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typedef struct {
cube_t cube;
cube_t inverse;
int8_t nmoves;
int8_t depth;
uint8_t moves[MAXLEN];
_Atomic int64_t *nsols;
int64_t maxsolutions;
uint8_t h;
uint8_t k;
uint8_t base;
const uint32_t *cocsepdata;
const uint8_t *h48data;
const uint8_t *h48data_fallback;
uint64_t solutions_size;
char **nextsol;
uint8_t nissbranch;
int8_t npremoves;
uint8_t premoves[MAXLEN];
} dfsarg_solveh48_t;
STATIC uint32_t allowednextmove_h48(uint8_t *, uint8_t, uint32_t);
STATIC void solve_h48_appendsolution(dfsarg_solveh48_t *);
STATIC_INLINE bool solve_h48_stop(dfsarg_solveh48_t *);
STATIC int64_t solve_h48_dfs(dfsarg_solveh48_t *);
STATIC int64_t solve_h48(cube_t, int8_t, int8_t,
int8_t, uint64_t, const void *, uint64_t, char *);
STATIC uint32_t
allowednextmove_h48(uint8_t *moves, uint8_t n, uint32_t h48branch)
{
uint32_t result = MM_ALLMOVES;
if (h48branch & MM_NORMALBRANCH)
result &= MM_NOHALFTURNS;
if (n < 1)
return result;
uint8_t base1 = movebase(moves[n-1]);
uint8_t axis1 = moveaxis(moves[n-1]);
result = disable_moves(result, base1 * 3);
if (base1 % 2)
result = disable_moves(result, (base1 - 1) * 3);
if (n == 1)
return result;
uint8_t base2 = movebase(moves[n-2]);
uint8_t axis2 = moveaxis(moves[n-2]);
if(axis1 == axis2)
result = disable_moves(result, base2 * 3);
return result;
}
STATIC void
solve_h48_appendsolution(dfsarg_solveh48_t *arg)
{
int64_t strl;
uint8_t invertedpremoves[MAXLEN];
char *solution = *arg->nextsol;
strl = writemoves(
arg->moves, arg->nmoves, arg->solutions_size, *arg->nextsol);
if (strl < 0)
goto solve_h48_appendsolution_error;
*arg->nextsol += strl-1;
arg->solutions_size -= strl-1;
if (arg->npremoves) {
**arg->nextsol = ' ';
(*arg->nextsol)++;
arg->solutions_size--;
invertmoves(arg->premoves, arg->npremoves, invertedpremoves);
strl = writemoves(invertedpremoves,
arg->npremoves, arg->solutions_size, *arg->nextsol);
if (strl < 0)
goto solve_h48_appendsolution_error;
*arg->nextsol += strl-1;
arg->solutions_size -= strl-1;
}
LOG("Solution found: %s\n", solution);
**arg->nextsol = '\n';
(*arg->nextsol)++;
arg->solutions_size--;
(*arg->nsols)++;
solve_h48_appendsolution_error:
/* We could add some logging, but writemoves() already does */
return;
}
STATIC_INLINE bool
solve_h48_stop(dfsarg_solveh48_t *arg)
{
uint32_t data, data_inv;
int8_t cbound, cbound_inv, h48bound, h48bound_inv;
arg->nissbranch = MM_NORMAL;
cbound = get_h48_cdata(arg->cube, arg->cocsepdata, &data);
if (cbound + arg->nmoves + arg->npremoves > arg->depth)
return true;
cbound_inv = get_h48_cdata(arg->inverse, arg->cocsepdata, &data_inv);
if (cbound_inv + arg->nmoves + arg->npremoves > arg->depth)
return true;
h48bound = get_h48_bound(arg->cube, data, arg->h, arg->k, arg->h48data);
/* If the h48 bound is > 0, we add the base value. */
/* Otherwise, we use the fallback h0k4 value instead. */
if (arg->k == 2) {
if (h48bound == 0) {
h48bound = get_h48_bound(
arg->cube, data, 0, 4, arg->h48data_fallback);
} else {
h48bound += arg->base;
}
}
if (h48bound + arg->nmoves + arg->npremoves > arg->depth)
