Bo Haglund, Soren Hein, Bob Richardson

Rev X, 2014-11-16

Latest DLL issue with this description is available at http://www.bahnhof.se/wb758135/

## Description of the DLL functions supported in Double Dummy Problem Solver 2.8

### Callable functions

The callable functions are all preceded with extern "C" __declspec(dllimport) int __stdcall. The prototypes are available in dll.h in the “include” directory.

Return codes are given at the end.

Not all functions are present in all versions of the DLL. For historical reasons, the function names are not entirely consistent with respect to the input format. Functions accepting binary deals will end on Bin, and those accepting PBN deals will end on PBN in the future. At some point existing function names may be changed as well, so use the new names!

The Basic Functions

The basic functions SolveBoard and SolveBoardPBN each solve a single hand and are thread-safe, making it possible to use them for solving several hands in parallel. The other callable functions use the SolveBoard functions either directly or indirectly.

The Multi-Thread Double Dummy Solver Functions

The double dummy trick values for all 5 × 4 = 20 possible combinations of a hand’s trump strain and declarer hand alternatives are solved by a single call to one of the functions CalcDDtable and CalcDDtablePBN. Threads are allocated per strain in order to save computations.

To obtain better utilization of available threads, the double dummy (DD) tables can be grouped using one of the functions CalcAllTables and CalcAllTablesPBN.

Solving hands can be done much more quickly using one of the multi-thread alternatives for calling SolveBoard. Then a number of hands are grouped for a single call to one of the functions SolveAllBoards, SolveAllChunksBin and SolveAllChunksPBN. The hands are then solved in parallel using the available threads.

The number of threads is automatically configured by DDS on Windows, taking into account the number of processor cores and available memory. The number of threads can be influenced by calling SetMaxThreads. This function should probably always be called on Linux/Mac, with a zero argument for auto-configuration.

Calling FreeMemory causes DDS to give up its dynamically allocated memory.

The PAR Calculation Functions

The PAR calculation functions find the optimal contract(s) assuming open cards and optimal bidding from both sides. In very rare cases it matters which side or hand that starts the bidding, i.e. which side or hand that is first to bid its optimal contract.

Two alternatives are given:

1. The PAR scores / contracts are calculated separately for each side. In almost all cases the results will be identical for both sides, but in rare cases the result is dependent on which side that “starts the bidding”, i.e. that first finds the bid that is most beneficial for the own side. One example is when both sides can make 1 NT.
2. The dealer hand is assumed to “start the bidding”.

The presentation of the par score and contracts are given in alternative formats.

The functions Par, SidesPar and DealerPar do the par calculation; their call must be preceded by a function call calculating the double dummy table values.

The functions SidesParBin and DealerParBin provide binary output of the par results, making it easy to tailor-make the output text format. Two such functions, ConvertToSidesTextFormat and ConvertToDealerTextFormat, are included as examples.

It is possible as an option to perform par calculation in CalcAllTables and CalcAllTablesPBN.

The par calculation is executed using a single thread. But the calculation is very fast and its duration is negligible compared to the double dummy calculation duration.

Double Dummy Value Analyser Functions

The functions AnalysePlayBin, AnalysePlayPBN, AnalyseAllPlaysBin and AnalyseAllPlaysPBN take the played cards in a game or games and calculate and present their double dummy values.

Function | Arguments | Format | Comment
SolveBoard | struct deal dl, int target, int solutions, int mode, struct futureTricks *futp, int threadIndex | Binary | The most basic function, solves a single hand from the beginning or from later play
SolveBoardPBN | struct dealPBN dlPBN, int target, int solutions, int mode, struct futureTricks *futp, int threadIndex | PBN | As SolveBoard, but with PBN deal format.
CalcDDtable | struct ddTableDeal tableDeal, struct ddTableResults * tablep | Binary | Solves an initial hand for all possible declarers and denominations (up to 20 combinations)
CalcDDtablePBN | struct ddTableDealPBN tableDealPBN, struct ddTableResults * tablep | PBN | As CalcDDtable, but with PBN deal format.
CalcAllTables | struct ddTableDeals * dealsp, int mode, int trumpFilter[5], struct ddTablesRes *resp, struct allParResults * presp | Binary | Solves a number of hands in parallel. Multi-threaded.
CalcAllTablesPBN | struct ddTableDealsPBN *dealsp, int mode, int trumpFilter[5], struct ddTablesRes *resp, struct allParResults * presp | PBN | As CalcAllTables, but with PBN deal format.
SolveAllBoards | struct boardsPBN *bop, struct solvedBoards * solvedp | PBN | Consider using this instead of the next 3 “Chunk” functions”!
SolveAllChunksBin | struct boards *bop, struct solvedBoards *solvedp, int chunkSize | Binary | Solves a number of hands in parallel. Multi-threaded.
SolveAllChunks | struct boardsPBN *bop, struct solvedBoards * solvedp, int chunkSize | PBN | Alias for SolveAllChunksPBN; don’t use!
SolveAllChunksPBN | struct boardsPBN *bop, struct solvedBoards * solvedp, int chunkSize | PBN | Solves a number of hands in parallel. Multi-threaded.

