1 /* $NetBSD: amdgpu_fixpt31_32.c,v 1.3 2021/12/19 12:02:39 riastradh Exp $ */
2
3 /*
4 * Copyright 2012-15 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
28 #include <sys/cdefs.h>
29 __KERNEL_RCSID(0, "$NetBSD: amdgpu_fixpt31_32.c,v 1.3 2021/12/19 12:02:39 riastradh Exp $");
30
31 #include "dm_services.h"
32 #include "include/fixed31_32.h"
33
abs_i64(long long arg)34 static inline unsigned long long abs_i64(
35 long long arg)
36 {
37 if (arg > 0)
38 return (unsigned long long)arg;
39 else
40 return (unsigned long long)(-arg);
41 }
42
43 /*
44 * @brief
45 * result = dividend / divisor
46 * *remainder = dividend % divisor
47 */
complete_integer_division_u64(unsigned long long dividend,unsigned long long divisor,unsigned long long * remainder)48 static inline unsigned long long complete_integer_division_u64(
49 unsigned long long dividend,
50 unsigned long long divisor,
51 unsigned long long *remainder)
52 {
53 unsigned long long result;
54 uint64_t r64;
55
56 ASSERT(divisor);
57
58 result = div64_u64_rem(dividend, divisor, &r64);
59 *remainder = r64;
60
61 return result;
62 }
63
64
65 #define FRACTIONAL_PART_MASK \
66 ((1ULL << FIXED31_32_BITS_PER_FRACTIONAL_PART) - 1)
67
68 #define GET_INTEGER_PART(x) \
69 ((x) >> FIXED31_32_BITS_PER_FRACTIONAL_PART)
70
71 #define GET_FRACTIONAL_PART(x) \
72 (FRACTIONAL_PART_MASK & (x))
73
dc_fixpt_from_fraction(long long numerator,long long denominator)74 struct fixed31_32 dc_fixpt_from_fraction(long long numerator, long long denominator)
75 {
76 struct fixed31_32 res;
77
78 bool arg1_negative = numerator < 0;
79 bool arg2_negative = denominator < 0;
80
81 unsigned long long arg1_value = arg1_negative ? -numerator : numerator;
82 unsigned long long arg2_value = arg2_negative ? -denominator : denominator;
83
84 unsigned long long remainder;
85
86 /* determine integer part */
87
88 unsigned long long res_value = complete_integer_division_u64(
89 arg1_value, arg2_value, &remainder);
90
91 ASSERT(res_value <= LONG_MAX);
92
93 /* determine fractional part */
94 {
95 unsigned int i = FIXED31_32_BITS_PER_FRACTIONAL_PART;
96
97 do {
98 remainder <<= 1;
99
100 res_value <<= 1;
101
102 if (remainder >= arg2_value) {
103 res_value |= 1;
104 remainder -= arg2_value;
105 }
106 } while (--i != 0);
107 }
108
109 /* round up LSB */
110 {
111 unsigned long long summand = (remainder << 1) >= arg2_value;
112
113 ASSERT(res_value <= LLONG_MAX - summand);
114
115 res_value += summand;
116 }
117
118 res.value = (long long)res_value;
119
120 if (arg1_negative ^ arg2_negative)
121 res.value = -res.value;
122
123 return res;
124 }
125
dc_fixpt_mul(struct fixed31_32 arg1,struct fixed31_32 arg2)126 struct fixed31_32 dc_fixpt_mul(struct fixed31_32 arg1, struct fixed31_32 arg2)
127 {
128 struct fixed31_32 res;
129
130 bool arg1_negative = arg1.value < 0;
131 bool arg2_negative = arg2.value < 0;
132
133 unsigned long long arg1_value = arg1_negative ? -arg1.value : arg1.value;
134 unsigned long long arg2_value = arg2_negative ? -arg2.value : arg2.value;
135
136 unsigned long long arg1_int = GET_INTEGER_PART(arg1_value);
137 unsigned long long arg2_int = GET_INTEGER_PART(arg2_value);
138
139 unsigned long long arg1_fra = GET_FRACTIONAL_PART(arg1_value);
140 unsigned long long arg2_fra = GET_FRACTIONAL_PART(arg2_value);
141
142 unsigned long long tmp;
143
144 res.value = arg1_int * arg2_int;
145
146 ASSERT(res.value <= LONG_MAX);
147
148 res.value <<= FIXED31_32_BITS_PER_FRACTIONAL_PART;
