aboutsummaryrefslogtreecommitdiffstats
path: root/source/language.rst
blob: 2ebe03c2f7a4f7851c0d93096b9fb035732c5f78 (plain)
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
.. highlight:: c++

.. _language:

==========================
 Maple Language Reference
==========================

The Maple can be programmed in the `Wiring
<http://www.wiring.org.co/reference/>`_ language, which is the same
language used to program the `Arduino <http://arduino.cc/>`_ boards.

C or C++ programmers curious about the differences between the Wiring
language and C++ may wish to skip to the
:ref:`arduino_c_for_c_hackers`.

.. contents:: Contents
   :local:

Unique Maple Additions
----------------------

.. _language-assert:

``ASSERT(...)``
    The ``ASSERT()`` function can be very useful for basic program
    debugging. The function accepts a boolean; for example::

      ASSERT(state == WAIT);

    zero is false and any other number is true. If the boolean is true
    the assertion passes and the program continues as usual. If it is
    false, the assertion fails: the program is halted, debug
    information is printed to USART2, and the status LED begins to
    throb in intensity (it's noticeably different from blinking). The
    debug information is printed at 9600 baud and consists of the
    filename and line number where the particular assertion failed.

    Including assertions in a program increases the program size. When
    using libmaple **from the command line only**, they can be
    disabled by making the definition ::

      #define DEBUG_LEVEL DEBUG_NONE

    before including either wirish.h or libmaple.h. In this case, all
    assertions will pass without any lost clock cycles.  Note that
    this will **not work in the IDE**; even with this definition,
    assertions will still be enabled.

.. _language-lang-docs:

Maple Language Reference
------------------------

The following table summarizes the available core language features.
A more exhaustive index is available at the :ref:`language-index`.