Par | struct ddTableResults * tablep, struct parResults *presp, int vulnerable | No format | Solves for the par contracts given a DD result table.
DealerPar | struct ddTableResults * tablep, struct parResultsDealer * presp, int dealer, int vulnerable | No format | Similar to Par(), but requires and uses knowledge of the dealer.
DealerParBin | struct ddTableResults * tablep, struct parResultsMaster * presp, int dealer, int vulnerable | Binary | Similar to DealerPar, but with binary output.
ConvertToDealerTextFormat | struct parResultsMaster * pres, char *resp | Text | Example of text output from DealerParBin.
SidesPar | struct ddTableResults *tablep, struct parResultsDealer * presp, int vulnerable | No format | Par results are given for sides with the DealerPar output format.
SidesParBin | struct ddTableResults * tablep, struct parResultsMaster sidesRes[2], int vulnerable | Binary | Similar to SidesPar, but with binary output.
ConvertToSidesTextFormat | struct parResultsMaster * pres, struct parTextResults * resp | Text | Example of text output from SidesParBin.
CalcPar | struct ddTableDeal tableDeal, int vulnerable, struct ddTableResults * tablep, struct parResults * presp | Binary | Solves for both the DD result table and the par contracts. Is deprecated, use a CalcDDtable function plus Par() instead!
CalcParPBN | struct ddTableDealPBN tableDealPBN, struct ddTableResults * tablep, int vulnerable, struct parResults * presp | PBN | As CalcPar, but with PBN input format. Is deprecated, use a CalcDDtable function plus Par() instead!

AnalysePlayBin | struct deal dl, struct playTraceBin play, struct solvedPlay * solvedp, int thrId | Binary | Returns the par result after each card in a particular play sequence
AnalysePlayPBN | struct dealPBN dlPBN, struct playTracePBN playPBN, struct solvedPlay * solvedp, int thrId | PBN | As AnalysePlayBin, but with PBN deal format.
AnalyseAllPlaysBin | struct boards *bop, struct playTracesBin *plp, struct solvedPlays * solvedp, int chunkSize | Binary | Solves a number of hands with play sequences in parallel. Multi-threaded.
AnalyseAllPlaysPBN | struct boardsPBN *bopPBN, struct playTracesPBN * plpPBN, struct solvedPlays * solvedp, int chunkSize | PBN | As AnalyseAllPlaysBin, but with PBN deal format.
SetMaxThreads | int userThreads |  | Used at initial start and can also be called with a request for allocating memory for a specified number of threads. Is apparently mandatory on Linux and Mac (optional on Windows)
FreeMemory | void |  | Frees all allocated dynamical memory.
GetDDSInfo | DDSInfo * info |  |
ErrorMessage | int code, char line[80] |  | Turns a return code into an error message string

### Data structures

Common encodings are as follows.

Encoding | Element | Value
Suit | Spades Hearts Diamonds Clubs NT | 0 1 2 3 4
Hand | North East South West | 0 1 2 3
Vulnerable | None Both NS only EW only | 0 1 2 3
Side | N-S E-W | 0 1
Card | Bit 2 … Bit 13 Bit 14 | Rank of deuce Rank of king Rank of ace
Holding | A value of 16388 = 16384 + 4 is the encoding for the holding “A2” (ace and deuce). The two lowest bits are always zero.
PBN | Whole hand | Example: W:T5.K4.652.A98542 K6.QJT976.QT7.Q6 432.A.AKJ93.JT73 AQJ987.8532.84.K

struct | Field | Comment
deal | int trump; | Suit encoding
| int first; | The hand leading to the trick. Hand encoding
| int currentTrickSuit[3]; | Up to 3 cards may already have been played to the trick. Suit encoding. Set to 0 if no card has been played.
| int currentTrickRank[3]; | Up to 3 cards may already have been played to the trick. Value range 2-14. Set to 0 if no card has been played.
| unsigned int remainCards[4][4]; | 1st index is Hand, 2nd index is Suit. remainCards uses Holding encoding.