149
150 tmp = arg1_int * arg2_fra;
151
152 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
153
154 res.value += tmp;
155
156 tmp = arg2_int * arg1_fra;
157
158 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
159
160 res.value += tmp;
161
162 tmp = arg1_fra * arg2_fra;
163
164 tmp = (tmp >> FIXED31_32_BITS_PER_FRACTIONAL_PART) +
165 (tmp >= (unsigned long long)dc_fixpt_half.value);
166
167 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
168
169 res.value += tmp;
170
171 if (arg1_negative ^ arg2_negative)
172 res.value = -res.value;
173
174 return res;
175 }
176
dc_fixpt_sqr(struct fixed31_32 arg)177 struct fixed31_32 dc_fixpt_sqr(struct fixed31_32 arg)
178 {
179 struct fixed31_32 res;
180
181 unsigned long long arg_value = abs_i64(arg.value);
182
183 unsigned long long arg_int = GET_INTEGER_PART(arg_value);
184
185 unsigned long long arg_fra = GET_FRACTIONAL_PART(arg_value);
186
187 unsigned long long tmp;
188
189 res.value = arg_int * arg_int;
190
191 ASSERT(res.value <= LONG_MAX);
192
193 res.value <<= FIXED31_32_BITS_PER_FRACTIONAL_PART;
194
195 tmp = arg_int * arg_fra;
196
197 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
198
199 res.value += tmp;
200
201 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
202
203 res.value += tmp;
204
205 tmp = arg_fra * arg_fra;
206
207 tmp = (tmp >> FIXED31_32_BITS_PER_FRACTIONAL_PART) +
208 (tmp >= (unsigned long long)dc_fixpt_half.value);
209
210 ASSERT(tmp <= (unsigned long long)(LLONG_MAX - res.value));
211
212 res.value += tmp;
213
214 return res;
215 }
216
dc_fixpt_recip(struct fixed31_32 arg)217 struct fixed31_32 dc_fixpt_recip(struct fixed31_32 arg)
218 {
219 /*
220 * @note
221 * Good idea to use Newton's method
222 */
223
224 ASSERT(arg.value);
225
226 return dc_fixpt_from_fraction(
227 dc_fixpt_one.value,
228 arg.value);
229 }
230
dc_fixpt_sinc(struct fixed31_32 arg)231 struct fixed31_32 dc_fixpt_sinc(struct fixed31_32 arg)
232 {
233 struct fixed31_32 square;
234
235 struct fixed31_32 res = dc_fixpt_one;
236
237 int n = 27;
238
239 struct fixed31_32 arg_norm = arg;
240
241 if (dc_fixpt_le(
242 dc_fixpt_two_pi,
243 dc_fixpt_abs(arg))) {
244 arg_norm = dc_fixpt_sub(
245 arg_norm,
246 dc_fixpt_mul_int(
247 dc_fixpt_two_pi,
248 (int)div64_s64(
249 arg_norm.value,
250 dc_fixpt_two_pi.value)));
251 }
252
253 square = dc_fixpt_sqr(arg_norm);
254
255 do {
256 res = dc_fixpt_sub(
257 dc_fixpt_one,
258 dc_fixpt_div_int(
259 dc_fixpt_mul(
260 square,
261 res),
262 n * (n - 1)));
263
264 n -= 2;
265 } while (n > 2);
266
267 if (arg.value != arg_norm.value)
268 res = dc_fixpt_div(
269 dc_fixpt_mul(res, arg_norm),
270 arg);
271
272 return res;
273 }
274
dc_fixpt_sin(struct fixed31_32 arg)275 struct fixed31_32 dc_fixpt_sin(struct fixed31_32 arg)
276 {
277 return dc_fixpt_mul(
278 arg,
279 dc_fixpt_sinc(arg));
280 }
281
dc_fixpt_cos(struct fixed31_32 arg)282 struct fixed31_32 dc_fixpt_cos(struct fixed31_32 arg)
283 {
284 /* TODO implement argument normalization */
285
286 const struct fixed31_32 square = dc_fixpt_sqr(arg);
287
288 struct fixed31_32 res = dc_fixpt_one;
289
290 int n = 26;
291
292 do {
293 res = dc_fixpt_sub(
294 dc_fixpt_one,
295 dc_fixpt_div_int(
296 dc_fixpt_mul(
297 square,
298 res),
299 n * (n - 1)));
300
301 n -= 2;
302 } while (n != 0);
303
304 return res;
305 }
306
307 /*
308 * @brief
309 * result = exp(arg),
310 * where abs(arg) < 1
311 *
312 * Calculated as Taylor series.
