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/*
* 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"
/*
* 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.
*
* The lazy-loaders are thread-safe pointer-like objects that create their
* instead on-demand. They also support access to a "data" object that is
* necessary for creating their instance. The data object, if specified,
* is accessed via pointer math, located at a location before the position
* of the loader itself. This avoids having to store a pointer to data
* for every lazy-loader. Multiple lazy-loaders can access the same data.
*/
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;
hb_lazy_loader_t () = default;
hb_lazy_loader_t (const hb_lazy_loader_t &other) = delete;
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_acquire ()); init (); }
void free_instance ()
{
retry:
Stored *p = instance.get_acquire ();
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 (); }
template <typename U = Returned, hb_enable_if (!hb_is_same (U, void))>
const U & 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_acquire ();
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 function can only be safely called directly if no
* other thread is 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 = new (p) Stored (data);
return p;
}
static Stored *create ()
{
Stored *p = (Stored *) hb_calloc (1, sizeof (Stored));
if (likely (p))
p = new (p) Stored ();
return p;
}
static void destroy (Stored *p)
{
p->~Stored ();
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>
{
// Hack; have them here for API parity with hb_table_lazy_loader_t
hb_blob_t *get_blob () { return this->get ()->get_blob (); }
};
template <typename T, unsigned int WheresFace, bool core=false>
struct hb_table_lazy_loader_t : hb_lazy_loader_t<T,
hb_table_lazy_loader_t<T, WheresFace, core>,
hb_face_t, WheresFace,
hb_blob_t>
{
static hb_blob_t *create (hb_face_t *face)
{
hb_sanitize_context_t c;
if (core)
c.set_num_glyphs (0); // So we don't recurse ad infinitum, or doesn't need num_glyphs
return c.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 (); }
};
#define HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T(Type) \
template <typename Subclass> \
struct hb_##Type##_funcs_lazy_loader_t : hb_lazy_loader_t<hb_##Type##_funcs_t, Subclass> \
{ \
static void destroy (hb_##Type##_funcs_t *p) \
{ hb_##Type##_funcs_destroy (p); } \
static const hb_##Type##_funcs_t *get_null () \
{ return hb_##Type##_funcs_get_empty (); } \
}
HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (font);
HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (unicode);
HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (draw);
HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T (paint);
#undef HB_DEFINE_TYPE_FUNCS_LAZY_LOADER_T
#endif /* HB_MACHINERY_HH */