/* * Copyright © 2007,2008,2009,2010 Red Hat, Inc. * Copyright © 2012,2018 Google, Inc. * * This is part of HarfBuzz, a text shaping library. * * Permission is hereby granted, without written agreement and without * license or royalty fees, to use, copy, modify, and distribute this * software and its documentation for any purpose, provided that the * above copyright notice and the following two paragraphs appear in * all copies of this software. * * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. * * Red Hat Author(s): Behdad Esfahbod * Google Author(s): Behdad Esfahbod */ #ifndef HB_MACHINERY_HH #define HB_MACHINERY_HH #include "hb.hh" #include "hb-blob.hh" #include "hb-dispatch.hh" #include "hb-sanitize.hh" #include "hb-serialize.hh" /* * Casts */ /* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory * location pointed to by P plus Ofs bytes. */ template<typename Type> static inline const Type& StructAtOffset(const void *P, unsigned int offset) { return * reinterpret_cast<const Type*> ((const char *) P + offset); } template<typename Type> static inline Type& StructAtOffset(void *P, unsigned int offset) { return * reinterpret_cast<Type*> ((char *) P + offset); } template<typename Type> static inline const Type& StructAtOffsetUnaligned(const void *P, unsigned int offset) { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wcast-align" return * reinterpret_cast<const Type*> ((const char *) P + offset); #pragma GCC diagnostic pop } template<typename Type> static inline Type& StructAtOffsetUnaligned(void *P, unsigned int offset) { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wcast-align" return * reinterpret_cast<Type*> ((char *) P + offset); #pragma GCC diagnostic pop } /* StructAfter<T>(X) returns the struct T& that is placed after X. * Works with X of variable size also. X must implement get_size() */ template<typename Type, typename TObject> static inline const Type& StructAfter(const TObject &X) { return StructAtOffset<Type>(&X, X.get_size()); } template<typename Type, typename TObject> static inline Type& StructAfter(TObject &X) { return StructAtOffset<Type>(&X, X.get_size()); } /* * Size checking */ /* Size signifying variable-sized array */ #ifndef HB_VAR_ARRAY #define HB_VAR_ARRAY 1 #endif /* Check _assertion in a method environment */ #define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \ void _instance_assertion_on_line_##_line () const \ { static_assert ((_assertion), ""); } # define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion) # define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion) /* Check that _code compiles in a method environment */ #define _DEFINE_COMPILES_ASSERTION1(_line, _code) \ void _compiles_assertion_on_line_##_line () const \ { _code; } # define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code) # define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code) #define DEFINE_SIZE_STATIC(size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)) \ unsigned int get_size () const { return (size); } \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size); \ static constexpr unsigned static_size = (size) #define DEFINE_SIZE_UNION(size, _member) \ DEFINE_COMPILES_ASSERTION ((void) this->u._member.static_size) \ DEFINE_INSTANCE_ASSERTION (sizeof(this->u._member) == (size)) \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_MIN(size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_UNBOUNDED(size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)) \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_ARRAY(size, array) \ DEFINE_COMPILES_ASSERTION ((void) (array)[0].static_size) \ DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + (HB_VAR_ARRAY+0) * sizeof ((array)[0])) \ static constexpr unsigned null_size = (size); \ static constexpr unsigned min_size = (size) #define DEFINE_SIZE_ARRAY_SIZED(size, array) \ unsigned int get_size () const { return (size - (array).min_size + (array).get_size ()); } \ DEFINE_SIZE_ARRAY(size, array) /* * Lazy loaders. */ template <typename Data, unsigned int WheresData> struct hb_data_wrapper_t { static_assert (WheresData > 0, ""); Data * get_data () const { return *(((Data **) (void *) this) - WheresData); } bool is_inert () const { return !get_data (); } template <typename