short_shift_right function.
 210  *
 211  ******************************************************************************/
 212
 213 acpi_status acpi_ut_short_shift_right(u64 operand, u32 count, u64 *out_result)
 214 {
 215
 216         ACPI_FUNCTION_TRACE(ut_short_shift_right);
 217
 218         /* Return only what was requested */
 219
 220         if (out_result) {
 221                 *out_result = operand >> count;
 222         }
 223
 224         return_ACPI_STATUS(AE_OK);
 225 }
 226 #endif
 227
 228 /*
 229  * Optional support for 64-bit double-precision integer divide. This code
 230  * is configurable and is implemented in order to support 32-bit kernel
 231  * environments where a 64-bit double-precision math library is not available.
 232  *
 233  * Support for a more normal 64-bit divide/modulo (with check for a divide-
 234  * by-zero) appears after this optional section of code.
 235  */
 236 #ifndef ACPI_USE_NATIVE_DIVIDE
 237
 238 /*******************************************************************************
 239  *
 240  * FUNCTION:    acpi_ut_short_divide
 241  *
 242  * PARAMETERS:  dividend            - 64-bit dividend
 243  *              divisor             - 32-bit divisor
 244  *              out_quotient        - Pointer to where the quotient is returned
 245  *              out_remainder       - Pointer to where the remainder is returned
 246  *
 247  * RETURN:      Status (Checks for divide-by-zero)
 248  *
 249  * DESCRIPTION: Perform a short (maximum 64 bits divided by 32 bits)
 250  *              divide and modulo. The result is a 64-bit quotient and a
 251  *              32-bit remainder.
 252  *
 253  ******************************************************************************/
 254
 255 acpi_status
 256 acpi_ut_short_divide(u64 dividend,
 257                      u32 divisor, u64 *out_quotient, u32 *out_remainder)
 258 {
 259         union uint64_overlay dividend_ovl;
 260         union uint64_overlay quotient;
 261         u32 remainder32;
 262
 263         ACPI_FUNCTION_TRACE(ut_short_divide);
 264
 265         /* Always check for a zero divisor */
 266
 267         if (divisor == 0) {
 268                 ACPI_ERROR((AE_INFO, "Divide by zero"));
 269                 return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO);
 270         }
 271
 272         dividend_ovl.full = dividend;
 273
 274         /*
 275          * The quotient is 64 bits, the remainder is always 32 bits,
 276          * and is generated by the second divide.
 277          */
 278         ACPI_DIV_64_BY_32(0, dividend_ovl.part.hi, divisor,
 279                           quotient.part.hi, remainder32);
 280
 281         ACPI_DIV_64_BY_32(remainder32, dividend_ovl.part.lo, divisor,
 282                           quotient.part.lo, remainder32);
 283
 284         /* Return only what was requested */
 285
 286         if (out_quotient) {
 287                 *out_quotient = quotient.full;
 288         }
 289         if (out_remainder) {
 290                 *out_remainder = remainder32;
 291         }
 292
 293         return_ACPI_STATUS(AE_OK);
 294 }
 295
 296 /*******************************************************************************
 297  *
 298  * FUNCTION:    acpi_ut_divide
 299  *
 300  * PARAMETERS:  in_dividend         - Dividend
 301  *              in_divisor          - Divisor
 302  *              out_quotient        - Pointer to where the quotient is returned
 303  *              out_remainder       - Pointer to where the remainder is returned
 304  *
 305  * RETURN:      Status (Checks for divide-by-zero)
 306  *
 307  * DESCRIPTION: Perform a divide and modulo.
 308  *
 309  ******************************************************************************/
 310
 311 acpi_status
 312 acpi_ut_divide(u64 in_dividend,
 313                u64 in_divisor, u64 *out_quotient, u64 *out_remainder)
 314 {
 315         union uint64_overlay dividend;
 316         union uint64_overlay divisor;
 317         union uint64_overlay quotient;
 318         union uint64_overlay remainder;
 319         union uint64_overlay normalized_dividend;
 320         union uint64_overlay normalized_divisor;
 321         u32 partial1;
 322         union uint64_overlay partial2;
 323         union uint64_overlay partial3;
 324
 325         ACPI_FUNCTION_TRACE(ut_divide);
 326
 327         /* Always check for a zero divisor */
 328
 329         if (in_divisor == 0) {
 330                 ACPI_ERROR((AE_INFO, "Divide by zero"));
 331                 return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO);
 332         }
 333
 334         divisor.full = in_divisor;
 335         dividend.full = in_dividend;
 336         if (divisor.part.hi == 0) {
 337                 /*
 338                  * 1) Simplest case is where the divisor is 32 bits, we can
 339                  * just do two divides
 340                  */
 341                 remainder.part.hi = 0;
 342
 343                 /*
 344                  * The quotient is 64 bits, the remainder is always 32 bits,
 345                  * and is generated by the second divide.
