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flip.c
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flip.c
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/*
* flip.c: Puzzle involving lighting up all the squares on a grid,
* where each click toggles an overlapping set of lights.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <ctype.h>
#include <limits.h>
#ifdef NO_TGMATH_H
# include <math.h>
#else
# include <tgmath.h>
#endif
#include "puzzles.h"
#include "tree234.h"
enum {
COL_BACKGROUND,
COL_WRONG,
COL_RIGHT,
COL_GRID,
COL_DIAG,
COL_HINT,
COL_CURSOR,
NCOLOURS
};
#define PREFERRED_TILE_SIZE 48
#define TILE_SIZE (ds->tilesize)
#define BORDER (TILE_SIZE / 2)
#define COORD(x) ( (x) * TILE_SIZE + BORDER )
#define FROMCOORD(x) ( ((x) - BORDER + TILE_SIZE) / TILE_SIZE - 1 )
#define ANIM_TIME 0.25F
#define FLASH_FRAME 0.07F
/*
* Possible ways to decide which lights are toggled by each click.
* Essentially, each of these describes a means of inventing a
* matrix over GF(2).
*/
enum {
CROSSES, RANDOM
};
struct game_params {
int w, h;
int matrix_type;
};
/*
* This structure is shared between all the game_states describing
* a particular game, so it's reference-counted.
*/
struct matrix {
int refcount;
unsigned char *matrix; /* array of (w*h) by (w*h) */
};
struct game_state {
int w, h;
int moves;
bool completed, cheated, hints_active;
unsigned char *grid; /* array of w*h */
struct matrix *matrix;
};
static game_params *default_params(void)
{
game_params *ret = snew(game_params);
ret->w = ret->h = 5;
ret->matrix_type = CROSSES;
return ret;
}
static const struct game_params flip_presets[] = {
{3, 3, CROSSES},
{4, 4, CROSSES},
{5, 5, CROSSES},
{3, 3, RANDOM},
{4, 4, RANDOM},
{5, 5, RANDOM},
};
static bool game_fetch_preset(int i, char **name, game_params **params)
{
game_params *ret;
char str[80];
if (i < 0 || i >= lenof(flip_presets))
return false;
ret = snew(game_params);
*ret = flip_presets[i];
sprintf(str, "%dx%d %s", ret->w, ret->h,
ret->matrix_type == CROSSES ? "Crosses" : "Random");
*name = dupstr(str);
*params = ret;
return true;
}
static void free_params(game_params *params)
{
sfree(params);
}
static game_params *dup_params(const game_params *params)
{
game_params *ret = snew(game_params);
*ret = *params; /* structure copy */
return ret;
}
static void decode_params(game_params *ret, char const *string)
{
ret->w = ret->h = atoi(string);
while (*string && isdigit((unsigned char)*string)) string++;
if (*string == 'x') {
string++;
ret->h = atoi(string);
while (*string && isdigit((unsigned char)*string)) string++;
}
if (*string == 'r') {
string++;
ret->matrix_type = RANDOM;
} else if (*string == 'c') {
string++;
ret->matrix_type = CROSSES;
}
}
static char *encode_params(const game_params *params, bool full)
{
char data[256];
sprintf(data, "%dx%d%s", params->w, params->h,
!full ? "" : params->matrix_type == CROSSES ? "c" : "r");
return dupstr(data);
}
static config_item *game_configure(const game_params *params)
{
config_item *ret = snewn(4, config_item);
char buf[80];
ret[0].name = "Width";
ret[0].type = C_STRING;
