Outline ![]()
Files ![]()
loading...
SourceVu![]()
Raspberry Pi Pico SDK and Examples![]()
PicoSDK![]()
src/rp2_common/hardware_divider/include/hardware/divider.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
/*
* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#ifndef _HARDWARE_DIVIDER_H
#define _HARDWARE_DIVIDER_H
#include "pico.h"
/** \file hardware/divider.h
* \defgroup hardware_divider hardware_divider
*
* \brief RP2040 Low Low-level hardware-divider API. Non-RP2040 platforms provide software versions of all the functions
*
* The SIO contains an 8-cycle signed/unsigned divide/modulo circuit, per core. Calculation is started by writing a dividend
* and divisor to the two argument registers, DIVIDEND and DIVISOR. The divider calculates the quotient / and remainder % of
* this division over the next 8 cycles, and on the 9th cycle the results can be read from the two result registers
* DIV_QUOTIENT and DIV_REMAINDER. A 'ready' bit in register DIV_CSR can be polled to wait for the calculation to
* complete, or software can insert a fixed 8-cycle delay
*
* This header provides low level macros and inline functions for accessing the hardware dividers directly,
* and perhaps most usefully performing asynchronous divides. These functions however do not follow the regular
* SDK conventions for saving/restoring the divider state, so are not generally safe to call from interrupt handlers
*
* The pico_divider library provides a more user friendly set of APIs over the divider (and support for
* 64 bit divides), and of course by default regular C language integer divisions are redirected through that library, meaning
* you can just use C level `/` and `%` operators and gain the benefits of the fast hardware divider.
*
* \if rp2350_specific
* On RP2350 there is no hardware divider, and the functions are implemented in software
* \endif
*
* @see pico_divider
*
* \subsection divider_example Example
* \addtogroup hardware_divider
* \include hello_divider.c
*/
#if HAS_SIO_DIVIDER
#include "hardware/structs/sio.h"
#else
#define PICO_EMULATE_DIVIDER 1
#endif
#ifdef __cplusplus
extern "C" {
#endif
typedef uint64_t divmod_result_t;
#if PICO_EMULATE_DIVIDER
extern divmod_result_t hw_divider_results[NUM_CORES];
static inline int __sign_of(int32_t v) {
return v > 0 ? 1 : (v < 0 ? -1 : 0);
}
#endif
/*! \brief Do a signed HW divide and wait for result
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return result as a pair of 32-bit quotient/remainder values.
*
* \param a The dividend
* \param b The divisor
* \return Results of divide as a pair of 32-bit quotient/remainder values.
*/
#if !PICO_EMULATE_DIVIDER
divmod_result_t hw_divider_divmod_s32(int32_t a, int32_t b);
#else
static inline divmod_result_t hw_divider_divmod_s32(int32_t a, int32_t b) {
if (!b) return (((uint64_t)a)<<32u) | (uint32_t)(-__sign_of(a));
return (((uint64_t)(a%b))<<32u) | (uint32_t)(a/b);
}
#endif
/*! \brief Do an unsigned HW divide and wait for result
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return result as a pair of 32-bit quotient/remainder values.
*
* \param a The dividend
* \param b The divisor
* \return Results of divide as a pair of 32-bit quotient/remainder values.
*/
#if !PICO_EMULATE_DIVIDER
divmod_result_t hw_divider_divmod_u32(uint32_t a, uint32_t b);
#else
static inline divmod_result_t hw_divider_divmod_u32(uint32_t a, uint32_t b) {
if (!b) return (((uint64_t)a)<<32u) | (uint32_t)(-1); // todo check this
return (((uint64_t)(a%b))<<32u) | (a/b);
}
#endif
/*! \brief Start a signed asynchronous divide
* \ingroup hardware_divider
*
* Start a divide of the specified signed parameters. You should wait for 8 cycles (__div_pause()) or wait for the ready bit to be set
* (hw_divider_wait_ready()) prior to reading the results.
