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
29static const struct fixed31_32 dc_fixpt_two_pi = { 26986075409LL };
30static const struct fixed31_32 dc_fixpt_ln2 = { 2977044471LL };
31static const struct fixed31_32 dc_fixpt_ln2_div_2 = { 1488522236LL };
32
33static 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 */
47static 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 result = div64_u64_rem(dividend, divisor, remainder);
55
56 return result;
57}
58
59
60#define FRACTIONAL_PART_MASK \
61 ((1ULL << FIXED31_32_BITS_PER_FRACTIONAL_PART) - 1)
62
63#define GET_INTEGER_PART(x) \
64 ((x) >> FIXED31_32_BITS_PER_FRACTIONAL_PART)
65
66#define GET_FRACTIONAL_PART(x) \
67 (FRACTIONAL_PART_MASK & (x))
68
69struct fixed31_32 dc_fixpt_from_fraction(long long numerator, long long denominator)
70{
71 struct fixed31_32 res;
72
73 bool arg1_negative = numerator < 0;
74 bool arg2_negative = denominator < 0;
75
76 unsigned long long arg1_value = arg1_negative ? -numerator : numerator;
77 unsigned long long arg2_value = arg2_negative ? -denominator : denominator;
78
79 unsigned long long remainder;
80
81 /* determine integer part */
82
83 unsigned long long res_value = complete_integer_division_u64(
84 dividend: arg1_value, divisor: arg2_value, remainder: &remainder);
85
86 ASSERT(res_value <= LONG_MAX);
87
88 /* determine fractional part */
89 {
90 unsigned int i = FIXED31_32_BITS_PER_FRACTIONAL_PART;
91
92 do {
93 remainder <<= 1;
94
95 res_value <<= 1;
96
97 if (remainder >= arg2_value) {
98 res_value |= 1;
99 remainder -= arg2_value;
100 }
101 } while (--i != 0);
102 }
103
104 /* round up LSB */
105 {
106 unsigned long long summand = (remainder << 1) >= arg2_value;
107
108 ASSERT(res_value <= LLONG_MAX - summand);
109
110 res_value += summand;
111 }
112
113 res.value = (long long)res_value;
114
115 if (arg1_negative ^ arg2_negative)
116 res.value = -res.value;
117
118 return res;
119}
120
121struct fixed31_32 dc_fixpt_mul(struct fixed31_32 arg1, struct fixed31_32 arg2)
122{
123 struct fixed31_32 res;
124
125 bool arg1_negative = arg1.value < 0;
126 bool arg2_negative = arg2.value < 0;
127
128 unsigned long long arg1_value = arg1_negative ? -arg1.value : arg1.value;
129 unsigned long long arg2_value = arg2_negative ? -arg2.value : arg2.value;
130
131 unsigned long long arg1_int = GET_INTEGER_PART(arg1_value);
132 unsigned long long arg2_int = GET_INTEGER_PART(arg2_value);
133
134 unsigned long long arg1_fra = GET_FRACTIONAL_PART(arg1_value);
135 unsigned long long arg2_fra = GET_FRACTIONAL_PART(arg2_value);
136
137 unsigned long long tmp;
138
139 res.value = arg1_int * arg2_int;
140
141 res.value <<= FIXED31_32_BITS_PER_FRACTIONAL_PART;
142
143 tmp = arg1_int * arg2_fra;
144
145 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
146
147 res.value += tmp;
148
149 tmp = arg2_int * arg1_fra;
150
151 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
152
153 res.value += tmp;
154
155 tmp = arg1_fra * arg2_fra;
156
157 tmp = (tmp >> FIXED31_32_BITS_PER_FRACTIONAL_PART) +
