C FFI

C-compatible bindings live in molex::ffi (source: src/ffi.rs). These expose COORDS conversion functions for consumption from C, C++, Swift, or any language with C FFI support.

Result type

typedef struct {
    const uint8_t *data;    // output bytes, or NULL on error
    size_t len;             // data length
    size_t data_len;        // allocated capacity
    const char *error;      // error string, or NULL on success
} CoordsResult;

Functions

pdb_to_coords_bytes

Parse a PDB string into COORDS binary format.

CoordsResult pdb_to_coords_bytes(const char *pdb_ptr, size_t pdb_len);

coords_to_pdb

Convert COORDS binary to a PDB-format string. Returns a null-terminated C string. The caller must free the string with coords_free_string.

const char *coords_to_pdb(const uint8_t *coords_ptr, size_t coords_len, size_t *out_len);

coords_from_coords

Deserialize and re-serialize COORDS bytes (round-trip validation).

CoordsResult coords_from_coords(const uint8_t *coords_ptr, size_t coords_len);

coords_from_backbone

Build COORDS from backbone positions. Currently returns an error (not yet implemented).

CoordsResult coords_from_backbone(
    const float *positions,
    size_t num_res,
    const char *sequence,
    const int32_t *chain_breaks,
    size_t chain_break_count
);

Memory management

void coords_free_result(const CoordsResult *result);
void coords_free_string(const char *s);

All pointers returned by FFI functions must be freed using the corresponding free function. Do not use free() directly.