Mikroelektronika MIKROE-350 Fiche De Données

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

For example:

dim a as byte
dim b as word
' ...

a = $AA
b = $F0F0
b = b and a
' a is extended with zeroes; b becomes $00A0

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

For example:

dim a as byte
dim b as word
' ...

a = -12
b = $70FF
b = b 

and a

' a is sign extended, upper byte is $FF;
' b becomes $70F4

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 5