158 (tmp >= (unsigned long long)dc_fixpt_half.value);
159
160 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
161
162 res.value += tmp;
163
164 if (arg1_negative ^ arg2_negative)
165 res.value = -res.value;
166
167 return res;
168}
169
170struct fixed31_32 dc_fixpt_sqr(struct fixed31_32 arg)
171{
172 struct fixed31_32 res;
173
174 unsigned long long arg_value = abs_i64(arg: arg.value);
175
176 unsigned long long arg_int = GET_INTEGER_PART(arg_value);
177
178 unsigned long long arg_fra = GET_FRACTIONAL_PART(arg_value);
179
180 unsigned long long tmp;
181
182 res.value = arg_int * arg_int;
183
184 res.value <<= FIXED31_32_BITS_PER_FRACTIONAL_PART;
185
186 tmp = arg_int * arg_fra;
187
188 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
189
190 res.value += tmp;
191
192 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
193
194 res.value += tmp;
195
196 tmp = arg_fra * arg_fra;
197
198 tmp = (tmp >> FIXED31_32_BITS_PER_FRACTIONAL_PART) +
199 (tmp >= (unsigned long long)dc_fixpt_half.value);
200
201 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
202
203 res.value += tmp;
204
205 return res;
206}
207
208struct fixed31_32 dc_fixpt_recip(struct fixed31_32 arg)
209{
210 /*
211 * @note
212 * Good idea to use Newton's method
213 */
214 return dc_fixpt_from_fraction(
215 numerator: dc_fixpt_one.value,
216 denominator: arg.value);
217}
218
219struct fixed31_32 dc_fixpt_sinc(struct fixed31_32 arg)
220{
221 struct fixed31_32 square;
222
223 struct fixed31_32 res = dc_fixpt_one;
224
225 int n = 27;
226
227 struct fixed31_32 arg_norm = arg;
228
229 if (dc_fixpt_le(
230 arg1: dc_fixpt_two_pi,
231 arg2: dc_fixpt_abs(arg))) {
232 arg_norm = dc_fixpt_sub(
233 arg1: arg_norm,
234 arg2: dc_fixpt_mul_int(
235 arg1: dc_fixpt_two_pi,
236 arg2: (int)div64_s64(
237 dividend: arg_norm.value,
238 divisor: dc_fixpt_two_pi.value)));
239 }
240
241 square = dc_fixpt_sqr(arg: arg_norm);
242
243 do {
244 res = dc_fixpt_sub(
245 arg1: dc_fixpt_one,
246 arg2: dc_fixpt_div_int(
247 arg1: dc_fixpt_mul(
248 arg1: square,
249 arg2: res),
250 arg2: n * (n - 1)));
251
252 n -= 2;
253 } while (n > 2);
254
255 if (arg.value != arg_norm.value)
256 res = dc_fixpt_div(
257 arg1: dc_fixpt_mul(arg1: res, arg2: arg_norm),
258 arg2: arg);
259
260 return res;
261}
262
263struct fixed31_32 dc_fixpt_sin(struct fixed31_32 arg)
264{
265 return dc_fixpt_mul(
266 arg1: arg,
267 arg2: dc_fixpt_sinc(arg));
268}
269
270struct fixed31_32 dc_fixpt_cos(struct fixed31_32 arg)
271{
272 /* TODO implement argument normalization */
273
274 const struct fixed31_32 square = dc_fixpt_sqr(arg);
275
276 struct fixed31_32 res = dc_fixpt_one;
277
278 int n = 26;
279
280 do {
281 res = dc_fixpt_sub(
282 arg1: dc_fixpt_one,
283 arg2: dc_fixpt_div_int(
284 arg1: dc_fixpt_mul(
285 arg1: square,
286 arg2: res),
287 arg2: (long long)n * (n - 1)));
288
289 n -= 2;
290 } while (n != 0);
291
292 return res;
293}
294
295/*
296 * @brief
297 * result = exp(arg),
298 * where abs(arg) < 1
299 *
300 * Calculated as Taylor series.
