ChangeLog

Release Notes DDS 2.8.0
----------------------- 
2.8.0 is about 15% faster than 2.7.0.

The move generation code has been re-implemented and is much faster.

The CalcAllTables function now allows solving a larger number of
DD tables in parallel (32 rather than 10).

A scheduler module rearranges hands within a batch of hands to
be solved.  This has two purposes:  

1.  It detects duplicate hands and does not solve the same hand 
twice.  So it a more general version of the "chunk" mechanism
which requires the user to construct a batch in a specific way.

2.  It attempts to solve hands first which are likely to be 
difficult to solve.  When the hands are scheduled onto multiple
threads, this reduces the average time wasted in the end while
one thread is finishing up its last hand.

The code for initialization and the SolveBoard interface functions 
have been restructured. 

Two bugs in the memory management of the transposition tables
have been fixed.  Thanks for Brian Dickens for pointing them out.
Brian also helped to make the code compile with fewer warnings
at high warning levels.

The directory structure of the distribution has been streamlined.

The old algorithm document has been updated, particularly in
the transposition table section.

An ErrorMessage() function has been added to the interface.

The old DDD program has been updated to work directly with the
"modern" DDS; DDS had not been touched for many years.

A more modern test program has been added, testing the main
modes of the current DDS.

The code has been cleaned up to compile with a very high level
of compiler warnings on Microsoft Visual Studio, minGW, Cygwin
g++, Ubuntu (and probably other Linux flavors with OpenMP),
Mac OS with clang (single-threaded) and with g++ (OpenMP).

There are Makefiles for each system and each program.

Soren has become a co-author as of this version.



Release Notes DDS 2.7.0
----------------------- 
The transposition table solution has been replaced by a faster one.
The new solution is 8-15% faster.  Many thanks to Soren Hein for 
writing this part of the code.  Soren has also improved the code 
at numerous places.  

Additional Par functions have been added to ease the use of a 
DDS user specific format.


Release Notes DDS 2.6.0
-----------------------  
2.6.0 is 2% faster than 2.5.2. 

The Par function has been corrected.

The DealerPar and the PlayAnalyser functions has been added, 
written by Soren Hein.  Soren Hein has contributed numerous 
improvements.


Release Notes DDS 2.5.2
-----------------------  
A bug in the par calculation has been fixed. The fault could 
wrongly cause presentation of extra par contracts in cases were 
the sides had different vulnerability.


Release Notes DDS 2.5.1
-----------------------  
The Windows DDS DLL now always uses the Windows API for implementing 
the multithread functions (i.e. OpenMP is not used for Windows).


Release Notes DDS 2.5.0
-----------------------  
Added function SolveAllChunks.


Release Notes DDS 2.4.3
-----------------------  
Problem pointed out by John Goacher with missing par contract 
has been corrected.  

Tuned code for increased performance, especially in function 
MoveGen and in the WeightAlloc function.


Release Notes DDS 2.4.2
-----------------------  
Fixing bugs in CalcAllTables, CalcAllTablesPBN and CalcPar.


Release Notes DDS 2.4.1
-----------------------  
Updates of functions CalcAllTables and CalcAllTablesPBN for 
improved performance. 


Release Notes DDS 2.4.0
-----------------------
Fixed a bug in the calculation of par score contracts.

Added the new functions CalcAllTables and CalcAllTablesPBN.

Numerous fixes for better adaptation to Linux.

Cleaning the code to remove some warnings given at code 
compilation.  

For Windows users, adding readable version information of the 
DDS DLL file. 


Release Notes DDS 2.3.0
-----------------------
The main news is the support of calculation of par 
scores / contracts.

The Mingw DLL now uses the Win API instead of OpenMP, so no
supporting DLL for pthreads is now needed.


Release Notes DDS 2.2.4
-----------------------
A newer port from GCC to Windows, the TDM-GCC 4.7.1 version is 
used.  It gives faster DLLs and only requires one supporting DLL, 
which supports OpenMP.

Also, the move ordering has been slighly improved.

A total speed increase of 4% is achieved compared to 2.2.3.


Release Notes DDS 1.1.18
------------------------
The main news is that this release is licensed under 
Apache 2.0 instead of GPL for the previous releases.

There is a slight change of the move ordering compared to 1.1.17.


