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
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
//! # Type-erased, value-level module for GPIO pins
//!
//! Although the type-level API is generally preferred, it is not suitable in
//! all cases. Because each pin is represented by a distinct type, it is not
//! possible to store multiple pins in a homogeneous data structure. The
//! value-level API solves this problem by erasing the type information and
//! tracking the pin at run-time.
//!
//! Value-level pins are represented by the [`DynPin`] type. [`DynPin`] has two
//! fields, `id` and `mode` with types [`DynPinId`] and [`DynPinMode`]
//! respectively. The implementation of these types closely mirrors the
//! type-level API.
//!
//! Instances of [`DynPin`] cannot be created directly. Rather, they must be
//! created from their type-level equivalents using [`From`]/[`Into`].
//!
//! ```
//! // Move a pin out of the Pins struct and convert to a DynPin
//! let pa27: DynPin = pins.pa27.into();
//! ```
//!
//! Conversions between pin modes use a value-level version of the type-level
//! API.
//!
//! ```
//! // Use one of the literal function names
//! pa27.into_floating_input();
//! // Use a method and a DynPinMode variant
//! pa27.into_mode(DYN_FLOATING_INPUT);
//! ```
//!
//! Because the pin state cannot be tracked at compile-time, many [`DynPin`]
//! operations become fallible. Run-time checks are inserted to ensure that
//! users don't try to, for example, set the output level of an input pin.
//!
//! Users may try to convert value-level pins back to their type-level
//! equivalents. However, this option is fallible, because the compiler cannot
//! guarantee the pin has the correct ID or is in the correct mode at
//! compile-time. Use [`TryFrom`](core::convert::TryFrom)/
//! [`TryInto`](core::convert::TryInto) for this conversion.
//!
//! ```
//! // Convert to a `DynPin`
//! let pa27: DynPin = pins.pa27.into();
//! // Change pin mode
//! pa27.into_floating_input();
//! // Convert back to a `Pin`
//! let pa27: Pin<PA27, FloatingInput> = pa27.try_into().unwrap();
//! ```
//!
//! # Embedded HAL traits
//!
//! This module implements all of the embedded HAL GPIO traits for [`DynPin`].
//! However, whereas the type-level API uses
//! `Error = core::convert::Infallible`, the value-level API can return a real
//! error. If the [`DynPin`] is not in the correct [`DynPinMode`] for the
//! operation, the trait functions will return
//! [`InvalidPinType`](Error::InvalidPinType).

use core::convert::TryFrom;

use paste::paste;

use crate::ehal::digital::v2::OutputPin;
#[cfg(feature = "unproven")]
use crate::ehal::digital::v2::{InputPin, StatefulOutputPin, ToggleableOutputPin};

use super::pin::*;
use super::reg::RegisterInterface;

//==============================================================================
//  DynPinMode configurations
//==============================================================================

/// Value-level `enum` for disabled configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynDisabled {
    Floating,
    PullDown,
    PullUp,
}

/// Value-level `enum` for input configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynInput {
    Floating,
    PullDown,
    PullUp,
}

/// Value-level `enum` for interrupt configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynInterrupt {
    Floating,
    PullDown,
    PullUp,
}

/// Value-level `enum` for output configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynOutput {
    PushPull,
    Readable,
}

/// Value-level `enum` for alternate peripheral function configurations
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynAlternate {
    B,
    C,
    D,
    E,
    F,
    G,
    #[cfg(any(feature = "samd21", feature = "min-samd51g"))]
    H,
    #[cfg(feature = "min-samd51g")]
    I,
    #[cfg(feature = "min-samd51g")]
    J,
    #[cfg(feature = "min-samd51g")]
    K,
    #[cfg(feature = "min-samd51g")]
    L,
    #[cfg(feature = "min-samd51g")]
    M,
    #[cfg(feature = "min-samd51g")]
    N,
}

//==============================================================================
//  DynPinMode
//==============================================================================

/// Value-level `enum` representing pin modes
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum DynPinMode {
    Disabled(DynDisabled),
    Input(DynInput),
    Interrupt(DynInterrupt),
    Output(DynOutput),
    Alternate(DynAlternate),
}

