When The Printer Driver Compression Mode Is Selected; How To Compress Data; Data Before Being Compressed; Data After Being Compressed - Toshiba B-EV4 Series Manual

[When the printer driver compression mode is selected]

(1) For the [ESC] SG0; -- command, only "A: Printer driver compression mode" can be selected
for the type of graphic data.
parameter for the type of graphic data. When the total number of data cannot be provided
by the printer driver, "00H, 00H, 00H, 00H" should be specified for the number of graphic
data. However, in this case, the printer diver cannot support printing through a serial
interface (RS-232C).

(2) How to compress data

Compression is performed for every data of one line specified for the number of graphic
width dots.
The data is made up in units of 8 dots. A repeated value is encoded in 2 bytes. The first
byte is a numeric value n indicating that a value is repeated (-n + 1) times.
The range is between -127 and -1. The second byte is the repeated value.
If a value is not repeated the first byte is the numeric value m. The length of the values is
indicated in (m+1). The range of "m" is between 0 and 126. The length of the repetition of
the value and "m" should not exceed 127 and 126, respectively.
If it exceeds the range, it should be divided into blocks of repetition.
When the same contents as the data for 1 line appear repeatedly in the next line and after,
the number of lines in which the same contents appear is encoded in 2 bytes. The first byte
is fixed as 127. The second byte indicates "N" times that the same contents are repeated.
Its range is between 1 and 255. "N" should not exceed 255. If it exceeds the range, the
data for the excess number of times should be compressed as the new data of 1 line, and
the remaining number of repetitions should be encoded.
[Example]
Data before being compressed (Width: 120 dots, Height: 300 lines)
Line No.
1
2
299
300

Data after being compressed

Line No.
1
2 to 256
257
258 to 300
The parameter for the data count is attached after the
Graphic data
AAh AAh AAh AAh AAh AAh AAh BBh CCh DDh EEh FFh FFh FFh FFh
AAh AAh AAh AAh AAh AAh AAh BBh CCh DDh EEh FFh FFh FFh FFh
AAh AAh AAh AAh AAh AAh AAh BBh CCh DDh EEh FFh FFh FFh FFh
AAh AAh AAh AAh AAh AAh AAh BBh CCh DDh EEh FFh FFh FFh FFh
Graphic data
FAh AAh 03h BBh CCh DDh EEh FEh FFh
7FH FFH
FAh AAh 03h BBh CCh DDh EEh FDh FFh
7FH 2BH
FAh = -6
-(-6) + 1 = 7
AAh is repeated 7 times.
- 158 -
FDh = -3
-(-3) + 1 = 4
FFh is repeated 4 times.
03h = 3
3 + 1 = 4
4-byte data (BBh CCh DDh EEh) without
repetition