45 lines
1.7 KiB
Markdown
45 lines
1.7 KiB
Markdown
# `puz` format specifications
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## Foreword
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The AcrossLite format is not publicly documented. This specification was built by probing dozens of `puz` files and is a living document that will be update as new sections of the format are figured out.
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## Format
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The `puz` file format is a binary blob with `latin1` encoding.
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### Header
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The header section is consistently 52 bytes long.
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|Label|Start offset|Length (bytes)|Notes|
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|:----|:----|:----|:----|
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|Puzzle width|`0x2c`|1|Self-explanatory.|
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|Puzzle height|`0x2d`|1|Self-explanatory.|
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### Body
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The body of the puzzle starts consistently at offset `0x34`.
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|Label|Start offset|Length (bytes)|Notes|
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|:----|:----|:----|:----|
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|Solution|`0x34`|`width * height`|Based on the height and width, the solution is written out as ASCII.|
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|Layout|(end of the solution)|`width * height`|The layout of the grid is defined with `.` used as "empty cell"|
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|Clues|(end of the layout)|???|`NUL` separated strings containing each of the clues, not numbered.|
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#### Clue numbering and tagging
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The file doesn't contain information in which cells correspond to across and down clues. This information can be derived from the puzzle layout and the set of clues available:
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```
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FOREACH cell IN grid:
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IF cell has a non-empty top neighbour
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THEN the cell is part of its top neighbour's down word
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ELSE the cell is part of the next available down word
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IF cell as a non-empty left neighbour
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THEN the cell is part of its left neighbour's across word
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ELSE the cell is part of the next available across word
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```
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By picking off clues from the across and down clue lists, assigning them using the algorithm above and numbering them as you go, you can build the correct cell <> clue mappings.
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