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/*
* Copyright © 2017 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.
*
* Google Author(s): Behdad Esfahbod
*/
#ifndef HB_AAT_LAYOUT_COMMON_PRIVATE_HH
#define HB_AAT_LAYOUT_COMMON_PRIVATE_HH
#include "hb-aat-layout-private.hh"
namespace AAT {
using namespace OT;
/*
* Binary Searching Tables
*/
struct BinSearchHeader
{
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this));
}
HBUINT16 unitSize; /* Size of a lookup unit for this search in bytes. */
HBUINT16 nUnits; /* Number of units of the preceding size to be searched. */
HBUINT16 searchRange; /* The value of unitSize times the largest power of 2
* that is less than or equal to the value of nUnits. */
HBUINT16 entrySelector; /* The log base 2 of the largest power of 2 less than
* or equal to the value of nUnits. */
HBUINT16 rangeShift; /* The value of unitSize times the difference of the
* value of nUnits minus the largest power of 2 less
* than or equal to the value of nUnits. */
public:
DEFINE_SIZE_STATIC (10);
};
template <typename Type>
struct BinSearchArrayOf
{
inline const Type& operator [] (unsigned int i) const
{
if (unlikely (i >= header.nUnits)) return Null(Type);
return StructAtOffset<Type> (bytes, i * header.unitSize);
}
inline Type& operator [] (unsigned int i)
{
return StructAtOffset<Type> (bytes, i * header.unitSize);
}
inline unsigned int get_size (void) const
{ return header.static_size + header.nUnits * header.unitSize; }
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
if (unlikely (!sanitize_shallow (c))) return_trace (false);
/* Note: for structs that do not reference other structs,
* we do not need to call their sanitize() as we already did
* a bound check on the aggregate array size. We just include
* a small unreachable expression to make sure the structs
* pointed to do have a simple sanitize(), ie. they do not
* reference other structs via offsets.
*/
(void) (false && StructAtOffset<Type> (bytes, 0).sanitize (c));
return_trace (true);
}
inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
if (unlikely (!sanitize_shallow (c))) return_trace (false);
unsigned int count = header.nUnits;
for (unsigned int i = 0; i < count; i++)
if (unlikely (!(*this)[i].sanitize (c, base)))
return_trace (false);
return_trace (true);
}
template <typename T>
inline const Type *bsearch (const T &key) const
{
unsigned int size = header.unitSize;
int min = 0, max = (int) header.nUnits - 1;
while (min <= max)
{
int mid = (min + max) / 2;
const Type *p = (const Type *) (((const char *) bytes) + (mid * size));
int c = p->cmp (key);
if (c < 0)
max = mid - 1;
else if (c > 0)
min = mid + 1;
else
return p;
}
return NULL;
}
private:
inline bool sanitize_shallow (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (header.sanitize (c) &&
Type::static_size >= header.unitSize &&
c->check_array (bytes, header.unitSize, header.nUnits));
}
protected:
BinSearchHeader header;
HBUINT8 bytes[VAR];
public:
DEFINE_SIZE_ARRAY (10, bytes);
};
/* TODO Move this to hb-open-type-private.hh and use it in ArrayOf, HeadlessArrayOf,
* and other places around the code base?? */
template <typename Type>
struct UnsizedArrayOf
{
inline const Type& operator [] (unsigned int i) const { return arrayZ[i]; }
inline Type& operator [] (unsigned int i) { return arrayZ[i]; }
inline bool sanitize (hb_sanitize_context_t *c, unsigned int count) const
{
TRACE_SANITIZE (this);
/* Note: for structs that do not reference other structs,
* we do not need to call their sanitize() as we already did
* a bound check on the aggregate array size. We just include
* a small unreachable expression to make sure the structs
* pointed to do have a simple sanitize(), ie. they do not
* reference other structs via offsets.
