bool ship_load_data(const uint8_t* data, size_t len){

	// (uint8_t)*data is the maximum module count
	// (uint8_t*)data+1 is the ptr to the start of module data
	// len - 1 is the length of the module data
	// (len - 1) / sizeof(shipmodule_t) is the number of modules

	uint8_t module_count = (len - 1) / sizeof(shipmodule_t);
	uint8_t *modules = alloca(len-1);
	if(!modules) return false;
	...
	rest of the code
}