sprintf(buf, "%d", params->w);
ret[0].u.string.sval = dupstr(buf);
ret[1].name = "Height";
ret[1].type = C_STRING;
sprintf(buf, "%d", params->h);
ret[1].u.string.sval = dupstr(buf);
ret[2].name = "Shape type";
ret[2].type = C_CHOICES;
ret[2].u.choices.choicenames = ":Crosses:Random";
ret[2].u.choices.selected = params->matrix_type;
ret[3].name = NULL;
ret[3].type = C_END;
return ret;
}
static game_params *custom_params(const config_item *cfg)
{
game_params *ret = snew(game_params);
ret->w = atoi(cfg[0].u.string.sval);
ret->h = atoi(cfg[1].u.string.sval);
ret->matrix_type = cfg[2].u.choices.selected;
return ret;
}
static const char *validate_params(const game_params *params, bool full)
{
int wh;
if (params->w <= 0 || params->h <= 0)
return "Width and height must both be greater than zero";
if (params->w > (INT_MAX - 3) / params->h)
return "Width times height must not be unreasonably large";
wh = params->w * params->h;
if (wh > (INT_MAX - 3) / wh)
return "Width times height is too large";
return NULL;
}
static char *encode_bitmap(unsigned char *bmp, int len)
{
int slen = (len + 3) / 4;
char *ret;
int i;
ret = snewn(slen + 1, char);
for (i = 0; i < slen; i++) {
int j, v;
v = 0;
for (j = 0; j < 4; j++)
if (i*4+j < len && bmp[i*4+j])
v |= 8 >> j;
ret[i] = "0123456789abcdef"[v];
}
ret[slen] = '\0';
return ret;
}
static void decode_bitmap(unsigned char *bmp, int len, const char *hex)
{
int slen = (len + 3) / 4;
int i;
for (i = 0; i < slen; i++) {
int j, v, c = hex[i];
if (c >= '0' && c <= '9')
v = c - '0';
else if (c >= 'A' && c <= 'F')
v = c - 'A' + 10;
else if (c >= 'a' && c <= 'f')
v = c - 'a' + 10;
else
v = 0; /* shouldn't happen */
for (j = 0; j < 4; j++) {
if (i*4+j < len) {
if (v & (8 >> j))
bmp[i*4+j] = 1;
else
bmp[i*4+j] = 0;
}
}
}
}
/*
* Structure used during random matrix generation, and a compare
* function to permit storage in a tree234.
*/
struct sq {
int cx, cy; /* coords of click square */
int x, y; /* coords of output square */
/*
* Number of click squares which currently affect this output
* square.
*/
int coverage;
/*
* Number of output squares currently affected by this click
* square.
*/
int ominosize;
};
#define SORT(field) do { \
if (a->field < b->field) \
return -1; \
else if (a->field > b->field) \
return +1; \
} while (0)
/*
* Compare function for choosing the next square to add. We must
* sort by coverage, then by omino size, then everything else.
*/
static int sqcmp_pick(void *av, void *bv)
{
struct sq *a = (struct sq *)av;
struct sq *b = (struct sq *)bv;
SORT(coverage);
SORT(ominosize);
SORT(cy);
SORT(cx);
SORT(y);
SORT(x);
return 0;
}
/*
* Compare function for adjusting the coverage figures after a
* change. We sort first by coverage and output square, then by
* everything else.
*/
static int sqcmp_cov(void *av, void *bv)
{
struct sq *a = (struct sq *)av;
struct sq *b = (struct sq *)bv;
SORT(coverage);
SORT(y);
SORT(x);
SORT(ominosize);
SORT(cy);
SORT(cx);
return 0;
}
/*
* Compare function for adjusting the omino sizes after a change.
* We sort first by omino size and input square, then by everything
* else.