+--------------------------------------------+----------------------------------------------+---------------------------------------------------+
| Structure                                  | Variables                                    | Functions                                         |
|                                            |                                              |                                                   |
+============================================+==============================================+===================================================+
|* :ref:`setup() <lang-setup>`               |**Constants**                                 |**Digital I/O**                                    |
|                                            |                                              |                                                   |
|* :ref:`loop() <lang-loop>`                 |* :ref:`HIGH <lang-constants-high>` |         |* :ref:`pinMode() <lang-pinmode>`                  |
|                                            |  :ref:`LOW <lang-constants-low>`             |                                                   |
|                                            |                                              |* :ref:`digitalWrite() <lang-digitalwrite>`        |
|**Control Structures**                      |* :ref:`INPUT <lang-constants-input>` |       |                                                   |
|                                            |  :ref:`OUTPUT <lang-constants-output>`       |* :ref:`digitalRead() <lang-digitalread>`          |
|* :ref:`if/else <lang-if>`                  |                                              |                                                   |
|                                            |* :ref:`true <lang-constants-true>` |         |* :ref:`togglePin() <lang-togglepin>`              |
|* :ref:`for <lang-for>`                     |  :ref:`false <lang-constants-false>`         |                                                   |
|                                            |                                              |* :ref:`toggleLED() <lang-toggleled>`              |
|* :ref:`switch/case <lang-switchcase>`      |* :ref:`BOARD_LED_PIN <lang-constants-led>` | |                                                   |
|                                            |  :ref:`BOARD_BUTTON_PIN <lang-constants-but>`|* :ref:`isButtonPressed() <lang-isbuttonpressed>`  |
|* :ref:`while <lang-while>`                 |                                              |                                                   |
|                                            |* :ref:`Constants                             |* :ref:`waitForButtonPress()                       |
|* :ref:`do...while <lang-dowhile>`          |  <lang-constants>` (:ref:`integers           |  <lang-waitforbuttonpress>`                       |
|                                            |  <lang-constants-integers>`, :ref:`floating  |                                                   |
|* :ref:`break <lang-break>`                 |  point <lang-constants-fp>`)                 |**Analog I/O**                                     |
|                                            |                                              |                                                   |
|* :ref:`continue <lang-continue>`           |**Data Types**                                |* :ref:`analogRead() <lang-analogread>`            |
|                                            |                                              |                                                   |
|* :ref:`return <lang-return>`               | The size of each datatype, in bytes, is      |* :ref:`pwmWrite() <lang-pwmwrite>`                |
|                                            | given in parentheses where appropriate.      |  (:ref:`analogWrite() <lang-analogwrite>` is      |
|* :ref:`goto <lang-goto>`                   |                                              |  also available, though its use is discouraged)   |
|                                            | *Note*: The ``word`` type is (deliberately)  |                                                   |
|                                            | :ref:`not supported <language-no-word>`.     |                                                   |
|**Further syntax**                          |                                              |**Advanced I/O**                                   |
|                                            |* :ref:`void <lang-void>`                     |                                                   |
|* :ref:`; (semicolon) <lang-semicolon>`     |                                              |* tone(): TODO                                     |
|                                            |* :ref:`boolean <lang-boolean>` (1 byte)      |                                                   |
|* :ref:`{} (curly braces)                   |                                              |* noTone(): TODO                                   |
|  <lang-curly-braces>`                      |* :ref:`char <lang-char>` (1 byte)            |                                                   |
|                                            |                                              |* shiftOut(): TODO                                 |
|* :ref:`// (single-line comment)            |* :ref:`unsigned char                         |                                                   |
|  <lang-comments-singleline>`               |  <lang-unsignedchar>` (1 byte)               |* pulseIn(): TODO                                  |
|                                            |                                              |                                                   |
|* :ref:`/\* \*/ (multi-line comment)        |* :ref:`byte <lang-byte>` (1 byte)            |                                                   |
|  <lang-comments-multiline>`                |                                              |**Time**                                           |
|                                            |* :ref:`int <lang-int>` (4 bytes)             |                                                   |
|* :ref:`#define <lang-define>`              |                                              |* :ref:`millis() <lang-millis>`                    |
|                                            |* :ref:`unsigned int <lang-unsignedint>`      |                                                   |
|* :ref:`#include <lang-include>`            |  (4 bytes)                                   |* :ref:`micros() <lang-micros>`                    |
|                                            |                                              |                                                   |
|                                            |* ``long`` (4 bytes), synonym for :ref:`int   |* :ref:`delay() <lang-delay>`                      |
|**Arithmetic Operators**                    |  <lang-int>`                                 |                                                   |
|                                            |                                              |* :ref:`delayMicroseconds()                        |
|* :ref:`= <lang-assignment>`                |* ``unsigned long`` (4 bytes), synonym for    |  <lang-delaymicroseconds>`                        |
|  (assignment operator)                     |  :ref:`unsigned int <lang-unsignedint>`      |                                                   |
|                                            |                                              |                                                   |
|* :ref:`+ <lang-arithmetic>` (addition)     |* :ref:`long long <lang-longlong>` (8 bytes)  |**Math**                                           |
|                                            |                                              |                                                   |
|* :ref:`- <lang-arithmetic>`                |* :ref:`unsigned long                         |* :ref:`min() <lang-min>`                          |
|  (subtraction)                             |  long <lang-unsignedlonglong>` (8 bytes)     |                                                   |
|                                            |                                              |* :ref:`max() <lang-max>`                          |
|* :ref:`* <lang-arithmetic>`                |* :ref:`float <lang-float>` (4 bytes)         |                                                   |
|  (multiplication)                          |                                              |* :ref:`abs() <lang-abs>`                          |
|                                            |* :ref:`double <lang-double>` (8 bytes)       |                                                   |
|* :ref:`/ <lang-arithmetic>` (division)     |                                              |* :ref:`constrain() <lang-constrain>`              |
|                                            |* :ref:`strings <lang-string>`                |                                                   |
|* :ref:`% <lang-modulo>` (modulo)           |                                              |* :ref:`map() <lang-map>`                          |
|                                            |* :ref:`arrays <lang-array>`                  |                                                   |
|                                            |                                              |* :ref:`pow() <lang-pow>`                          |
|**Comparison Operators**                    |* :ref:`enum <lang-enum>`                     |                                                   |
|                                            |                                              |* :ref:`sqrt() <lang-sqrt>`                        |
|* :ref:`== <lang-comparison>` (equal to)    |* :ref:`numeric types <lang-built-in-types>`  |                                                   |
|                                            |                                              |                                                   |
|* :ref:`\!= <lang-comparison>`              |**Conversion**                                |**Trigonometry**                                   |
|  (not equal to)                            |                                              |                                                   |
|                                            |* :ref:`char() <lang-charcast>`               |* :ref:`sin() <lang-sin>`                          |
|* :ref:`< <lang-comparison>` (less than)    |                                              |                                                   |
|                                            |* :ref:`byte() <lang-bytecast>`               |* :ref:`cos() <lang-cos>`                          |
|* :ref:`> <lang-comparison>`                |                                              |                                                   |
|  (greater than)                            |* :ref:`int() <lang-intcast>`                 |* :ref:`tan() <lang-tan>`                          |
|                                            |                                              |                                                   |
|* :ref:`<= <lang-comparison>`               |* :ref:`long() <lang-longcast>`               |                                                   |
|  (less than or equal to)                   |                                              |**Random Numbers**                                 |
|                                            |* :ref:`float() <lang-floatcast>`             |                                                   |