301 */
302static struct fixed31_32 fixed31_32_exp_from_taylor_series(struct fixed31_32 arg)
303{
304 unsigned int n = 9;
305
306 struct fixed31_32 res = dc_fixpt_from_fraction(
307 numerator: n + 2,
308 denominator: n + 1);
309 /* TODO find correct res */
310
311 ASSERT(dc_fixpt_lt(arg, dc_fixpt_one));
312
313 do
314 res = dc_fixpt_add(
315 arg1: dc_fixpt_one,
316 arg2: dc_fixpt_div_int(
317 arg1: dc_fixpt_mul(
318 arg1: arg,
319 arg2: res),
320 arg2: n));
321 while (--n != 1);
322
323 return dc_fixpt_add(
324 arg1: dc_fixpt_one,
325 arg2: dc_fixpt_mul(
326 arg1: arg,
327 arg2: res));
328}
329
330struct fixed31_32 dc_fixpt_exp(struct fixed31_32 arg)
331{
332 /*
333 * @brief
334 * Main equation is:
335 * exp(x) = exp(r + m * ln(2)) = (1 << m) * exp(r),
336 * where m = round(x / ln(2)), r = x - m * ln(2)
337 */
338
339 if (dc_fixpt_le(
340 arg1: dc_fixpt_ln2_div_2,
341 arg2: dc_fixpt_abs(arg))) {
342 int m = dc_fixpt_round(
343 arg: dc_fixpt_div(
344 arg1: arg,
345 arg2: dc_fixpt_ln2));
346
347 struct fixed31_32 r = dc_fixpt_sub(
348 arg1: arg,
349 arg2: dc_fixpt_mul_int(
350 arg1: dc_fixpt_ln2,
351 arg2: m));
352
353 ASSERT(m != 0);
354
355 ASSERT(dc_fixpt_lt(
356 dc_fixpt_abs(r),
357 dc_fixpt_one));
358
359 if (m > 0)
360 return dc_fixpt_shl(
361 arg: fixed31_32_exp_from_taylor_series(arg: r),
362 shift: (unsigned char)m);
363 else
364 return dc_fixpt_div_int(
365 arg1: fixed31_32_exp_from_taylor_series(arg: r),
366 arg2: 1LL << -m);
367 } else if (arg.value != 0)
368 return fixed31_32_exp_from_taylor_series(arg);
369 else
370 return dc_fixpt_one;
371}
372
373struct fixed31_32 dc_fixpt_log(struct fixed31_32 arg)
374{
375 struct fixed31_32 res = dc_fixpt_neg(arg: dc_fixpt_one);
376 /* TODO improve 1st estimation */
377
378 struct fixed31_32 error;
379
380 ASSERT(arg.value > 0);
381 /* TODO if arg is negative, return NaN */
382 /* TODO if arg is zero, return -INF */
383
384 do {
385 struct fixed31_32 res1 = dc_fixpt_add(
386 arg1: dc_fixpt_sub(
387 arg1: res,
388 arg2: dc_fixpt_one),
389 arg2: dc_fixpt_div(
390 arg1: arg,
391 arg2: dc_fixpt_exp(arg: res)));
392
393 error = dc_fixpt_sub(
394 arg1: res,
395 arg2: res1);
396
397 res = res1;
398 /* TODO determine max_allowed_error based on quality of exp() */
399 } while (abs_i64(arg: error.value) > 100ULL);
400
401 return res;
402}
403
404
405/* this function is a generic helper to translate fixed point value to
406 * specified integer format that will consist of integer_bits integer part and
407 * fractional_bits fractional part. For example it is used in
408 * dc_fixpt_u2d19 to receive 2 bits integer part and 19 bits fractional
409 * part in 32 bits. It is used in hw programming (scaler)
410 */
411
412static inline unsigned int ux_dy(
413 long long value,
414 unsigned int integer_bits,
415 unsigned int fractional_bits)
416{
417 /* 1. create mask of integer part */
418 unsigned int result = (1 << integer_bits) - 1;
419 /* 2. mask out fractional part */
420 unsigned int fractional_part = FRACTIONAL_PART_MASK & value;
421 /* 3. shrink fixed point integer part to be of integer_bits width*/
422 result &= GET_INTEGER_PART(value);