*
* \param a The dividend
* \param b The divisor
*/
static inline void hw_divider_divmod_s32_start(int32_t a, int32_t b) {
#if !PICO_EMULATE_DIVIDER
check_hw_layout( sio_hw_t, div_sdividend, SIO_DIV_SDIVIDEND_OFFSET);
sio_hw->div_sdividend = (uint32_t)a;
sio_hw->div_sdivisor = (uint32_t)b;
#else
hw_divider_divmod_s32(a, b);
#endif
}
/*! \brief Start an unsigned asynchronous divide
* \ingroup hardware_divider
*
* Start a divide of the specified unsigned parameters. You should wait for 8 cycles (__div_pause()) or wait for the ready bit to be set
* (hw_divider_wait_ready()) prior to reading the results.
*
* \param a The dividend
* \param b The divisor
*/
static inline void hw_divider_divmod_u32_start(uint32_t a, uint32_t b) {
#if !PICO_EMULATE_DIVIDER
check_hw_layout(
sio_hw_t, div_udividend, SIO_DIV_UDIVIDEND_OFFSET);
sio_hw->div_udividend = a;
sio_hw->div_udivisor = b;
#else
hw_divider_divmod_u32(a, b);
#endif
}
/*! \brief Wait for a divide to complete
* \ingroup hardware_divider
*
* Wait for a divide to complete
*/
static inline void hw_divider_wait_ready(void) {
#if !PICO_EMULATE_DIVIDER
// this is #1 in lsr below
static_assert(SIO_DIV_CSR_READY_BITS == 1, "");
// we use one less register and instruction than gcc which uses a TST instruction
uint32_t tmp; // allow compiler to pick scratch register
pico_default_asm_volatile (
"hw_divider_result_loop_%=:"
"ldr %0, [%1, %2]\n\t"
"lsrs %0, %0, #1\n\t"
"bcc hw_divider_result_loop_%=\n\t"
: "=&l" (tmp)
: "l" (sio_hw), "I" (SIO_DIV_CSR_OFFSET)
: "cc"
);
#endif
}
/*! \brief Return result of HW divide, nowait
* \ingroup hardware_divider
*
* \note This is UNSAFE in that the calculation may not have been completed.
*
* \return Current result. Most significant 32 bits are the remainder, lower 32 bits are the quotient.
*/
static inline divmod_result_t hw_divider_result_nowait(void) {
#if !PICO_EMULATE_DIVIDER
// as ugly as this looks it is actually quite efficient
divmod_result_t rc = ((divmod_result_t) sio_hw->div_remainder) << 32u;
rc |= sio_hw->div_quotient;
return rc;
#else
return hw_divider_results[get_core_num()];
#endif
}
/*! \brief Return result of last asynchronous HW divide
* \ingroup hardware_divider
*
* This function waits for the result to be ready by calling hw_divider_wait_ready().
*
* \return Current result. Most significant 32 bits are the remainder, lower 32 bits are the quotient.
*/
static inline divmod_result_t hw_divider_result_wait(void) {
hw_divider_wait_ready();
return hw_divider_result_nowait();
}
/*! \brief Efficient extraction of unsigned quotient from 32p32 fixed point
* \ingroup hardware_divider
*
* \param r A pair of 32-bit quotient/remainder values.
* \return Unsigned quotient
*/
inline static uint32_t to_quotient_u32(divmod_result_t r) {
return (uint32_t) r;
}
/*! \brief Efficient extraction of signed quotient from 32p32 fixed point
* \ingroup hardware_divider
*
* \param r A pair of 32-bit quotient/remainder values.
* \return Unsigned quotient
*/
inline static int32_t to_quotient_s32(divmod_result_t r) {
return (int32_t)(uint32_t)r;
}
/*! \brief Efficient extraction of unsigned remainder from 32p32 fixed point
* \ingroup hardware_divider
*
* \param r A pair of 32-bit quotient/remainder values.
* \return Unsigned remainder
*
* \note On Arm this is just a 32 bit register move or a nop
*/
inline static uint32_t to_remainder_u32(divmod_result_t r) {
return (uint32_t)(r >> 32u);
}
/*! \brief Efficient extraction of signed remainder from 32p32 fixed point
* \ingroup hardware_divider
*
* \param r A pair of 32-bit quotient/remainder values.