|* :ref:`>= <lang-comparison>`               |                                              |* :ref:`randomSeed() <lang-randomseed>`            |
|  (greater than or equal to)                |* :ref:`double() <lang-doublecast>`           |                                                   |
|                                            |                                              |* :ref:`random() <lang-random>`                    |
|                                            |                                              |                                                   |
|**Boolean Operators**                       |**Variable Scope & Qualifiers**               |                                                   |
|                                            |                                              |**Bits and Bytes**                                 |
|* :ref:`&& <lang-boolean-and>` (and)        |* :ref:`variables <lang-variables>`,          |                                                   |
|                                            |  :ref:`scope <lang-variables-scope>`         |* :ref:`lowByte() <lang-lowbyte>`                  |
|* :ref:`|| <lang-boolean-or>` (or)          |                                              |                                                   |
|                                            |* :ref:`static <lang-static>`                 |* :ref:`highByte() <lang-highbyte>` is             |
|* :ref:`\! <lang-boolean-not>` (not)        |                                              |  provided, though its use is discouraged.         |
|                                            |* :ref:`volatile <lang-volatile>`             |                                                   |
|                                            |                                              |* :ref:`bitRead() <lang-bitread>`                  |
|**Pointer Operators**                       |* :ref:`const <lang-const>`                   |                                                   |
|                                            |                                              |* :ref:`bitWrite() <lang-bitwrite>`                |
|* :ref:`* dereference operator              |                                              |                                                   |
|  <lang-pointer>`                           |**Utilities**                                 |* :ref:`bitSet() <lang-bitset>`                    |
|                                            |                                              |                                                   |
|* :ref:`& reference operator                |* :ref:`sizeof() <lang-sizeof>`               |* :ref:`bitClear() <lang-bitclear>`                |
|  <lang-pointer>`                           |                                              |                                                   |
|                                            |                                              |* :ref:`bit() <lang-bit>`                          |
|                                            |                                              |                                                   |
|**Bitwise Operators**                       |                                              |                                                   |
|                                            |                                              |**External Interrupts**                            |
|* :ref:`& <lang-bitwisemath-and>`           |                                              |                                                   |
|  (bitwise and)                             |                                              |* :ref:`Reference Page <external-interrupts>`      |
|                                            |                                              |                                                   |
|* :ref:`| <lang-bitwisemath-or>`            |                                              |* :ref:`attachInterrupt()                          |
|  (bitwise or)                              |                                              |  <lang-attachinterrupt>`                          |
|                                            |                                              |                                                   |
|* :ref:`^ <lang-bitwisemath-xor>`           |                                              |* :ref:`detachInterrupt()                          |
|  (bitwise xor)                             |                                              |  <lang-detachinterrupt>`                          |
|                                            |                                              |                                                   |
|* :ref:`~ <lang-bitwisemath-not>`           |                                              |                                                   |
|  (bitwise not)                             |                                              |**Interrupts**                                     |
|                                            |                                              |                                                   |
|* :ref:`\<\< <lang-bitshift>`               |                                              |* :ref:`interrupts() <lang-interrupts>`            |
|  (shift left)                              |                                              |                                                   |
|                                            |                                              |* :ref:`noInterrupts() <lang-nointerrupts>`        |
|* :ref:`>> <lang-bitshift>`                 |                                              |                                                   |
|  (shift right)                             |                                              |                                                   |
|                                            |                                              |**Communication**                                  |
|                                            |                                              |                                                   |
|**Compound Operators**                      |                                              |* :ref:`SerialUSB <lang-serialusb>`                |
|                                            |                                              |                                                   |
|* :ref:`++ <lang-increment>`                |                                              |* :ref:`Serial <lang-serial>`                      |
|  (increment)                               |                                              |                                                   |
|                                            |                                              |**Looking for something else?**                    |
|* :ref:`- - <lang-increment>`               |                                              |                                                   |
|  (decrement)                               |                                              | See the :ref:`libraries` page for interfacing with|
|                                            |                                              | particular types of hardware.  Maple links        |
|* :ref:`+= <lang-compoundarithmetic>`       |                                              | against `newlib <http://sourceware.org/newlib/>`_ |
|  (compound add)                            |                                              | and allows the use of any of its functions; see   |
|                                            |                                              | its documentation for more details.               |
|* :ref:`-=                                  |                                              |                                                   |
|  <lang-compoundarithmetic>` (compound      |                                              |                                                   |
|  subtract)                                 |                                              |                                                   |
|                                            |                                              |                                                   |
|* :ref:`*=                                  |                                              |                                                   |
|  <lang-compoundarithmetic>` (compound      |                                              |                                                   |
|  multiply)                                 |                                              |                                                   |
|                                            |                                              |                                                   |
|* :ref:`/=                                  |                                              |                                                   |
|  <lang-compoundarithmetic>` (compound      |                                              |                                                   |
|  divide)                                   |                                              |                                                   |
|                                            |                                              |                                                   |
|* :ref:`&=                                  |                                              |                                                   |
|  <lang-compoundbitwise>` (compound         |                                              |                                                   |
|  bitwise and)                              |                                              |                                                   |
|                                            |                                              |                                                   |
|* :ref:`|=                                  |                                              |                                                   |
|  <lang-compoundbitwise>` (compound         |                                              |                                                   |
|  bitwise or)                               |                                              |                                                   |
|                                            |                                              |                                                   |
|**Keywords**                                |                                              |                                                   |
|                                            |                                              |                                                   |
|* :ref:`C++ Keywords <lang-keywords>`       |                                              |                                                   |
|                                            |                                              |                                                   |
|                                            |                                              |                                                   |
+--------------------------------------------+----------------------------------------------+---------------------------------------------------+

