merge libmaple docs ("leaflabs-docs") into ./docs

In the past, libample documentation was forked out of this repository
because the documentation had increased in scope. For the librambutan,
and the rambutan project in general, we will try to keep documentation
closer to the source code, so the librambutan-specific documentation
should live here. Other sections of leaflabs-docs will be culled in a
following commit.

This merge attempts to maintain history by using a subtree strategy.
Followed directions at:

    http://nuclearsquid.com/writings/subtree-merging-and-you/

Full history for files should be accessible using the "--follow" flag to
git log, eg:

    git log --follow docs/source/adc.rst

It should be possible to pull patches from leaflabs-docs with:

    git pull -s subtree leaflabs-docs master

... at least until the docs in this repository diverge significantly.

1 files changed, 431 insertions, 0 deletions

diff --git a/docs/source/language.rst b/docs/source/language.rst
new file mode 100644
index 0000000..a24bb5f
--- /dev/null
+++ b/docs/source/language.rst
@@ -0,0 +1,431 @@
+.. highlight:: c++
+
+.. _language:
+
+====================
+ 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 who are new to Wiring may wish to skip to the
+:ref:`arduino_c_for_c_hackers`.
+
+.. contents:: Contents
+   :local:
+
+.. admonition:: Looking for something else? Try these
+
+   - See the :ref:`libraries` for extra built-in libraries.
+
+   - If you prefer C or C++ over Wiring, see :ref:`libmaple` and the
+     :ref:`unix-toolchain`.
+
+   - If you're looking for something from the C standard library (like
+     ``atoi()``, for instance), see :ref:`this FAQ <faq-atoi>`.
+
+   - An :ref:`stm32` and other :ref:`language-recommended-reading` are
+     also available.
+
+.. _language-lang-docs:
+
+Maple Language Reference
+------------------------
+
+This table is a summary of the most important language features.  See
+the :ref:`language-index` for a complete listing.
+
++--------------------------------------------+----------------------------------------------+---------------------------------------------------+
+| 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:`Constants                             |                                                   |
+|                                            |  <lang-constants>` (:ref:`integers           |* :ref:`isButtonPressed() <lang-isbuttonpressed>`  |
+|* :ref:`while <lang-while>`                 |  <lang-constants-integers>`, :ref:`floating  |                                                   |
+|                                            |  point <lang-constants-fp>`)                 |* :ref:`waitForButtonPress()                       |
+|* :ref:`do...while <lang-dowhile>`          |                                              |  <lang-waitforbuttonpress>`                       |
+|                                            |* :ref:`Board-specific values                 |                                                   |
+|* :ref:`break <lang-break>`                 |  <lang-board-values>`                        |**Analog I/O**                                     |
+|                                            |                                              |                                                   |
+|* :ref:`continue <lang-continue>`           |**Data Types**                                |* :ref:`analogRead() <lang-analogread>`            |
+|                                            |                                              |                                                   |
+|* :ref:`return <lang-return>`               | The size of each data type, 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)            |                                                   |
+|                                            |                                              |* :ref:`shiftOut() <lang-shiftout>`                |
+|* :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)                              |  :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:`ASSERT() <lang-assert>`               |* :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)                               |                                              |                                                   |
+|                                            |                                              |                                                   |
+|* :ref:`- - <lang-increment>`               |                                              |                                                   |
+|  (decrement)                               |                                              |                                                   |
+|                                            |                                              |                                                   |
+|* :ref:`+= <lang-compoundarithmetic>`       |                                              |                                                   |
+|  (compound add)                            |                                              |                                                   |
+|                                            |                                              |                                                   |
+|* :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.
+
+- `tone() <http://www.arduino.cc/en/Reference/Tone>`_
+- `noTone() <http://www.arduino.cc/en/Reference/NoTone>`_
+- `pulseIn() <http://www.arduino.cc/en/Reference/PulseIn>`_
+- `String <http://arduino.cc/en/Reference/StringObject>`_
+
+.. _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++ 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.  If you're using the Unix
+toolchain and want to skip past the Wiring conveniences and get
+straight to the details, you are encouraged to move on to the
+:ref:`libmaple` documentation.
+
+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 Wiring language also does not require you to define your own
+``main`` method (in fact, we currently forbid you from doing so).
+Instead, you are required to define two functions, ``setup`` and
+``loop``, whose prototypes are ::
+
+  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, forever.  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>`_.  In the
+future, we'll do this correctly, using a better 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
+<https://github.com/leaflabs/libmaple/blob/master/wirish/WProgram.h>`_
+(which includes the Wirish and libmaple proper 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
+``main()``.  The final step of compilation provides ``main()``, which
+behaves roughly like::
+
+  int main(void) {
+    // Call libmaple's built-in initialization routines
+    init();
+
+    // Perform the user's initialization
+    setup();
+
+    // Call user loop() forever.
+    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() {
+    init();
+    setup();
+    while (true) loop();
+  }
+
+.. _language-recommended-reading:
+
+Recommended Reading
+-------------------
+
+* :ref:`Your board's documentation <index-boards>` page, which
+  includes references to the relevant ST materials (reference manual,
+  datashseet, etc.) for your board.
+* `ARM Cortex-M3 Technical Reference Manual, Revision r1p1 <http://infocenter.arm.com/help/topic/com.arm.doc.ddi0337e/DDI0337E_cortex_m3_r1p1_trm.pdf>`_
+  (PDF).  This ARM manual specifies the Cortex-M3 architecture,
+  including instruction timings.
+* :ref:`libmaple`
+* `newlib's Documentation <http://sourceware.org/newlib/>`_
+  (see :ref:`arm-gcc-libc`)