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LibC: Implement ungetwc()

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This commit is contained in:
Ali Mohammad Pur 2021-12-19 23:29:21 +03:30 • committed by Ali Mohammad Pur
parent 14b91a3fe9
commit e717ca32d1
7 changed files with 63 additions and 18 deletions
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37
Userland/Libraries/LibC/stdio.cpp
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@ -5,6 +5,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BuiltinWrappers.h>
#include <AK/Format.h>
#include <AK/PrintfImplementation.h>
#include <AK/ScopedValueRollback.h>
@ -351,7 +352,7 @@ FILE::Buffer::~Buffer()
bool FILE::Buffer::may_use() const
{
return m_ungotten || m_mode != _IONBF;
return m_ungotten != 0u || m_mode != _IONBF;
}
void FILE::Buffer::realize(int fd)
@ -384,7 +385,7 @@ void FILE::Buffer::drop()
}
m_begin = m_end = 0;
m_empty = true;
m_ungotten = false;
m_ungotten = 0u;
}
size_t FILE::Buffer::buffered_size() const
@ -402,9 +403,10 @@ size_t FILE::Buffer::buffered_size() const
const u8* FILE::Buffer::begin_dequeue(size_t& available_size) const
{
if (m_ungotten) {
available_size = 1;
return &m_unget_buffer;
if (m_ungotten != 0u) {
auto available_bytes = count_trailing_zeroes(m_ungotten) + 1;
available_size = available_bytes;
return &m_unget_buffer[unget_buffer_size - available_bytes];
}
if (m_empty) {
@ -424,9 +426,10 @@ void FILE::Buffer::did_dequeue(size_t actual_size)
{
VERIFY(actual_size > 0);
if (m_ungotten) {
VERIFY(actual_size == 1);
m_ungotten = false;
if (m_ungotten != 0u) {
VERIFY(actual_size <= static_cast<size_t>(popcount(m_ungotten & ungotten_mask)));
auto available_bytes = count_trailing_zeroes(m_ungotten);
m_ungotten &= (0xffffffffu << (actual_size + available_bytes));
return;
}
@ -476,13 +479,21 @@ void FILE::Buffer::did_enqueue(size_t actual_size)
bool FILE::Buffer::enqueue_front(u8 byte)
{
if (m_ungotten) {
// Sorry, the place is already taken!
return false;
size_t placement_index;
if (m_ungotten == 0u) {
placement_index = 3u;
m_ungotten = 1u;
} else {
auto first_zero_index = count_trailing_zeroes(bit_cast<u32>(~m_ungotten)); // Thanks C.
if (first_zero_index >= unget_buffer_size) {
// Sorry, the place is already taken!
return false;
}
placement_index = unget_buffer_size - first_zero_index - 1;
m_ungotten |= (1 << first_zero_index);
}
m_ungotten = true;
m_unget_buffer = byte;
m_unget_buffer[placement_index] = byte;
return true;
}