*/
static int sqcmp_osize(void *av, void *bv)
{
struct sq *a = (struct sq *)av;
struct sq *b = (struct sq *)bv;
SORT(ominosize);
SORT(cy);
SORT(cx);
SORT(coverage);
SORT(y);
SORT(x);
return 0;
}
static void addsq(tree234 *t, int w, int h, int cx, int cy,
int x, int y, unsigned char *matrix)
{
int wh = w * h;
struct sq *sq;
int i;
if (x < 0 || x >= w || y < 0 || y >= h)
return;
if (abs(x-cx) > 1 || abs(y-cy) > 1)
return;
if (matrix[(cy*w+cx) * wh + y*w+x])
return;
sq = snew(struct sq);
sq->cx = cx;
sq->cy = cy;
sq->x = x;
sq->y = y;
sq->coverage = sq->ominosize = 0;
for (i = 0; i < wh; i++) {
if (matrix[i * wh + y*w+x])
sq->coverage++;
if (matrix[(cy*w+cx) * wh + i])
sq->ominosize++;
}
if (add234(t, sq) != sq)
sfree(sq); /* already there */
}
static void addneighbours(tree234 *t, int w, int h, int cx, int cy,
int x, int y, unsigned char *matrix)
{
addsq(t, w, h, cx, cy, x-1, y, matrix);
addsq(t, w, h, cx, cy, x+1, y, matrix);
addsq(t, w, h, cx, cy, x, y-1, matrix);
addsq(t, w, h, cx, cy, x, y+1, matrix);
}
static char *new_game_desc(const game_params *params, random_state *rs,
char **aux, bool interactive)
{
int w = params->w, h = params->h, wh = w * h;
int i, j;
unsigned char *matrix, *grid;
char *mbmp, *gbmp, *ret;
matrix = snewn(wh * wh, unsigned char);
grid = snewn(wh, unsigned char);
/*
* First set up the matrix.
*/
switch (params->matrix_type) {
case CROSSES:
for (i = 0; i < wh; i++) {
int ix = i % w, iy = i / w;
for (j = 0; j < wh; j++) {
int jx = j % w, jy = j / w;
if (abs(jx - ix) + abs(jy - iy) <= 1)
matrix[i*wh+j] = 1;
else
matrix[i*wh+j] = 0;
}
}
break;
case RANDOM:
while (1) {
tree234 *pick, *cov, *osize;
int limit;
pick = newtree234(sqcmp_pick);
cov = newtree234(sqcmp_cov);
osize = newtree234(sqcmp_osize);
memset(matrix, 0, wh * wh);
for (i = 0; i < wh; i++) {
matrix[i*wh+i] = 1;
}
for (i = 0; i < wh; i++) {
int ix = i % w, iy = i / w;
addneighbours(pick, w, h, ix, iy, ix, iy, matrix);
addneighbours(cov, w, h, ix, iy, ix, iy, matrix);
addneighbours(osize, w, h, ix, iy, ix, iy, matrix);
}
/*
* Repeatedly choose a square to add to the matrix,
* until we have enough. I'll arbitrarily choose our
* limit to be the same as the total number of set bits
* in the crosses matrix.
*/
limit = 4*wh - 2*(w+h); /* centre squares already present */
while (limit-- > 0) {
struct sq *sq, *sq2, sqlocal;
int k;
/*
* Find the lowest element in the pick tree.
*/
sq = index234(pick, 0);
/*
* Find the highest element with the same coverage
* and omino size, by setting all other elements to
* lots.
*/
sqlocal = *sq;
sqlocal.cx = sqlocal.cy = sqlocal.x = sqlocal.y = wh;
sq = findrelpos234(pick, &sqlocal, NULL, REL234_LT, &k);
assert(sq != 0);
/*
* Pick at random from all elements up to k of the
* pick tree.
*/
k = random_upto(rs, k+1);
sq = delpos234(pick, k);
del234(cov, sq);
del234(osize, sq);
/*
* Add this square to the matrix.
*/
matrix[(sq->cy * w + sq->cx) * wh + (sq->y * w + sq->x)] = 1;
/*
* Correct the matrix coverage field of any sq
* which points at this output square.
