Add VM user data

include/lauf/runtime/process.h

@@ -38,6 +38,8 @@ typedef enum lauf_runtime_fiber_status
 //=== queries ===//
 /// The VM that is executing the program.
 lauf_vm* lauf_runtime_get_vm(lauf_runtime_process* process);
+/// The user data of the VM that is executing the program.
+void* lauf_runtime_get_vm_user_data(lauf_runtime_process* process);
 
 /// The program that is running.
 const lauf_asm_program* lauf_runtime_get_program(lauf_runtime_process* process);

include/lauf/vm.h

@@ -50,6 +50,9 @@ typedef struct lauf_vm_options
     lauf_vm_panic_handler panic_handler;
     /// The allocator used when the program wants to allocate heap memory.
     lauf_vm_allocator allocator;
+
+    // Arbitrary user data.
+    void* user_data;
 } lauf_vm_options;
 
 extern const lauf_vm_options lauf_default_vm_options;
@@ -68,6 +71,11 @@ lauf_vm_allocator lauf_vm_set_allocator(lauf_vm* vm, lauf_vm_allocator a);
 /// Returns the allocator.
 lauf_vm_allocator lauf_vm_get_allocator(lauf_vm* vm);
 
+/// Exchanges the user data.
+void* lauf_vm_set_user_data(lauf_vm* vm, void* user_data);
+/// Returns the user data.
+void* lauf_vm_get_user_data(lauf_vm* vm);
+
 /// Starts a new process for the program.
 ///
 /// It creates a fiber for the entry function and turns it into the current fiber,

src/lauf/runtime/process.cpp

@@ -106,6 +106,11 @@ lauf_vm* lauf_runtime_get_vm(lauf_runtime_process* process)
     return process->vm;
 }
 
+void* lauf_runtime_get_vm_user_data(lauf_runtime_process* process)
+{
+    return process->vm->user_data;
+}
+
 const lauf_asm_program* lauf_runtime_get_program(lauf_runtime_process* process)
 {
     return &process->program;

src/lauf/vm.cpp

@@ -20,7 +20,7 @@ const lauf_vm_allocator lauf_vm_malloc_allocator
        [](void*, void* memory, size_t) { std::free(memory); }};
 
 const lauf_vm_options lauf_default_vm_options = [] {
-    lauf_vm_options result;
+    lauf_vm_options result{};
 
     result.initial_vstack_size_in_elements = 1024ull;
     result.max_vstack_size_in_elements     = 16 * 1024ull;
@@ -38,6 +38,8 @@ const lauf_vm_options lauf_default_vm_options = [] {
 
     result.allocator = lauf_vm_malloc_allocator;
 
+    result.user_data = nullptr;
+
     return result;
 }();
 
@@ -70,6 +72,18 @@ lauf_vm_allocator lauf_vm_get_allocator(lauf_vm* vm)
     return vm->heap_allocator;
 }
 
+void* lauf_vm_set_user_data(lauf_vm* vm, void* user_data)
+{
+    auto old      = vm->user_data;
+    vm->user_data = user_data;
+    return old;
+}
+
+void* lauf_vm_get_user_data(lauf_vm* vm)
+{
+    return vm->user_data;
+}
+
 lauf_runtime_process* lauf_vm_start_process(lauf_vm* vm, const lauf_asm_program* program)
 {
     auto fn = program->_entry;

src/lauf/vm.hpp

@@ -26,14 +26,16 @@ struct lauf_vm : lauf::intrinsic_arena<lauf_vm>
     std::size_t step_limit;
 
     lauf_runtime_process process;
+    void*                user_data;
 
     explicit lauf_vm(lauf::arena_key key, lauf_vm_options options)
     : lauf::intrinsic_arena<lauf_vm>(key), panic_handler(options.panic_handler),
       heap_allocator(options.allocator),
       initial_vstack_size(options.initial_vstack_size_in_elements),
       max_vstack_size(options.max_vstack_size_in_elements),
       initial_cstack_size(options.initial_cstack_size_in_bytes),
-      max_cstack_size(options.max_cstack_size_in_bytes), step_limit(options.step_limit)
+      max_cstack_size(options.max_cstack_size_in_bytes), step_limit(options.step_limit),
+      user_data(options.user_data)
     {}
 
     ~lauf_vm()