+ case CFG_DESC:
+ error = midend_game_id_int(me, cfg[0].sval,
+ (which == CFG_SEED ? DEF_SEED : DEF_DESC));
+ if (error)
+ return error;
+ break;
+ }
+
+ return NULL;
+}
+
+int midend_can_format_as_text_now(midend *me)
+{
+ if (me->ourgame->can_format_as_text_ever)
+ return me->ourgame->can_format_as_text_now(me->params);
+ else
+ return FALSE;
+}
+
+char *midend_text_format(midend *me)
+{
+ if (me->ourgame->can_format_as_text_ever && me->statepos > 0 &&
+ me->ourgame->can_format_as_text_now(me->params))
+ return me->ourgame->text_format(me->states[me->statepos-1].state);
+ else
+ return NULL;
+}
+
+char *midend_solve(midend *me)
+{
+ game_state *s;
+ char *msg, *movestr;
+
+ if (!me->ourgame->can_solve)
+ return "This game does not support the Solve operation";
+
+ if (me->statepos < 1)
+ return "No game set up to solve"; /* _shouldn't_ happen! */
+
+ msg = NULL;
+ movestr = me->ourgame->solve(me->states[0].state,
+ me->states[me->statepos-1].state,
+ me->aux_info, &msg);
+ if (!movestr) {
+ if (!msg)
+ msg = "Solve operation failed"; /* _shouldn't_ happen, but can */
+ return msg;
+ }
+ s = me->ourgame->execute_move(me->states[me->statepos-1].state, movestr);
+ assert(s);
+
+ /*
+ * Now enter the solved state as the next move.
+ */
+ midend_stop_anim(me);
+ midend_purge_states(me);
+ ensure(me);
+ me->states[me->nstates].state = s;
+ me->states[me->nstates].movestr = movestr;
+ me->states[me->nstates].movetype = SOLVE;
+ me->statepos = ++me->nstates;
+ if (me->ui)
+ me->ourgame->changed_state(me->ui,
+ me->states[me->statepos-2].state,
+ me->states[me->statepos-1].state);
+ me->dir = +1;
+ if (me->ourgame->flags & SOLVE_ANIMATES) {
+ me->oldstate = me->ourgame->dup_game(me->states[me->statepos-2].state);
+ me->anim_time =
+ me->ourgame->anim_length(me->states[me->statepos-2].state,
+ me->states[me->statepos-1].state,
+ +1, me->ui);
+ me->anim_pos = 0.0;
+ } else {
+ me->anim_time = 0.0;
+ midend_finish_move(me);
+ }
+ if (me->drawing)
+ midend_redraw(me);
+ midend_set_timer(me);
+ return NULL;
+}
+
+int midend_status(midend *me)
+{
+ /*
+ * We should probably never be called when the state stack has no
+ * states on it at all - ideally, midends should never be left in
+ * that state for long enough to get put down and forgotten about.
+ * But if we are, I think we return _true_ - pedantically speaking
+ * a midend in that state is 'vacuously solved', and more
+ * practically, a user whose midend has been left in that state
+ * probably _does_ want the 'new game' option to be prominent.
+ */
+ if (me->statepos == 0)
+ return +1;
+
+ return me->ourgame->status(me->states[me->statepos-1].state);
+}
+
+char *midend_rewrite_statusbar(midend *me, char *text)
+{
+ /*
+ * An important special case is that we are occasionally called
+ * with our own laststatus, to update the timer.
