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/*
* positionid.c
*
* by Gary Wong <gary@cs.arizona.edu>, 1998-1999.
*
* An implementation of the position "external" key/IDs at:
*
* http://www.gnu.org/manual/gnubg/html_node/A-technical-description-of-the-Position-ID.html
*
* Please see that page for more information.
*
* For internal use, we use another "key", much faster to encode or decode
* that is essentially the raw board squeezed down to 4 bits/point.
*
* This library also calculates bearoff IDs, which are enumerations of the
*
* c+6
* C
* 6
*
* combinations of (up to c) chequers among 6 points.
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 3 or later of the GNU General Public License as
* published by the Free Software Foundation.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: positionid.c,v 1.54 2014/10/07 07:14:28 plm Exp $
*/
#include "config.h"
#include <glib.h>
#include <errno.h>
#include <string.h>
#include "positionid.h"
extern void
PositionKey(const TanBoard anBoard, positionkey * pkey)
{
unsigned int i, j;
unsigned int *anpBoard = pkey->data;
for (i = 0, j = 0; i < 3; i++, j += 8) {
anpBoard[i] = anBoard[1][j] + (anBoard[1][j + 1] << 4)
+ (anBoard[1][j + 2] << 8) + (anBoard[1][j + 3] << 12)
+ (anBoard[1][j + 4] << 16) + (anBoard[1][j + 5] << 20)
+ (anBoard[1][j + 6] << 24) + (anBoard[1][j + 7] << 28);
anpBoard[i + 3] = anBoard[0][j] + (anBoard[0][j + 1] << 4)
+ (anBoard[0][j + 2] << 8) + (anBoard[0][j + 3] << 12)
+ (anBoard[0][j + 4] << 16) + (anBoard[0][j + 5] << 20)
+ (anBoard[0][j + 6] << 24) + (anBoard[0][j + 7] << 28);
}
anpBoard[6] = anBoard[0][24] + (anBoard[1][24] << 4);
}
extern void
PositionFromKey(TanBoard anBoard, const positionkey * pkey)
{
unsigned int i, j;
unsigned int const *anpBoard = pkey->data;
for (i = 0, j = 0; i < 3; i++, j += 8) {
anBoard[1][j] = anpBoard[i] & 0x0f;
anBoard[1][j + 1] = (anpBoard[i] >> 4) & 0x0f;
anBoard[1][j + 2] = (anpBoard[i] >> 8) & 0x0f;
anBoard[1][j + 3] = (anpBoard[i] >> 12) & 0x0f;
anBoard[1][j + 4] = (anpBoard[i] >> 16) & 0x0f;
anBoard[1][j + 5] = (anpBoard[i] >> 20) & 0x0f;
anBoard[1][j + 6] = (anpBoard[i] >> 24) & 0x0f;
anBoard[1][j + 7] = (anpBoard[i] >> 28) & 0x0f;
anBoard[0][j] = anpBoard[i + 3] & 0x0f;
anBoard[0][j + 1] = (anpBoard[i + 3] >> 4) & 0x0f;
anBoard[0][j + 2] = (anpBoard[i + 3] >> 8) & 0x0f;
anBoard[0][j + 3] = (anpBoard[i + 3] >> 12) & 0x0f;
anBoard[0][j + 4] = (anpBoard[i + 3] >> 16) & 0x0f;
anBoard[0][j + 5] = (anpBoard[i + 3] >> 20) & 0x0f;
anBoard[0][j + 6] = (anpBoard[i + 3] >> 24) & 0x0f;
anBoard[0][j + 7] = (anpBoard[i + 3] >> 28) & 0x0f;
}
anBoard[0][24] = anpBoard[6] & 0x0f;
anBoard[1][24] = (anpBoard[6] >> 4) & 0x0f;
}
/* In evaluations, the function above is often followed by swapping
* the board. This is expensive (SwapSides is about as costly as
* PositionFromKey itself).