*/
(void) (false && count && arrayZ->sanitize (c));
return_trace (c->check_array (arrayZ, arrayZ[0].static_size, count));
}
protected:
Type arrayZ[VAR];
public:
DEFINE_SIZE_ARRAY (0, arrayZ);
};
/*
* Lookup Table
*/
template <typename T> struct Lookup;
template <typename T>
struct LookupFormat0
{
friend struct Lookup<T>;
private:
inline const T* get_value (hb_codepoint_t glyph_id, unsigned int num_glyphs) const
{
if (unlikely (glyph_id >= num_glyphs)) return nullptr;
return &arrayZ[glyph_id];
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (arrayZ.sanitize (c, c->num_glyphs));
}
protected:
HBUINT16 format; /* Format identifier--format = 0 */
UnsizedArrayOf<T>
arrayZ; /* Array of lookup values, indexed by glyph index. */
public:
DEFINE_SIZE_ARRAY (2, arrayZ);
};
template <typename T>
struct LookupSegmentSingle
{
inline int cmp (hb_codepoint_t g) const {
return g < first ? -1 : g <= last ? 0 : +1 ;
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && value.sanitize (c));
}
GlyphID last; /* Last GlyphID in this segment */
GlyphID first; /* First GlyphID in this segment */
T value; /* The lookup value (only one) */
public:
DEFINE_SIZE_STATIC (4 + sizeof (T));
};
template <typename T>
struct LookupFormat2
{
friend struct Lookup<T>;
private:
inline const T* get_value (hb_codepoint_t glyph_id) const
{
const LookupSegmentSingle<T> *v = segments.bsearch (glyph_id);
return v ? &v->value : nullptr;
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (segments.sanitize (c));
}
protected:
HBUINT16 format; /* Format identifier--format = 2 */
BinSearchArrayOf<LookupSegmentSingle<T> >
segments; /* The actual segments. These must already be sorted,
* according to the first word in each one (the last
* glyph in each segment). */
public:
DEFINE_SIZE_ARRAY (8, segments);
};
template <typename T>
struct LookupSegmentArray
{
inline const T* get_value (hb_codepoint_t glyph_id, const void *base) const
{
return first <= glyph_id && glyph_id <= last ? &(base+valuesZ)[glyph_id - first] : nullptr;
}
inline int cmp (hb_codepoint_t g) const {
return g < first ? -1 : g <= last ? 0 : +1 ;
}
inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) &&
first <= last &&
valuesZ.sanitize (c, base, last - first + 1));
}
GlyphID last; /* Last GlyphID in this segment */
GlyphID first; /* First GlyphID in this segment */
OffsetTo<UnsizedArrayOf<T> >
valuesZ; /* A 16-bit offset from the start of
* the table to the data. */
public:
DEFINE_SIZE_STATIC (6);
};
template <typename T>
struct LookupFormat4
{
friend struct Lookup<T>;
private:
inline const T* get_value (hb_codepoint_t glyph_id) const
{
const LookupSegmentArray<T> *v = segments.bsearch (glyph_id);
return v ? v->get_value (glyph_id, this) : nullptr;
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (segments.sanitize (c, this));
}
protected:
HBUINT16 format; /* Format identifier--format = 2 */
BinSearchArrayOf<LookupSegmentArray<T> >
segments; /* The actual segments. These must already be sorted,
* according to the first word in each one (the last
* glyph in each segment). */
public:
DEFINE_SIZE_ARRAY (8, segments);
};
template <typename T>
struct LookupSingle
{
inline int cmp (hb_codepoint_t g) const { return glyph.cmp (g); }
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && value.sanitize (c));
}
GlyphID glyph; /* Last GlyphID */
T value; /* The lookup value (only one) */
public:
DEFINE_SIZE_STATIC (4 + sizeof (T));
};
template <typename T>
struct LookupFormat6
{
friend struct Lookup<T>;
private:
inline const T* get_value (hb_codepoint_t glyph_id) const
{
const LookupSingle<T> *v = entries.bsearch (glyph_id);
return v ? &v->value : nullptr;
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (entries.sanitize (c));
}
protected:
HBUINT16 format; /* Format identifier--format = 6 */
BinSearchArrayOf<LookupSingle<T> >
entries; /* The actual entries, sorted by glyph index. */
public:
DEFINE_SIZE_ARRAY (8, entries);
};
template <typename T>
struct LookupFormat8
{
friend struct Lookup<T>;
private:
inline const T* get_value (hb_codepoint_t glyph_id) const
{
return firstGlyph <= glyph_id && glyph_id - firstGlyph < glyphCount ? &valueArrayZ[glyph_id - firstGlyph] : nullptr;
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
return_trace (c->check_struct (this) && valueArrayZ.sanitize (c, glyphCount));
}
protected:
HBUINT16 format; /* Format identifier--format = 6 */
GlyphID firstGlyph; /* First glyph index included in the trimmed array. */
HBUINT16 glyphCount; /* Total number of glyphs (equivalent to the last
* glyph minus the value of firstGlyph plus 1). */
UnsizedArrayOf<T>
valueArrayZ; /* The lookup values (indexed by the glyph index
* minus the value of firstGlyph). */
public:
DEFINE_SIZE_ARRAY (6, valueArrayZ);
};
template <typename T>
struct Lookup
{
inline const T* get_value (hb_codepoint_t glyph_id, unsigned int num_glyphs) const
{
switch (u.format) {
case 0: return u.format0.get_value (glyph_id, num_glyphs);
case 2: return u.format2.get_value (glyph_id);
case 4: return u.format4.get_value (glyph_id);
case 6: return u.format6.get_value (glyph_id);
case 8: return u.format8.get_value (glyph_id);
default:return nullptr;
}
}
inline bool sanitize (hb_sanitize_context_t *c) const
{
TRACE_SANITIZE (this);
if (!u.format.sanitize (c)) return_trace (false);
switch (u.format) {
case 0: return_trace (u.format0.sanitize (c));
case 2: return_trace (u.format2.sanitize (c));
case 4: return_trace (u.format4.sanitize (c));
case 6: return_trace (u.format6.sanitize (c));
case 8: return_trace (u.format8.sanitize (c));
default:return_trace (true);
}
}
protected:
union {
HBUINT16 format; /* Format identifier */
LookupFormat0<T> format0;
LookupFormat2<T> format2;
LookupFormat4<T> format4;
LookupFormat6<T> format6;
LookupFormat8<T> format8;
} u;
public:
DEFINE_SIZE_UNION (2, format);
};
} /* namespace AAT */
#endif /* HB_AAT_LAYOUT_COMMON_PRIVATE_HH */
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