atfits-rs

Shared low-level cfitsio helpers for the at*-rs family of FITS tools (fitscube-rs, convolve-rs, …).

These are the project-agnostic mechanics that are easy to get subtly wrong against cfitsio, factored out so each tool shares one tested implementation:

PixelType / CubeElem — pixel precision (f32/f64, from BITPIX) and monomorphic section read/write.
keys — update-in-place keyword editing via ffuky* (cfitsio's ffpky* appends duplicate cards) plus convenience readers.
header — HeaderGeom (shape/BITPIX) and WCS find_target_axis.
image — image-HDU creation/resize and header-only copying, including create_cube_open: the single-open-handle pattern that writes the data unit once instead of a doubled zero-fill pass on close.
output_path — output-path construction.

Domain logic (beams, combine/extract, convolution, spectral specs) stays in the individual crates.

Install

[dependencies]
atfits-rs = "0.1"

Features

fitsio-src — compile cfitsio from source (needs only a C compiler). Off by default; consumers that build wheels enable it. Without it, the system cfitsio is linked.
```
atfits-rs = { version = "0.1", features = ["fitsio-src"] }
```

Example

Create a cube from a 2D template, stream planes via CubeElem section I/O, then read them back:

use atfits_rs::{CubeElem, create_cube_open, update_key_f64};
use fitsio::FitsFile;

let dims = vec![size, size, nchan]; // FITS axis order: NAXIS1, NAXIS2, NAXIS3
let plane_elems = size * size;

// Single open handle — writes the data unit once, no doubled zero-fill on close.
let mut out = create_cube_open(&template, &cube_path, -32, &dims)?;
update_key_f64(&mut out, "CRVAL3", 1.0e9)?; // ffuky* — updates in place

for c in 0..nchan {
    let plane: Vec<f32> = (0..plane_elems).map(|i| (c * 100 + i) as f32).collect();
    let start = c * plane_elems;
    f32::write_section(&mut out, start, start + plane_elems, &plane)?;
}

// Read back.
let mut f = FitsFile::open(cube_path.to_str().unwrap())?;
let all = f32::read_full(&mut f)?;
# Ok::<(), atfits_rs::AtfitsError>(())

Docs

Full API reference: https://docs.rs/atfits-rs. Build locally with:

cargo doc --no-deps --features fitsio-src --open

License