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diff --git a/docs/source/arduino/bitwisecompound.rst b/docs/source/arduino/bitwisecompound.rst deleted file mode 100644 index c3c808f..0000000 --- a/docs/source/arduino/bitwisecompound.rst +++ /dev/null @@ -1,227 +0,0 @@ -.. _arduino-bitwisecompound: - -compound bitwise AND (&=), compound bitwise OR (\|=) -==================================================== - -The compound bitwise operators perform their calculations at the -bit level of variables. They are often used to clear and set -specific bits of a variable. - - - -See the -`bitwise AND (&) <http://arduino.cc/en/Reference/BitwiseAnd>`_ and -`bitwise OR (\|) <http://arduino.cc/en/Reference/BitwiseAnd>`_ -operators for the details of their operation, and also the -`Bitmath Tutorial <http://www.arduino.cc/playground/Code/BitMath>`_ -for more information on bitwise operators. - - - -compound bitwise AND (&=) -========================= - -Description ------------ - -The compound bitwise AND operator (&=) is often used with a -variable and a constant to force particular bits in a variable to -the LOW state (to 0). This is often referred to in programming -guides as "clearing" or "resetting" bits. - - - -Syntax: -------- - -:: - - x &= y; // equivalent to x = x & y; - - - -Parameters ----------- - -x: a char, int or long variable -y: an integer constant or char, int, or long - - - -Example: --------- - -First, a review of the Bitwise AND (&) operator - -:: - - 0 0 1 1 operand1 - 0 1 0 1 operand2 - ---------- - 0 0 0 1 (operand1 & operand2) - returned result - - - -Bits that are "bitwise ANDed" with 0 are cleared to 0 so, if myByte -is a byte variable, -``myByte & B00000000 = 0;`` - - - -Bits that are "bitwise ANDed" with 1 are unchanged so, -``myByte & B11111111 = myByte;`` - - - -Note: because we are dealing with bits in a bitwise operator - it -is convenient to use the binary formatter with -`constants. <http://arduino.cc/en/Reference/IntegerConstants>`_ The -numbers are still the same value in other representations, they are -just not as easy to understand. Also, B00000000 is shown for -clarity, but zero in any number format is zero (hmmm something -philosophical there?) - - - -Consequently - to clear (set to zero) bits 0 & 1 of a variable, -while leaving the rest of the variable unchanged, use the compound -bitwise AND operator (&=) with the constant B11111100 - -:: - - 1 0 1 0 1 0 1 0 variable - 1 1 1 1 1 1 0 0 mask - ---------------------- - 1 0 1 0 1 0 0 0 - - variable unchanged - bits cleared - - -Here is the same representation with the variable's bits replaced -with the symbol x - - - -:: - - x x x x x x x x variable - 1 1 1 1 1 1 0 0 mask - ---------------------- - x x x x x x 0 0 - - variable unchanged - bits cleared - - -So if: - -:: - - myByte = 10101010; - - myByte &= B1111100 == B10101000; - - - -compound bitwise OR (\|=) -========================= - -Description ------------ - -The compound bitwise OR operator (\|=) is often used with a -variable and a constant to "set" (set to 1) particular bits in a -variable. - - - -Syntax: -------- - -:: - - x |= y; // equivalent to x = x | y; - - - -Parameters ----------- - -x: a char, int or long variable -y: an integer constant or char, int, or long - - - -Example: --------- - -First, a review of the Bitwise OR (\|) operator - -:: - - 0 0 1 1 operand1 - 0 1 0 1 operand2 - ---------- - 0 1 1 1 (operand1 | operand2) - returned result - -Bits that are "bitwise ORed" with 0 are unchanged, so if myByte is -a byte variable, -myByte \| B00000000 = myByte; - - - -Bits that are "bitwise ORed" with 1 are set to 1 so: -myByte & B11111111 = B11111111; - - - -Consequently - to set bits 0 & 1 of a variable, while leaving the -rest of the variable unchanged, use the compound bitwise AND -operator (&=) with the constant B00000011 - -:: - - 1 0 1 0 1 0 1 0 variable - 0 0 0 0 0 0 1 1 mask - ---------------------- - 1 0 1 0 1 0 1 1 - - variable unchanged - bits set - - -Here is the same representation with the variables bits replaced -with the symbol x - - - -:: - - x x x x x x x x variable - 0 0 0 0 0 0 1 1 mask - ---------------------- - x x x x x x 1 1 - - variable unchanged - bits set - -So if: - -:: - - myByte = B10101010; - - myByte |= B00000011 == B10101011; - - - -See Also - - -- `& <http://arduino.cc/en/Reference/BitwiseAnd>`_ (bitwise AND) -- `\| <http://arduino.cc/en/Reference/BitwiseAnd>`_ (bitwise OR) -- `&& <http://arduino.cc/en/Reference/Boolean>`_ (Boolean AND) -- `\|\| <http://arduino.cc/en/Reference/Boolean>`_ (Boolean OR) - - |