RLE man page on DigitalUNIX

Man page or keyword search:  
man Server   12896 pages
apropos Keyword Search (all sections)
Output format
DigitalUNIX logo
[printable version]

RLE(5)									RLE(5)

       rle - Run length encoded file format produced by the rle library

       The  output  file format is (note: all words are 16 bits, and in PDP-11
       byte order):

       Word 0 A "magic" number 0xcc52.	(Byte order 0x52, 0xcc.)

       Words 1-4
	      The structure (chars saved in PDP-11 order)

		  short	  xpos,			      /* Lower left corner
			  xsize,		      /* Size of saved box

       Byte 10
	      (flags) The following flags are defined:

		   (0x1) If set, clear the frame buffer	 to  background	 color
		   before restoring.

		   (0x2)   If  set,  no	 background  color  is	supplied.   If
		   H_CLEARFIRST is also set, it should be ignored (or alterna‐
		   tively, a clear-to-black operation could be performed).

		   (0x4)  If  set,  an alpha channel is saved as color channel
		   -1.	The alpha channel does not contribute to the count  of
		   colors in ncolors.

		   (0x8)  If  set,  comments  will follow the color map in the

       Byte 11
	      (ncolors) Number of color channels present.  0 means  load  only
	      the  color map (if present), 1 means a B&W image, 3 means a nor‐
	      mal color image.

       Byte 12
	      (pixelbits) Number of bits per pixel, per color channel.	Values
	      greater than 8 currently will not work.

       Byte 13
	      (ncmap) Number of color map channels present.  Need not be iden‐
	      tical to ncolors.	 If this is non-zero, the  color  map  follows
	      immediately after the background colors.

       Byte 14
	      (cmaplen)	 Log  base 2 of the number of entries in the color map
	      for each color channel.  I.e., would be 8 for a color  map  with
	      256 entries.

       Bytes 15-...
	      The  background  color.	There  are ncolors bytes of background
	      color.  If ncolors is even, an extra padding byte is inserted to
	      end  on a 16 bit boundary.  The background color is only present
	      if H_NO_BACKGROUND is not set in flags.  IF H_NO	BACKGROUND  is
	      set,  there  is  a  single  filler  byte.	  Background  color is
	      ignored, but present, if H_CLEARFIRST is not set in flags.

	      If ncmap	is  non-zero,  then  the  color	 map  will  follow  as
	      ncmap*2^cmaplen 16 bit words.  The color map data is left justi‐
	      fied in each word.

	      If the H_COMMENT flag is set, a set  of  comments	 will  follow.
	      The first 16 bit word gives the length of the comments in bytes.
	      If this is odd, a filler byte will be appended to the  comments.
	      The  comments  are  interpreted as a sequence of null terminated
	      strings which should be, by convention, of the form  name=value,
	      or just name.

	      Following the setup information is the Run Length Encoded image.
	      Each instruction consists of an opcode, a datum and possibly one
	      or  more following words (all words are 16 bits).	 The opcode is
	      encoded in the first byte of the instruction word.  Instructions
	      come  in	either	a  short or long form.	In the short form, the
	      datum is in the second byte of the instruction word; in the long
	      form,  the  datum	 is  a	16 bit value in the word following the
	      instruction word.	 Long form instructions are  distinguished  by
	      having  the  0x40	 bit  set in the opcode byte.  The instruction
	      opcodes are:

       SkipLines (1)
	      The datum is an unsigned number to be added  to  the  current  Y

       SetColor (2)
	      The  datum  indicates  which color is to be loaded with the data
	      described by the following ByteData  and	RunData	 instructions.
	      Typically,  0→red,  1→green,  2→blue.  The operation also resets
	      the X position to the initial X (i.e. a carriage	return	opera‐
	      tion is performed).

       SkipPixels (3)
	      The  datum  is  an  unsigned number to be added to the current X

       ByteData (5)
	      The datum is one less than the number of	bytes  of  color  data
	      following.  If the number of bytes is odd, a filler byte will be
	      appended to the end of the byte string to make an integral  num‐
	      ber  of  16-bit  words.  The X position is incremented to follow
	      the last byte of data.

       RunData (6)
	      The datum is one less than the run length.  The  following  word
	      contains	(in  its  lower	 8  bits) the color of the run.	 The X
	      position is incremented to follow the last byte in the run.

       EOF (7)
	      This opcode indicates the logical end of image data.  A physical
	      end-of-file will also serve as well.  The EOF opcode may be used
	      to concatenate several images in a single file.


       Spencer W. Thomas, Todd Fuqua

4th Berkeley Distribution	    9/14/82				RLE(5)

List of man pages available for DigitalUNIX

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net