.. _language-missing-features:

Missing Arduino Features
------------------------

.. _langage-missing-analogreference:

**analogReference()**

    It is not possible to implement this function on the Maple
    hardware.  It will be possible on the upcoming Maple Native.

.. _language-no-word:

**word**

    Readers familiar with the Arduino environment may notice that the
    ``word`` datatype is missing from the above table's list of data
    types.  We chose **not to provide** the ``word`` data type on the
    Maple.  If you want a 16-bit unsigned integer, use the ``uint16``
    type instead.

    While the Maple has 32-bit words, the word size on an Arduino
    board is only 16 bits, and code that uses the ``word`` type is
    likely to rely on that fact.

    By not supporting ``word``, you'll get a compile error when
    porting Arduino code to the Maple instead of potentially weird,
    hard-to-debug runtime behavior.

    If you really must have ``word``, you can include the following
    ``typedef`` in your program::

        typedef uint16 word;

Unimplemented Arduino Features
------------------------------

The following Wiring/Arduino features are currently unimplemented on
the Maple.  However, they will be present in future versions:

- `noTone() <http://www.arduino.cc/en/Reference/NoTone>`_
- `pulseIn() <http://www.arduino.cc/en/Reference/PulseIn>`_
- `shiftOut() <http://www.arduino.cc/en/Reference/ShiftOut>`_
- `String <http://arduino.cc/en/Reference/StringObject>`_
- `tone() <http://www.arduino.cc/en/Reference/Tone>`_

.. _our reference page: http://leaflabs.com/docs/external-interrupts/

.. _newlib: http://sourceware.org/newlib/

.. _cpp-for-maple:

C++ for Maple
--------------

If you haven't programmed in C++, or if you just need to jog your
memory, you may want to check out our :ref:`Language Index
<language-index>`.  It provides some introductory coverage of
programming ideas and C++.

.. _arduino_c_for_c_hackers:

Note for C/C++ Hackers
----------------------

This is a note for programmers comfortable with C or C++ (although,
you C programmers should remember that `C++ is not a superset of C
<http://en.wikipedia.org/wiki/Compatibility_of_C_and_C%2B%2B>`_) who
want a better understanding of the differences between C++ and the
Wiring language.  The good news is that the differences are relatively
few; Wiring is just a thin wrapper around C++.