*/
sqlocal = *sq;
sqlocal.cx = sqlocal.cy = sqlocal.ominosize = -1;
while ((sq2 = findrel234(cov, &sqlocal, NULL,
REL234_GT)) != NULL &&
sq2->coverage == sq->coverage &&
sq2->x == sq->x && sq2->y == sq->y) {
del234(pick, sq2);
del234(cov, sq2);
del234(osize, sq2);
sq2->coverage++;
add234(pick, sq2);
add234(cov, sq2);
add234(osize, sq2);
}
/*
* Correct the omino size field of any sq which
* points at this input square.
*/
sqlocal = *sq;
sqlocal.x = sqlocal.y = sqlocal.coverage = -1;
while ((sq2 = findrel234(osize, &sqlocal, NULL,
REL234_GT)) != NULL &&
sq2->ominosize == sq->ominosize &&
sq2->cx == sq->cx && sq2->cy == sq->cy) {
del234(pick, sq2);
del234(cov, sq2);
del234(osize, sq2);
sq2->ominosize++;
add234(pick, sq2);
add234(cov, sq2);
add234(osize, sq2);
}
/*
* The sq we actually picked out of the tree is
* finished with; but its neighbours now need to
* appear.
*/
addneighbours(pick, w,h, sq->cx,sq->cy, sq->x,sq->y, matrix);
addneighbours(cov, w,h, sq->cx,sq->cy, sq->x,sq->y, matrix);
addneighbours(osize, w,h, sq->cx,sq->cy, sq->x,sq->y, matrix);
sfree(sq);
}
/*
* Free all remaining sq structures.
*/
{
struct sq *sq;
while ((sq = delpos234(pick, 0)) != NULL)
sfree(sq);
}
freetree234(pick);
freetree234(cov);
freetree234(osize);
/*
* Finally, check to see if any two matrix rows are
* exactly identical. If so, this is not an acceptable
* matrix, and we give up and go round again.
*
* I haven't been immediately able to think of a
* plausible means of algorithmically avoiding this
* situation (by, say, making a small perturbation to
* an offending matrix), so for the moment I'm just
* going to deal with it by throwing the whole thing
* away. I suspect this will lead to scalability
* problems (since most of the things happening in
* these matrices are local, the chance of _some_
* neighbourhood having two identical regions will
* increase with the grid area), but so far this puzzle
* seems to be really hard at large sizes so I'm not
* massively worried yet. Anyone needs this done
* better, they're welcome to submit a patch.
*/
for (i = 0; i < wh; i++) {
for (j = 0; j < wh; j++)
if (i != j &&
!memcmp(matrix + i * wh, matrix + j * wh, wh))
break;
if (j < wh)
break;
}
if (i == wh)
break; /* no matches found */
}
break;
}
/*
* Now invent a random initial set of lights.
*
* At first glance it looks as if it might be quite difficult
* to choose equiprobably from all soluble light sets. After
* all, soluble light sets are those in the image space of the
* transformation matrix; so first we'd have to identify that
* space and its dimension, then pick a random coordinate for
* each basis vector and recombine. Lot of fiddly matrix
* algebra there.
*
* However, vector spaces are nicely orthogonal and relieve us
* of all that difficulty. For every point in the image space,
* there are precisely as many points in the input space that
* map to it as there are elements in the kernel of the
* transformation matrix (because adding any kernel element to
* the input does not change the output, and because any two
* inputs mapping to the same output must differ by an element
* of the kernel because that's what the kernel _is_); and
* these cosets are all disjoint (obviously, since no input
* point can map to more than one output point) and cover the
* whole space (equally obviously, because no input point can
* map to fewer than one output point!).
*
* So the input space contains the same number of points for
* each point in the output space; thus, we can simply choose
* equiprobably from elements of the _input_ space, and filter
* the result through the transformation matrix in the obvious
* way, and we thereby guarantee to choose equiprobably from
* all the output points. Phew!
*/
while (1) {
memset(grid, 0, wh);
for (i = 0; i < wh; i++) {
int v = random_upto(rs, 2);
if (v) {
for (j = 0; j < wh; j++)
grid[j] ^= matrix[i*wh+j];
}
}
/*
* Ensure we don't have the starting state already!
