wai/wai-web/src/neural_int.rs

@@ -133,3 +133,42 @@ pub fn det_build_index(sigma_q: i64, edges_q: &[i64]) -> usize {
 pub fn blake3_hex(bytes: &[u8]) -> String {
     blake3::hash(bytes).to_hex().to_string()
 }
+
+// ---- JPEG-AI byte-exact mANS: the ISO entropy decode, in the browser ----
+
+/// Decode the ISO/IEC 6048 JPEG-AI **mANS** entropy stream in the browser, byte-exact —
+/// the same pure-i64 decoder native sinks run (`wai::jpegai_mans`), compiled to wasm32.
+///
+/// A **reproduction vector**: given the reference stream `mem`, the integer PMF rows
+/// (`pmf_flat`, `n_rows × 256` row-major), the per-distribution `bounds`, and the
+/// per-position `sigma` distribution indices + coded-position `masks` (0/1), it returns
+/// the decoded residual symbols. The decode is entirely integer, so the symbols — and
+/// their hash — are identical on every machine. The page hashes them and compares to the
+/// digest the native reference produced; a byte-identical match across host + browser is
+/// the whole point of the integer-entropy contract. This is the same stream and
+/// symbols the cross-architecture byte-equality matrix checks natively.
+#[wasm_bindgen(js_name = decodeJpegAiMans)]
+pub fn decode_jpegai_mans(
+    mem: &[u8],
+    pmf_flat: &[i64],
+    bounds: &[u8],
+    sigma: &[u8],
+    masks: &[u8],
+) -> Vec<i16> {
+    use wai::jpegai_mans::{build_decode_transitions, cdf_from_pmf, MansDecoder};
+    const WIDTH: usize = 256;
+    let rows = pmf_flat.len() / WIDTH;
+    let pmf: Vec<Vec<i64>> =
+        (0..rows).map(|r| pmf_flat[r * WIDTH..(r + 1) * WIDTH].to_vec()).collect();
+    let flat: Vec<u32> = build_decode_transitions(&pmf, &cdf_from_pmf(&pmf))
+        .iter()
+        .flatten()
+        .copied()
+        .collect();
+    let mut dec = MansDecoder::new(mem, &[mem.len() as u32]);
+    dec.set_sgm_transitions(&flat, bounds);
+    let masks_b: Vec<bool> = masks.iter().map(|&m| m != 0).collect();
+    let mut out = vec![0i16; sigma.len()];
+    dec.decode_sgm(sigma, &mut out, &masks_b);
+    out
+}