313 */
fixed31_32_exp_from_taylor_series(struct fixed31_32 arg)314 static struct fixed31_32 fixed31_32_exp_from_taylor_series(struct fixed31_32 arg)
315 {
316 unsigned int n = 9;
317
318 struct fixed31_32 res = dc_fixpt_from_fraction(
319 n + 2,
320 n + 1);
321 /* TODO find correct res */
322
323 ASSERT(dc_fixpt_lt(arg, dc_fixpt_one));
324
325 do
326 res = dc_fixpt_add(
327 dc_fixpt_one,
328 dc_fixpt_div_int(
329 dc_fixpt_mul(
330 arg,
331 res),
332 n));
333 while (--n != 1);
334
335 return dc_fixpt_add(
336 dc_fixpt_one,
337 dc_fixpt_mul(
338 arg,
339 res));
340 }
341
dc_fixpt_exp(struct fixed31_32 arg)342 struct fixed31_32 dc_fixpt_exp(struct fixed31_32 arg)
343 {
344 /*
345 * @brief
346 * Main equation is:
347 * exp(x) = exp(r + m * ln(2)) = (1 << m) * exp(r),
348 * where m = round(x / ln(2)), r = x - m * ln(2)
349 */
350
351 if (dc_fixpt_le(
352 dc_fixpt_ln2_div_2,
353 dc_fixpt_abs(arg))) {
354 int m = dc_fixpt_round(
355 dc_fixpt_div(
356 arg,
357 dc_fixpt_ln2));
358
359 struct fixed31_32 r = dc_fixpt_sub(
360 arg,
361 dc_fixpt_mul_int(
362 dc_fixpt_ln2,
363 m));
364
365 ASSERT(m != 0);
366
367 ASSERT(dc_fixpt_lt(
368 dc_fixpt_abs(r),
369 dc_fixpt_one));
370
371 if (m > 0)
372 return dc_fixpt_shl(
373 fixed31_32_exp_from_taylor_series(r),
374 (unsigned char)m);
375 else
376 return dc_fixpt_div_int(
377 fixed31_32_exp_from_taylor_series(r),
378 1LL << -m);
379 } else if (arg.value != 0)
380 return fixed31_32_exp_from_taylor_series(arg);
381 else
382 return dc_fixpt_one;
383 }
384
dc_fixpt_log(struct fixed31_32 arg)385 struct fixed31_32 dc_fixpt_log(struct fixed31_32 arg)
386 {
387 struct fixed31_32 res = dc_fixpt_neg(dc_fixpt_one);
388 /* TODO improve 1st estimation */
389
390 struct fixed31_32 error;
391
392 ASSERT(arg.value > 0);
393 /* TODO if arg is negative, return NaN */
394 /* TODO if arg is zero, return -INF */
395
396 do {
397 struct fixed31_32 res1 = dc_fixpt_add(
398 dc_fixpt_sub(
399 res,
400 dc_fixpt_one),
401 dc_fixpt_div(
402 arg,
403 dc_fixpt_exp(res)));
404
405 error = dc_fixpt_sub(
406 res,
407 res1);
408
409 res = res1;
410 /* TODO determine max_allowed_error based on quality of exp() */
411 } while (abs_i64(error.value) > 100ULL);
412
413 return res;
414 }
415
416
417 /* this function is a generic helper to translate fixed point value to
418 * specified integer format that will consist of integer_bits integer part and
419 * fractional_bits fractional part. For example it is used in
420 * dc_fixpt_u2d19 to receive 2 bits integer part and 19 bits fractional
421 * part in 32 bits. It is used in hw programming (scaler)