/// Value-level variant of [`DynPinMode`] for floating disabled mode
pub const DYN_FLOATING_DISABLED: DynPinMode = DynPinMode::Disabled(DynDisabled::Floating);
/// Value-level variant of [`DynPinMode`] for pull-down disabled mode
pub const DYN_PULL_DOWN_DISABLED: DynPinMode = DynPinMode::Disabled(DynDisabled::PullDown);
/// Value-level variant of [`DynPinMode`] for pull-up disabled mode
pub const DYN_PULL_UP_DISABLED: DynPinMode = DynPinMode::Disabled(DynDisabled::PullUp);

/// Value-level variant of [`DynPinMode`] for floating input mode
pub const DYN_FLOATING_INPUT: DynPinMode = DynPinMode::Input(DynInput::Floating);
/// Value-level variant of [`DynPinMode`] for pull-down input mode
pub const DYN_PULL_DOWN_INPUT: DynPinMode = DynPinMode::Input(DynInput::PullDown);
/// Value-level variant of [`DynPinMode`] for pull-up input mode
pub const DYN_PULL_UP_INPUT: DynPinMode = DynPinMode::Input(DynInput::PullUp);

/// Value-level variant of [`DynPinMode`] for floating interrupt mode
pub const DYN_FLOATING_INTERRUPT: DynPinMode = DynPinMode::Interrupt(DynInterrupt::Floating);
/// Value-level variant of [`DynPinMode`] for pull-down interrupt mode
pub const DYN_PULL_DOWN_INTERRUPT: DynPinMode = DynPinMode::Interrupt(DynInterrupt::PullDown);
/// Value-level variant of [`DynPinMode`] for pull-up interrupt mode
pub const DYN_PULL_UP_INTERRUPT: DynPinMode = DynPinMode::Interrupt(DynInterrupt::PullUp);

/// Value-level variant of [`DynPinMode`] for push-pull output mode
pub const DYN_PUSH_PULL_OUTPUT: DynPinMode = DynPinMode::Output(DynOutput::PushPull);
/// Value-level variant of [`DynPinMode`] for readable push-pull output mode
pub const DYN_READABLE_OUTPUT: DynPinMode = DynPinMode::Output(DynOutput::Readable);

macro_rules! dyn_alternate {
    ( $($Letter:ident),+ ) => {
        paste! {
            $(
                #[
                    doc = "Value-level variant of [`DynPinMode`] for alternate "
                    "peripheral function " $Letter
                ]
                pub const [<DYN_ALTERNATE_ $Letter>]: DynPinMode =
                DynPinMode::Alternate(DynAlternate::$Letter);
            )+
        }
    };
}

dyn_alternate!(B, C, D, E, F, G);
#[cfg(any(feature = "samd21", feature = "min-samd51g"))]
dyn_alternate!(H);
#[cfg(feature = "min-samd51g")]
dyn_alternate!(I, J, K, L, M, N);

//==============================================================================
//  DynGroup & DynPinId
//==============================================================================

/// Value-level `enum` for pin groups
#[derive(PartialEq, Clone, Copy)]
pub enum DynGroup {
    A,
    #[cfg(any(feature = "samd21", feature = "min-samd51g"))]
    B,
    #[cfg(feature = "min-samd51n")]
    C,
    #[cfg(feature = "min-samd51p")]
    D,
}

/// Value-level `struct` representing pin IDs
#[derive(PartialEq, Clone, Copy)]
pub struct DynPinId {
    pub group: DynGroup,
    pub num: u8,
}

//==============================================================================
//  DynRegisters
//==============================================================================

/// Provide a safe register interface for [`DynPin`]s
///
/// This `struct` takes ownership of a [`DynPinId`] and provides an API to
/// access the corresponding regsiters.
struct DynRegisters {
    id: DynPinId,
}

// [`DynRegisters`] takes ownership of the [`DynPinId`], and [`DynPin`]
// guarantees that each pin is a singleton, so this implementation is safe.
unsafe impl RegisterInterface for DynRegisters {
    #[inline]
    fn id(&self) -> DynPinId {
        self.id
    }
}

impl DynRegisters {
    /// Create a new instance of [`DynRegisters`]
    ///
    /// # Safety
    ///
    /// Users must never create two simultaneous instances of this `struct` with
    /// the same [`DynPinId`]
    #[inline]
    unsafe fn new(id: DynPinId) -> Self {
        DynRegisters { id }
    }
}

//==============================================================================
//  Error
//==============================================================================

/// GPIO error type
///
/// [`DynPin`]s are not tracked and verified at compile-time, so run-time
/// operations are fallible. This `enum` represents the corresponding errors.
pub enum Error {
    /// The pin did not have the correct ID or mode for the requested operation
    InvalidPinType,
}

