mana: improve offset_ptr_t and related code

src/internal/mana_c_api.h

@@ -15,18 +15,31 @@ typedef enum
     mana_uint8,
     mana_sint8,
     mana_uint16,
+    mana_sint16,
     mana_uint32,
+    mana_sint32,
     mana_uint64,
+    mana_sint64,
     mana_float,
     mana_double,
 } mana_data_type_t;
 
+// Offset based pointer. Allows to memcpy() structures with these pointers
+// inside as long as the range covered by the pointers is also copied.
+//
+// Raw pointer value is '&ptr + offset'. nullptr is defined as offset=1.
+// => Cannot point to the first byte of the struct itself but that's fine.
+// Do not create temporaries of these. The offset will then be relative to the
+// temporary on the stack! Do not copy these unless you copy the full memory
+// range so that the offset_ptr_t in the new location stays valid.
 typedef struct
 {
     mana_data_type_t data_type;
     ptrdiff_t offset;
 } mana_offset_ptr_t;
 
+// Typed offset pointer based array. Stores the array size in bytes instead of
+// elements to allow storing any type using mana_custom.
 typedef struct
 {
     mana_offset_ptr_t ptr;

src/internal/mana_lib.hpp

@@ -16,8 +16,11 @@
 namespace mesytec::mnode::mana
 {
 
+inline bool is_null(const mana_offset_ptr_t &ptr) { return ptr.offset == 1; }
+
 namespace detail
 {
+
 inline void set(mana_offset_ptr_t &ptr, void *p)
 {
     assert(p != reinterpret_cast<u8 *>(&ptr) + 1);
@@ -33,31 +36,6 @@ inline void set(mana_offset_ptr_t &ptr, void *p)
         ptr.offset = 1;
     }
 }
-} // namespace detail
-
-inline bool is_null(const mana_offset_ptr_t &ptr) { return ptr.offset == 1; }
-
-inline void *get(mana_offset_ptr_t &ptr)
-{
-    return is_null(ptr) ? nullptr : reinterpret_cast<u8 *>(&ptr) + ptr.offset;
-}
-
-template <typename T> T *get(mana_offset_ptr_t &ptr); // to catch unsupported types
-
-template <typename T> T *get_(mana_offset_ptr_t &ptr, mana_data_type_t expected)
-{
-    if (ptr.data_type != expected)
-        return nullptr;
-
-    return reinterpret_cast<T *>(get(ptr));
-}
-
-template <> u32 *get(mana_offset_ptr_t &ptr) { return get_<u32>(ptr, mana_uint32); }
-template <> u64 *get(mana_offset_ptr_t &ptr) { return get_<u64>(ptr, mana_uint64); }
-template <> s8 *get(mana_offset_ptr_t &ptr) { return get_<s8>(ptr, mana_sint8); }
-template <> char *get(mana_offset_ptr_t &ptr) { return get_<char>(ptr, mana_sint8); }
-template <> float *get(mana_offset_ptr_t &ptr) { return get_<float>(ptr, mana_float); }
-template <> double *get(mana_offset_ptr_t &ptr) { return get_<double>(ptr, mana_double); }
 
 inline void set(mana_offset_ptr_t &ptr, mana_data_type_t data_type, void *p)
 {
@@ -65,13 +43,47 @@ inline void set(mana_offset_ptr_t &ptr, mana_data_type_t data_type, void *p)
     detail::set(ptr, p);
 }
 