Some potentially better news is that the Maple can be programmed using
a :ref:`standard Unix toolchain <unix-toolchain>`, so if you'd rather
stick with :command:`gcc`, :command:`make`, and friends, you can.

A *sketch* is the IDE's notion of a project; it consists of one or
more files written in the Wiring language, which is mostly the same as
C++.  The major difference between the two is that in Wiring, it's not
necessary to declare global functions before they are used.  That is,
the following is valid Wiring, and ``f()`` returns ``5``::

  int f() {
    return g();
  }

  int g() {
    return 5;
  }

All of the files in a sketch share the same (global) namespace.  That
is, the behavior is as if all of a sketch's files were part of the
same translation unit, so they don't have to include one another in
order to access each other's definitions.  The only other major
difference between Wiring and C++ is that Wiring doesn't support
dynamically allocated memory -- that is, ``new`` and ``delete`` won't
work.  As of |today|, Maple only has 20 KB RAM, anyway, so it's
doubtful that static allocation is not what you want.

The Wiring language also does not require you to define your own
``main`` method (in fact, it forbids you from doing so).  Instead, you
are required to define two functions, ``setup`` and ``loop``, with
type signatures ::

  void setup(void);
  void loop(void);

Once a sketch is uploaded to a Maple and begins to run, ``setup()`` is
called once, and then ``loop()`` is called repeatedly.  The IDE
compilation process proceeds via a source-to-source translation from
the files in a sketch to C++.

This translation process first concatenates the sketch files, then
parses the result to produce a list of all functions defined in the
global scope.  (We borrow this stage from the Arduino IDE, which in
turn borrows it from Wiring.  It uses regular expressions to parse
C++, which is, of course, `Bad and Wrong
<http://www.retrologic.com/jargon/B/Bad-and-Wrong.html>`_.  An
upcoming rewrite of the IDE performs this preprocessing step
correctly, using a real parser.  Until then, you have our apologies.)
The order in which the individual sketch files are concatenated is not
defined; it is unwise to write code that depends on a particular
ordering.

The concatenated sketch files are then appended onto a file which
includes `WProgram.h
<http://github.com/leaflabs/libmaple/blob/master/wirish/WProgram.h>`_
(which includes the wirish and libmaple libraries, and declares
``setup()`` and ``loop()``), and then provides declarations for all
the function definitions found in the previous step.  At this point,
we have a file that is a valid C++ translation unit, but lacks a
``main()`` method.  The final step of compilation provides this
method, which behaves roughly like::

  int main(void) {
    setup();
    while (true) loop();
  }

(The truth is a little bit more complicated, but not by much).

As an example, consider a sketch with two files.  The first file
contains ``setup()`` and ``loop()``::

  int the_pin;

  void setup() {
    the_pin = choose_a_pin();
    pinMode(the_pin, OUTPUT);
  }

  void loop() {
    togglePin(the_pin);
  }

The second file contains the (not very useful) implementation for
``choose_a_pin()``::

  int choose_a_pin() {
     return random(5, 15);
  }

Then the results of the concatenation process might be ::

  int the_pin;

  void setup() {
    the_pin = choose_a_pin();
    pinMode(the_pin, OUTPUT);
  }

  void loop() {
    togglePin(the_pin);
  }

  int choose_a_pin(void);

  int choose_a_pin() {
     return random(5, 15);
  }

Which could plausibly be turned into the final source file ::

  #include "WProgram.h"

  void setup(void);
  void loop(void);
  int choose_a_pin(void);

  int the_pin;

  void setup() {
    the_pin = choose_a_pin();
    pinMode(the_pin, OUTPUT);
  }

  void loop() {
    togglePin(the_pin);
  }

  int choose_a_pin(void);

  int choose_a_pin() {
     return random(5, 15);
  }

  int main() {
    setup();
    while (true) loop();
  }

(Recall that it's legal C++ for a function to be declared multiple
times, as long as it's defined exactly once).


Recommended Reading
-------------------

* `newlib Documentation <http://sourceware.org/newlib/>`_
* STMicro documentation for STM32F103RB microcontroller:

    * `Datasheet <http://www.st.com/stonline/products/literature/ds/13587.pdf>`_ (pdf)
    * `Reference Manual <http://www.st.com/stonline/products/literature/rm/13902.pdf>`_ (pdf)
    * `Programming Manual <http://www.st.com/stonline/products/literature/pm/15491.pdf>`_ (assembly language and register reference)