* Provide one that fills the board already swapped. */
extern void
PositionFromKeySwapped(TanBoard anBoard, const positionkey * pkey)
{
unsigned int i, j;
unsigned int const *anpBoard = pkey->data;
for (i = 0, j = 0; i < 3; i++, j += 8) {
anBoard[0][j] = anpBoard[i] & 0x0f;
anBoard[0][j + 1] = (anpBoard[i] >> 4) & 0x0f;
anBoard[0][j + 2] = (anpBoard[i] >> 8) & 0x0f;
anBoard[0][j + 3] = (anpBoard[i] >> 12) & 0x0f;
anBoard[0][j + 4] = (anpBoard[i] >> 16) & 0x0f;
anBoard[0][j + 5] = (anpBoard[i] >> 20) & 0x0f;
anBoard[0][j + 6] = (anpBoard[i] >> 24) & 0x0f;
anBoard[0][j + 7] = (anpBoard[i] >> 28) & 0x0f;
anBoard[1][j] = anpBoard[i + 3] & 0x0f;
anBoard[1][j + 1] = (anpBoard[i + 3] >> 4) & 0x0f;
anBoard[1][j + 2] = (anpBoard[i + 3] >> 8) & 0x0f;
anBoard[1][j + 3] = (anpBoard[i + 3] >> 12) & 0x0f;
anBoard[1][j + 4] = (anpBoard[i + 3] >> 16) & 0x0f;
anBoard[1][j + 5] = (anpBoard[i + 3] >> 20) & 0x0f;
anBoard[1][j + 6] = (anpBoard[i + 3] >> 24) & 0x0f;
anBoard[1][j + 7] = (anpBoard[i + 3] >> 28) & 0x0f;
}
anBoard[1][24] = anpBoard[6] & 0x0f;
anBoard[0][24] = (anpBoard[6] >> 4) & 0x0f;
}
static inline void
addBits(unsigned char auchKey[10], unsigned int bitPos, unsigned int nBits)
{
unsigned int k = bitPos / 8;
unsigned int r = (bitPos & 0x7);
unsigned int b = (((unsigned int) 0x1 << nBits) - 1) << r;
auchKey[k] |= (unsigned char) b;
if (k < 8) {
auchKey[k + 1] |= (unsigned char) (b >> 8);
auchKey[k + 2] |= (unsigned char) (b >> 16);
} else if (k == 8) {
auchKey[k + 1] |= (unsigned char) (b >> 8);
}
}
extern void
oldPositionKey(const TanBoard anBoard, oldpositionkey * pkey)
{
unsigned int i, iBit = 0;
const unsigned int *j;
memset(pkey, 0, sizeof(oldpositionkey));
for (i = 0; i < 2; ++i) {
const unsigned int *const b = anBoard[i];
for (j = b; j < b + 25; ++j) {
const unsigned int nc = *j;
if (nc) {
addBits(pkey->auch, iBit, nc);
iBit += nc + 1;
} else {
++iBit;
}
}
}
}
extern void
oldPositionFromKey(TanBoard anBoard, const oldpositionkey * pkey)
{
int i = 0, j = 0, k;
const unsigned char *a;
memset(anBoard[0], 0, sizeof(anBoard[0]));
memset(anBoard[1], 0, sizeof(anBoard[1]));
for (a = pkey->auch; a < pkey->auch + 10; ++a) {
unsigned char cur = *a;
for (k = 0; k < 8; ++k) {
if ((cur & 0x1)) {
if (i >= 2 || j >= 25) { /* Error, so return - will probably show error message */
return;
}
++anBoard[i][j];
} else {
if (++j == 25) {
++i;
j = 0;
}
}
cur >>= 1;
}
}
}
static char *
oldPositionIDFromKey(const oldpositionkey * pkey)
{
unsigned char const *puch = pkey->auch;
static char szID[L_POSITIONID + 1];
char *pch = szID;
static char aszBase64[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int i;
for (i = 0; i < 3; i++) {
*pch++ = aszBase64[puch[0] >> 2];
*pch++ = aszBase64[((puch[0] & 0x03) << 4) | (puch[1] >> 4)];
*pch++ = aszBase64[((puch[1] & 0x0F) << 2) | (puch[2] >> 6)];
*pch++ = aszBase64[puch[2] & 0x3F];
puch += 3;
}
