December 2001 Commands 7 – 139
7.7.59 BIT TEST (BT)
Syntax: BT (BIT TEST)
Operands: B, W, D, K, X
Action:
With the BIT TEST you can interrogate the status of each bit in the
accumulator. With the BT command there is a direct transition from word to
logic processing, i.e. the TNC checks the state of a bit in the word accumulator
and then sets the logic accumulator. If the interrogated bit = 1, the TNC sets
the logic accumulator to 1; otherwise it sets it to 0. The corresponding bits are
selected (addressed) by the content of the specified operand or by a constant.
As to the bit numbering, bit 0 = LSB and bit 31 = MSB. For operand contents
greater than 32, the TNC uses the operand value modulo 32, i.e. the integral
remainder of the result of the operand value divided by 32.
Example:
Load the double word D8 into the accumulator and assign the logical state of
bit 0 to output O12.
Initial state:
Double word D8 = 3E 81 (hex)
Output O12 = ?
The word accumulator and operand contents are shown here in hexadecimal
notation, the logic accumulator in binary notation.
Function STL Accumulator contents (hex or [bit]) Operand content (hex or
[Bit])
xx xx xx xx
Load the double
word D8 into the
word accumulator.
L D8 00 00 3E 81 00 00 3E 81
Check the state of
the bit specified in
the operand.
BT K+0 00 00 3E 81
31..15 ..................... 7 .................. 0
Assign the result to
output O12.
= O12 x ..... x xxxxxxx1xxxxxxx 1
To Next Page
Loading...