* \return Signed remainder
*
* \note On arm this is just a 32 bit register move or a nop
*/
inline static int32_t to_remainder_s32(divmod_result_t r) {
return (int32_t)(r >> 32u);
}
/*! \brief Return result of last asynchronous HW divide, unsigned quotient only
* \ingroup hardware_divider
*
* This function waits for the result to be ready by calling hw_divider_wait_ready().
*
* \return Current unsigned quotient result.
*/
static inline uint32_t hw_divider_u32_quotient_wait(void) {
#if !PICO_EMULATE_DIVIDER
hw_divider_wait_ready();
return sio_hw->div_quotient;
#else
return to_quotient_u32(hw_divider_result_wait());
#endif
}
/*! \brief Return result of last asynchronous HW divide, signed quotient only
* \ingroup hardware_divider
*
* This function waits for the result to be ready by calling hw_divider_wait_ready().
*
* \return Current signed quotient result.
*/
static inline int32_t hw_divider_s32_quotient_wait(void) {
#if !PICO_EMULATE_DIVIDER
hw_divider_wait_ready();
return (int32_t)sio_hw->div_quotient;
#else
return to_quotient_s32(hw_divider_result_wait());
#endif
}
/*! \brief Return result of last asynchronous HW divide, unsigned remainder only
* \ingroup hardware_divider
*
* This function waits for the result to be ready by calling hw_divider_wait_ready().
*
* \return Current unsigned remainder result.
*/
static inline uint32_t hw_divider_u32_remainder_wait(void) {
#if !PICO_EMULATE_DIVIDER
hw_divider_wait_ready();
uint32_t rc = sio_hw->div_remainder;
sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
return rc;
#else
return to_remainder_u32(hw_divider_result_wait());
#endif
}
/*! \brief Return result of last asynchronous HW divide, signed remainder only
* \ingroup hardware_divider
*
* This function waits for the result to be ready by calling hw_divider_wait_ready().
*
* \return Current remainder results.
*/
static inline int32_t hw_divider_s32_remainder_wait(void) {
#if !PICO_EMULATE_DIVIDER
hw_divider_wait_ready();
int32_t rc = (int32_t)sio_hw->div_remainder;
sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
return rc;
#else
return to_remainder_s32(hw_divider_result_wait());
#endif
}
/*! \brief Do an unsigned HW divide, wait for result, return quotient
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return quotient.
*
* \param a The dividend
* \param b The divisor
* \return Quotient results of the divide
*/
static inline uint32_t hw_divider_u32_quotient(uint32_t a, uint32_t b) {
#if !PICO_EMULATE_DIVIDER
return to_quotient_u32(hw_divider_divmod_u32(a, b));
#else
return b ? (a / b) : (uint32_t)(-1);
#endif
}
/*! \brief Do an unsigned HW divide, wait for result, return remainder
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return remainder.
*
* \param a The dividend
* \param b The divisor
* \return Remainder results of the divide
*/
static inline uint32_t hw_divider_u32_remainder(uint32_t a, uint32_t b) {
#if !PICO_EMULATE_DIVIDER
return to_remainder_u32(hw_divider_divmod_u32(a, b));
#else
return b ? (a % b) : a;
#endif
}
/*! \brief Do a signed HW divide, wait for result, return quotient
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return quotient.
*
* \param a The dividend
* \param b The divisor
* \return Quotient results of the divide
*/
static inline int32_t hw_divider_quotient_s32(int32_t a, int32_t b) {
#if !PICO_EMULATE_DIVIDER
return to_quotient_s32(hw_divider_divmod_s32(a, b));
#else
return b ? (a / b) : -1;
#endif
}
/*! \brief Do a signed HW divide, wait for result, return remainder
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return remainder.
*
* \param a The dividend
* \param b The divisor
* \return Remainder results of the divide
*/
static inline int32_t hw_divider_remainder_s32(int32_t a, int32_t b) {
#if !PICO_EMULATE_DIVIDER
return to_remainder_s32(hw_divider_divmod_s32(a, b));
#else
return b ? (a % b) : a;
#endif
}
/*! \brief Pause for exact amount of time needed for a asynchronous divide to complete
* \ingroup hardware_divider
*/
static inline void hw_divider_pause(void) {
#if !PICO_EMULATE_DIVIDER
pico_default_asm_volatile(
"b _1_%=\n"
"_1_%=:\n"
"b _2_%=\n"
"_2_%=:\n"
"b _3_%=\n"
"_3_%=:\n"
"b _4_%=\n"
"_4_%=:\n"
:::);
#endif
}
/*! \brief Do a hardware unsigned HW divide, wait for result, return quotient
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return quotient.