struct | Field | Comment
dealPBN | int trump; | Suit encoding
| int first; | The hand leading to the trick. Hand encoding
| int currentTrickSuit[3]; | Up to 3 cards may already have been played to the trick. Suit encoding.
| int currentTrickRank[3]; | Up to 3 cards may already have been played to the trick. Value range 2-14. Set to 0 if no card has been played.
| char remainCards[80]; | Remaining cards. PBN encoding.

struct | Field | Comment
ddTableDeal | unsigned int cards[4][4]; | Encodes a deal. First index is hand. Hand encoding. Second index is suit. Suit encoding.

struct | Field | Comment
ddTableDealPBN | char cards[80]; | Encodes a deal. PBN encoding.

struct | Field | Comment
ddTableDeals | int noOfTables; | Number of DD table deals in structure, at most MAXNOOFTABLES
| struct ddTableDeal deals[X]; | X = MAXNOOFTABLES * DDS_STRAINS

struct | Field | Comment
ddTableDealsPBN | int noOfTables; | Number of DD table deals in structure
| struct ddTableDealPBN deals[X]; | X = MAXNOOFTABLES * DDS_STRAINS

struct | Field | Comment
boards | int noOfBoards; | Number of boards
| struct deal [MAXNOOFBOARDS]; |
| int target [MAXNOOFBOARDS]; | See SolveBoard
| int solutions [MAXNOOFBOARDS]; | See SolveBoard
| int mode [MAXNOOFBOARDS]; | See SolveBoard

struct | Field | Comment
boardsPBN | int noOfBoards; | Number of boards
| struct dealPBN [MAXNOOFBOARDS]; |
| int target [MAXNOOFBOARDS]; | See SolveBoard
| int solutions [MAXNOOFBOARDS]; | See SolveBoard
| int mode [MAXNOOFBOARDS]; | See SolveBoard
struct | Field | Comment
futureTricks | int nodes; | Number of nodes searched by the DD solver
| int cards; | Number of cards for which a result is returned. May be all the cards, but equivalent ranks are omitted, so for a holding of KQ76 only the cards K and 7 would be returned, and the “equals” field below would be 2048 (Q) for the king and 54 (6) for the 7.
| int suit[13]; | Suit of the each returned card. Suit encoding
| int rank[13]; | Rank of the returned card. Value range 2-14.
| int equals[13]; | Lower-ranked equals. Holding encoding.
| int score[13]; | -1: target not reached. Otherwise: Target of maximum number of tricks.

struct | Field | Comment
solvedBoards | int noOfBoards; |
| struct futureTricks solvedBoard [MAXNOOFBOARDS]; |

Struct | Field | Comment
ddTableResults | int resTable[5][4]; | Encodes the solution of a deal for combinations of denomination and declarer. First index is denomination. Suit encoding. Second index is declarer. Hand encoding. Each entry is a number of tricks.

###

Struct | Field | Comment
ddTablesRes | int noOfBoards; | Number of DD table deals in structure, at most MAXNOOFTABLES
| struct ddTableResults results[X]; | X = MAXNOOFTABLES * DDS_STRAINS

###

###

###

###

struct | Field | Comment
parResults | char parScore[2][16]; | First index is NS/EW. Side encoding.
| char parContractsString [2][128]; | First index is NS/EW. Side encoding.

###

###

struct | Field | Comment
allParResults | struct parResults [MAXNOOFTABLES]; | There are up to 20 declarer/strain combinations per DD table

###

struct | Field | Comment
parResultsDealer | int number; |
| int score; |
| char contracts[10][10]; |

###

struct | Field | Comment
parResultsMaster | int score; |
| int number; |
| struct contractType contracts[10]; |

struct | Field | Comment
contractType | int underTricks; |
| int overTricks; |
| int level; |
| int denom; |
| int seats; |

struct | Field | Comment
parTextResults | char parText[2][128]; |
| int equal; |

struct | Field | Comment
DDSInfo | int major, minor patch; |
| char versionString[10]; | Printable version string
| int system; | 0 unknown, 1 Windows, 2 Cygwin, 3 Linux, 4 Apple
| int compiler; | 0 unknown, 1 Microsoft Visual C++, 2 mingw, 3 GNU g++, 4 clang
| int constructor; | 0 none, 1 DLLMain, 2 Unix-style
| int threading; | 0 none, 1 Windows, 2 OpenMP
| int noOfThreads; |
| char systemString[512]; | Printable summary string

struct | Field | Comment
playTraceBin | int number; | Number of cards in the play trace, starting from the beginning of the hand
| int suit[52]; | Suit encoding.
| int rank[52]; | Encoding 2 .. 14 (not Card encoding).

