drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c

   1 /*
   2  * Copyright 2012-15 Advanced Micro Devices, Inc.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  20  * OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * Authors: AMD
  23  *
  24  */
  25
  26 #include "dm_services.h"
  27 #include "include/fixed31_32.h"
  28
  29 static const struct fixed31_32 dc_fixpt_two_pi = { 26986075409LL };
  30 static const struct fixed31_32 dc_fixpt_ln2 = { 2977044471LL };
  31 static const struct fixed31_32 dc_fixpt_ln2_div_2 = { 1488522236LL };
  32
  33 static inline unsigned long long abs_i64(
  34         long long arg)
  35 {
  36         if (arg > 0)
  37                 return (unsigned long long)arg;
  38         else
  39                 return (unsigned long long)(-arg);
  40 }
  41
  42 /*
  43  * @brief
  44  * result = dividend / divisor
  45  * *remainder = dividend % divisor
  46  */
  47 static inline unsigned long long complete_integer_division_u64(
  48         unsigned long long dividend,
  49         unsigned long long divisor,
  50         unsigned long long *remainder)
  51 {
  52         unsigned long long result;
  53
  54         ASSERT(divisor);
  55
  56         result = div64_u64_rem(dividend, divisor, remainder);
  57
  58         return result;
  59 }
  60
  61
  62 #define FRACTIONAL_PART_MASK \
  63         ((1ULL << FIXED31_32_BITS_PER_FRACTIONAL_PART) - 1)
  64
  65 #define GET_INTEGER_PART(x) \
  66         ((x) >> FIXED31_32_BITS_PER_FRACTIONAL_PART)
  67
  68 #define GET_FRACTIONAL_PART(x) \
  69         (FRACTIONAL_PART_MASK & (x))
  70
  71 struct fixed31_32 dc_fixpt_from_fraction(long long numerator, long long denominator)
  72 {
  73         struct fixed31_32 res;
  74
  75         bool arg1_negative = numerator < 0;
  76         bool arg2_negative = denominator < 0;
  77
  78         unsigned long long arg1_value = arg1_negative ? -numerator : numerator;
  79         unsigned long long arg2_value = arg2_negative ? -denominator : denominator;
  80
  81         unsigned long long remainder;
  82
  83         /* determine integer part */
  84
  85         unsigned long long res_value = complete_integer_division_u64(
  86                 arg1_value, arg2_value, &remainder);
  87
  88         ASSERT(res_value <= LONG_MAX);
  89
  90         /* determine fractional part */
  91         {
  92                 unsigned int i = FIXED31_32_BITS_PER_FRACTIONAL_PART;
  93
  94                 do {
  95                         remainder <<= 1;
  96
  97                         res_value <<= 1;
  98
  99                         if (remainder >= arg2_value) {
 100                                 res_value |= 1;
 101                                 remainder -= arg2_value;
 102                         }
 103                 } while (--i != 0);
 104         }
 105
 106         /* round up LSB */
 107         {
 108                 unsigned long long summand = (remainder << 1) >= arg2_value;
 109
 110                 ASSERT(res_value <= LLONG_MAX - summand);
 111
 112                 res_value += summand;
 113         }
 114
 115         res.value = (long long)res_value;
 116
 117         if (arg1_negative ^ arg2_negative)
 118                 res.value = -res.value;
 119
 120         return res;
 121 }
 122
 123 struct fixed31_32 dc_fixpt_mul(struct fixed31_32 arg1, struct fixed31_32 arg2)
 124 {
 125         struct fixed31_32 res;
 126
 127         bool arg1_negative = arg1.value < 0;
 128         bool arg2_negative = arg2.value < 0;
 129
 130         unsigned long long arg1_value = arg1_negative ? -arg1.value : arg1.value;
 131         unsigned long long arg2_value = arg2_negative ? -arg2.value : arg2.value;
 132
 133         unsigned long long arg1_int = GET_INTEGER_PART(arg1_value);
 134         unsigned long long arg2_int = GET_INTEGER_PART(arg2_value);