//==============================================================================
//  DynPin
//==============================================================================

/// A value-level pin, parameterized by [`DynPinId`] and [`DynPinMode`]
///
/// This type acts as a type-erased version of [`Pin`]. Every pin is represented
/// by the same type, and pins are tracked and distinguished at run-time.
pub struct DynPin {
    regs: DynRegisters,
    mode: DynPinMode,
}

impl DynPin {
    /// Create a new [`DynPin`]
    ///
    /// # Safety
    ///
    /// Each [`DynPin`] must be a singleton. For a given [`DynPinId`], there
    /// must be at most one corresponding [`DynPin`] in existence at any given
    /// time.  Violating this requirement is `unsafe`.
    #[inline]
    unsafe fn new(id: DynPinId, mode: DynPinMode) -> Self {
        DynPin {
            regs: DynRegisters::new(id),
            mode,
        }
    }

    /// Return a copy of the pin ID
    #[inline]
    pub fn id(&self) -> DynPinId {
        self.regs.id
    }

    /// Return a copy of the pin mode
    #[inline]
    pub fn mode(&self) -> DynPinMode {
        self.mode
    }

    /// Convert the pin to the requested [`DynPinMode`]
    #[inline]
    pub fn into_mode(&mut self, mode: DynPinMode) {
        // Only modify registers if we are actually changing pin mode
        if mode != self.mode {
            self.regs.change_mode(mode);
            self.mode = mode;
        }
    }

    /// Disable the pin and set it to float
    #[inline]
    pub fn into_floating_disabled(&mut self) {
        self.into_mode(DYN_FLOATING_DISABLED);
    }

    /// Disable the pin and set it to pull down
    #[inline]
    pub fn into_pull_down_disabled(&mut self) {
        self.into_mode(DYN_PULL_DOWN_DISABLED);
    }

    /// Disable the pin and set it to pull up
    #[inline]
    pub fn into_pull_up_disabled(&mut self) {
        self.into_mode(DYN_PULL_UP_DISABLED);
    }

    /// Configure the pin to operate as a floating input
    #[inline]
    pub fn into_floating_input(&mut self) {
        self.into_mode(DYN_FLOATING_INPUT);
    }

    /// Configure the pin to operate as a pulled down input
    #[inline]
    pub fn into_pull_down_input(&mut self) {
        self.into_mode(DYN_PULL_DOWN_INPUT);
    }

    /// Configure the pin to operate as a pulled up input
    #[inline]
    pub fn into_pull_up_input(&mut self) {
        self.into_mode(DYN_PULL_UP_INPUT);
    }

    /// Configure the pin to operate as a floating interrupt
    #[inline]
    pub fn into_floating_interrupt(&mut self) {
        self.into_mode(DYN_FLOATING_INTERRUPT);
    }

    /// Configure the pin to operate as a pulled down interrupt
    #[inline]
    pub fn into_pull_down_interrupt(&mut self) {
        self.into_mode(DYN_PULL_DOWN_INTERRUPT);
    }

    /// Configure the pin to operate as a pulled up interrupt
    #[inline]
    pub fn into_pull_up_interrupt(&mut self) {
        self.into_mode(DYN_PULL_UP_INTERRUPT);
    }

    /// Configure the pin to operate as a push-pull output
    #[inline]
    pub fn into_push_pull_output(&mut self) {
        self.into_mode(DYN_PUSH_PULL_OUTPUT);
    }

    /// Configure the pin to operate as a readable push pull output
    #[inline]
    pub fn into_readable_output(&mut self) {
        self.into_mode(DYN_READABLE_OUTPUT);
    }

    /// Configure the pin to operate as the corresponding peripheral function.
    ///
    /// The `config` argument indicates the desired peripheral function.
    #[inline]
    pub fn into_alternate(&mut self, config: DynAlternate) {
        self.into_mode(DynPinMode::Alternate(config));
    }

    /// Read the current drive strength of the pin.
    ///
    /// The drive strength is reset to normal on every change in pin mode.
    #[inline]
    pub fn get_drive_strength(&self) -> bool {
        self.regs.read_drive_strength()
    }

    /// Set the drive strength for the pin.
    ///
    /// The drive strength is reset to normal on every change in pin mode.
    #[inline]
    pub fn set_drive_strength(&mut self, stronger: bool) {
        self.regs.write_drive_strength(stronger);
    }