###

###

struct | Field | Comment
playTracePBN | int number; | Number of cards in the play trace, starting from the beginning of the hand
| int cards[106]; | String of cards with no space in between, also not between tricks. Each card consists of a suit (C/D/H/S) and then a rank (2 .. A). The string must be null-terminated.

###

struct | Field | Comment
playTracesBin | int noOfBoards; |
| struct playTraceBin plays[MAXNOOFBOARDS]; |

struct | Field | Comment
playTracesPBN | int noOfBoards; |
| Struct playTracePBN plays[MAXNOOFBOARDS]; |

###

struct | Field | Comment
solvedPlay | int number; |
| int tricks[53]; | Starting position and up to 52 cards

struct | Field | Comment
solvedPlays | int noOfBoards; |
| struct solvedPlay solved[MAXNOOFBOARDS]; |

### Functions

### SolveBoard struct deal dl, int target, int solutions, int mode, struct futureTricks *futp, int threadIndex | ### SolveBoardPBN struct dealPBN dl, int target, int solutions, int mode, struct futureTricks *futp, ### int threadIndex

### SolveBoardPBN is just like SolveBoard, except for the input format. Historically it was one of the first functions, and it exposes the thread index directly to the user. Later functions generally don’t do that, and they also hide the implementation details such as transposition tables, see below.

###

### SolveBoard solves a single deal “dl” and returns the result in “*futp” which must be declared before calling SolveBoard.

### If you have multiple hands to solve, it is always better to group them together into a single function call than to use SolveBoard.

SolveBoard is thread-safe, so several threads can call SolveBoard in parallel. Thus the user of DDS can create threads and call SolveBoard in parallel over them. The maximum number of threads is fixed in the DLL at compile time and is currently 16. So “threadIndex” must be between 0 and 15 inclusive; see also the function SetMaxThreads. Together with the PlayAnalyse functions, this is the only function that exposes the thread number to the user.

There is a “transposition table” memory associated with each thread. Each node in the table is effectively a position after certain cards have been played and other certain cards remain. The table is not deleted automatically after each call to SolveBoard, so it can be reused from call to call. However, it only really makes sense to reuse the table when the hand is very similar in the two calls. The function will still run if this is not the case, but it won’t be as efficient. The reuse of the transposition table can be controlled by the “mode” parameter, but normally this is not needed and should not be done.

The three parameters “target”, “solutions” and “mode” together control the function. Generally speaking, the target is the number of tricks to be won (at least) by the side to play; solutions controls how many solutions should be returned; and mode controls the search behavior. See next page for definitions.

For equivalent cards, only the highest is returned, and lower equivalent cards are encoded in the futureTricks structure (see “equals”).

target | solutions | Comment
-1 | 1 | Find the maximum number of tricks for the side to play. Return only one of the optimum cards and its score.
-1 | 2 | Find the maximum number of tricks for the side to play. Return all optimum cards and their scores.
0 | 1 | Return only one of the cards legal to play, with score set to 0.
0 | 2 | Return all cards that legal to play, with score set to 0.
1 .. 13 | 1 | If score is -1: Target cannot be reached. If score is 0: In fact no tricks at all can be won. If score is > 0: score will always equal target, even if more tricks can be won. One of the cards achieving the target is returned.
1 .. 13 | 2 | Return all cards meeting (at least) the target. If the target cannot be achieved, only one card is returned with the score set as above.
any | 3 | Return all cards that can be legally played, with their scores in descending order.

mode | Reuse TT? | Comment
0 | Automatic if same trump suit and the same or nearly the same cards distribution, deal.first can be different. | Do not search to find the score if the hand to play has only one card, including its equivalents, to play. Score is set to –2 for this card, indicating that there are no alternative cards. If there are multiple choices for cards to play, search is done to find the score. This mode is very fast but you don’t always search to find the score.
1 | Always search to find the score. Even when the hand to play has only one card, with possible equivalents, to play.
2 | Always

Note: mode no longer always has this effect internally in DDS. We think mode is no longer useful, and we may use it for something else in the future. If you think you need it, let us know!

“Reuse” means “reuse the transposition table from the previous run with the same thread number”. For mode = 2 it is the responsibility of the programmer using the DLL to ensure that reusing the table is safe in the actual situation. Example: Deal is the same, except for deal.first. The trump suit is the same.

