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/*
* Copyright © 2018 Christian Persch
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <https://www.gnu.org/licenses/>.
*/
#pragma once
#include <cassert>
#include <cstdint>
#include <cstring>
#include "vtedefines.hh"
namespace vte {
namespace terminal {
class Tabstops {
public:
using position_t = unsigned int;
using signed_position_t = int;
static inline constexpr position_t const npos = -1;
private:
typedef unsigned long storage_t;
/* Number of bits used in storage */
position_t m_size{0};
/* Number of blocks in m_storage */
position_t m_capacity{0};
/* Bit storage */
storage_t* m_storage{nullptr};
inline position_t bits() const noexcept
{
return 8 * sizeof(storage_t);
}
inline position_t block(position_t position) const noexcept
{
return position / bits();
}
inline position_t block_first(position_t position) const noexcept
{
return position & ~(bits() - 1);
}
/* Mask with exactly the position's bit set */
inline storage_t mask(position_t position) const noexcept
{
return storage_t(1) << (position & (bits() - 1));
}
/* Mask with all bits set from position (excl.) up to the MSB */
inline storage_t mask_lower(position_t position) const noexcept
{
return ~(mask(position) | (mask(position) - 1));
}
/* Mask with all bits set from 0 to position (excl.) */
inline storage_t mask_upper(position_t position) const noexcept
{
return mask(position) - 1;
}
inline position_t next_position(position_t position) const noexcept
{
auto b = block(position);
auto v = m_storage[b] & mask_lower(position);
if (v != 0)
return b * bits() + __builtin_ctzl(v);
while (++b < m_capacity) {
v = m_storage[b];
if (v != 0)
return b * bits() + __builtin_ctzl(v);
}
return npos;
}
inline position_t previous_position(position_t position) const noexcept
{
auto b = block(position);
auto v = m_storage[b] & mask_upper(position);
if (v != 0)
return (b + 1) * bits() - __builtin_clzl(v) - 1;
while (b > 0) {
v = m_storage[--b];
if (v != 0)
return (b + 1) * bits() - __builtin_clzl(v) - 1;
}
return npos;
}
public:
Tabstops(position_t size = VTE_COLUMNS,
bool set_default = true,
position_t tab_width = VTE_TAB_WIDTH) noexcept
{
resize(size, set_default, tab_width);
}
Tabstops(Tabstops const&) = delete;
Tabstops(Tabstops&&) = delete;
~Tabstops()
{
free(m_storage);
};
Tabstops& operator=(Tabstops const&) = delete;
Tabstops& operator=(Tabstops&&) = delete;
inline position_t size() const noexcept
{
return m_size;
}
void resize(position_t size,
bool set_default = true,
position_t tab_width = VTE_TAB_WIDTH) noexcept
{
/* We want an even number of blocks */
auto const new_capacity = ((size + 8 * sizeof(storage_t) - 1) / (8 * sizeof(storage_t)) + 1) & ~1;
g_assert_cmpuint(new_capacity % 2, ==, 0);
g_assert_cmpuint(new_capacity * 8 * sizeof(storage_t), >=, size);
if (new_capacity > m_capacity) {
auto const new_capacity_bytes = new_capacity * sizeof(storage_t);
m_storage = reinterpret_cast<storage_t*>(realloc(m_storage, new_capacity_bytes));
}
if (size > m_size) {
/* Clear storage */
auto b = block(m_size);
m_storage[b] &= mask_upper(m_size);
while (++b < new_capacity)
m_storage[b] = 0;
}
auto const old_size = m_size;
m_size = size;
m_capacity = new_capacity;
if (set_default) {
auto const r = old_size % tab_width;
position_t start = r ? old_size + tab_width - r : old_size;
for (position_t i = start; i < m_size; i += tab_width)
set(i);
}
}
inline void clear() noexcept
{
memset(m_storage, 0, m_capacity * sizeof(m_storage[0]));
}
inline void reset(position_t tab_width = VTE_TAB_WIDTH) noexcept
{
clear();
for (position_t i = 0; i < m_size; i += tab_width)
set(i);
}
inline void set(position_t position) noexcept
{
assert(position < m_size);
m_storage[block(position)] |= mask(position);
}
inline void unset(position_t position) noexcept
{
assert(position < m_size);
m_storage[block(position)] &= ~mask(position);
}
inline bool get(position_t position) const noexcept
{
return (m_storage[block(position)] & mask(position)) != 0;
}
inline position_t get_next(position_t position,
int count = 1,
position_t endpos = npos) const noexcept
{
while (count-- && position < m_size)
position = next_position(position);
return position < m_size ? position : endpos;
}
inline position_t get_previous(position_t position,
int count = 1,
position_t endpos = npos) const noexcept
{
while (count-- && position != npos)
position = previous_position(position);
return position != npos ? position : endpos;
}
};
} // namespace terminal
} // namespace vte
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