DL205 User Manual, 4th Edition, Rev. D
5-169
Chapter 5: Standard RLL Instructions
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Table Shift Left (TSHFL)
The Table Shift Left instruction shifts all the bits in a V-memory
table to the left a specified number of bit positions.
Table Shift Right (TSHFR)
The Table Shift Right instruction shifts all the bits in a V-memory
table to the right a specified number of bit positions.
The following description applies to both the Table Shift Left and
Table Shift Right instructions. A table is a range of V-memory
locations. The Table Shift Left and Table Shift Right instructions shift bits serially throughout
the entire table. Bits are shifted out the end of one word and into the opposite end of an
adjacent word. At the ends of the table, bits are either discarded, or zeros are shifted into the
table. The example tables below are arbitrarily four words long.
Step 1: Load the length of the table (number of V-memory locations) into the first level of the
accumulator stack. This parameter must be a HEX value, 0 to FF.
Step 2: Load the starting V-memory location for the table into the accumulator. This parameter
must be a HEX value. You can use the LDA instruction to convert an octal address to hex.
Step 3: Insert the Table Shift Left or Table Shift Right instruction. This specifies the number of bit
positions you wish to shift the entire table. The number of bit positions must be in octal.
Helpful hint: Remember that each V-memory location contains 16 bits. The bits of the first
word of the table are numbered from 0 to 17 octal. If you want to shift the entire table by 20
bits, that is 24 octal. Flag 53 will be set if the number of bits to be shifted is larger than the
total bits contained within the table. Flag 67 will be set if the last bit shifted (just before it is
discarded) is a “1”.
Vaaa
TSHF L
230
240
250-1
260
Vaaa
TSHFR
230
240
250-1
260
Table Shift Left
Table Shift Right
Discard Bit
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