 346                  */
 347                 ACPI_DIV_64_BY_32(0, dividend.part.hi, divisor.part.lo,
 348                                   quotient.part.hi, partial1);
 349
 350                 ACPI_DIV_64_BY_32(partial1, dividend.part.lo, divisor.part.lo,
 351                                   quotient.part.lo, remainder.part.lo);
 352         }
 353
 354         else {
 355                 /*
 356                  * 2) The general case where the divisor is a full 64 bits
 357                  * is more difficult
 358                  */
 359                 quotient.part.hi = 0;
 360                 normalized_dividend = dividend;
 361                 normalized_divisor = divisor;
 362
 363                 /* Normalize the operands (shift until the divisor is < 32 bits) */
 364
 365                 do {
 366                         ACPI_SHIFT_RIGHT_64(normalized_divisor.part.hi,
 367                                             normalized_divisor.part.lo);
 368                         ACPI_SHIFT_RIGHT_64(normalized_dividend.part.hi,
 369                                             normalized_dividend.part.lo);
 370
 371                 } while (normalized_divisor.part.hi != 0);
 372
 373                 /* Partial divide */
 374
 375                 ACPI_DIV_64_BY_32(normalized_dividend.part.hi,
 376                                   normalized_dividend.part.lo,
 377                                   normalized_divisor.part.lo, quotient.part.lo,
 378                                   partial1);
 379
 380                 /*
 381                  * The quotient is always 32 bits, and simply requires
 382                  * adjustment. The 64-bit remainder must be generated.
 383                  */
 384                 partial1 = quotient.part.lo * divisor.part.hi;
 385                 partial2.full = (u64) quotient.part.lo * divisor.part.lo;
 386                 partial3.full = (u64) partial2.part.hi + partial1;
 387
 388                 remainder.part.hi = partial3.part.lo;
 389                 remainder.part.lo = partial2.part.lo;
 390
 391                 if (partial3.part.hi == 0) {
 392                         if (partial3.part.lo >= dividend.part.hi) {
 393                                 if (partial3.part.lo == dividend.part.hi) {
 394                                         if (partial2.part.lo > dividend.part.lo) {
 395                                                 quotient.part.lo--;
 396                                                 remainder.full -= divisor.full;
 397                                         }
 398                                 } else {
 399                                         quotient.part.lo--;
 400                                         remainder.full -= divisor.full;
 401                                 }
 402                         }
 403
 404                         remainder.full = remainder.full - dividend.full;
 405                         remainder.part.hi = (u32)-((s32)remainder.part.hi);
 406                         remainder.part.lo = (u32)-((s32)remainder.part.lo);
 407
 408                         if (remainder.part.lo) {
 409                                 remainder.part.hi--;
 410                         }
 411                 }
 412         }
 413
 414         /* Return only what was requested */
 415
 416         if (out_quotient) {
 417                 *out_quotient = quotient.full;
 418         }
 419         if (out_remainder) {
 420                 *out_remainder = remainder.full;
 421         }
 422
 423         return_ACPI_STATUS(AE_OK);
 424 }
 425
 426 #else
 427
 428 /*******************************************************************************
 429  *
 430  * FUNCTION:    acpi_ut_short_divide, acpi_ut_divide
 431  *
 432  * PARAMETERS:  See function headers above
 433  *
 434  * DESCRIPTION: Native versions of the ut_divide functions. Use these if either
 435  *              1) The target is a 64-bit platform and therefore 64-bit
 436  *                 integer math is supported directly by the machine.
 437  *              2) The target is a 32-bit or 16-bit platform, and the
 438  *                 double-precision integer math library is available to
 439  *                 perform the divide.
 440  *
 441  ******************************************************************************/
 442
 443 acpi_status
 444 acpi_ut_short_divide(u64 in_dividend,
 445                      u32 divisor, u64 *out_quotient, u32 *out_remainder)
 446 {
 447
 448         ACPI_FUNCTION_TRACE(ut_short_divide);
 449
 450         /* Always check for a zero divisor */
 451
 452         if (divisor == 0) {
 453                 ACPI_ERROR((AE_INFO, "Divide by zero"));
 454                 return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO);
 455         }
 456
 457         /* Return only what was requested */
 458
 459         if (out_quotient) {
 460                 *out_quotient = in_dividend / divisor;
 461         }
 462         if (out_remainder) {
 463                 *out_remainder = (u32) (in_dividend % divisor);
 464         }
 465
 466         return_ACPI_STATUS(AE_OK);
 467 }
 468
 469 acpi_status
 470 acpi_ut_divide(u64 in_dividend,
 471                u64 in_divisor, u64 *out_quotient, u64 *out_remainder)
 472 {
 473         ACPI_FUNCTION_TRACE(ut_divide);
 474
 475         /* Always check for a zero divisor */
 476
 477         if (in_divisor == 0) {
 478                 ACPI_ERROR((AE_INFO, "Divide by zero"));
 479                 return_ACPI_STATUS(AE_AML_DIVIDE_BY_ZERO);
 480         }
 481
 482         /* Return only what was requested */
 483
 484         if (out_quotient) {
 485                 *out_quotient = in_dividend / in_divisor;
 486         }
 487         if (out_remainder) {
 488                 *out_remainder = in_dividend % in_divisor;
 489         }
 490
 491         return_ACPI_STATUS(AE_OK);
 492 }
 493
 494 #endif