From d9cbd78e29d42e70bb46641dd43ee0772c8c975f Mon Sep 17 00:00:00 2001 From: Marti Bolivar Date: Sun, 28 Nov 2010 11:23:33 -0500 Subject: reorganized all the arduino/ docs into a lang/ subdirectory since they're properly CC attributed now. --- source/arduino/arithmetic.rst | 129 ------------------------------------------ 1 file changed, 129 deletions(-) delete mode 100644 source/arduino/arithmetic.rst (limited to 'source/arduino/arithmetic.rst') diff --git a/source/arduino/arithmetic.rst b/source/arduino/arithmetic.rst deleted file mode 100644 index 69cf166..0000000 --- a/source/arduino/arithmetic.rst +++ /dev/null @@ -1,129 +0,0 @@ -.. highlight:: cpp - -.. _arduino-arithmetic: - -Addition, Subtraction, Multiplication, & Division -================================================= - -.. contents:: Contents - :local: - -Description ------------ - -These operators return the sum, difference, product, or quotient -(respectively) of the two operands. The operation is conducted using -the data type of the operands, so, for example, ``9 / 4`` gives ``2`` -since 9 and 4 are :ref:`int variables `. - -This also means that the operation can overflow if the result is -larger than that which can be stored in the data type (e.g. adding 1 -to an :ref:`arduino-int` with the value 2147483647 gives --2147483648). If the operands are of different types, the "larger" -type is used for the calculation. - -.. _arduino-arithmetic-typeconversion: - -.. note:: The specifics of these rules are beyond the scope of this - documentation; for more information, see `The C++ Programming - Language `_\ , by Bjarne - Stroustroup, Appendix C, especially §§C.4-C.6, or `this WikiBooks - entry on C++ type conversion - `_. - -.. note:: For more information on how computers represent integers, - see the Wikipedia page on `two's complement - `_. - -If one of the numbers (operands) are of the type **float** or of type -**double**, floating point math will be used for the -calculation. - -Examples --------- - - :: - - y = y + 3; - x = x - 7; - i = j * 6; - r = r / 5; - - -Syntax ------- - - :: - - result = value1 + value2; - result = value1 - value2; - result = value1 * value2; - result = value1 / value2; - - -Parameters ----------- - -**value1**: any numeric variable or constant - -**value2**: any numeric variable or constant - -Programming Tips ----------------- - -- Know that :ref:`integer constants ` - default to :ref:`int `, so some constant calculations - may overflow (e.g., 200000 * 5000000 will yield a negative result). - -- Choose variable sizes that are large enough to hold the largest - results from your calculations. - -- Know at what point your variable will "roll over" and also what - happens in the other direction e.g. (0 - 1) for unsigned arithmetic, - or (0 - -2,147,483,648) for signed arithmetic. - -- For math that requires fractions, float variables may be used, but - be aware of their drawbacks: large size and slow computation speeds - (the STM32 has no floating point hardware, so all floating point - calculations have to be done in software). - -- Use cast operator, e.g. ``(int)myFloat`` to convert one variable type - to another on the fly. - -Arduino Compatibility ---------------------- - -Since the STM32 processor on the Maple is a 32-bit machine, the int -type overflows at a much higher value on Maple than on Arduino. In -particular, on Maple, ints do not overflow (become negative) until -they reach 2,147,483,648; on the Arduino, they overflow at 32,767. -Because of this, programs running on Maple are much less likely to run -into overflow issues. The following table summarizes the sizes and -ranges of integer datatypes on the Maple (the ranges of long long -types are approximate): - -.. _arduino-arithmetic-int-sizes: - -.. csv-table:: - :header: Datatype, Unsigned range, Signed range, Size (bytes) - :widths: 8, 12, 17, 8 - - ``char``, 0 --- 255, -128 --- 127, 1 - ``short``, "0 --- 65,535", "-32,768 --- 32,767", 2 - ``int``, "0 --- 4,294,967,295", "-2,147,483,648 --- 2,147,483,647", 4 - ``long``, "0 --- 4,294,967,295", "-2,147,483,648 --- 2,147,483,647", 4 - ``long long``, "0 --- 1.8*10\ :sup:`19`\ " (approx.), "-9.2*10\ :sup:`18` --- 9.2*10\ :sup:`18` (approx.)", 8 - - -See Also --------- - -- The individual sizes (in bits) of various available types are - defined in `libmaple_types.h - `_\ - . - -- :ref:`sizeof `\ () - - -.. include:: cc-attribution.txt -- cgit v1.2.3