HEIDENHAIN TNC 306 Technical Manual - Manual (Page 371)

3/2000
TNC 416/TNC 406/TNC 306 Commands 7-81
3.9
Shift Commands
3.9.1 SHIFT LEFT (<<) <<
Abbreviation for PLC Editor: << (SHIFT LEFT)
Byte/Word/Double Constant
Execution time [µs] 2.0 + 0.2 x n 2.0 + 0.2 x n
Number of bytes 6 8
Operands: B, W, D, K
Operation:
Since the sign bit (MSB) is included with this command, it is grouped in with arithmetic commands.
For this reason and out of time considerations, this command should not be used for the isolation of bits.
A SHIFT LEFT instruction causes the contents of the Word Accumulator to be multiplied by two. For this
purpose, the bits in the Accumulator are simply shifted by one place to the left. The number of the shift
operations is determined via the operand. Thus the set bits, which are shifted beyond the Accumulator to
the left, are lost; the Accumulator is filled with nulls from the right-hand side. With operand contents
greater than 32, the operand value Modulo 32 is used, i.e. the integer remainder from the division (operand
value)/32.
Example:
The content of the Double word D8 is to be shifted four times to the left and then stored in D12.
Initial state: Double word D8 = 3E 80 (hex)
Double word D12 = ?
The Accumulator content is shown here in binary notation, and the operand content in hexadecimal
notation.
Line Instruction Accumulator content Operand content
xxxxxxxx xxxxxxxx xxxxxxxxx xxxxxxxxx
1 L D8 00000000 00000000 00111110 10000000 00 00 3E 80
2 << K+1 00000000 00000000 01111101 00000000
3 << K+1 00000000 00000000 11111010 00000000
4 << K+1 00000000 00000001 11110100 00000000
5 << K+1 00000000 00000011 11101000 00000000
6 = D12 00000000 00000011 11101000 00000000 00 03 E8 00
Line 1: Load Double word D8 into the Accumulator.
Line 2 to 5: The content of the Word Accumulator is shifted to the left by the number of bits
specified in the operand. The complete operation can also be undertaken with the
command << K+4.
Line 6: The result is stored in the Double word D12.