Brother HL-Series Technical Reference Manual page 96

Revision C 16/01/96
Command byte for mode 9 compression (non repeated replacement data)
7
0
If the control bit is 0, replacement data is not repeated data. Bits 6 to 3 contain the offset count. This field value
is from 0 to 15. If this value is 15, the next byte of the control bytes is an optional offset count. The value of
this optional offset count byte is from 0 to 255. If this optional offset count value is 255, then the next byte is
another (second) optional offset count byte. Optional offset count bytes will continue until the value is less than
255. The total Offset value is the sum of the offset count in the control byte and all the optional offset bytes.
Bits 2 to 0 of the control byte contains the replacement count - 1. The value is from 0 to 7. If this value is 7,
optional replacement byte(s) follow the control byte or optional offset byte(s) (if any).
If the first optional replacement count byte is 255, then a second optional count byte follows the first optional
count byte. Optional offset count bytes will continue until the value becomes less than 255. The addition of the
replacement count in the control byte and all optional replacement count bytes gives the total replacement
count.
Replacement data bytes follow the control byte and any optional offset bytes and any optional replacement
count bytes.
<Example>
Seed row
Current row
<Different section 11 11 22 33 44 55 66 77>
Offset count = 5
Replacement count = 8
Replacement data = 11 11 22 33 44 55 66 77
7 6
0 0
Offset count = 5
Command byte for mode 9 compression (repeated replacement data)
7
1
6 5 4
Offset count
Control bit
55 55 55 55 55 55 55 55 55 55 55 55 55
55 55 55 55 55 11 11 22 33 44 55 66 77
5 4 3 2 1 0
1 0 1 1 1 1
Replacement count = 7 + 1 = 8
6 5 4
Offset count
Control bit
Chapter 2 "PCL" - 81
3 2 1
Replacement count-1
Optional offset count byte = 0
3 2 1
Replacement count
0
11 11 22 33 44 55 66 77
8 bytes of repracement data
0