1st call, East leads: SolveBoard(deal, -1, 1, 1, &fut, 0), deal.first=1

2nd call, South leads: SolveBoard(deal, -1, 1, 2, &fut, 0), deal.first=2

3rd call, West leads: SolveBoard(deal, -1, 1, 2, &fut, 0), deal.first=3

4th call, North leads: SolveBoard(deal, -1, 1, 2, &fut, 0), deal.first=0

### CalcDDtable struct ddTableDeal tableDeal, struct ddTableResults * tablep | CalcDDtablePBN struct ddTableDealPBN tableDealPBN, struct ddTableResults * tablep

###

### CalcDDtablePBN is just like CalcDDtable, except for the input format.

CalcDDtable solves a single deal “tableDeal” and returns the double-dummy values for the initial 52 cards for all the 20 combinations of denomination and declarer in “*tablep”, which must be declared before calling CalcDDtable.

###

CalcAllTables struct ddTableDeals *dealsp, int mode, int trumpFilter[5], struct ddTablesRes *resp, struct allParResults *presp ###  | CalcAllTablesPBN struct ddTableDealsPBN *dealsp, int mode, int trumpFilter[5], struct ddTablesRes *resp, struct allParResults *presp

### CalcAllTablesPBN is just like CalcAllTables, except for the input format.

CalcAllTables calculates the double dummy values of the denomination/declarer hand combinations in “*dealsp” for a number of DD tables in parallel. This increases the speed compared to calculating these values using a CalcDDtable call for each DD table. The results are returned in “*resp” which must be defined before CalcAllTables is called.

The “mode” parameter contains the vulnerability (Vulnerable encoding; not to be confused with the SolveBoard mode) for use in the par calculation. It is set to -1 if no par calculation is to be performed.

There are 5 possible denominations or strains (the four trump suits and no trump). The parameter “trumpFilter” describes which, if any, of the 5 possibilities that will be excluded from the calculations. They are defined in Suit encoding order, so setting trumpFilter to {FALSE, FALSE, TRUE, TRUE, TRUE} means that values will only be calculated for the trump suits spades and hearts.

The maximum number of DD tables in a CalcAllTables call depends on the number of strains required, see the following table:

Number of strains | Maximum number of DD tables
5 | 32
4 | 40
3 | 53
2 | 80
1 | 160

### SolveAllBoards struct boards *bop, struct solvedBoards * solvedp | ### SolveAllChunksBin struct boards *bop, struct solvedBoards *solvedp, int chunkSize | ### SolveAllChunksPBN struct boardsPBN *bop, struct solvedBoards *solvedp, int chunkSize

SolveAllChunks is an alias for SolveAllChunksPBN; don’t use it.

SolveAllBoards used to be an alias for SolveAllChunksPBN with a chunkSize of 1; however this has been changed in v2.8, and we now recommend only to use SolveAllBoards and not the chunk functions any more; explanation follows.

The SolveAll* functions invoke SolveBoard several times in parallel in multiple threads, rather than sequentially in a single thread. This increases execution speed. Up to 200 boards are permitted per call.

It is important to understand the parallelism and the concept of a chunk.

If the chunk size is 1, then each of the threads starts out with a single board. If there are four threads, then boards 0, 1, 2 and 3 are initially solved. If thread 2 is finished first, it gets the next available board, in this case board 4. Perhaps this is a particularly easy board, so thread 2 also finishes this board before any other thread completes. Thread 2 then also gets board 5, and so on. This continues until all boards have been solved. In the end, three of the threads will be waiting for the last thread to finish, which causes a bit of inefficiency.

The transposition table in a given thread (see SolveBoard) is generally not reused between board 2, 4 and 5 in thread 2. This only happens if SolveBoard itself determines that the boards are suspiciously similar.

If the chunk size is 2, then initially thread 0 gets boards 0 and 1, thread 1 gets boards 2 and 3, thread 2 gets boards 4 and 5, and thread 3 gets boards 6 and 7. When a thread is finished, it gets two new boards in one go, for instance boards 8 and 9. The transposition table in a given thread is reused within a chunk.

No matter what the chunk size is, the boards are solved in parallel. If the user knows that boards are grouped in chunks of 2 or 10, it is possible to force the DD solver to use this knowledge. However, this is rather limiting on the user, as the alignment must remain perfect throughout the batch.

SolveAllBoards now detects repetitions automatically within a batch, whether or not the hands are evenly arranged and whether or not the duplicates are next to each other. This is more flexible and transparent to the user, and the overhead is negligible. Therefore, use SolveAllBoards!