423 /* 4. make space for fractional part to be filled in after integer */
424 result <<= fractional_bits;
425 /* 5. shrink fixed point fractional part to of fractional_bits width*/
426 fractional_part >>= FIXED31_32_BITS_PER_FRACTIONAL_PART - fractional_bits;
427 /* 6. merge the result */
428 return result | fractional_part;
429}
430
431static inline unsigned int clamp_ux_dy(
432 long long value,
433 unsigned int integer_bits,
434 unsigned int fractional_bits,
435 unsigned int min_clamp)
436{
437 unsigned int truncated_val = ux_dy(value, integer_bits, fractional_bits);
438
439 if (value >= (1LL << (integer_bits + FIXED31_32_BITS_PER_FRACTIONAL_PART)))
440 return (1 << (integer_bits + fractional_bits)) - 1;
441 else if (truncated_val > min_clamp)
442 return truncated_val;
443 else
444 return min_clamp;
445}
446
447unsigned int dc_fixpt_u4d19(struct fixed31_32 arg)
448{
449 return ux_dy(value: arg.value, integer_bits: 4, fractional_bits: 19);
450}
451
452unsigned int dc_fixpt_u3d19(struct fixed31_32 arg)
453{
454 return ux_dy(value: arg.value, integer_bits: 3, fractional_bits: 19);
455}
456
457unsigned int dc_fixpt_u2d19(struct fixed31_32 arg)
458{
459 return ux_dy(value: arg.value, integer_bits: 2, fractional_bits: 19);
460}
461
462unsigned int dc_fixpt_u0d19(struct fixed31_32 arg)
463{
464 return ux_dy(value: arg.value, integer_bits: 0, fractional_bits: 19);
465}
466
467unsigned int dc_fixpt_clamp_u0d14(struct fixed31_32 arg)
468{
469 return clamp_ux_dy(value: arg.value, integer_bits: 0, fractional_bits: 14, min_clamp: 1);
470}
471
472unsigned int dc_fixpt_clamp_u0d10(struct fixed31_32 arg)
473{
474 return clamp_ux_dy(value: arg.value, integer_bits: 0, fractional_bits: 10, min_clamp: 1);
475}
476
477int dc_fixpt_s4d19(struct fixed31_32 arg)
478{
479 if (arg.value < 0)
480 return -(int)ux_dy(value: dc_fixpt_abs(arg).value, integer_bits: 4, fractional_bits: 19);
481 else
482 return ux_dy(value: arg.value, integer_bits: 4, fractional_bits: 19);
483}
484
485struct fixed31_32 dc_fixpt_from_ux_dy(unsigned int value,
486 unsigned int integer_bits,
487 unsigned int fractional_bits)
488{
489 struct fixed31_32 fixpt_value = dc_fixpt_zero;
490 struct fixed31_32 fixpt_int_value = dc_fixpt_zero;
491 long long frac_mask = ((long long)1 << (long long)integer_bits) - 1;
492
493 fixpt_value.value = (long long)value << (FIXED31_32_BITS_PER_FRACTIONAL_PART - fractional_bits);
494 frac_mask = frac_mask << fractional_bits;
495 fixpt_int_value.value = value & frac_mask;
496 fixpt_int_value.value <<= (FIXED31_32_BITS_PER_FRACTIONAL_PART - fractional_bits);
497 fixpt_value.value |= fixpt_int_value.value;
498 return fixpt_value;
499}
500
501struct fixed31_32 dc_fixpt_from_int_dy(unsigned int int_value,
502 unsigned int frac_value,
503 unsigned int integer_bits,
504 unsigned int fractional_bits)
505{
506 struct fixed31_32 fixpt_value = dc_fixpt_from_int(arg: int_value);
507
508 fixpt_value.value |= (long long)frac_value << (FIXED31_32_BITS_PER_FRACTIONAL_PART - fractional_bits);
509 return fixpt_value;
510}
511

source code of linux/drivers/gpu/drm/amd/display/dc/basics/fixpt31_32.c