CVSROOT: /sources/gnash
Module name: gnash
Changes by: Chad Musick <cmusick> 07/10/07 05:09:19
Modified files:
. : ChangeLog
Added files:
server/vm : SafeStack.h
Log message:
A utility class for multiple-stack simulation and memory safe stack
access.
CVSWeb URLs:
http://cvs.savannah.gnu.org/viewcvs/gnash/ChangeLog?cvsroot=gnash&r1=1.4560&r2=1.4561
http://cvs.savannah.gnu.org/viewcvs/gnash/server/vm/SafeStack.h?cvsroot=gnash&rev=1.1
Patches:
Index: ChangeLog
===================================================================
RCS file: /sources/gnash/gnash/ChangeLog,v
retrieving revision 1.4560
retrieving revision 1.4561
diff -u -b -r1.4560 -r1.4561
--- ChangeLog 7 Oct 2007 03:19:48 -0000 1.4560
+++ ChangeLog 7 Oct 2007 05:09:18 -0000 1.4561
@@ -1,5 +1,12 @@
2007-10-07 Chad Musick <[EMAIL PROTECTED]>
+ * server/vm/SafeStack.h: New file. Complete definition of a stack
+ which can be used for obtaining references valid for the life of
+ the stack and has facilities for simulating multiple stacks
+ in one stack. See the class for documentation.
+
+2007-10-07 Chad Musick <[EMAIL PROTECTED]>
+
* server/vm/CodeStream.h: New file. Complete definition of a stream
for safely reading code, with necessary reader functions for AS3.
Index: server/vm/SafeStack.h
===================================================================
RCS file: server/vm/SafeStack.h
diff -N server/vm/SafeStack.h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ server/vm/SafeStack.h 7 Oct 2007 05:09:19 -0000 1.1
@@ -0,0 +1,131 @@
+// Copyright (C) 2007 Free Software Foundation, Inc.
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+#ifndef GNASH_SAFESTACK_H
+#define GNASH_SAFESTACK_H
+
+#include <vector>
+
+namespace gnash {
+
+class StackException {/**/};
+
+/// A stack in which all references given remain valid while the stack lives.
+///
+/// Safe in SafeStack means that you can maintain a reference
+/// given by the stack as long as the stack is alive. Since it is a reference,
+/// there is no guarantee that it will remain constant, but it is guaranteed
+/// that it will remain valid.
+///
+/// Access outside of the bounds of the stack will result in a StackException
+/// being thrown.
+template <class T>
+class SafeStack
+{
+public:
+ /// From the top of the stack, get the i'th value down. 0 is the topmost
+ /// value.
+ T& top(unsigned int i)
+ {
+ if (i >= mDownstop)
+ throw StackException();
+ unsigned int offset = mEnd - i;
+ return mData[offset >> mChunkShift][offset & mChunkMod];
+ }
+
+ /// From the bottom of the stack, get the i'th value up. 0 is the
+ /// bottommost value.
+ T& value(unsigned int i)
+ {
+ if (i >= mDownstop)
+ throw StackException();
+ unsigned int offset = mEnd - mDownstop + i;
+ return mData[offset >> mChunkShift][offset & mChunkMod];
+ }
+
+ /// Shrink the stack by i entries. Does not invalidate any entries
+ /// previously given, it just sets the top for pop, push, and top
+ /// operations.
+ void drop(unsigned int i)
+ { if (i >= mDownstop) throw StackException(); mDownstop -= i; mEnd -=
i; }
+
+ /// Put a new value onto the top of the stack. The value will be
+ /// copied.
+ void push(const T t)
+ { grow(1); top(0) = t; }
+
+ /// Grow by i entries. Normally this is 1, but there might be sometime
+ /// when you need more than that. Cannot grow by more than the size
+ /// of block allocations, which is (1 << mChunkShift)
+ /// For mChunkShift == 6, this is 64.
+ void grow(unsigned int i)
+ {
+ if (((mEnd + i) >> mChunkShift) > mData.size())
+ {
+ if (i > (1 << mChunkShift))
+ throw StackException();
+ mData.push_back(new T[1 << mChunkShift]);
+ }
+ mDownstop += i;
+ mEnd += i;
+ }
+
+ /// Gives the size of the stack which is currently accessible.
+ unsigned int getDownstop() const
+ { return mDownstop; }
+
+ /// Makes the stack appear empty to subsequent callers. This can be
used
+ /// to simulate multiple stacks with a single stack, as in function
+ /// calling. Returns the portion of the stack which is newly
inaccessible.
+ unsigned int fixDownstop()
+ { unsigned int ret = mDownstop; mDownstop = 0; return ret; }
+
+ /// Makes the stack read to a depth of 'i'. This cannot be more than
+ /// totalSize()
+ void setDownstop(unsigned int i)
+ { if (mDownstop > mEnd) throw StackException(); mDownstop = i; }
+
+ /// The total size of the stack. This is not what can be read. That
+ /// value is given by getDownstop()
+ ///
+ /// This function is probably not what you need for anything except for
+ /// setting downstops that weren't returned by either fixDownstop() or
+ /// getDownstop()
+ unsigned int totalSize() const { return mEnd - 1; }
+
+ /// Default constructor.
+ SafeStack() : mData(), mDownstop(1), mEnd(1)
+ { /**/ }
+
+ /// Delete the allocated data.
+ ~SafeStack()
+ {
+ for (unsigned int i = 0; i < mData.size(); ++i)
+ delete mData[i];
+ }
+
+private:
+ typedef std::vector<T*> stack_type;
+ stack_type mData;
+ unsigned int mDownstop;
+ unsigned int mEnd;
+
+ // If mChunkMod is not a power of 2 less 1, it will not work properly.
+ static const unsigned int mChunkShift = 6;
+ static const unsigned int mChunkMod = (1 << mChunkShift) - 1;
+};
+
+} // namespace gnash
+#endif /* GNASH_SAFESTACK_H */
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