Par struct ddTableResults *tablep, struct parResults *presp, int vulnerable | DealerPar struct ddTableResults *tablep, struct parResultsDealer *presp, int dealer, int vulnerable
SidesPar struct ddTableResults *tablep, struct parResultsDealer *sidesRes[2], int vulnerable |
DealerParBin struct ddTableResults *tablep, struct parResultsMaster * presp, int vulnerable | SidesParBin struct ddTableResults *tablep, struct parResultsMaster * presp, int dealer, int vulnerable
ConvertToDealerTextFormat struct parResultsMaster *pres, char *resp | ConvertToSidesTextFormat struct parResultsMaster *pres, struct parTextResults *resp

The functions Par, DealerPar, SidesPar, DealerParBin and SidesParBin calculate the par score and par contracts of a given double-dummy solution matrix “*tablep” which would often be the solution of a call to CalcDDtable. Since the input is a table, there is no PBN and non-PBN version of these functions.

Before the functions can be called, a structure of the type “parResults”, “parResultsDealer” or “parResultsMaster” must already have been defined.

The “vulnerable” parameter is given using Vulnerable encoding.

The Par() function uses knowledge of the vulnerability, but not of the dealer. It attempts to return results for both declaring sides. These results can be different in some rare cases, for instance when both sides can make 1NT due to the opening lead.

The DealerPar() function also uses knowledge of the “dealer” using Hand encoding. The argument is that in all practical cases, the dealer is known when the vulnerability is known. Therefore all results returned will be for the same side.

The SidesPar() function is similar to the Par() function, the only difference is that the par results are given in the same format as for DealerPar().

In Par() and SidesPar() there may be more than one par score; in DealerPar() that is not the case. Par() returns the scores as a text string, for instance “NS -460”, while DealerPar() and SidesPar() use an integer, -460.

There may be several par contracts, for instance 3NT just making and 5C just making. Each par contract is returned as a text string. The formats are a bit different betweeen the two output format alternatives.

Par() returns the par contracts separated by commas. Possible different trick levels of par score contracts are enumerated in the contract description, e.g the possible trick levels 3, 4 and 5 in no trump are given as 345N. Examples:

· “NS:NS 23S,NS 23H”. North and South as declarer make 2 or 3 spades and hearts contracts, 2 spades and 2 hearts with an overtrick. This is from the NS view, shown by “NS:” meaning that NS made the first bid. Note that this information is actually not enough, as it may be that N and S can make a given contract and that either E or W can bid this same contract (for instance 1NT) before N but not before S. So in the rare cases where the NS and EW sides are not the same, the results will take some manual inspection.

· “NS:NS 23S,N 23H”: Only North makes 3 hearts.

· “EW:NS 23S,N 23H”: This time the result is the same when EW open the bidding.

DealerPar() and SidesPar() give each par contract as a separate text string:

· “4S*-EW-1” means that E and W can both sacrifice in four spades doubled, going down one trick.

· “3N-EW” means that E and W can both make exactly 3NT.

· “4N-W+1” means that only West can make 4NT +1. In the last example, 5NT just making can also be considered a par contract, but North-South don’t have a profitable sacrifice against 4NT, so the par contract is shown in this way. If North-South did indeed have a profitable sacrifice, perhaps 5C*_NS-2, then par contract would have been shown as “5N-W”. Par() would show “4N-W+1” as “W 45N”.

· SidesPar() give the par contract text strings as described above for each side.

DealerParBin and SidesParBin are similar to DealerPar and SidesPar, respectively, except that both functions give the output results in binary using the “parResultsMaster” structure. This simplifies the writing of a conversion program to get an own result output format. Examples of such programs are ConvertToDealerTextFormat and ConvertToSidesTextFormat.

After DealerParBin or SidesParBin is called, the results in parResultsMaster are used when calling ConvertToDealerTextFormat resp. ConvertToSidesTextFormat.

Output example from ConvertToDealerTextFormat:

“Par 110: NS 2S NS 2H”

Output examples from ConvertToSidesTextFormat:

“NS Par 130: NS 2D+2 NS 2C+2” when it does not matter who starts the bidding.

”NS Par -120: W 2NT

EW Par 120: W 1NT+1” when it matters who starts the bidding.

CalcPar struct ddTableDeal dl int vulnerable, struct ddTableResults * tp, struct parResults *presp | CalcParPBN struct ddTableDealPBN dl, struct ddTableResults * tp, int vulnerable, struct parResults *presp |

### CalcParPBN is just like CalcPar, except for the input format.

### Each of these functions calculates both the double-dummy table solution and the par solution to a given deal.

Both functions are deprecated. Instead use one of the CalcDDtable functions followed by Par().