 135
 136         unsigned long long arg1_fra = GET_FRACTIONAL_PART(arg1_value);
 137         unsigned long long arg2_fra = GET_FRACTIONAL_PART(arg2_value);
 138
 139         unsigned long long tmp;
 140
 141         res.value = arg1_int * arg2_int;
 142
 143         ASSERT(res.value <= LONG_MAX);
 144
 145         res.value <<= FIXED31_32_BITS_PER_FRACTIONAL_PART;
 146
 147         tmp = arg1_int * arg2_fra;
 148
 149         ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
 150
 151         res.value += tmp;
 152
 153         tmp = arg2_int * arg1_fra;
 154
 155         ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
 156
 157         res.value += tmp;
 158
 159         tmp = arg1_fra * arg2_fra;
 160
 161         tmp = (tmp >> FIXED31_32_BITS_PER_FRACTIONAL_PART) +
 162                 (tmp >= (unsigned long long)dc_fixpt_half.value);
 163
 164         ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
 165
 166         res.value += tmp;
 167
 168         if (arg1_negative ^ arg2_negative)
 169                 res.value = -res.value;
 170
 171         return res;
 172 }
 173
 174 struct fixed31_32 dc_fixpt_sqr(struct fixed31_32 arg)
 175 {
 176         struct fixed31_32 res;
 177
 178         unsigned long long arg_value = abs_i64(arg.value);
 179
 180         unsigned long long arg_int = GET_INTEGER_PART(arg_value);
 181
 182         unsigned long long arg_fra = GET_FRACTIONAL_PART(arg_value);
 183
 184         unsigned long long tmp;
 185
 186         res.value = arg_int * arg_int;
 187
 188         ASSERT(res.value <= LONG_MAX);
 189
 190         res.value <<= FIXED31_32_BITS_PER_FRACTIONAL_PART;
 191
 192         tmp = arg_int * arg_fra;
 193
 194         ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
 195
 196         res.value += tmp;
 197
 198         ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
 199
 200         res.value += tmp;
 201
 202         tmp = arg_fra * arg_fra;
 203
 204         tmp = (tmp >> FIXED31_32_BITS_PER_FRACTIONAL_PART) +
 205                 (tmp >= (unsigned long long)dc_fixpt_half.value);
 206
 207         ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
 208
 209         res.value += tmp;
 210
 211         return res;
 212 }
 213
 214 struct fixed31_32 dc_fixpt_recip(struct fixed31_32 arg)
 215 {
 216         /*
 217          * @note
 218          * Good idea to use Newton's method
 219          */
 220
 221         ASSERT(arg.value);
 222
 223         return dc_fixpt_from_fraction(
 224                 dc_fixpt_one.value,
 225                 arg.value);
 226 }
 227
 228 struct fixed31_32 dc_fixpt_sinc(struct fixed31_32 arg)
 229 {
 230         struct fixed31_32 square;
 231
 232         struct fixed31_32 res = dc_fixpt_one;
 233
 234         int n = 27;
 235
 236         struct fixed31_32 arg_norm = arg;
 237
 238         if (dc_fixpt_le(
 239                 dc_fixpt_two_pi,
 240                 dc_fixpt_abs(arg))) {
 241                 arg_norm = dc_fixpt_sub(
 242                         arg_norm,
 243                         dc_fixpt_mul_int(
 244                                 dc_fixpt_two_pi,
 245                                 (int)div64_s64(
 246                                         arg_norm.value,
 247                                         dc_fixpt_two_pi.value)));
 248         }
 249
 250         square = dc_fixpt_sqr(arg_norm);
 251
 252         do {
 253                 res = dc_fixpt_sub(
 254                         dc_fixpt_one,
 255                         dc_fixpt_div_int(
 256                                 dc_fixpt_mul(
 257                                         square,
 258                                         res),
 259                                 n * (n - 1)));
 260
 261                 n -= 2;
 262         } while (n > 2);
 263
 264         if (arg.value != arg_norm.value)
