RFC 8878, "Zstandard Compression and the 'application/zstd' Media Type", February 2021

Errata ID: 8085
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Nianqi Tang
Date Reported: 2024-08-19

Section 3.1.1.5 says:

   +=======+==========+===========+===========+===========+============+
   |offset_|literals_ | Repeated_ | Repeated_ | Repeated_ |Comment     |
   | value |  length  |  Offset1  |  Offset2  |  Offset3  |            |
   +=======+==========+===========+===========+===========+============+
   |       |          |     1     |     4     |     8     |starting    |
   |       |          |           |           |           |values      |
   +-------+----------+-----------+-----------+-----------+------------+
   |   1114|    11    |    1111   |     1     |     4     |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |      1|    22    |    1111   |     1     |     4     |repeat 1; no|
   |       |          |           |           |           |change      |
   +-------+----------+-----------+-----------+-----------+------------+
   |   2225|    22    |    2222   |    1111   |     1     |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |   1114|   111    |    1111   |    2222   |    1111   |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |   3336|    33    |    3333   |    1111   |    2222   |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |      2|    22    |    1111   |    3333   |    2222   |repeat 2;   |
   |       |          |           |           |           |swap 1 & 2  |
   +-------+----------+-----------+-----------+-----------+------------+
   |      3|    33    |    2222   |    1111   |    3333   |repeat 3;   |
   |       |          |           |           |           |rotate 3 to |
   |       |          |           |           |           |1           |
   +-------+----------+-----------+-----------+-----------+------------+
   |      1|    0     |    2221   |    2222   |    1111   |insert      |
   |       |          |           |           |           |resolved    |
   |       |          |           |           |           |offset      |
   +-------+----------+-----------+-----------+-----------+------------+
   |      1|    0     |    2222   |    2221   |    3333   |repeat 2    |
   +-------+----------+-----------+-----------+-----------+------------+

It should say:

   +=======+==========+===========+===========+===========+============+
   |offset_|literals_ | Repeated_ | Repeated_ | Repeated_ |Comment     |
   | value |  length  |  Offset1  |  Offset2  |  Offset3  |            |
   +=======+==========+===========+===========+===========+============+
   |       |          |     1     |     4     |     8     |starting    |
   |       |          |           |           |           |values      |
   +-------+----------+-----------+-----------+-----------+------------+
   |   1114|    11    |    1111   |     1     |     4     |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |      1|    22    |    1111   |     1     |     4     |repeat 1; no|
   |       |          |           |           |           |change      |
   +-------+----------+-----------+-----------+-----------+------------+
   |   2225|    22    |    2222   |    1111   |     1     |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |   1114|   111    |    1111   |    2222   |    1111   |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |   3336|    33    |    3333   |    1111   |    2222   |non-repeat  |
   +-------+----------+-----------+-----------+-----------+------------+
   |      2|    22    |    1111   |    3333   |    2222   |repeat 2;   |
   |       |          |           |           |           |swap 1 & 2  |
   +-------+----------+-----------+-----------+-----------+------------+
   |      3|    33    |    2222   |    1111   |    3333   |repeat 3;   |
   |       |          |           |           |           |rotate 3 to |
   |       |          |           |           |           |1           |
   +-------+----------+-----------+-----------+-----------+------------+
   |      3|    0     |    2221   |    2222   |    1111   |insert      |
   |       |          |           |           |           |resolved    |
   |       |          |           |           |           |offset      |
   +-------+----------+-----------+-----------+-----------+------------+
   |      1|    0     |    2222   |    2221   |    1111   |repeat 2    |
   +-------+----------+-----------+-----------+-----------+------------+

Notes:

According to the description in 3.1.1.5, an offset value 1 with literal length 0 shall use Repeated Offset 2. However, in the last row of the example table, this is not the case. Since the second-to-last row has no "3333" value, I believe that the fifth column in the last row should be "1111".

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