Update specs

Signed-off-by: Alexey Galakhov <agalakhov@gmail.com>

SPECS

@@ -21,6 +21,7 @@ inside "ccpd" daemon.
 
 
 1.1. General format of CAPT commands
+------------------------------------
 
 All transmit are in 16-bit, little-endian words. Each command has the HEADER
 of 4 bytes followed:
@@ -54,9 +55,89 @@ Example: decimal 57 may be encoded as 0x57 0x00 and not as 0x39 0x00.
 
 
 1.2. Common printer control commands
-
-
-1.3. Compression control commands
+------------------------------------
+
+* 0xA0A0
+NOP? Get status?
+
+* 0xA0A1
+Get printer status. See section 1.3.
+
+* 0xA0A8
+Get printer extended status. See section 1.3.
+
+* 0xA1A0
+Get printer identification string (IEEE-1284). This command does NOT use the
+common reply format and just returns raw string data.
+
+* 0xA1A1
+Get printer capabitilies?
+
+
+1.3. Printer status
+-------------------
+
+Extended status record (reply to the 0xA0A8 command):
+
+  0-1:   uint16_t bits STATUS0
+  2-7:   ? 00 00 0f 00 00 00 (constant sequence)
+  8-9:   uint16_t bits STATUS1
+  10-11: uint16_t bits STATUS2
+  12-13: uint16_t bits STATUS3
+  14-15: uint16_t page number being decoded
+  16-17: uint16_t page number being printed
+  18-19: uint16_t page number being pushed out
+  20-21: uint16_t page number completed
+  22-23: 00 00
+  24-25: uint16_t bits STATUS4
+  26-27: 00 00
+  28-29: uint16_t job number being processed
+  30-31: uint16_t bits STATUS5
+  32:    ? 55
+  33:    uint8_t number of 0xE0A5 commands sent
+  34-35: uint16_t number of received pages
+  36-37: 00 00
+  38-39: uint16_t bits STATUS6
+  40-41: uint16_t number of pages in job (set by user 0xE1A1)
+  42-43: 00 00
+  44-45: uint16_t number of page printed in job
+  46-63: 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 00 00
+  64-65: uint16_t event counter
+  66-83: 00 00 00 ...
+
+Status bits:
+
+  STATUS0
+    15:   ? 0 initially, 1 after UPLOAD_0
+ 14-12:   ? 0 0 0
+    11:   ? 0 initially, 1 after UPLOAD_0
+    10:   ?
+     9:   0xA0A1 result changed
+     8:   XSTATUS changed
+     7:   Busy, try to get status again
+     6:   ? 0
+   5-4:   Uninitialized (not ready), reset by 0xE0A5
+     3:   ?
+     2:   1 = buffer full (do not send data), 0 = buffer empty
+     1:   Paper out?
+     0:   Processing job
+
+  STATUS1
+
+  STATUS2
+
+  STATUS3
+
+  STATUS4
+
+  STATUS5
+
+  STATUS6
+
+ (to be done)
+
+1.4. Compression control commands
+---------------------------------
 
 All 0xD0xx commands have no reply. They all are one-way.
 
@@ -121,6 +202,7 @@ of others. Band size may vary. It seems that most printers may work with
 different band sizes. The algorithm is known completely.
 
 3.1. Data encoding
+------------------
 
 Hi-SCoA data are represented as a bit stream. Bits are written MSB first. The
 entire stream is always 4-byte aligned by adding 1s up to 32-bit boundary. On a
@@ -134,6 +216,7 @@ The above example becomes CE A8 BC BC.
 
 
 3.2. Command encoding
+---------------------
 
 Hi-SCoA bit stream consists of commands. Command opcodes are written using
 unary coding. There are 8 commands. Some commands have two subcommands which are
@@ -155,6 +238,7 @@ Bit sequence 11111111 used for alignment only and seems to be NOP.
 
 
 3.3. Number encoding
+--------------------
 
 LONGREP commands use number parameter that is encoded in Elias gamma coding.
 First, order is encoded by putting [order] 1s and one 0 to the stream. The order
@@ -187,8 +271,8 @@ The resulting value is given by:  prefix = 128 * ((1 << order) - 1 - N).
 
 Numbers of more than 512 are not encoded this way.
 
-
 3.4. Command description
+------------------------
 
 Hi-SCoA uses a significantly simplified and limited variant of LZ77 compression.
 In addition to the usual window it maintains a stash of no more than 16 bytes.
@@ -225,7 +309,7 @@ The stream consists of the following commands:
               11 - unknown/never seen
 
 Compression constants L0, L2, L3, L4, L5 and LINESIZE are sent to the
-decompressor in 0xD0A0 and 0xD0A4 commands (see section 1.3). L0 is always 0,
+decompressor in 0xD0A0 and 0xD0A4 commands (see section 1.4). L0 is always 0,
 other values are typically
  L2 = -7, L3 = 1, L4 = (not used), L5 = 4, LINESIZE = 592 or 608
  L2 = -5, L3 = 4, L4 = 384, L5 = 12, LINESIZE = 592