Revert "Kernel: Make DoubleBuffer use a KBuffer instead of kmalloc()ing"

This reverts commit 1cca5142afbd76833deedfdb238230ac53424855.

This appears to be causing intermittent triple-faults and I don't know
why yet, so I'll just revert it to keep the tree in decent shape.

1 files changed, 15 insertions, 30 deletions

diff --git a/Kernel/DoubleBuffer.cpp b/Kernel/DoubleBuffer.cpp
index 512c506407..d4015f12e5 100644
--- a/Kernel/DoubleBuffer.cpp
+++ b/Kernel/DoubleBuffer.cpp
@@ -1,32 +1,20 @@
 #include <Kernel/DoubleBuffer.h>
 
-inline void DoubleBuffer::compute_lockfree_metadata()
+inline void DoubleBuffer::compute_emptiness()
 {
-    InterruptDisabler disabler;
-    m_empty = m_read_buffer_index >= m_read_buffer->size && m_write_buffer->size == 0;
-    m_space_for_writing = m_capacity - m_write_buffer->size;
-}
-
-DoubleBuffer::DoubleBuffer(size_t capacity)
-    : m_write_buffer(&m_buffer1)
-    , m_read_buffer(&m_buffer2)
-    , m_storage(KBuffer::create_with_size(capacity * 2))
-    , m_capacity(capacity)
-{
-    m_buffer1.data = m_storage.data();
-    m_buffer1.size = 0;
-    m_buffer2.data = m_storage.data() + capacity;
-    m_buffer2.size = 0;
-    m_space_for_writing = capacity;
+    m_empty = m_read_buffer_index >= m_read_buffer->size() && m_write_buffer->is_empty();
 }
 
 void DoubleBuffer::flip()
 {
-    ASSERT(m_read_buffer_index == m_read_buffer->size);
+    ASSERT(m_read_buffer_index == m_read_buffer->size());
     swap(m_read_buffer, m_write_buffer);
-    m_write_buffer->size = 0;
+    if (m_write_buffer->capacity() < 32)
+        m_write_buffer->clear_with_capacity();
+    else
+        m_write_buffer->clear();
     m_read_buffer_index = 0;
-    compute_lockfree_metadata();
+    compute_emptiness();
 }
 
 ssize_t DoubleBuffer::write(const u8* data, ssize_t size)
@@ -34,11 +22,8 @@ ssize_t DoubleBuffer::write(const u8* data, ssize_t size)
     if (!size)
         return 0;
     LOCKER(m_lock);
-    ASSERT(size <= (ssize_t)space_for_writing());
-    u8* write_ptr = m_write_buffer->data + m_write_buffer->size;
-    m_write_buffer->size += size;
-    compute_lockfree_metadata();
-    memcpy(write_ptr, data, size);
+    m_write_buffer->append(data, size);
+    compute_emptiness();
     return size;
 }
 
@@ -47,13 +32,13 @@ ssize_t DoubleBuffer::read(u8* data, ssize_t size)
     if (!size)
         return 0;
     LOCKER(m_lock);
-    if (m_read_buffer_index >= m_read_buffer->size && m_write_buffer->size != 0)
+    if (m_read_buffer_index >= m_read_buffer->size() && !m_write_buffer->is_empty())
         flip();
-    if (m_read_buffer_index >= m_read_buffer->size)
+    if (m_read_buffer_index >= m_read_buffer->size())
         return 0;
-    ssize_t nread = min((ssize_t)m_read_buffer->size - (ssize_t)m_read_buffer_index, size);
-    memcpy(data, m_read_buffer->data + m_read_buffer_index, nread);
+    ssize_t nread = min((ssize_t)m_read_buffer->size() - m_read_buffer_index, size);
+    memcpy(data, m_read_buffer->data() + m_read_buffer_index, nread);
     m_read_buffer_index += nread;
-    compute_lockfree_metadata();
+    compute_emptiness();
     return nread;
 }