Mikroelektronika MIKROE-742 데이터 시트

$1234 

and $5678          // equals $1230 

{ because ..

$1234 : 0001 0010 0011 0100
$5678 : 0101 0110 0111 1000
----------------------------

and  : 0001 0010 0011 0000

.. that is, $1230 }// Similarly:

$1234 

$5678      

// equals $567C

$1234 

xor $5678   

// equals $444C

not $1234          

// equals $EDCB

If a number is converted from less complex to more complex data type, the upper
bytes are filled with zeroes. If a number is converted from more complex to less
complex data type, the data is simply truncated (the upper bytes are lost).

For example:

var a : byte; b : word;
...

a := $AA;
b := $F0F0;

b := b 

and a;

{ a is extended with zeroes; b becomes $00A0 }

If number is converted from less complex data type to more complex, upper bytes
are filled with ones if sign bit is 1 (number is negative); upper bytes are filled with
zeroes if sign bit is 0 (number is positive). If number is converted from more com-
plex data type to less complex, data is simply truncated (upper bytes are lost).

For example:

var a : byte; b : word;
...

a := -12;

b := $70FF;

b := b 

and a;

{ a is sign extended, with the upper byte equal to $FF;

b becomes $70F4 }

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 5