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authorbrain <brain@e03df62e-2008-0410-955e-edbf42e46eb7>2006-11-17 23:23:32 +0000
committerbrain <brain@e03df62e-2008-0410-955e-edbf42e46eb7>2006-11-17 23:23:32 +0000
commit11f73970236f910a63ff77fbc8e2ee4a8ee23bc3 (patch)
tree5f765fa3f87643d73016838a6a219e83c5364e32 /src
parent3f1e3f22b57e934481193811d878dafb4c78691d (diff)
Add irc::dynamicbitmask class. Feel free to take a look and offer suggestions, as far as i can tell its about as efficient as im going to make it.
git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@5757 e03df62e-2008-0410-955e-edbf42e46eb7
Diffstat (limited to 'src')
-rw-r--r--src/hashcomp.cpp95
1 files changed, 95 insertions, 0 deletions
diff --git a/src/hashcomp.cpp b/src/hashcomp.cpp
index f7a67b13a..23d4928a6 100644
--- a/src/hashcomp.cpp
+++ b/src/hashcomp.cpp
@@ -473,3 +473,98 @@ long irc::portparser::GetToken()
}
}
+irc::dynamicbitmask::dynamicbitmask() : bits_size(4)
+{
+ /* We start with 4 bytes allocated which is room
+ * for 4 items. Something makes me doubt its worth
+ * allocating less than 4 bytes.
+ */
+ bits = new unsigned char[bits_size];
+ freebits = new unsigned char[bits_size];
+ memset(bits, 0, bits_size);
+ memset(freebits, 0, bits_size);
+}
+
+irc::dynamicbitmask::~dynamicbitmask()
+{
+ /* Tidy up the entire used memory on delete */
+ delete[] bits;
+ delete[] freebits;
+}
+
+irc::bitfield irc::dynamicbitmask::Allocate()
+{
+ for (size_t i = 0; i < bits_size; i++)
+ {
+ for (unsigned char current_pos = 1; current_pos; current_pos = current_pos << 1)
+ {
+ if (!(freebits[i] & current_pos))
+ {
+ freebits[i] |= current_pos;
+ return std::make_pair(i, current_pos);
+ }
+ }
+ }
+ /* We dont have any free space left, increase by one */
+ int old_bits_size = bits_size;
+ bits_size++;
+ /* Allocate new bitfield space */
+ unsigned char* temp_bits = new unsigned char[bits_size];
+ unsigned char* temp_freebits = new unsigned char[bits_size];
+ /* Copy the old data in */
+ memcpy(temp_bits, bits, old_bits_size);
+ memcpy(temp_freebits, freebits, old_bits_size);
+ /* Delete the old data pointers */
+ delete[] bits;
+ delete[] freebits;
+ /* Swap the pointers over so now the new
+ * pointers point to our member values
+ */
+ bits = temp_bits;
+ freebits = temp_freebits;
+ /* Initialize the new byte on the end of
+ * the bitfields, pre-allocate the one bit
+ * for this allocation
+ */
+ bits[old_bits_size] = 0;
+ bits[old_bits_size] = 1;
+ /* We already know where we just allocated
+ * the bitfield, so no loop needed
+ */
+ return std::make_pair(old_bits_size, 1);
+}
+
+bool irc::dynamicbitmask::Deallocate(irc::bitfield &pos)
+{
+ /* We dont bother to shrink the bitfield
+ * on deallocation, the most we could do
+ * is save one byte (!) and this would cost
+ * us a loop (ugly O(n) stuff) so we just
+ * clear the bit and leave the memory
+ * claimed -- nobody will care about one
+ * byte.
+ */
+ if (pos.first < bits_size)
+ {
+ freebits[pos.first] &= ~pos.second;
+ return true;
+ }
+ /* They gave a bitfield outside of the
+ * length of our array. BAD programmer.
+ */
+ return false;
+}
+
+void irc::dynamicbitmask::Toggle(irc::bitfield &pos, bool state)
+{
+ if (pos.first < bits_size)
+ {
+ if (state)
+ /* Set state, OR the state in */
+ bits[pos.first] |= pos.second;
+ else
+ /* Clear state, AND the !state out */
+ bits[pos.first] &= ~pos.second;
+ }
+}
+