static VdbeCursor AllocateCursor(Vdbe p, int curID, int fields, int db, bool isBtreeCursor)
{
// Find the memory cell that will be used to store the blob of memory required for this VdbeCursor structure. It is convenient to use a
// vdbe memory cell to manage the memory allocation required for a VdbeCursor structure for the following reasons:
//
// * Sometimes cursor numbers are used for a couple of different purposes in a vdbe program. The different uses might require
// different sized allocations. Memory cells provide growable allocations.
//
// * When using ENABLE_MEMORY_MANAGEMENT, memory cell buffers can be freed lazily via the sqlite3_release_memory() API. This
// minimizes the number of malloc calls made by the system.
//
// Memory cells for cursors are allocated at the top of the address space. Memory cell (p->nMem) corresponds to cursor 0. Space for
// cursor 1 is managed by memory cell (p->nMem-1), etc.
VdbeCursor cx = null;
Debug.Assert(curID < p.Cursors.length);
if (p.Cursors[curID] != null)
{
p.FreeCursor(p.Cursors[curID]);
p.Cursors[curID] = null;
}
//: if (Vdbe.MemGrow(mem, bytes, false) == RC.OK)
{
p.Cursors[curID] = cx = new VdbeCursor();
cx.Db = db;
cx.Fields = fields;
if (fields != 0)
cx.Types = new uint[fields];
if (isBtreeCursor)
{
cx.Cursor = sqlite3MemMallocBtCursor(cx.Cursor);
Btree.CursorZero(cx.Cursor);
}
}
return cx;
}
static void CloseAllCursors(Vdbe p)
{
if (p.Frames.data != null)
{
VdbeFrame frame;
for (frame = p.Frames.data; frame.Parent != null; frame = frame.Parent) { }
FrameRestore(frame);
}
p.Frames.data = null;
p.Frames.length = 0;
if (p.Cursors.data != null)
{
int i;
for (i = 0; i < p.Cursors.length; i++)
{
VdbeCursor cur = p.Cursors[i];
if (cur != null)
{
p.FreeCursor(cur);
p.Cursors[i] = null;
}
}
}
if (p.Mems.data != null)
ReleaseMemArray(p.Mems.data, 1, p.Mems.length);
while (p.DelFrames != null)
{
VdbeFrame del = p.DelFrames;
p.DelFrames = del.Parent;
FrameDelete(del);
}
}