*/
for (i = 0; i < wh; i++)
if (grid[i])
break;
if (i < wh)
break;
}
/*
* Now encode the matrix and the starting grid as a game
* description. We'll do this by concatenating two great big
* hex bitmaps.
*/
mbmp = encode_bitmap(matrix, wh*wh);
gbmp = encode_bitmap(grid, wh);
ret = snewn(strlen(mbmp) + strlen(gbmp) + 2, char);
sprintf(ret, "%s,%s", mbmp, gbmp);
sfree(mbmp);
sfree(gbmp);
sfree(matrix);
sfree(grid);
return ret;
}
static const char *validate_desc(const game_params *params, const char *desc)
{
int w = params->w, h = params->h, wh = w * h;
int mlen = (wh*wh+3)/4, glen = (wh+3)/4;
if (strspn(desc, "0123456789abcdefABCDEF") != mlen)
return "Matrix description is wrong length";
if (desc[mlen] != ',')
return "Expected comma after matrix description";
if (strspn(desc+mlen+1, "0123456789abcdefABCDEF") != glen)
return "Grid description is wrong length";
if (desc[mlen+1+glen])
return "Unexpected data after grid description";
return NULL;
}
static game_state *new_game(midend *me, const game_params *params,
const char *desc)
{
int w = params->w, h = params->h, wh = w * h;
int mlen = (wh*wh+3)/4;
game_state *state = snew(game_state);
state->w = w;
state->h = h;
state->completed = false;
state->cheated = false;
state->hints_active = false;
state->moves = 0;
state->matrix = snew(struct matrix);
state->matrix->refcount = 1;
state->matrix->matrix = snewn(wh*wh, unsigned char);
decode_bitmap(state->matrix->matrix, wh*wh, desc);
state->grid = snewn(wh, unsigned char);
decode_bitmap(state->grid, wh, desc + mlen + 1);
return state;
}
static game_state *dup_game(const game_state *state)
{
game_state *ret = snew(game_state);
ret->w = state->w;
ret->h = state->h;
ret->completed = state->completed;
ret->cheated = state->cheated;
ret->hints_active = state->hints_active;
ret->moves = state->moves;
ret->matrix = state->matrix;
state->matrix->refcount++;
ret->grid = snewn(ret->w * ret->h, unsigned char);
memcpy(ret->grid, state->grid, ret->w * ret->h);
return ret;
}
static void free_game(game_state *state)
{
sfree(state->grid);
if (--state->matrix->refcount <= 0) {
sfree(state->matrix->matrix);
sfree(state->matrix);
}
sfree(state);
}
static void rowxor(unsigned char *row1, unsigned char *row2, int len)
{
int i;
for (i = 0; i < len; i++)
row1[i] ^= row2[i];
}
static char *solve_game(const game_state *state, const game_state *currstate,
const char *aux, const char **error)
{
int w = state->w, h = state->h, wh = w * h;
unsigned char *equations, *solution, *shortest;
int *und, nund;
int rowsdone, colsdone;
int i, j, k, len, bestlen;
char *ret;
/*
* Set up a list of simultaneous equations. Each one is of
* length (wh+1) and has wh coefficients followed by a value.
*/
equations = snewn((wh + 1) * wh, unsigned char);
for (i = 0; i < wh; i++) {
for (j = 0; j < wh; j++)
equations[i * (wh+1) + j] = currstate->matrix->matrix[j*wh+i];
equations[i * (wh+1) + wh] = currstate->grid[i] & 1;
}
/*
* Perform Gaussian elimination over GF(2).
*/
rowsdone = colsdone = 0;
nund = 0;
und = snewn(wh, int);
do {
/*
* Find the leftmost column which has a 1 in it somewhere
* outside the first `rowsdone' rows.
