docs(core): document translations blob format

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mmilata/blob-doc
Martin Milata 3 months ago
parent 1cddc4cdb2
commit 5572b932ff

@ -18,6 +18,7 @@
- [SLIP-39](core/misc/slip0039.md)
- [Exceptions usage](core/misc/exceptions.md)
- [Memory fragmentation management](core/misc/fragmentation.md)
- [Translation data format](core/misc/translations.md)
- [DISC1](core/misc/disc1.md)
- [Legacy](legacy/index.md)
- [Firmware format](legacy/firmware-format.md)

@ -7,3 +7,4 @@ Topics that do not fit elsewhere:
- [Exceptions usage](exceptions.md)
- [Memory fragmentation management](fragmentation.md)
- [Running Trezor firmware on STM32F429I-DISC1](disc1.md)
- [Translation data format](translations.md)

@ -0,0 +1,74 @@
# Translations blob format
| offset | length | name | description | hash |
|-------:|-------------------:|-------------------|---------------------------------------------------|--------|
| 0x0000 | 6 | magic | blob magic `TRTR00` | |
| 0x0006 | 2 | container\_len | total length (up to padding) | |
| 0x0008 | 2 | header\_len | header length | |
| 0x000A | 2 | header\_magic | header magic `TR` | |
| 0x000C | 8 | language\_tag | BCP 47 language tag (e.g. `cs-CZ`, `en-US`, ...) | header |
| 0x0014 | 4 | version | 4 bytes of version (major, minor, patch, build) | header |
| 0x0018 | 2 | data\_len | length of the raw data, i.e. translations + fonts | header |
| 0x001A | 32 | data\_hash | SHA-256 hash of the data | header |
| 0x003A | `header_len - 48` | ignored | reserved for forward compatibility | header |
| ? | 2 | proof\_len | length of merkle proof and signature in bytes | |
| ? | 1 | proof\_count | number of merkle proof items following | |
| ? | `proof_count * 20` | proof | array of sha256 hashes | |
| ? | 1 | sig\_mask | CoSi signature mask | |
| ? | 64 | sig | ed25519 CoSi signature of merkle root | |
| ? | 2 | translations\_len | length of the translated strings | data |
| ? | `translations_len` | translations | translated string data | data |
| ? | 2 | fonts\_len | length of the font data | data |
| ? | `fonts_len` | fonts | font data | data |
| ? | ? | padding | `0xff` bytes padding to flash sector boundary | |
## Translation data
Offsets refer to the strings field, up to the following offset. First offset is
always 0, following offset must always be equal or greater (equal denotes empty
string).
| offset | length | name | description |
|-------:|-------------------------------------:|-------------------|--------------------------------------------------------|
| 0x0000 | 2 | count | number of offsets, excluding the sentinel |
| 0x0002 | 2 | offset[0] | offset of string id 0 in the `strings` field |
| ... | 2 | ... | |
| ? | 2 | offset[count - 1] | offset of string id `count - 1` in the `strings` field |
| ? | 2 | offset[count] | offset past the last element |
| ? | `translations_len - 2 * (count + 2)` | strings | concatenation of UTF-8 strings |
## Fonts
Ids must be in increasing order, offsets must be in non-decreasing order. First
offset must be 0.
| offset | length | name | description |
|-------:|-------------------------------------:|-------------------|-------------------------------------------------------------|
| 0x0000 | 2 | count | number of items in the offset table, excluding the sentinel |
| 0x0002 | 2 | id[0] | numeric id of the first font |
| 0x0004 | 2 | offset[0] | offset of the first font in the `fonts` field |
| ... | ... | ... | |
| ? | ? | id[count - 1] | numeric id of the last font |
| ? | ? | offset[count - 1] | offset of the last font in the `fonts` field |
| ? | ? | sentinel\_id | sentinel `0xffff` |
| ? | ? | sentinel\_offset | offset past the end of last element |
| | ? | fonts | concatenation of fonts, format defined in the next section |
| ? | 0-3 | padding | padding (any value) for alignment purposes |
## Font data
The format is exactly the same as the previous table, the only difference is
the interpretation of the payload.
| offset | length | name | description |
|-------:|-------------------------------------:|-------------------|-------------------------------------------------------------|
| 0x0000 | 2 | count | number of items in the offset table, excluding the sentinel |
| 0x0002 | 2 | id[0] | id (Unicode code point) of the first glyph |
| 0x0004 | 2 | offset[0] | offset of the first glyph in the `glyphs` field |
| ... | ... | ... | |
| ? | ? | id[count - 1] | id (Unicode code point) of the last glyph |
| ? | ? | offset[count - 1] | offset of the last glyph in the `glyphs` field |
| ? | ? | sentinel\_id | sentinel `0xffff` |
| ? | ? | sentinel\_offset | offset past the end of last element |
| | ? | glyphs | concatenation of glyph bitmaps |
| ? | 0-3 | padding | padding (any value) for alignment purposes |
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