# ReadStat for the web (johnmcm.com)

The WebAssembly module behind johnmcm.com's SPSS & SAS Viewer (/spss-viewer):
[ReadStat](https://github.com/WizardMac/ReadStat) by Evan Miller (MIT), at
commit `835b88c8c79d00fcd028c9cfa1226de2fd18be20`, with zlib (for .zsav),
behind a few plain C functions in `src/wrapper.c`.

The wrapper reads from memory through ReadStat's I/O hooks and keeps the data
column by column - numbers as doubles with a missing-value code (system,
user-defined, or the tag of a tagged missing value), text as UTF-8 with
offsets - and the metadata (variables, labels, formats, user-missing ranges,
value-label sets, notes) as JSON. It also reads a SAS format catalog
(.sas7bcat) for the value labels of a .sas7bdat.

`Dockerfile` builds it with the Emscripten image pinned by digest, compiling
ReadStat's readers only (no writers, tools or tests), unmodified. Run
`build.ps1` with Docker Desktop running; the module goes to
`frontend/vendor/local/readstat@1/`.

Licence notices: `LICENSE-ReadStat.txt` is ReadStat's LICENSE at the commit
above; `LICENSE-zlib.txt` is zlib's LICENSE at v1.3.2, the version the
Emscripten 6.0.10 zlib port builds. The built module in
`vendor/local/readstat@1/` carries no notice of its own, so these stand for it.