-inline void set(mana_offset_ptr_t &ptr, std::nullptr_t) { set(ptr, mana_uint32, nullptr); }
+inline void *get(mana_offset_ptr_t &ptr)
-inline void set(mana_offset_ptr_t &ptr, u32 *p) { set(ptr, mana_uint32, p); }
+{
-inline void set(mana_offset_ptr_t &ptr, u64 *p) { set(ptr, mana_uint64, p); }
+    return is_null(ptr) ? nullptr : reinterpret_cast<u8 *>(&ptr) + ptr.offset;
-inline void set(mana_offset_ptr_t &ptr, s8 *p) { set(ptr, mana_sint8, p); }
+}
-inline void set(mana_offset_ptr_t &ptr, char *p) { set(ptr, mana_sint8, p); }
+
-inline void set(mana_offset_ptr_t &ptr, float *p) { set(ptr, mana_float, p); }
+template <typename T> T *get(mana_offset_ptr_t &ptr, mana_data_type_t expected)
-inline void set(mana_offset_ptr_t &ptr, double *p) { set(ptr, mana_double, p); }
+{
+    if (ptr.data_type != expected)
+        return nullptr;
+
+    return reinterpret_cast<T *>(get(ptr));
+}
+
+} // namespace detail
+
+template <typename T> T *get(mana_offset_ptr_t &ptr); // to catch unsupported types
+
+template <> u32 *get(mana_offset_ptr_t &ptr) { return detail::get<u32>(ptr, mana_uint32); }
+template <> u64 *get(mana_offset_ptr_t &ptr) { return detail::get<u64>(ptr, mana_uint64); }
+template <> s8 *get(mana_offset_ptr_t &ptr) { return detail::get<s8>(ptr, mana_sint8); }
+template <> char *get(mana_offset_ptr_t &ptr) { return detail::get<char>(ptr, mana_sint8); }
+template <> float *get(mana_offset_ptr_t &ptr) { return detail::get<float>(ptr, mana_float); }
+template <> double *get(mana_offset_ptr_t &ptr) { return detail::get<double>(ptr, mana_double); }
+
+// To make 'set(ptr, nullptr)' work.
+inline void set(mana_offset_ptr_t &ptr, std::nullptr_t)
+{
+    detail::set(ptr, ptr.data_type, nullptr);
+}
+
+inline void set(mana_offset_ptr_t &ptr, u8 *p) { detail::set(ptr, mana_uint8, p); }
+inline void set(mana_offset_ptr_t &ptr, s8 *p) { detail::set(ptr, mana_sint8, p); }
+inline void set(mana_offset_ptr_t &ptr, char *p) { detail::set(ptr, mana_sint8, p); }
+inline void set(mana_offset_ptr_t &ptr, u16 *p) { detail::set(ptr, mana_uint16, p); }
+inline void set(mana_offset_ptr_t &ptr, s16 *p) { detail::set(ptr, mana_sint16, p); }
+inline void set(mana_offset_ptr_t &ptr, u32 *p) { detail::set(ptr, mana_uint32, p); }
+inline void set(mana_offset_ptr_t &ptr, s32 *p) { detail::set(ptr, mana_sint32, p); }
+inline void set(mana_offset_ptr_t &ptr, u64 *p) { detail::set(ptr, mana_uint64, p); }
+inline void set(mana_offset_ptr_t &ptr, s64 *p) { detail::set(ptr, mana_sint64, p); }
+inline void set(mana_offset_ptr_t &ptr, float *p) { detail::set(ptr, mana_float, p); }
+inline void set(mana_offset_ptr_t &ptr, double *p) { detail::set(ptr, mana_double, p); }
 
 template <typename T>
 T *push_offset_array(mana::Arena &arena, mana_offset_array_t &dest, size_t size)
@@ -86,7 +98,7 @@ template <typename T>
 T *push_typed_offset_array(mana::Arena &arena, mana_offset_array_t &dest, size_t size)
 {
     T *ptr = arena.push_t<T>(size);
-    mana::set(dest.ptr, ptr);
+    set(dest.ptr, ptr);
     dest.size_bytes = size * sizeof(T);
     return ptr;
 }
@@ -98,7 +110,7 @@ template <typename T> size_t element_count(mana_offset_array_t &array)
 
 template <typename T> mvlc::util::span<T> get_span(mana_offset_array_t &array)
 {
-    auto ptr = reinterpret_cast<T *>(get(array.ptr));
+    auto ptr = get<T>(array.ptr);
     auto size = element_count<T>(array);
     return {ptr, size};
 }