Stored, typename Subclass> Stored * call_create () const { return Subclass::create (get_data ()); } }; template <> struct hb_data_wrapper_t<void, 0> { bool is_inert () const { return false; } template <typename Stored, typename Funcs> Stored * call_create () const { return Funcs::create (); } }; template <typename T1, typename T2> struct hb_non_void_t { typedef T1 value; }; template <typename T2> struct hb_non_void_t<void, T2> { typedef T2 value; }; template <typename Returned, typename Subclass = void, typename Data = void, unsigned int WheresData = 0, typename Stored = Returned> struct hb_lazy_loader_t : hb_data_wrapper_t<Data, WheresData> { typedef typename hb_non_void_t<Subclass, hb_lazy_loader_t<Returned,Subclass,Data,WheresData,Stored> >::value Funcs; void init0 () {} /* Init, when memory is already set to 0. No-op for us. */ void init () { instance.set_relaxed (nullptr); } void fini () { do_destroy (instance.get ()); } void free_instance () { retry: Stored *p = instance.get (); if (unlikely (p && !cmpexch (p, nullptr))) goto retry; do_destroy (p); } static void do_destroy (Stored *p) { if (p && p != const_cast<Stored *> (Funcs::get_null ())) Funcs::destroy (p); } const Returned * operator -> () const { return get (); } const Returned & operator * () const { return *get (); } explicit operator bool () const { return get_stored () != Funcs::get_null (); } template <typename C> operator const C * () const { return get (); } Stored * get_stored () const { retry: Stored *p = this->instance.get (); if (unlikely (!p)) { if (unlikely (this->is_inert ())) return const_cast<Stored *> (Funcs::get_null ()); p = this->template call_create<Stored, Funcs> (); if (unlikely (!p)) p = const_cast<Stored *> (Funcs::get_null ()); if (unlikely (!cmpexch (nullptr, p))) { do_destroy (p); goto retry; } } return p; } Stored * get_stored_relaxed () const { return this->instance.get_relaxed (); } bool cmpexch (Stored *current, Stored *value) const { /* This *must* be called when there are no other threads accessing. */ return this->instance.cmpexch (current, value); } const Returned * get () const { return Funcs::convert (get_stored ()); } const Returned * get_relaxed () const { return Funcs::convert (get_stored_relaxed ()); } Returned * get_unconst () const { return const_cast<Returned *> (Funcs::convert (get_stored ())); } /* To be possibly overloaded by subclasses. */ static Returned* convert (Stored *p) { return p; } /* By default null/init/fini the object. */ static const Stored* get_null () { return &Null (Stored); } static Stored *create (Data *data) { Stored *p = (Stored *) hb_calloc (1, sizeof (Stored)); if (likely (p)) p->init (data); return p; } static Stored *create () { Stored *p = (Stored *) hb_calloc (1, sizeof (Stored)); if (likely (p)) p->init (); return p; } static void destroy (Stored *p) { p->fini (); hb_free (p); } // private: /* Must only have one pointer. */ hb_atomic_ptr_t<Stored *> instance; }; /* Specializations. */ template <typename T, unsigned int WheresFace> struct hb_face_lazy_loader_t : hb_lazy_loader_t<T, hb_face_lazy_loader_t<T, WheresFace>, hb_face_t, WheresFace> {}; template <typename T, unsigned int WheresFace> struct hb_table_lazy_loader_t : hb_lazy_loader_t<T, hb_table_lazy_loader_t<T, WheresFace>, hb_face_t, WheresFace, hb_blob_t> { static hb_blob_t *create (hb_face_t *face) { return hb_sanitize_context_t ().reference_table<T> (face); } static void destroy (hb_blob_t *p) { hb_blob_destroy (p); } static const hb_blob_t *get_null () { return hb_blob_get_empty (); } static const T* convert (const hb_blob_t *blob) { return blob->as<T> (); } hb_blob_t* get_blob () const { return this->get_stored (); } }; template <typename Subclass> struct hb_font_funcs_lazy_loader_t : hb_lazy_loader_t<hb_font_funcs_t, Subclass> { static void destroy (hb_font_funcs_t *p) { hb_font_funcs_destroy (p); } static const hb_font_funcs_t *get_null () { return hb_font_funcs_get_empty (); } }; template <typename Subclass> struct hb_unicode_funcs_lazy_loader_t : hb_lazy_loader_t<hb_unicode_funcs_t, Subclass> { static void destroy (hb_unicode_funcs_t *p) { hb_unicode_funcs_destroy (p); } static const hb_unicode_funcs_t *get_null () { return hb_unicode_funcs_get_empty (); } }; #endif /* HB_MACHINERY_HH */