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, 90 insertions, 0 deletions

diff --git a/docs/source/lang/cpp/boolean.rst b/docs/source/lang/cpp/boolean.rst
new file mode 100644
index 0000000..f09345e
--- /dev/null
+++ b/docs/source/lang/cpp/boolean.rst
@@ -0,0 +1,90 @@
+.. highlight:: cpp
+
+.. _lang-boolean:
+
+Boolean Operators
+=================
+
+These can be used inside the condition of an :ref:`if <lang-if>`
+statement.  Evaluate to :ref:`true <lang-constants-true>` or
+:ref:`false <lang-constants-false>`.
+
+.. contents:: Contents
+   :local:
+
+.. _lang-boolean-and:
+
+&& (logical and)
+----------------
+
+True only if both operands are true.  For example::
+
+    if (digitalRead(2) == HIGH  && digitalRead(3) == HIGH) { // read two switches
+      // ...
+    }
+
+is true only if both inputs are high.  Another example::
+
+    if (a >= 10 && a <= 20){}   // true if a is between 10 and 20
+
+**Be careful** not to say ``10 <= a <= 20``!  This won't work the way
+you want.  You have to separately test whether ``a`` is at least 10
+using ``a >= 10``, then test whether ``a`` is at most 20 using ``a <=
+20``, then combine the results using ``&&``.
+
+
+.. _lang-boolean-or:
+
+\|\| (logical or)
+-----------------
+
+True if either operand is true.  For example::
+
+    if (x > 0 || y > 0) {
+      // ...
+    }
+
+is true if either ``x`` or ``y`` is greater than 0.
+
+.. _lang-boolean-not:
+
+! (logical not)
+---------------
+
+True if the operand is false.  For example::
+
+    if (!x) {
+      // ...
+    }
+
+is true if ``x`` is false (i.e. if ``x`` is zero).
+
+Some Advice
+-----------
+
+.. warning::
+
+   Make sure you don't mistake the boolean AND operator ``&&``
+   (double ampersand) for the :ref:`bitwise AND operator
+   <lang-bitwisemath-and>` ``&`` (single ampersand). They are
+   entirely different beasts.
+
+   Similarly, do not confuse the boolean OR operator ``||`` (double
+   pipe) with the :ref:`bitwise OR operator <lang-bitwisemath-or>`
+   ``|`` (single pipe).
+
+   The :ref:`bitwise NOT operator <lang-bitwisemath-not>` ``~``
+   (tilde) looks much different than the boolean not operator ``!``
+   (exclamation point, or "bang", as some programmers say), but you
+   still have to be sure which one you want.
+
+
+See Also
+--------
+
+- :ref:`Bitwise operators <lang-bitwisemath>` (``&``, ``|``, ``^``, ``~``)
+- :ref:`Compound bitwise operators <lang-compoundbitwise>` (``&=``,
+  ``|=``, ``^=``).
+- :ref:`if statement <lang-if>`
+
+.. include:: /arduino-cc-attribution.txt