Ring buffer implementation ported from OSCL

src/Cpl/Container/Ring.cpp

@@ -0,0 +1,169 @@
+/*-----------------------------------------------------------------------------
+* This file is part of the Colony.Core Project.  The Colony.Core Project is an
+* open source project with a BSD type of licensing agreement.  See the license
+* agreement (license.txt) in the top/ directory or on the Internet at
+* http://integerfox.com/colony.core/license.txt
+*
+* Copyright (c) 2023 Michael N. Moran
+*
+* Redistributions of the source code must retain the above copyright notice.
+*
+* This implementation is an adaptation/simplification of the OSCL
+* Oscl::Buffer::Ring ring buffer code.
+* This adaptation was done by myself (Michael N. Moran)
+* and donated to the Colony.Core Project.
+*----------------------------------------------------------------------------*/
+
+#include "Ring.h"
+
+///
+using namespace Cpl::Container::Ring;
+
+TxDesc::TxDesc(
+    Header&     header
+    ) noexcept:
+        _allocationOffset(0),
+        _header(header)
+{
+}
+
+bool    TxDesc::alloc(uint32_t& index) noexcept
+{
+    uint32_t
+    nElements    = _header._nElements;
+
+    uint32_t
+    writeIndex    = _header._writeIndex + _allocationOffset;
+
+    writeIndex    %=    nElements;
+
+    uint32_t
+    nextIndex    = (writeIndex + 1) % nElements;
+
+    if( nextIndex == _header._readIndex )
+    {
+        return false;
+    }
+    else
+    {
+        index    = writeIndex;
+        ++_allocationOffset;
+        return true;
+    }
+}
+
+bool    TxDesc::isFull() const noexcept
+{
+    uint32_t
+    nElements    = _header._nElements;
+
+    uint32_t
+    index    = _header._writeIndex + _allocationOffset;
+
+    index    %=    nElements;
+
+    uint32_t
+    nextIndex    =    (index + 1) % nElements;
+
+    return nextIndex == _header._readIndex;
+}
+
+void    TxDesc::commit() noexcept
+{
+    if( !_allocationOffset )
+    {
+        /* This is a client error where no
+           slot has been allocated before
+           calling commit().
+         */
+        return;
+    }
+
+    uint32_t
+    index    = _header._writeIndex;
+
+    uint32_t
+    nextIndex    = (index + 1) % _header._nElements;
+
+    _header._writeIndex = nextIndex;
+
+    --_allocationOffset;
+}
+
+void    TxDesc::reset() noexcept
+{
+    _allocationOffset   = 0;
+}
+
+RxDesc::RxDesc(
+    Header& header
+    ) noexcept:
+        _allocationOffset(0),
+        _header(header)
+{
+}
+
+bool    RxDesc::alloc(uint32_t& index) noexcept
+{
+    uint32_t
+    readIndex    = _header._readIndex + _allocationOffset;
+
+    uint32_t
+    nElements    = _header._nElements;
+
+    readIndex        %= nElements;
+
+    uint32_t
+    writeIndex    = _header._writeIndex;
+
+    if( readIndex == writeIndex )
+    {
+        return false;
+    }
+    else
+    {
+        ++_allocationOffset;
+        index    = readIndex;
+        return true;
+    }
+}
+
+void    RxDesc::resetAllocationOffset() noexcept
+{
+    _allocationOffset    = 0;
+}
+
+void    RxDesc::commit() noexcept
+{
+    uint32_t
+    nElements    = _header._nElements;
+
+    uint32_t
+    index        =    _header._readIndex + 1;
+    index        %=    nElements;
+
+    _header._readIndex  = index;
+
+    --_allocationOffset;
+
+}
+
+void    RxDesc::commitAll() noexcept
+{
+    uint32_t
+    nElements    = _header._nElements;
+
+    uint32_t
+    index        =    _header._readIndex + _allocationOffset;
+    index        %=    nElements;
+
+    _header._readIndex  = index;
+
+    _allocationOffset    = 0;
+}
+
+void    RxDesc::reset() noexcept
+{
+    _allocationOffset   = 0;
+}
+