*/
j = -1;
for (i = colsdone; i < wh; i++) {
for (j = rowsdone; j < wh; j++)
if (equations[j * (wh+1) + i])
break;
if (j < wh)
break; /* found one */
/*
* This is a column which will not have an equation
* controlling it. Mark it as undetermined.
*/
und[nund++] = i;
}
/*
* If there wasn't one, then we've finished: all remaining
* equations are of the form 0 = constant. Check to see if
* any of them wants 0 to be equal to 1; this is the
* condition which indicates an insoluble problem
* (therefore _hopefully_ one typed in by a user!).
*/
if (i == wh) {
for (j = rowsdone; j < wh; j++)
if (equations[j * (wh+1) + wh]) {
*error = "No solution exists for this position";
sfree(equations);
sfree(und);
return NULL;
}
break;
}
/*
* We've found a 1. It's in column i, and the topmost 1 in
* that column is in row j. Do a row-XOR to move it up to
* the topmost row if it isn't already there.
*/
assert(j != -1);
if (j > rowsdone)
rowxor(equations + rowsdone*(wh+1), equations + j*(wh+1), wh+1);
/*
* Do row-XORs to eliminate that 1 from all rows below the
* topmost row.
*/
for (j = rowsdone + 1; j < wh; j++)
if (equations[j*(wh+1) + i])
rowxor(equations + j*(wh+1),
equations + rowsdone*(wh+1), wh+1);
/*
* Mark this row and column as done.
*/
rowsdone++;
colsdone = i+1;
/*
* If we've done all the rows, terminate.
*/
} while (rowsdone < wh);
/*
* If we reach here, we have the ability to produce a solution.
* So we go through _all_ possible solutions (each
* corresponding to a set of arbitrary choices of those
* components not directly determined by an equation), and pick
* one requiring the smallest number of flips.
*/
solution = snewn(wh, unsigned char);
shortest = snewn(wh, unsigned char);
memset(solution, 0, wh);
bestlen = wh + 1;
while (1) {
/*
* Find a solution based on the current values of the
* undetermined variables.
*/
for (j = rowsdone; j-- ;) {
int v;
/*
* Find the leftmost set bit in this equation.
*/
for (i = 0; i < wh; i++)
if (equations[j * (wh+1) + i])
break;
assert(i < wh); /* there must have been one! */
/*
* Compute this variable using the rest.
*/
v = equations[j * (wh+1) + wh];
for (k = i+1; k < wh; k++)
if (equations[j * (wh+1) + k])
v ^= solution[k];
solution[i] = v;
}
/*
* Compare this solution to the current best one, and
* replace the best one if this one is shorter.
*/
len = 0;
for (i = 0; i < wh; i++)
if (solution[i])
len++;
if (len < bestlen) {
bestlen = len;
memcpy(shortest, solution, wh);
}
/*
* Now increment the binary number given by the
* undetermined variables: turn all 1s into 0s until we see
* a 0, at which point we turn it into a 1.
*/
for (i = 0; i < nund; i++) {
solution[und[i]] = !solution[und[i]];
if (solution[und[i]])
break;
}
/*
* If we didn't find a 0 at any point, we have wrapped
* round and are back at the start, i.e. we have enumerated
* all solutions.
*/
if (i == nund)
break;
}
/*
* We have a solution. Produce a move string encoding the
* solution.