Release Notes DDS 1.1.17
------------------------
A newer port from GCC to Windows, the TDM-GCC 4.7.1 version is 
used.  It gives faster DLLs and does not require any supporting DLLs.

Also, the move ordering has been slighly improved.

A total speed increase of 4% is achieved compared to 1.1.16.


Release Notes DDS 2.2.3
----------------------- 
DDS 2.2.3 adds Mingw compiled DLLs and makes a number of code 
improvements.

Maximum number of threads is increased to 16.

The 2.2.3 Mingw DLLs are about 5% faster than the 2.2.2 DLLs. 


Release Notes DDS 1.1.16
------------------------
DDS 1.1.16 add Mingw compiled DLLs and makes a number of code 
improvements.

The 1.1.16 Mingw DLLs are about 5% faster than the 1.1.15 DLLs.


Release Notes DDS 1.1.15
------------------------
The rel table missed initialization for absRank and relRank when 
all cards in a suit are missing.

DDS 1.1.15 is about 7% faster than 1.1.14.


Release Notes DDS 2.2.2
----------------------- 
DDS 2.2.2 is mainly a bug fix release.

1. An uninitialized variable used in move generation required that 
the compiler initialized it by setting it to zero.  This is true 
for Visual C++ but might perhaps have caused a problem with some 
other compiler.

2. The rel table missed initialization for absRank and relRank 
when all cards in a suit are missing. 

DDS 2.2.2 is slightly faster than 2.2.1, about 4%.


Release Notes DDS 1.1.14
------------------------
Bug fixed in using the Windows function to detect RAM memory size 
that could cause DDS termination.


Release Notes DDS 2.2.1
----------------------- 
Bug fixed in using the Windows function to detect RAM memory size 
that could cause DDS termination.

Clarifying that DDS 2.2.1 is a 32-bit DLL not capable of using 
more than 4 GB.

The maximum number of threads is 8. 


Release Notes DDS 1.1.13
------------------------
DDS used a deficient function in Windows to detect RAM memory size, 
which could cause too few threads to be allocated. DDS now uses a 
correct Windows function to detect the RAM size. 

1.1.13 is 5-10% faster than 1.1.12.


Release Notes DDS 2.2.0
----------------------- 
A new callable function, SolveAllBoards, has been added.

Bug fixed:

1. DDS used a deficient function in Windows to detect RAM memory 
size, which could cause too few threads to be allocated. DDS now 
uses a correct Windows function to detect the RAM size.

2. DDS failed to detect PBN text coded card distributions with 
less than 52 cards.

3. DDS hanged when a faulty card distribution was provided in 
the CalcDDtable call.  This fault was not present in the openMP 
alternative, though.

2.2.0 is 10-15% faster than 2.1.2. 


Release Notes DDS 1.1.12
------------------------
Two new callable functions have been added: 
SolveBoardPBN and CalcDDtablePBN.

They both accept PBN format for the remaining cards in the 
deal information instead of the bit codes.

Code improvements have been done concerning quick tricks 
detection and move ordering. 

1.1.12 is about 15-20% faster than 1.1.11.


Release Notes DDS 2.1.2
-----------------------
Two new callable functions have been added:
SolveBoardPBN and CalcDDtablePBN.

They both accept PBN format for the remaining cards in the 
deal information instead of the bit codes.

Code improvements have been done concerning quick tricks 
detection and move ordering. 

2.1.2 is about 10% faster than 2.1.1.


Release Notes DDS 2.1.1
-----------------------
The maximum number of threads is now configurable depending on 
the size of the physical memory. The configuration is either 
done automatically by reading out the physical memory size by 
the operating system, or by supplying parameter values in InitStart.


Release Notes DDS 2.1.0
-----------------------
Added OpenMP as multi-thread support for CalcDDtable when 
compiling with gcc 4.4.0 or later.

Added a similarity deals test function for reuse of the 
transposition table contents when the current deal is similar 
to the previous deal. 


Release Notes DDS 2.0.1
-----------------------
In 2.0.0, the contents of the transposition table could erronously
be reused when the previous position contained a different number 
of cards. This was caused by an erroneous implementation of the
deal similarity test. This bug was fixed by removing the 
similarity test.

The DDS version number is defined by a #define statement in dll.h. 


Release Notes DDS 2.0.0
-----------------------
A bug was fixed.

SolveBoard is now thread-safe.

The SolveBoard parameter "mode" no longer needs to be set to 2.
DDS automatically detect situations when the transposition
table contents can be reused.

