mirror of
https://github.com/RGBCube/serenity
synced 2025-05-28 13:45:07 +00:00
87 lines
1.8 KiB
C++
87 lines
1.8 KiB
C++
#include "FIFO.h"
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#include <AK/StdLib.h>
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//#define FIFO_DEBUG
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RetainPtr<FIFO> FIFO::create()
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{
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return adopt(*new FIFO);
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}
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FIFO::FIFO()
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{
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}
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void FIFO::open(Direction direction)
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{
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if (direction == Reader) {
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++m_readers;
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#ifdef FIFO_DEBUG
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kprintf("open reader (%u)\n", m_readers);
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#endif
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} else if (direction == Writer) {
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++m_writers;
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#ifdef FIFO_DEBUG
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kprintf("open writer (%u)\n", m_writers);
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#endif
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}
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}
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void FIFO::close(Direction direction)
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{
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if (direction == Reader) {
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#ifdef FIFO_DEBUG
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kprintf("close reader (%u - 1)\n", m_readers);
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#endif
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ASSERT(m_readers);
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--m_readers;
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} else if (direction == Writer) {
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#ifdef FIFO_DEBUG
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kprintf("close writer (%u - 1)\n", m_writers);
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#endif
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ASSERT(m_writers);
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--m_writers;
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}
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}
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bool FIFO::can_read() const
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{
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return !m_queue.isEmpty() || !m_writers;
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}
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bool FIFO::can_write() const
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{
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#ifdef FIFO_DEBUG
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dbgprintf("can_write? size(%u) < capacity(%u) || !readers(%u)\n", m_queue.size(), m_queue.capacity(), m_readers);
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#endif
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return m_queue.size() < m_queue.capacity() || !m_readers;
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}
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ssize_t FIFO::read(byte* buffer, size_t size)
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{
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if (!m_writers && m_queue.isEmpty())
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return 0;
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#ifdef FIFO_DEBUG
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dbgprintf("fifo: read(%u)\n",size);
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#endif
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size_t nread = min(size, m_queue.size());
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for (size_t i = 0; i < nread; ++i)
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buffer[i] = m_queue.dequeue();
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#ifdef FIFO_DEBUG
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dbgprintf(" -> read (%c) %u\n", buffer[0], nread);
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#endif
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return nread;
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}
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ssize_t FIFO::write(const byte* buffer, size_t size)
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{
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if (!m_readers)
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return 0;
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#ifdef FIFO_DEBUG
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dbgprintf("fifo: write(%p, %u)\n", buffer, size);
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#endif
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size_t nwritten = min(size, m_queue.capacity() - m_queue.size());
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for (size_t i = 0; i < nwritten; ++i)
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m_queue.enqueue(buffer[i]);
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return nwritten;
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}
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