return true;
if (h48bound + arg->nmoves + arg->npremoves == arg->depth)
arg->nissbranch = MM_INVERSEBRANCH;
h48bound_inv = get_h48_bound(arg->inverse, data_inv, arg->h, arg->k, arg->h48data);
if (arg->k == 2) {
if (h48bound_inv == 0) {
h48bound_inv = get_h48_bound(
arg->inverse, data_inv, 0, 4, arg->h48data_fallback);
} else {
h48bound_inv += arg->base;
}
}
if (h48bound_inv + arg->nmoves + arg->npremoves > arg->depth)
return true;
if (h48bound_inv + arg->nmoves + arg->npremoves == arg->depth)
arg->nissbranch = MM_NORMALBRANCH;
return false;
}
STATIC int64_t
solve_h48_dfs(dfsarg_solveh48_t *arg)
{
dfsarg_solveh48_t nextarg;
int64_t ret;
uint8_t m;
if (*arg->nsols == arg->maxsolutions)
return 0;
if (solve_h48_stop(arg))
return 0;
if (issolved(arg->cube)) {
if (arg->nmoves + arg->npremoves != arg->depth)
return 0;
solve_h48_appendsolution(arg);
return 1;
}
nextarg = *arg;
ret = 0;
uint32_t allowed;
if(arg->nissbranch & MM_INVERSE) {
allowed = allowednextmove_h48(arg->premoves, arg->npremoves, arg->nissbranch);
for (m = 0; m < 18; m++) {
if(allowed & (1 << m)) {
nextarg.npremoves = arg->npremoves + 1;
nextarg.premoves[arg->npremoves] = m;
nextarg.inverse = move(arg->inverse, m);
nextarg.cube = premove(arg->cube, m);
ret += solve_h48_dfs(&nextarg);
}
}
} else {
allowed = allowednextmove_h48(arg->moves, arg->nmoves, arg->nissbranch);
for (m = 0; m < 18; m++) {
if (allowed & (1 << m)) {
nextarg.nmoves = arg->nmoves + 1;
nextarg.moves[arg->nmoves] = m;
nextarg.cube = move(arg->cube, m);
nextarg.inverse = premove(arg->inverse, m);
ret += solve_h48_dfs(&nextarg);
}
}
}
return ret;
}
STATIC int64_t
solve_h48(
cube_t cube,
int8_t minmoves,
int8_t maxmoves,
int8_t maxsolutions,
uint64_t data_size,
const void *data,
uint64_t solutions_size,
char *solutions
)
{
_Atomic int64_t nsols;
dfsarg_solveh48_t arg;
tableinfo_t info, fbinfo;
if(readtableinfo_n(data_size, data, 2, &info) != NISSY_OK)
goto solve_h48_error_data;
arg = (dfsarg_solveh48_t) {
.cube = cube,
.inverse = inverse(cube),
.nsols = &nsols,
.maxsolutions = maxsolutions,
.h = info.h48h,
.k = info.bits,
.base = info.base,
.cocsepdata = (uint32_t *)((char *)data + INFOSIZE),
.h48data = (uint8_t *)data + COCSEP_FULLSIZE + INFOSIZE,
.solutions_size = solutions_size,
.nextsol = &solutions
};
if (info.bits == 2) {
if (readtableinfo_n(data_size, data, 3, &fbinfo) != NISSY_OK)
goto solve_h48_error_data;
/* We only support h0k4 as fallback table */
if (fbinfo.h48h != 0 || fbinfo.bits != 4)
goto solve_h48_error_data;
arg.h48data_fallback = arg.h48data + info.next;
} else {
arg.h48data_fallback = NULL;
}
nsols = 0;
for (arg.depth = minmoves;
arg.depth <= maxmoves && nsols < maxsolutions;
arg.depth++)
{
LOG("Found %" PRId64 " solutions, searching at depth %"
PRId8 "\n", nsols, arg.depth);
arg.nmoves = 0;
arg.npremoves = 0;
solve_h48_dfs(&arg);
}
**arg.nextsol = '\0';
(*arg.nextsol)++;
return nsols;
solve_h48_error_data:
LOG("solve_h48: error reading table\n");
return NISSY_ERROR_DATA;
}
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