 265                 res = dc_fixpt_div(
 266                         dc_fixpt_mul(res, arg_norm),
 267                         arg);
 268
 269         return res;
 270 }
 271
 272 struct fixed31_32 dc_fixpt_sin(struct fixed31_32 arg)
 273 {
 274         return dc_fixpt_mul(
 275                 arg,
 276                 dc_fixpt_sinc(arg));
 277 }
 278
 279 struct fixed31_32 dc_fixpt_cos(struct fixed31_32 arg)
 280 {
 281         /* TODO implement argument normalization */
 282
 283         const struct fixed31_32 square = dc_fixpt_sqr(arg);
 284
 285         struct fixed31_32 res = dc_fixpt_one;
 286
 287         int n = 26;
 288
 289         do {
 290                 res = dc_fixpt_sub(
 291                         dc_fixpt_one,
 292                         dc_fixpt_div_int(
 293                                 dc_fixpt_mul(
 294                                         square,
 295                                         res),
 296                                 n * (n - 1)));
 297
 298                 n -= 2;
 299         } while (n != 0);
 300
 301         return res;
 302 }
 303
 304 /*
 305  * @brief
 306  * result = exp(arg),
 307  * where abs(arg) < 1
 308  *
 309  * Calculated as Taylor series.
 310  */
 311 static struct fixed31_32 fixed31_32_exp_from_taylor_series(struct fixed31_32 arg)
 312 {
 313         unsigned int n = 9;
 314
 315         struct fixed31_32 res = dc_fixpt_from_fraction(
 316                 n + 2,
 317                 n + 1);
 318         /* TODO find correct res */
 319
 320         ASSERT(dc_fixpt_lt(arg, dc_fixpt_one));
 321
 322         do
 323                 res = dc_fixpt_add(
 324                         dc_fixpt_one,
 325                         dc_fixpt_div_int(
 326                                 dc_fixpt_mul(
 327                                         arg,
 328                                         res),
 329                                 n));
 330         while (--n != 1);
 331
 332         return dc_fixpt_add(
 333                 dc_fixpt_one,
 334                 dc_fixpt_mul(
 335                         arg,
 336                         res));
 337 }
 338
 339 struct fixed31_32 dc_fixpt_exp(struct fixed31_32 arg)
 340 {
 341         /*
 342          * @brief
 343          * Main equation is:
 344          * exp(x) = exp(r + m * ln(2)) = (1 << m) * exp(r),
 345          * where m = round(x / ln(2)), r = x - m * ln(2)
 346          */
 347
 348         if (dc_fixpt_le(
 349                 dc_fixpt_ln2_div_2,
 350                 dc_fixpt_abs(arg))) {
 351                 int m = dc_fixpt_round(
 352                         dc_fixpt_div(
 353                                 arg,
 354                                 dc_fixpt_ln2));
 355
 356                 struct fixed31_32 r = dc_fixpt_sub(
 357                         arg,
 358                         dc_fixpt_mul_int(
 359                                 dc_fixpt_ln2,
 360                                 m));
 361
 362                 ASSERT(m != 0);
 363
 364                 ASSERT(dc_fixpt_lt(
 365                         dc_fixpt_abs(r),
 366                         dc_fixpt_one));
 367
 368                 if (m > 0)
 369                         return dc_fixpt_shl(
 370                                 fixed31_32_exp_from_taylor_series(r),
 371                                 (unsigned char)m);
 372                 else
 373                         return dc_fixpt_div_int(
 374                                 fixed31_32_exp_from_taylor_series(r),
 375                                 1LL << -m);
 376         } else if (arg.value != 0)
 377                 return fixed31_32_exp_from_taylor_series(arg);
 378         else
 379                 return dc_fixpt_one;
 380 }
 381
 382 struct fixed31_32 dc_fixpt_log(struct fixed31_32 arg)
 383 {
 384         struct fixed31_32 res = dc_fixpt_neg(dc_fixpt_one);
