Marshalling

The wrapper is a single generic marshaller (src/runtime.mjs) driven by a generated descriptor: each C argument carries a kind that says how to convert it. This page documents those kinds — useful when reading the reference or the descriptor itself.

Input kinds

Kind	C type	JS type	Notes
iint	int, MMG5_int, enums	number	truncated to int32
idouble	double	number
istring	const char*	string \| null	copied into the heap for the call; null passes NULL
handle	MMG5_pMesh, MMG5_pSol (by value)	MeshHandle / SolHandle	the boxed struct pointer is dereferenced
handleref	MMG5_pMesh*, MMG5_pSol*	MeshHandle / SolHandle	the box itself is passed (init/free shims, loadAllSols, ...)
iarrayint	MMG5_int*, int* (bulk)	number[] \| Int32Array \| null	copied in; MMG reads the length from prior set*Size calls
iarraydouble	double* (bulk)	number[] \| Float64Array \| null	copied in

Output kinds

Kind	C type	JS result	Notes
oint	int*, MMG5_int*	number	scalar out-param
odouble	double*	number	scalar out-param
oarrayint	MMG5_int*, int*	Int32Array	buffer allocated by the wrapper, copied out
oarraydouble	double*	Float64Array	buffer allocated by the wrapper, copied out

Output array sizes come from one of:

• a trailing count argument you pass (e.g. getVertices(mesh, np) allocates 3*np doubles + np-sized int arrays; the count name is shown in the reference), or
• a fixed size from the C declaration (e.g. getAdjaTet fills listet[4], computeEigenv returns lambda[3] and vp[9]).

Return shape

• No outputs → the scalar return (libcode/int/double modes) or undefined.
• Outputs → an object keyed by the C parameter names; a meaningful scalar return is added as value.

const r = mmg2d.getAdjaVertices(h.mesh, ip);
// -> { value: count, lispoi: Int32Array(1024) } (first `count` entries valid)

Memory discipline

Every call is transactional: input copies and output buffers are malloced before the call and freed in a finally block; returned typed arrays are JS-owned copies, never views into WASM memory (safe against memory growth and later frees). The only persistent allocations are the 4-byte handle boxes created by init() and released by free().

Heap views and memory growth

The WASM memory starts at 64 MB and grows on demand (ALLOW_MEMORY_GROWTH); the marshaller re-fetches HEAP* views on every access, so growth never invalidates a call in progress.