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Placed explicit bit pattern table for MNIBBLES to avoid any doubts

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Joe Tsai 2015-10-22 09:11:04 -07:00
parent c996c06e8d
commit efeb59c4a2
1 changed files with 20 additions and 12 deletions
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32
docs/draft-alakuijala-brotli-07.nroff
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@ -217,7 +217,7 @@ In other words, if one were to print out the compressed data as
a sequence of bytes, starting with the first byte at the
*right* margin and proceeding to the *left*, with the most-
significant bit of each byte on the left as usual, one would be
able to parse the result from right-to-left, with fixed-width
able to parse the result from right to left, with fixed-width
elements in the correct MSB-to-LSB order and prefix codes in
bit-reversed order (i.e., with the first bit of the code in the
relative LSB position).
@ -570,9 +570,9 @@ Step 3 produces the following code values:
.KE
.fi
The above prefix code contains codes that are parsed from left-to-right
The above prefix code contains codes that are parsed from left to right
(with MSB on the left). All subsequent prefix codes in this
specification will have codes that are parsed from right-to-left
specification will have codes that are parsed from right to left
(with MSB on the right) as they actually appear in the compressed data.
.ti 0
@ -714,7 +714,7 @@ code lengths.
The bit lengths of the prefix code over the code length alphabet
are compressed with the following static prefix code (as it appears
in the compressed data, where the bits are parsed from right-to-left):
in the compressed data, where the bits are parsed from right to left):
.nf
.KS
@ -1399,7 +1399,7 @@ The stream header has only the following one field:
1-7 bits: WBITS, a value in the range 10 - 24, encoded with
the following variable length code (as it appears in
the compressed data, where the bits are parsed from
right-to-left):
right to left):
Value Bit Pattern
----- -----------
@ -1447,11 +1447,19 @@ the following:
of the compressed stream filled with zeros (if the
fill bits are not zero, then the stream should be
rejected as invalid)
2 bits: MNIBBLES - 4, # of nibbles to represent the uncompressed
length. If MNIBBLES is 7, then MNIBBLES is set to 0 and
the meta-block is empty, i.e. it does not generate any
uncompressed data. In this case, the rest of the
meta-block has the following format:
2 bits: MNIBBLES, # of nibbles to represent the uncompressed
length, encoded with the following fixed length code:
Value Bit Pattern
----- -----------
0 11
4 00
5 01
6 10
If MNIBBLES is 0, the meta-block is empty, i.e. it does
not generate any uncompressed data. In this case, the
rest of the meta-block has the following format:
1 bit: reserved, must be zero
@ -1467,7 +1475,7 @@ the following:
as invalid)
0 - 7 bits: fill bits until the next byte boundary,
must be all zeros
must be all zeros
MSKIPLEN bytes of metadata, not part of the
uncompressed data or the sliding window
@ -1488,7 +1496,7 @@ the following:
1-11 bits: NBLTYPESL, # of literal block types, encoded with
the following variable length code (as it appears in
the compressed data, where the bits are parsed from
right-to-left, so 0110111 has the value 12):
right to left, so 0110111 has the value 12):
Value Bit Pattern
----- -----------