HP PCL 5 User Manual download pdf (Page 145)

EN Raster Graphics 6-25

The command byte identifies two things: 1) the number of

replacement (delta) bytes that follow; and 2) where to position the

replacement byte string (the left offset). The replacement bytes are

some number (up to eight bytes) of consecutive bytes that are used to

create the new row from the seed row.

If more than eight replacement (delta) bytes are needed, additional

command byte/replacement bytes may be added, as shown below:

?*3m#W [(Command Byte)(1 to 8 Replacement

Bytes)][(Command Byte)(1 to 8 Replacement Bytes)]. . .

In the command byte, the upper three bits identify the number of

replacement (delta) bytes (which can be 1 to 8 bytes). The lower five

bits identify the location the replacement bytes are to be positioned.

This position is identified as the offset, or the number of bytes from

the treated byte. For example, if there are 5 replacement bytes and

the offset is 7, then the replacement bytes replace bytes 7, 8, 9, 10,

and 11 (the five bytes beginning at byte 7 from the seed row).

If there is more than one replacement in a row, the second offset is

counted from the next untreated byte in the row: the first byte

following the last replacement byte.

7 5 4 0

Number of bytes to replace (1-8) Relative offset from last untreated

byte

1 2 ... 140 141 142 143 144 145 146 147 148 149 150 ... 285 286

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HP PCL 5 User Manual Page 145