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/*
* Copyright © 2012,2017 Google, Inc.
* Copyright © 2021 Behdad Esfahbod
*
* 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_BIT_PAGE_HH
#define HB_BIT_PAGE_HH
#include "hb.hh"
struct hb_bit_page_t
{
void init0 () { v.clear (); }
void init1 () { v.clear (0xFF); }
constexpr unsigned len () const
{ return ARRAY_LENGTH_CONST (v); }
bool is_empty () const
{
for (unsigned int i = 0; i < len (); i++)
if (v[i])
return false;
return true;
}
void add (hb_codepoint_t g) { elt (g) |= mask (g); }
void del (hb_codepoint_t g) { elt (g) &= ~mask (g); }
void set (hb_codepoint_t g, bool v) { if (v) add (g); else del (g); }
bool get (hb_codepoint_t g) const { return elt (g) & mask (g); }
void add_range (hb_codepoint_t a, hb_codepoint_t b)
{
elt_t *la = &elt (a);
elt_t *lb = &elt (b);
if (la == lb)
*la |= (mask (b) << 1) - mask(a);
else
{
*la |= ~(mask (a) - 1);
la++;
memset (la, 0xff, (char *) lb - (char *) la);
*lb |= ((mask (b) << 1) - 1);
}
}
void del_range (hb_codepoint_t a, hb_codepoint_t b)
{
elt_t *la = &elt (a);
elt_t *lb = &elt (b);
if (la == lb)
*la &= ~((mask (b) << 1) - mask(a));
else
{
*la &= mask (a) - 1;
la++;
memset (la, 0, (char *) lb - (char *) la);
*lb &= ~((mask (b) << 1) - 1);
}
}
void set_range (hb_codepoint_t a, hb_codepoint_t b, bool v)
{ if (v) add_range (a, b); else del_range (a, b); }
bool is_equal (const hb_bit_page_t &other) const
{
return 0 == hb_memcmp (&v, &other.v, sizeof (v));
}
bool is_subset (const hb_bit_page_t &larger_page) const
{
for (unsigned i = 0; i < len (); i++)
if (~larger_page.v[i] & v[i])
return false;
return true;
}
unsigned int get_population () const
{
unsigned int pop = 0;
for (unsigned int i = 0; i < len (); i++)
pop += hb_popcount (v[i]);
return pop;
}
bool next (hb_codepoint_t *codepoint) const
{
unsigned int m = (*codepoint + 1) & MASK;
if (!m)
{
*codepoint = INVALID;
return false;
}
unsigned int i = m / ELT_BITS;
unsigned int j = m & ELT_MASK;
const elt_t vv = v[i] & ~((elt_t (1) << j) - 1);
for (const elt_t *p = &vv; i < len (); p = &v[++i])
if (*p)
{
*codepoint = i * ELT_BITS + elt_get_min (*p);
return true;
}
*codepoint = INVALID;
return false;
}
bool previous (hb_codepoint_t *codepoint) const
{
unsigned int m = (*codepoint - 1) & MASK;
if (m == MASK)
{
*codepoint = INVALID;
return false;
}
unsigned int i = m / ELT_BITS;
unsigned int j = m & ELT_MASK;
/* Fancy mask to avoid shifting by elt_t bitsize, which is undefined. */
const elt_t mask = j < 8 * sizeof (elt_t) - 1 ?
((elt_t (1) << (j + 1)) - 1) :
(elt_t) -1;
const elt_t vv = v[i] & mask;
const elt_t *p = &vv;
while (true)
{
if (*p)
{
*codepoint = i * ELT_BITS + elt_get_max (*p);
return true;
}
if ((int) i <= 0) break;
p = &v[--i];
}
*codepoint = INVALID;
return false;
}
hb_codepoint_t get_min () const
{
for (unsigned int i = 0; i < len (); i++)
if (v[i])
return i * ELT_BITS + elt_get_min (v[i]);
return INVALID;
}
hb_codepoint_t get_max () const
{
for (int i = len () - 1; i >= 0; i--)
if (v[i])
return i * ELT_BITS + elt_get_max (v[i]);
return 0;
}
static constexpr hb_codepoint_t INVALID = HB_SET_VALUE_INVALID;
typedef unsigned long long elt_t;
static constexpr unsigned PAGE_BITS = 512;
static_assert ((PAGE_BITS & ((PAGE_BITS) - 1)) == 0, "");
static unsigned int elt_get_min (const elt_t &elt) { return hb_ctz (elt); }
static unsigned int elt_get_max (const elt_t &elt) { return hb_bit_storage (elt) - 1; }
typedef hb_vector_size_t<elt_t, PAGE_BITS / 8> vector_t;
static constexpr unsigned ELT_BITS = sizeof (elt_t) * 8;
static constexpr unsigned ELT_MASK = ELT_BITS - 1;
static constexpr unsigned BITS = sizeof (vector_t) * 8;
static constexpr unsigned MASK = BITS - 1;
static_assert ((unsigned) PAGE_BITS == (unsigned) BITS, "");
elt_t &elt (hb_codepoint_t g) { return v[(g & MASK) / ELT_BITS]; }
const elt_t& elt (hb_codepoint_t g) const { return v[(g & MASK) / ELT_BITS]; }
static constexpr elt_t mask (hb_codepoint_t g) { return elt_t (1) << (g & ELT_MASK); }
vector_t v;
};
static_assert (hb_bit_page_t::PAGE_BITS == sizeof (hb_bit_page_t) * 8, "");
#endif /* HB_BIT_PAGE_HH */
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