tensor4all-capi

tensor4all-capi

C-compatible FFI interface to the tensor4all Rust library, focused on the minimal Julia-facing surface.

Features

• Index API: Immutable index handles with constructor/getter-only access
• Tensor API: Dense, diagonal, and structured f64 / Complex64 construction, payload export, dense export, and contraction
• TreeTN API: General tree tensor network accessors and core operations
• QTT layout API: Canonical binary QTT layout descriptors for transform materialization
• Generated C header: include/tensor4all_capi.h for downstream bindings
• Error handling: StatusCode + out constructors/clones plus t4a_last_error_message
• Panic safety: All exported functions catch Rust panics at the FFI boundary

API Conventions

• Opaque pointers with lifecycle management (*_new(..., out), *_release, *_clone(..., out))
• Status codes: T4A_SUCCESS, T4A_NULL_POINTER, T4A_INVALID_ARGUMENT, etc.
• Column-major data layout for dense logical tensor data and compact payload buffers
• Complex buffers use interleaved doubles: [re, im, re, im, ...]

Example (C)

/* Create a tagged index with explicit plev. */
struct t4a_index *idx = NULL;
t4a_index_new(2, "Site", 0, &idx);

/* Construct a dense tensor in column-major order. */
double data[] = {1.0, 2.0};
struct t4a_tensor *tensor = NULL;
const struct t4a_index *indices[] = {idx};
t4a_tensor_new_dense_f64(1, indices, data, 2, &tensor);

/* Release objects */
t4a_tensor_release(tensor);
t4a_index_release(idx);

Regenerating the Header

mkdir -p crates/tensor4all-capi/include
cbindgen crates/tensor4all-capi \
  --config crates/tensor4all-capi/cbindgen.toml \
  --output crates/tensor4all-capi/include/tensor4all_capi.h

License

MIT License