*pch++ = aszBase64[*puch >> 2];
*pch++ = aszBase64[(*puch & 0x03) << 4];
*pch = 0;
return szID;
}
extern char *
PositionIDFromKey(const positionkey * pkey)
{
TanBoard anBoard;
oldpositionkey okey;
PositionFromKey(anBoard, pkey);
oldPositionKey((ConstTanBoard) anBoard, &okey);
return oldPositionIDFromKey(&okey);
}
extern char *
PositionID(const TanBoard anBoard)
{
oldpositionkey key;
oldPositionKey(anBoard, &key);
return oldPositionIDFromKey(&key);
}
extern int
PositionFromXG(TanBoard anBoard, const char *pos)
{
int i;
for (i = 0; i < 26; i++) {
int p0, p1;
if (i == 0) {
p0 = 24;
p1 = -1;
} else if (i == 25) {
p0 = -1;
p1 = 24;
} else {
p0 = 24 - i;
p1 = i - 1;
}
if (pos[i] >= 'A' && pos[i] <= 'P') {
if (p0 > -1)
anBoard[0][p0] = 0;
anBoard[1][p1] = pos[i] - 'A' + 1;
} else if (pos[i] >= 'a' && pos[i] <= 'p') {
anBoard[0][p0] = pos[i] - 'a' + 1;
if (p1 > -1)
anBoard[1][p1] = 0;
} else if (pos[i] == '-') {
if (p0 > -1)
anBoard[0][p0] = 0;
if (p1 > -1)
anBoard[1][p1] = 0;
} else {
return 1;
}
}
return 0;
}
extern int
CheckPosition(const TanBoard anBoard)
{
unsigned int ac[2], i;
/* Check for a player with over 15 chequers */
for (i = ac[0] = ac[1] = 0; i < 25; i++)
if ((ac[0] += anBoard[0][i]) > 15 || (ac[1] += anBoard[1][i]) > 15) {
errno = EINVAL;
return 0;
}
/* Check for both players having chequers on the same point */
for (i = 0; i < 24; i++)
if (anBoard[0][i] && anBoard[1][23 - i]) {
errno = EINVAL;
return 0;
}
/* Check for both players on the bar against closed boards */
for (i = 0; i < 6; i++)
if (anBoard[0][i] < 2 || anBoard[1][i] < 2)
return 1;
if (!anBoard[0][24] || !anBoard[1][24])
return 1;
errno = EINVAL;
return 0;
}
extern void
ClosestLegalPosition(TanBoard anBoard)
{
unsigned int i, j, ac[2];
/* Limit each player to 15 chequers */
for (i = 0; i < 2; i++) {
ac[i] = 15;
for (j = 0; j < 25; j++) {
if (anBoard[i][j] <= ac[i])
ac[i] -= anBoard[i][j];
else {
anBoard[i][j] = ac[i];
ac[i] = 0;
}
}
}
/* Forbid both players having a chequer on the same point */
for (i = 0; i < 24; i++)
if (anBoard[0][i])
anBoard[1][23 - i] = 0;
/* If both players have closed boards, let at least one of them off
* the bar */
for (i = 0; i < 6; i++)
if (anBoard[0][i] < 2 || anBoard[1][i] < 2)
/* open board */
return;
if (anBoard[0][24])
anBoard[1][24] = 0;
}
extern unsigned char
Base64(const unsigned char ch)
{
if (ch >= 'A' && ch <= 'Z')
return ch - 'A';
if (ch >= 'a' && ch <= 'z')
return (ch - 'a') + 26;
if (ch >= '0' && ch <= '9')
return (ch - '0') + 52;
if (ch == '+')
return 62;
if (ch == '/')
return 63;
return 255;
}
extern int
PositionFromID(TanBoard anBoard, const char *pchEnc)
{
oldpositionkey key;
unsigned char ach[L_POSITIONID + 1], *pch = ach, *puch = key.auch;
int i;
memset(ach, 0, L_POSITIONID + 1);
for (i = 0; i < L_POSITIONID && pchEnc[i]; i++)
pch[i] = Base64((unsigned char) pchEnc[i]);
for (i = 0; i < 3; i++) {