AnalysePlayBin struct deal dl, struct playTraceBin play, struct solvedPlay *solvedp, int thrId | AnalysePlayPBN struct dealPBN dlPBN, struct playTracePBN playPBN, struct solvedPlay *solvedp, int thrId

###
AnalysePlayPBN is just like AnalysePlayBin, except for the input format.

### The function returns a list of double-dummy values after each specific played card in a hand. Since the function uses SolveBoard, the same comments apply concerning the thread number “thrId” and the transposition tables.

### As an example, let us say the DD result in a given contract is 9 tricks for declarer. The play consists of the first trick, two cards from the second trick, and then declarer claims. The lead and declarer’s play to the second trick (he wins the first trick) are sub-optimal. Then the trace would look like this, assuming each sub-optimal costs 1 trick:

###

### 9 10 10 10 10 9 9

###

### The number of tricks are always seen from declarer’s viewpoint (he is the one to the right of the opening leader). There is one more result in the trace than there are cards played, because there is a DD value before any card is played, and one DD value after each card played.

AnalyseAllPlaysBin struct boards *bop, struct playTracesBin *plp, struct solvedPlays *solvedp, int chunkSize | AnalyseAllPlaysPBN struct boardsPBN *bopPBN, struct playTracesPBN *plpPBN, struct solvedPlays *solvedp, int chunkSize

###
AnalyseAllPlaysPBN is just like AnalyseAllPlaysBin, except for the input format.

The AnalyseAllPlays* functions invoke SolveBoard several times in parallel in multiple threads, rather than sequentially in a single thread. This increases execution speed. Up to 20 boards are permitted per call.

Concerning chunkSize, exactly the same remarks apply as with SolveAllChunksBin.

SetMaxThreads int userThreads | FreeMemory void

# SetMaxThreads returns the actual number of threads.

# DDS has a preferred memory size per thread, currently about 95 MB, and a maximum memory size per thread, currently about 160 MB. It will also not use more than 70% of the available memory. It will not create more threads than there are processor cores, as this will only require more memory and will not improve performance. Within these constraints, DDS auto-configures the number of threads.

#

# DDS first detects the number of cores and the available memory. If this doesn't work for some reason, it defaults to 1 thread which is allowed to use the maximum memory size per thread.

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# DDS then checks whether a number of threads equal to the number of cores will fit within the available memory when each thread may use the maximum memory per thread. If there is not enough memory for this, DDS scales back its ambition. If there is enough memory for the preferred memory size, then DDS still creates a number of threads equal to the number of cores. If there is not even enough memory for this, DDS scales back the number of threads to fit within the memory.

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# The user can suggest to DDS a number of threads by calling SetMaxThreads. DDS will never create more threads than requested, but it may create fewer if there is not enough memory, calculated as above. Calling SetMaxThreads is optional, not mandatory. DDS will always select a suitable number of threads on its own.

# It may be possible, especially on non-Windows systems, to call SetMaxThreads() actively, even though the user does not want to influence the default values. In this case, use a 0 argument.

#

# SetMaxThreads can be called multiple times even within the same session. So it is theoretically possible to change the number of threads dynamically.

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# It is possible to ask DDS to give up its dynamically allocated memory by calling FreeMemory. This could be useful for instance if there is a long pause where DDS is not used within a session. DDS will free its memory when the DLL detaches from the user program, so there is no need for the user to call this function before detaching.