*/
ret = snewn(wh + 2, char);
ret[0] = 'S';
for (i = 0; i < wh; i++)
ret[i+1] = shortest[i] ? '1' : '0';
ret[wh+1] = '\0';
sfree(shortest);
sfree(solution);
sfree(equations);
sfree(und);
return ret;
}
static bool game_can_format_as_text_now(const game_params *params)
{
return true;
}
#define RIGHT 1
#define DOWN gw
static char *game_text_format(const game_state *state)
{
int w = state->w, h = state->h, wh = w*h, r, c, dx, dy;
int cw = 4, ch = 4, gw = w * cw + 2, gh = h * ch + 1, len = gw * gh;
char *board = snewn(len + 1, char);
memset(board, ' ', len - 1);
for (r = 0; r < h; ++r) {
for (c = 0; c < w; ++c) {
int cell = r*ch*gw + c*cw, center = cell+(ch/2)*DOWN + cw/2*RIGHT;
char flip = (state->grid[r*w + c] & 1) ? '#' : '.';
for (dy = -1 + (r == 0); dy <= 1 - (r == h - 1); ++dy)
for (dx = -1 + (c == 0); dx <= 1 - (c == w - 1); ++dx)
if (state->matrix->matrix[(r*w+c)*wh + ((r+dy)*w + c+dx)])
board[center + dy*DOWN + dx*RIGHT] = flip;
board[cell] = '+';
for (dx = 1; dx < cw; ++dx) board[cell+dx*RIGHT] = '-';
for (dy = 1; dy < ch; ++dy) board[cell+dy*DOWN] = '|';
}
board[r*ch*gw + gw - 2] = '+';
board[r*ch*gw + gw - 1] = '\n';
for (dy = 1; dy < ch; ++dy) {
board[r*ch*gw + gw - 2 + dy*DOWN] = '|';
board[r*ch*gw + gw - 1 + dy*DOWN] = '\n';
}
}
memset(board + len - gw, '-', gw - 2);
for (c = 0; c <= w; ++c) board[len - gw + cw*c] = '+';
board[len - 1] = '\n';
board[len] = '\0';
return board;
}
#undef RIGHT
#undef DOWN
struct game_ui {
int cx, cy;
bool cdraw;
};
static game_ui *new_ui(const game_state *state)
{
game_ui *ui = snew(game_ui);
ui->cx = ui->cy = 0;
ui->cdraw = getenv_bool("PUZZLES_SHOW_CURSOR", false);
return ui;
}
static void free_ui(game_ui *ui)
{
sfree(ui);
}
static void game_changed_state(game_ui *ui, const game_state *oldstate,
const game_state *newstate)
{
}
static const char *current_key_label(const game_ui *ui,
const game_state *state, int button)
{
if (IS_CURSOR_SELECT(button)) return "Flip";
return "";
}
struct game_drawstate {
int w, h;
bool started;
unsigned char *tiles;
int tilesize;
};
static char *interpret_move(const game_state *state, game_ui *ui,
const game_drawstate *ds,
int x, int y, int button)
{
int w = state->w, h = state->h, wh = w * h;
char buf[80], *nullret = MOVE_UNUSED;
if (button == LEFT_BUTTON || IS_CURSOR_SELECT(button)) {
int tx, ty;
if (button == LEFT_BUTTON) {
tx = FROMCOORD(x), ty = FROMCOORD(y);
ui->cdraw = false;
} else {
tx = ui->cx; ty = ui->cy;
ui->cdraw = true;
}
nullret = MOVE_UI_UPDATE;
if (tx >= 0 && tx < w && ty >= 0 && ty < h) {
/*
* It's just possible that a manually entered game ID
* will have at least one square do nothing whatsoever.
* If so, we avoid encoding a move at all.
*/
int i = ty*w+tx, j;
bool makemove = false;
for (j = 0; j < wh; j++) {
if (state->matrix->matrix[i*wh+j])
makemove = true;
}
if (makemove) {
sprintf(buf, "M%d,%d", tx, ty);
return dupstr(buf);
} else {
return MOVE_NO_EFFECT;
}
}
} else if (IS_CURSOR_MOVE(button))
nullret = move_cursor(button, &ui->cx, &ui->cy, state->w, state->h,
false, &ui->cdraw);
return nullret;
}
static game_state *execute_move(const game_state *from, const char *move)
{
int w = from->w, h = from->h, wh = w * h;
game_state *ret;
int x, y;
if (move[0] == 'S' && strlen(move) == wh+1) {
int i;