    #[inline]
    fn _read(&self) -> Result<bool, Error> {
        match self.mode {
            DynPinMode::Input(_) | DYN_READABLE_OUTPUT => Ok(self.regs.read_pin()),
            _ => Err(Error::InvalidPinType),
        }
    }
    #[inline]
    fn _write(&mut self, bit: bool) -> Result<(), Error> {
        match self.mode {
            DynPinMode::Output(_) => {
                self.regs.write_pin(bit);
                Ok(())
            }
            _ => Err(Error::InvalidPinType),
        }
    }
    #[inline]
    fn _toggle(&mut self) -> Result<(), Error> {
        match self.mode {
            DynPinMode::Output(_) => {
                self.regs.toggle_pin();
                Ok(())
            }
            _ => Err(Error::InvalidPinType),
        }
    }
    #[inline]
    fn _read_out(&self) -> Result<bool, Error> {
        match self.mode {
            DYN_READABLE_OUTPUT => Ok(self.regs.read_out_pin()),
            _ => Err(Error::InvalidPinType),
        }
    }
    #[inline]
    fn _is_low(&self) -> Result<bool, Error> {
        Ok(self._read()? == false)
    }
    #[inline]
    fn _is_high(&self) -> Result<bool, Error> {
        Ok(self._read()? == true)
    }
    #[inline]
    fn _set_low(&mut self) -> Result<(), Error> {
        self._write(false)
    }
    #[inline]
    fn _set_high(&mut self) -> Result<(), Error> {
        self._write(true)
    }
    #[inline]
    fn _is_set_low(&self) -> Result<bool, Error> {
        Ok(self._read_out()? == false)
    }
    #[inline]
    fn _is_set_high(&self) -> Result<bool, Error> {
        Ok(self._read_out()? == true)
    }
}

//==============================================================================
//  Convert between Pin and DynPin
//==============================================================================

impl<I, M> From<Pin<I, M>> for DynPin
where
    I: PinId,
    M: PinMode,
{
    /// Erase the type-level information in a [`Pin`] and return a value-level
    /// [`DynPin`]
    #[inline]
    fn from(_pin: Pin<I, M>) -> Self {
        // The `Pin` is consumed, so it is safe to replace it with the
        // corresponding `DynPin`
        unsafe { DynPin::new(I::DYN, M::DYN) }
    }
}

impl<I, M> TryFrom<DynPin> for Pin<I, M>
where
    I: PinId,
    M: PinMode,
{
    type Error = Error;

    /// Try to recreate a type-level [`Pin`] from a value-level [`DynPin`]
    ///
    /// There is no way for the compiler to know if the conversion will be
    /// successful at compile-time. We must verify the conversion at run-time
    /// or refuse to perform it.
    #[inline]
    fn try_from(pin: DynPin) -> Result<Self, Error> {
        if pin.regs.id == I::DYN && pin.mode == M::DYN {
            // The `DynPin` is consumed, so it is safe to replace it with the
            // corresponding `Pin`
            Ok(unsafe { Self::new() })
        } else {
            Err(Error::InvalidPinType)
        }
    }
}

//==============================================================================
// Embedded HAL traits
//==============================================================================

impl OutputPin for DynPin {
    type Error = Error;
    #[inline]
    fn set_high(&mut self) -> Result<(), Self::Error> {
        self._set_high()
    }
    #[inline]
    fn set_low(&mut self) -> Result<(), Self::Error> {
        self._set_low()
    }
}

#[cfg(feature = "unproven")]
impl InputPin for DynPin {
    type Error = Error;
    #[inline]
    fn is_high(&self) -> Result<bool, Self::Error> {
        self._is_high()
    }
    #[inline]
    fn is_low(&self) -> Result<bool, Self::Error> {
        self._is_low()
    }
}

#[cfg(feature = "unproven")]
impl ToggleableOutputPin for DynPin {
    type Error = Error;
    #[inline]
    fn toggle(&mut self) -> Result<(), Self::Error> {
        self._toggle()
    }
}

#[cfg(feature = "unproven")]
impl StatefulOutputPin for DynPin {
    #[inline]
    fn is_set_high(&self) -> Result<bool, Self::Error> {
        self._is_set_high()
    }
    #[inline]
    fn is_set_low(&self) -> Result<bool, Self::Error> {
        self._is_set_low()
    }
}