*puch++ = (unsigned char) (pch[0] << 2) | (pch[1] >> 4);
*puch++ = (unsigned char) (pch[1] << 4) | (pch[2] >> 2);
*puch++ = (unsigned char) (pch[2] << 6) | pch[3];
pch += 4;
}
*puch = (unsigned char) (pch[0] << 2) | (pch[1] >> 4);
oldPositionFromKey(anBoard, &key);
return CheckPosition((ConstTanBoard) anBoard);
}
extern int
EqualBoards(const TanBoard anBoard0, const TanBoard anBoard1)
{
int i;
for (i = 0; i < 25; i++)
if (anBoard0[0][i] != anBoard1[0][i] || anBoard0[1][i] != anBoard1[1][i])
return 0;
return 1;
}
#define MAX_N 40
#define MAX_R 25
static unsigned int anCombination[MAX_N][MAX_R], fCalculated = 0;
static void
InitCombination(void)
{
unsigned int i, j;
for (i = 0; i < MAX_N; i++)
anCombination[i][0] = i + 1;
for (j = 1; j < MAX_R; j++)
anCombination[0][j] = 0;
for (i = 1; i < MAX_N; i++)
for (j = 1; j < MAX_R; j++)
anCombination[i][j] = anCombination[i - 1][j - 1] + anCombination[i - 1][j];
fCalculated = 1;
}
extern unsigned int
Combination(const unsigned int n, const unsigned int r)
{
g_assert(n <= MAX_N && r <= MAX_R);
if (!fCalculated)
InitCombination();
return anCombination[n - 1][r - 1];
}
static unsigned int
PositionF(unsigned int fBits, unsigned int n, unsigned int r)
{
if (n == r)
return 0;
return (fBits & (1u << (n - 1))) ? Combination(n - 1, r) +
PositionF(fBits, n - 1, r - 1) : PositionF(fBits, n - 1, r);
}
extern unsigned int
PositionBearoff(const unsigned int anBoard[], unsigned int nPoints, unsigned int nChequers)
{
unsigned int i, fBits, j;
for (j = nPoints - 1, i = 0; i < nPoints; i++)
j += anBoard[i];
fBits = 1u << j;
for (i = 0; i < nPoints - 1; i++) {
j -= anBoard[i] + 1;
fBits |= (1u << j);
}
return PositionF(fBits, nChequers + nPoints, nPoints);
}
static unsigned int
PositionInv(unsigned int nID, unsigned int n, unsigned int r)
{
unsigned int nC;
if (!r)
return 0;
else if (n == r)
return (1u << n) - 1;
nC = Combination(n - 1, r);
return (nID >= nC) ? (1u << (n - 1)) | PositionInv(nID - nC, n - 1, r - 1) : PositionInv(nID, n - 1, r);
}
extern void
PositionFromBearoff(unsigned int anBoard[], unsigned int usID, unsigned int nPoints, unsigned int nChequers)
{
unsigned int fBits = PositionInv(usID, nChequers + nPoints, nPoints);
unsigned int i, j;
for (i = 0; i < nPoints; i++)
anBoard[i] = 0;
j = nPoints - 1;
for (i = 0; i < (nChequers + nPoints); i++) {
if (fBits & (1u << i)) {
if (j == 0)
break;
j--;
} else
anBoard[j]++;
}
}
extern unsigned short
PositionIndex(unsigned int g, const unsigned int anBoard[6])
{
unsigned int i, fBits;
unsigned int j = g - 1;
for (i = 0; i < g; i++)
j += anBoard[i];
fBits = 1u << j;
for (i = 0; i < g - 1; i++) {
j -= anBoard[i] + 1;
fBits |= (1u << j);
}
/* FIXME: 15 should be replaced by nChequers, but the function is
* only called from bearoffgammon, so this should be fine. */
return (unsigned short) PositionF(fBits, 15, g);
}
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