422 */
423
ux_dy(long long value,unsigned int integer_bits,unsigned int fractional_bits)424 static inline unsigned int ux_dy(
425 long long value,
426 unsigned int integer_bits,
427 unsigned int fractional_bits)
428 {
429 /* 1. create mask of integer part */
430 unsigned int result = (1 << integer_bits) - 1;
431 /* 2. mask out fractional part */
432 unsigned int fractional_part = FRACTIONAL_PART_MASK & value;
433 /* 3. shrink fixed point integer part to be of integer_bits width*/
434 result &= GET_INTEGER_PART(value);
435 /* 4. make space for fractional part to be filled in after integer */
436 result <<= fractional_bits;
437 /* 5. shrink fixed point fractional part to of fractional_bits width*/
438 fractional_part >>= FIXED31_32_BITS_PER_FRACTIONAL_PART - fractional_bits;
439 /* 6. merge the result */
440 return result | fractional_part;
441 }
442
clamp_ux_dy(long long value,unsigned int integer_bits,unsigned int fractional_bits,unsigned int min_clamp)443 static inline unsigned int clamp_ux_dy(
444 long long value,
445 unsigned int integer_bits,
446 unsigned int fractional_bits,
447 unsigned int min_clamp)
448 {
449 unsigned int truncated_val = ux_dy(value, integer_bits, fractional_bits);
450
451 if (value >= (1LL << (integer_bits + FIXED31_32_BITS_PER_FRACTIONAL_PART)))
452 return (1 << (integer_bits + fractional_bits)) - 1;
453 else if (truncated_val > min_clamp)
454 return truncated_val;
455 else
456 return min_clamp;
457 }
458
dc_fixpt_u4d19(struct fixed31_32 arg)459 unsigned int dc_fixpt_u4d19(struct fixed31_32 arg)
460 {
461 return ux_dy(arg.value, 4, 19);
462 }
463
dc_fixpt_u3d19(struct fixed31_32 arg)464 unsigned int dc_fixpt_u3d19(struct fixed31_32 arg)
465 {
466 return ux_dy(arg.value, 3, 19);
467 }
468
dc_fixpt_u2d19(struct fixed31_32 arg)469 unsigned int dc_fixpt_u2d19(struct fixed31_32 arg)
470 {
471 return ux_dy(arg.value, 2, 19);
472 }
473
dc_fixpt_u0d19(struct fixed31_32 arg)474 unsigned int dc_fixpt_u0d19(struct fixed31_32 arg)
475 {
476 return ux_dy(arg.value, 0, 19);
477 }
478
dc_fixpt_clamp_u0d14(struct fixed31_32 arg)479 unsigned int dc_fixpt_clamp_u0d14(struct fixed31_32 arg)
480 {
481 return clamp_ux_dy(arg.value, 0, 14, 1);
482 }
483
dc_fixpt_clamp_u0d10(struct fixed31_32 arg)484 unsigned int dc_fixpt_clamp_u0d10(struct fixed31_32 arg)
485 {
486 return clamp_ux_dy(arg.value, 0, 10, 1);
487 }
488
dc_fixpt_s4d19(struct fixed31_32 arg)489 int dc_fixpt_s4d19(struct fixed31_32 arg)
490 {
491 if (arg.value < 0)
492 return -(int)ux_dy(dc_fixpt_abs(arg).value, 4, 19);
493 else
494 return ux_dy(arg.value, 4, 19);
495 }
496