- StringPool class added

This is a specialized stripped doen FMemArena.

src/CMakeLists.txt

@@ -1222,6 +1222,7 @@ set( ZDOOM_SOURCES
 	common/filesystem/files.cpp
 	common/filesystem/files_decompress.cpp
 	common/filesystem/fs_findfile.cpp
+	common/filesystem/fs_stringpool.cpp
 
 )
 

src/common/filesystem/fs_stringpool.cpp

@@ -0,0 +1,123 @@
+/*
+** stringpool.cpp
+** allocate static strings from larger blocks
+**
+**---------------------------------------------------------------------------
+** Copyright 2010 Randy Heit
+** Copyright 2023 Christoph Oelckers
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions
+** are met:
+**
+** 1. Redistributions of source code must retain the above copyright
+**    notice, this list of conditions and the following disclaimer.
+** 2. Redistributions in binary form must reproduce the above copyright
+**    notice, this list of conditions and the following disclaimer in the
+**    documentation and/or other materials provided with the distribution.
+** 3. The name of the author may not be used to endorse or promote products
+**    derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**---------------------------------------------------------------------------
+**
+*/
+
+#include "stringpool.h"
+
+struct StringPool::Block
+{
+	Block *NextBlock;
+	void *Limit;			// End of this block
+	void *Avail;			// Start of free space in this block
+	void *alignme;			// align to 16 bytes.
+
+	void *Alloc(size_t size);
+};
+
+//==========================================================================
+//
+// StringPool Destructor
+//
+//==========================================================================
+
+StringPool::~StringPool()
+{
+	for (Block *next, *block = top; block != nullptr; block = next)
+	{
+		next = block->NextBlock;
+		free(block);
+	}
+	top = nullptr;
+}
+
+//==========================================================================
+//
+// StringPool :: Alloc
+//
+//==========================================================================
+
+void *StringPool::Block::Alloc(size_t size)
+{
+	if ((char *)Avail + size > Limit)
+	{
+		return nullptr;
+	}
+	void *res = Avail;
+	Avail = RoundPointer((char *)Avail + size);
+	return res;
+}
+
+StringPool::Block *StringPool::AddBlock(size_t size)
+{
+	size += sizeof(Block);		// Account for header size
+
+	// Allocate a new block
+	if (size < BlockSize)
+	{
+		size = BlockSize;
+	}
+	auto mem = (Block *)malloc(size);
+	if (mem == nullptr)
+	{
+		
+	}
+	mem->Limit = (uint8_t *)mem + size;
+	mem->Avail = &mem[1];
+	mem->NextBlock = TopBlock;
+	TopBlock = mem;
+	return mem;
+}
+
+void *StringPool::iAlloc(size_t size)
+{
+	Block *block;
+
+	for (block = TopBlock; block != nullptr; block = block->NextBlock)
+	{
+		void *res = block->Alloc(size);
+		if (res != nullptr)
+		{
+			return res;
+		}
+	}
+	block = AddBlock(size);
+	return block->Alloc(size);
+}
+
+const char* StringPool::Strdup(const char* str)
+{
+	char* p = (char*)iAlloc((strlen(str) + 15) & ~15 );
+	strcpy(p, str);
+	return p;
+}

src/common/filesystem/fs_stringpool.h

@@ -0,0 +1,23 @@
+#pragma once
+
+// Storage for all the static strings the file system must hold.
+class StringPool
+{
+public:
+	StringPool(size_t blocksize = 10*1024) : TopBlock(nullptr), FreeBlocks(nullptr), BlockSize(blocksize) {}
+	~StringPool();
+	const char* Strdup(const char*);
+
+protected:
+	struct Block;
+
+	Block *AddBlock(size_t size);
+	void *iAlloc(size_t size);
+
+	Block *TopBlock;
+	Block *FreeBlocks;
+	size_t BlockSize;
+public:
+	bool shared;
+};
+