*
* \param a The dividend
* \param b The divisor
* \return Quotient result of the divide
*/
static inline uint32_t hw_divider_u32_quotient_inlined(uint32_t a, uint32_t b) {
#if !PICO_EMULATE_DIVIDER
hw_divider_divmod_u32_start(a, b);
hw_divider_pause();
return sio_hw->div_quotient;
#else
return hw_divider_u32_quotient(a,b);
#endif
}
/*! \brief Do a hardware unsigned HW divide, wait for result, return remainder
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return remainder.
*
* \param a The dividend
* \param b The divisor
* \return Remainder result of the divide
*/
static inline uint32_t hw_divider_u32_remainder_inlined(uint32_t a, uint32_t b) {
#if !PICO_EMULATE_DIVIDER
hw_divider_divmod_u32_start(a, b);
hw_divider_pause();
uint32_t rc = sio_hw->div_remainder;
sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
return rc;
#else
return hw_divider_u32_remainder(a,b);
#endif
}
/*! \brief Do a hardware signed HW divide, wait for result, return quotient
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return quotient.
*
* \param a The dividend
* \param b The divisor
* \return Quotient result of the divide
*/
static inline int32_t hw_divider_s32_quotient_inlined(int32_t a, int32_t b) {
#if !PICO_EMULATE_DIVIDER
hw_divider_divmod_s32_start(a, b);
hw_divider_pause();
return (int32_t)sio_hw->div_quotient;
#else
return hw_divider_quotient_s32(a,b);
#endif
}
/*! \brief Do a hardware signed HW divide, wait for result, return remainder
* \ingroup hardware_divider
*
* Divide \p a by \p b, wait for calculation to complete, return remainder.
*
* \param a The dividend
* \param b The divisor
* \return Remainder result of the divide
*/
static inline int32_t hw_divider_s32_remainder_inlined(int32_t a, int32_t b) {
#if !PICO_EMULATE_DIVIDER
hw_divider_divmod_s32_start(a, b);
hw_divider_pause();
int32_t rc = (int32_t)sio_hw->div_remainder;
sio_hw->div_quotient; // must read quotient to cooperate with other SDK code
return rc;
#else
return hw_divider_remainder_s32(a,b);
#endif
}
#if !PICO_EMULATE_DIVIDER
typedef struct {
uint32_t values[4];
} hw_divider_state_t;
#else
typedef uint64_t hw_divider_state_t;
#endif
/*! \brief Save the calling cores hardware divider state
* \ingroup hardware_divider
*
* Copy the current core's hardware divider state into the provided structure. This method
* waits for the divider results to be stable, then copies them to memory.
* They can be restored via hw_divider_restore_state()
*
* \param dest the location to store the divider state
*/
#if !PICO_EMULATE_DIVIDER
void hw_divider_save_state(hw_divider_state_t *dest);
#else
static inline void hw_divider_save_state(hw_divider_state_t *dest) {
*dest = hw_divider_results[get_core_num()];
}
#endif
/*! \brief Load a saved hardware divider state into the current core's hardware divider
* \ingroup hardware_divider
*
* Copy the passed hardware divider state into the hardware divider.
*
* \param src the location to load the divider state from
*/
#if !PICO_EMULATE_DIVIDER
void hw_divider_restore_state(hw_divider_state_t *src);
#else
static inline void hw_divider_restore_state(hw_divider_state_t *src) {
hw_divider_results[get_core_num()] = *src;
}
#endif
#ifdef __cplusplus
}
#endif
#endif // _HARDWARE_DIVIDER_H
Details ![]()
Show: from Types: Columns: ![]( "Show Project Names")
![]( "Show Locations")
![]( "Show Referring Symbols")
![]( "Show Scope")
This file uses the notable symbols shown below. Click anywhere in the file to view more details.