Used with a single thread, DDS 2.0.0 has about the same speed as 
DDS 1.1.9.  Used with 2 parallel threads, DDS 2.0.0 is twice as 
fast as the single thread case. 

A new function, CalcDDtable, has been added.  CalcDDtable calls 
SolveBoard using parallel threads. The number of parallel threads 
is the same as the number of processor cores.  CalcDDtable 
calculates the double dummy values of the initial 52 cards
for all the 20 trump suit/leading hand combinations. 


Release Notes DDS 1.1.9
-----------------------
1.1.9 is about 10-15% faster than 1.1.8.

Main improvements come from 1) and 2) below.

1.  Much faster initialization of variable rel (struct type 
relRanksType).  Implementation done by Thomas Andrews.

2.  Move generation: If the hand-to-play is trick leading hand, 
the first positions in the move list now come each from a 
different suit.  In 1.1.8, the first positions were groups of 
2 cards from each suit.

3.  DismissX renamed to NextMove. A bug was corrected
in NextMove, increasing performance. (The bug did not give
incorrect result.)  The bug was found by Joël Bradmetz.

4.  The function CountOnes is replaced by a table look-up.
Implementation by Thomas Andrews.

5.  The handStore variable is replaced by a macro. Based on
an implementation by Thomas Andrews.

6.  The WinAdapt function is replaced by a table look-up.

7.  A new table, highestRank, gives the highest rank from a
bitmap of ranks. Makes functions UpdateWinner, UpdateSecondBest
and QuickTricks slightly faster.



Release Notes DDS 1.1.8
--------------------------- 
The transposition table solution has been redesigned.
Each "winning ranks node" now contains all ranks for one suit.

When a new transposition table entry is created, it is now
positioned at the front of the alternative "winning ranks node"
list rather than at the end as before.

Each leading hand now has own root pointers pointing to
the "suit lengths combination" tree.

Some changes in QuickTricks.


Release Notes DDS 1.1.7
---------------------------
A bug fix and recoding of the dynamic transposition table 
implementation. 


Release Notes DDS 1.1.6
---------------------------  
A bug has been fixed. It could show up (but hasn't as far as I know)
after the transposition table became full. 

Only a minor part of the maximum transposition table, about 30 MB, is 
now allocated at initialization.  If more is needed it is dynamically 
added as need arises. Each incremental addition is about 2 MB. 
This continues until the maximum allowed space is reached, 
for 512 MB PC this is about 400 MB.  Then the incrementally added 
transposition table pieces are wiped out and the initially allocated 
table is cleared. 


Release Notes DDS 1.1.5
---------------------------  
A correction has been made removing a risk of DD value miscalculation.
The fault has not however yet showed up as far as I know.

A survival mechanism has been added to handle the situation if the
transposition table becomess full: The transposition table is emptied.

Before this, a full transposition table would in practise lock up 
the program.  Therefore the present size of the transposition table 
is quite large (393 MB) to handle the most difficult deals.

This could lead to extensive memory swapping with the hard drive 
if the PC RAM size is 256 MB or less, slowing down the program.

With the new survival mechanism, the program will not lock up in
case of a full transposition table.  The calculation time will 
increase because of the extra time to build up stored positions in 
the table, but the increase will be reasonable.  This means that 
DDS should be possible to run with such small PC RAM sizes as 
64 MB (this has not been tested, though).


Release Notes DDS 1.1.4
---------------------------
Improvements when the SolveBoard parameter mode is set to 2.
The mode parameter can now be set to 2 for SolveBoard calls 
with parameter target set to -1 or a value 0-13,
and solutions set to 1, 2 or 3.

Following the first SolveBoard call with mode = 1, mode
can be set to 2 for any further SolveBoard call for
the same deal, also when an opponent hand leads the trick.

If scores are to be calculated for all 4 possible leading hands
of the deal, one SolveBoard call can be made with mode = 1, and 
the other 3 SolveBoard calls for the other 3 leading hands can be
made with mode = 2.

Compared to dds 1.1.3, the better support of mode = 2 means improved
calculation speed.  Compared to using only mode = 1 when calling 
Solveboard 4 times, each time for each alternative leading hand, 
the calculation time is roughly halved using mode = 2 as described 
above. 