 385         /* TODO improve 1st estimation */
 386
 387         struct fixed31_32 error;
 388
 389         ASSERT(arg.value > 0);
 390         /* TODO if arg is negative, return NaN */
 391         /* TODO if arg is zero, return -INF */
 392
 393         do {
 394                 struct fixed31_32 res1 = dc_fixpt_add(
 395                         dc_fixpt_sub(
 396                                 res,
 397                                 dc_fixpt_one),
 398                         dc_fixpt_div(
 399                                 arg,
 400                                 dc_fixpt_exp(res)));
 401
 402                 error = dc_fixpt_sub(
 403                         res,
 404                         res1);
 405
 406                 res = res1;
 407                 /* TODO determine max_allowed_error based on quality of exp() */
 408         } while (abs_i64(error.value) > 100ULL);
 409
 410         return res;
 411 }
 412
 413
 414 /* this function is a generic helper to translate fixed point value to
 415  * specified integer format that will consist of integer_bits integer part and
 416  * fractional_bits fractional part. For example it is used in
 417  * dc_fixpt_u2d19 to receive 2 bits integer part and 19 bits fractional
 418  * part in 32 bits. It is used in hw programming (scaler)
 419  */
 420
 421 static inline unsigned int ux_dy(
 422         long long value,
 423         unsigned int integer_bits,
 424         unsigned int fractional_bits)
 425 {
 426         /* 1. create mask of integer part */
 427         unsigned int result = (1 << integer_bits) - 1;
 428         /* 2. mask out fractional part */
 429         unsigned int fractional_part = FRACTIONAL_PART_MASK & value;
 430         /* 3. shrink fixed point integer part to be of integer_bits width*/
 431         result &= GET_INTEGER_PART(value);
 432         /* 4. make space for fractional part to be filled in after integer */
 433         result <<= fractional_bits;
 434         /* 5. shrink fixed point fractional part to of fractional_bits width*/
 435         fractional_part >>= FIXED31_32_BITS_PER_FRACTIONAL_PART - fractional_bits;
 436         /* 6. merge the result */
 437         return result | fractional_part;
 438 }
 439
 440 static inline unsigned int clamp_ux_dy(
 441         long long value,
 442         unsigned int integer_bits,
 443         unsigned int fractional_bits,
 444         unsigned int min_clamp)
 445 {
 446         unsigned int truncated_val = ux_dy(value, integer_bits, fractional_bits);
 447
 448         if (value >= (1LL << (integer_bits + FIXED31_32_BITS_PER_FRACTIONAL_PART)))
 449                 return (1 << (integer_bits + fractional_bits)) - 1;
 450         else if (truncated_val > min_clamp)
 451                 return truncated_val;
 452         else
 453                 return min_clamp;
 454 }
 455
 456 unsigned int dc_fixpt_u4d19(struct fixed31_32 arg)
 457 {
 458         return ux_dy(arg.value, 4, 19);
 459 }
 460
 461 unsigned int dc_fixpt_u3d19(struct fixed31_32 arg)
 462 {
 463         return ux_dy(arg.value, 3, 19);
 464 }
 465
 466 unsigned int dc_fixpt_u2d19(struct fixed31_32 arg)
 467 {
 468         return ux_dy(arg.value, 2, 19);
 469 }
 470
 471 unsigned int dc_fixpt_u0d19(struct fixed31_32 arg)
 472 {
 473         return ux_dy(arg.value, 0, 19);
 474 }
 475
 476 unsigned int dc_fixpt_clamp_u0d14(struct fixed31_32 arg)
 477 {
 478         return clamp_ux_dy(arg.value, 0, 14, 1);
 479 }
 480
 481 unsigned int dc_fixpt_clamp_u0d10(struct fixed31_32 arg)
 482 {
 483         return clamp_ux_dy(arg.value, 0, 10, 1);
 484 }
 485
 486 int dc_fixpt_s4d19(struct fixed31_32 arg)
 487 {
 488         if (arg.value < 0)
 489                 return -(int)ux_dy(dc_fixpt_abs(arg).value, 4, 19);
 490         else
 491                 return ux_dy(arg.value, 4, 19);
 492 }