#

GetDDSInfo DDSInfo * info |

#

# This function returns various system and version information.
Return codes

#

# Value | # Code | # Comment
# 1 | # RETURN_NO_FAULT | #
# -1 | # RETURN_UNKNOWN_FAULT | # Currently happens when fopen() returns an error or when AnalyseAllPlaysBin() gets a different number of boards in its first two arguments.
# -2 | # RETURN_ZERO_CARDS | # SolveBoard(), self-explanatory.
# -3 | # RETURN_TARGET_TOO_HIGH | # SolveBoard(), target is higher than the number of tricks remaining.
# -4 | # RETURN_DUPLICATE_CARDS | # SolveBoard(), self-explanatory.
# -5 | # RETURN_TARGET_WRONG_LO | # SolveBoard(), target is less than -1.
# -7 | # RETURN_TARGET_WRONG_HI | # SolveBoard(), target is higher than 13.
# -8 | # RETURN_SOLNS_WRONG_LO | # SolveBoard(), solutions is less than 1.
# -9 | # RETURN_SOLNS_WRONG_HI | # SolveBoard(), solutions is higher than 3.
# -10 | # RETURN_TOO_MANY_CARDS | # SolveBoard(), self-explanatory.
# -12 | # RETURN_SUIT_OR_RANK | # SolveBoard(), either currentTrickSuit or currentTrickRank have wrong data.
# -13 | # RETURN_PLAYED_CARD | # SolveBoard(), card already played is also a card still remaining to play.
# -14 | # RETURN_CARD_COUNT | # SolveBoard(), wrong number of remaining cards for a hand.
# -15 | # RETURN_THREAD_INDEX | # SolveBoard(), thread number is less than 0 or higher than the maximum permitted.
# -16 | # RETURN_MODE_WRONG_LO | # SolveBoard(), mode is less than 0.
# -17 | # RETURN_MODE_WRONG_HI | # SolveBoard(), mode is greater than 2.
# -18 | # RETURN_TRUMP_WRONG | # SolveBoard(), trump is not one or 0, 1, 2, 3, 4
# -19 | # RETURN_FIRST_WRONG | # SolveBoard(), first is not one or 0, 1, 2
# -98 | # RETURN_PLAY_FAULT | # AnalysePlay*() family of functions. (a) Less than 0 or more than 52 cards supplied. (b) Invalid suit or rank supplied. (c) A played card is not held by the right player.
# -99 | # RETURN_PBN_FAULT | # Returned from a number of places if a PBN string is faulty.
# -101 | # RETURN_TOO_MANY_THREADS | # Currently never returned.
# -102 | # RETURN_THREAD_CREATE | # Returned from multi-threading functions.
# -103 | # RETURN_THREAD_WAIT | # Returned from multi-threading functions when something went wrong while waiting for all threads to complete.
# -201 | # RETURN_NO_SUIT | # CalcAllTables*(), returned when the denomination filter vector has no entries
# -202 | # RETURN_TOO_MANY_TABLES | # CalcAllTables*(), returned when too many tables are requested.
# -301 | # RETURN_CHUNK_SIZE | # SolveAllChunks*(), returned when the chunk size is < 1.

# Revision History

Rev A, 2006-02-25. First issue.

Rev B, 2006-03-20 Updated issue.

Rev C, 2006-03-28 Updated issue. Addition of the SolveBoard parameter ”mode”.

Rev D, 2006-04-05 Updated issue. Usage of target=0 to list all cards that are legal to play.

Rev E, 2006-05-29 Updated issue. New error code –10 for number of cards > 52.

Rev F, 2006-08-09 Updated issue. New mode parameter value = 2. New error code –11 for calling SolveBoard with mode = 2 and forbidden values of other parameters.

Rev F1, 2006-08-14 Clarifications on conditions for returning scores for the different combinations of the values for target and solutions.

Rev F2, 2006-08-26 New error code –12 for wrongly set values of deal.currentTrickSuit and deal.currentTrickRank.

Rev G, 2007-01-04 New DDS release 1.1, otherwise no change compared to isse F2.

Rev H, 2007-04-23 DDS release 1.4, changes for parameter mode=2.

Rev I, 2010-04-10 DDS release 2.0, multi-thread support.

Rev J, 2010-05-29 DDS release 2.1, OpenMP support, reuse of previous DD transposition table results of similar deals.

Rev K, 2010-10-27 Correction of fault in the description: 2nd index in resTable of the structure ddTableResults is declarer hand.

Rev L, 2011-10-14 Added SolveBoardPBN and CalcDDtablePBN.

Rev M, 2012-07-06 Added SolveAllBoards.

Rev N, 2012-07-16 Max number of threads is 8.

Rev O, 2012-10-21 Max number of threads is configured at initial start-up, but never exceeds 16.

Rev P, 2013-03-16 Added functions CalcPar and CalcParPBN.

Rev Q, 2014-01-09 Added functions CalcAllTables/CalcAllTablesPBN.

Rev R, 2014-01-13 Updated functions CalcAllTables/CalcAllTablesPBN.

Rev S, 2014-01-13 Updated functions CalcAllTables/CalcAllTablesPBN.

Rev T, 2014-03-01 Added function SolveAllChunks.

Rev U, 2014-09-15 Added functions DealerPar, SidesPar, AnalysePlayBin, AnalysePlayPBN, AnalyseAllPlaysBin, AnalyseAllPlaysPBN.

Rev V, 2014-10-14 Added functions SetMaxThreads, FreeMemory, DealerParBin, SidesParBin, ConvertToDealerTextFormat, ConvertToSidesTextFormat.

Rev X, 2014-11-16 Extended maximum number of tables when calling CalcAllTables.