Release Notes DDS 1.1.3
---------------------------
1.  Compiles with Visual C++ 2005 Express edition

2.  Some improvements in move ordering, quick tricks and the new 
later tricks algorithms.

3.  Total improvement about 20% including the faster code 
generated by Visual C++ and the algorithm improvements.


Release Notes DDS 1.1.2
---------------------------
1.  Increased performance of about 15% due to improved algorithm 
for move ordering. For more information, look in the algorithm 
description.


Release Notes DDS 1.1.1
---------------------------
1.  For target = -1 and solutions = 1/2/3, the transposition table 
contents are now reused also when SolveBoard is called with a new 
target value.

2) Slight improvement of the QuickTricks algorithm.

3) Moderate speed improvement compared to 1.1.1.


Release Notes DDS 1.1.0
---------------------------
1.  Performance improvement giving a speed of about twice that 
of 1.0.6.

2.  Redesign of the transposition table solution, see algorithm 
description.

3.  Improvements in the Quicktricks algorithm, see algorithm 
description.

4.  Dump in text file of SolveBoard parameters if SolveBoard 
returns with error code.


Release Notes DDS 1.0.6
--------------------------
1.  A bug has been fixed in the DDS start up code.  The bug did 
not affect the accuracy of the solver.  Thanks to Fabien Bradmetz 
for spotting this!

2.  About 10% increased speed due to improvements in Quick Tricks. 

3.  An error code has been added for checking the input of of 
cards earlier played in the trick.

4.  A document (mode2.txt) describes source code examples of 
calling SolveBoard using the parameter mode set to 2.


Release Notes DDS 1.0.5
--------------------------
1.  About 25% speed improvement due to a search algorithm 
improvement:  For moves generated in the search tree, only one 
"small" card move per hand and suit is generated. By "small" 
card is meant a card with a rank that is not winning due to its 
rank value.  Earlier all "small" cards generated their own moves.
This improvement comes from a tip by Hans Kuijf.

2.  The size of the transposition table has been increased by 25%. 
This was done after realizing that for some extreme deals, rarely 
occurring, when solutions = 2 and 3 the transposition table could 
get completely filled up, making the search time extremely long 
for those cases.  The increased transposition table size should 
still fit well inside a 256 MB machine.

3.  Parameter mode = 2 indicates that the transposition table is 
reused from an earlier SolveBoard call. It is restricted to the 
case where the same conditions apply for the two calls, except 
that the leading hand in the second call is the partner to the 
leading hand in the first call.  I.e. same deal incl same trump 
suit, same target (not equal to -1), solutions = 1. 


Release Notes DDS 1.0.4
-----------------------
When introducing the possibility of reusing the transposition 
table between subsequent searches in 1.0.1, unfortunately a bug 
was introduced as well.  It occassionally gives wrong scores 
when evaluating the last hand of the trick using 
solutions = 2 or 3.  This bug is fixed in 1.0.4.


Release Notes DDS 1.0.3
----------------------- 
Includes:
1.  An improvement of the move ordering algorithm.  When LHO ruffs,
this is now given a low weight if the highest rank of RHO beats both
the rank of the leading card and the highest rank of the leading suit
at the partner of the leading hand, assuming that the partner of the 
leading hand is not void in the suit of the leading card.
If these conditions do not hold, the weight for the LHO ruffing card 
is high.

2.  For the SolveBoard parameter solutions = 3, reuse of the 
transposition table contents between card searches has been added.
1 and 2 together give on average an improvement performance. 


Release Notes DDS 1.0.2
-----------------------
Includes a bug fix for the case when the SolveBoard parameter
"solutions" is set to 3.  SolveBoard did not correctly handle the 
case when the scores of the alternative cards were a mix of zero 
and non-zero. This is now fixed in 1.0.2.


Release Notes DDS 1.0.1
-----------------------
Includes support for reuse of the transposition table contents 
for a subsequent search. (This idea was brought forward 
independently by Alex Martelli and Flip Cronje.)

When setting the SolveBoard solutions to 2, the transposition 
table contents will be reused when searching for alternative cards,
giving a slightly decreased search time in most cases, in a few cases
the decrease is substantial.  Earlier the contents of the 
transposition table was always emptied between searches.

The way to control whether or not to empty the transposition table
is to properly set the parameter mtd in the InitSearch function:

mtd = FALSE means that the transposition table is emptied, 
mtd = TRUE that it is not emptied.