+ */
+ if (me->laststatus != text) {
+ sfree(me->laststatus);
+ me->laststatus = dupstr(text);
+ }
+
+ if (me->ourgame->is_timed) {
+ char timebuf[100], *ret;
+ int min, sec;
+
+ sec = (int)me->elapsed;
+ min = sec / 60;
+ sec %= 60;
+ sprintf(timebuf, "[%d:%02d] ", min, sec);
+
+ ret = snewn(strlen(timebuf) + strlen(text) + 1, char);
+ strcpy(ret, timebuf);
+ strcat(ret, text);
+ return ret;
+
+ } else {
+ return dupstr(text);
+ }
+}
+
+#define SERIALISE_MAGIC "Simon Tatham's Portable Puzzle Collection"
+#define SERIALISE_VERSION "1"
+
+void midend_serialise(midend *me,
+ void (*write)(void *ctx, void *buf, int len),
+ void *wctx)
+{
+ int i;
+
+ /*
+ * Each line of the save file contains three components. First
+ * exactly 8 characters of header word indicating what type of
+ * data is contained on the line; then a colon followed by a
+ * decimal integer giving the length of the main string on the
+ * line; then a colon followed by the string itself (exactly as
+ * many bytes as previously specified, no matter what they
+ * contain). Then a newline (of reasonably flexible form).
+ */
+#define wr(h,s) do { \
+ char hbuf[80]; \
+ char *str = (s); \
+ sprintf(hbuf, "%-8.8s:%d:", (h), (int)strlen(str)); \
+ write(wctx, hbuf, strlen(hbuf)); \
+ write(wctx, str, strlen(str)); \
+ write(wctx, "\n", 1); \
+} while (0)
+
+ /*
+ * Magic string identifying the file, and version number of the
+ * file format.
+ */
+ wr("SAVEFILE", SERIALISE_MAGIC);
+ wr("VERSION", SERIALISE_VERSION);
+
+ /*
+ * The game name. (Copied locally to avoid const annoyance.)
+ */
+ {
+ char *s = dupstr(me->ourgame->name);
+ wr("GAME", s);
+ sfree(s);
+ }
+
+ /*
+ * The current long-term parameters structure, in full.
+ */
+ if (me->params) {
+ char *s = me->ourgame->encode_params(me->params, TRUE);
+ wr("PARAMS", s);
+ sfree(s);
+ }
+
+ /*
+ * The current short-term parameters structure, in full.
+ */
+ if (me->curparams) {
+ char *s = me->ourgame->encode_params(me->curparams, TRUE);
+ wr("CPARAMS", s);
+ sfree(s);
+ }
+
+ /*
+ * The current game description, the privdesc, and the random seed.
+ */
+ if (me->seedstr)
+ wr("SEED", me->seedstr);
+ if (me->desc)
+ wr("DESC", me->desc);
+ if (me->privdesc)
+ wr("PRIVDESC", me->privdesc);
+
+ /*
+ * The game's aux_info. We obfuscate this to prevent spoilers
+ * (people are likely to run `head' or similar on a saved game
+ * file simply to find out what it is, and don't necessarily
+ * want to be told the answer to the puzzle!)
+ */
+ if (me->aux_info) {
+ unsigned char *s1;
+ char *s2;
+ int len;
+
+ len = strlen(me->aux_info);
+ s1 = snewn(len, unsigned char);
+ memcpy(s1, me->aux_info, len);
+ obfuscate_bitmap(s1, len*8, FALSE);
+ s2 = bin2hex(s1, len);
+
+ wr("AUXINFO", s2);
+
+ sfree(s2);
+ sfree(s1);
+ }
+
+ /*
+ * Any required serialisation of the game_ui.
+ */
+ if (me->ui) {
+ char *s = me->ourgame->encode_ui(me->ui);
+ if (s) {
+ wr("UI", s);
+ sfree(s);
+ }
+ }
+
+ /*
+ * The game time, if it's a timed game.
+ */
+ if (me->ourgame->is_timed) {
+ char buf[80];
+ sprintf(buf, "%g", me->elapsed);
+ wr("TIME", buf);
+ }
+
+ /*
+ * The length of, and position in, the states list.
+ */
+ {
+ char buf[80];
+ sprintf(buf, "%d", me->nstates);
+ wr("NSTATES", buf);
+ sprintf(buf, "%d", me->statepos);
+ wr("STATEPOS", buf);
+ }
+
+ /*
+ * For each state after the initial one (which we know is
+ * constructed from either privdesc or desc), enough
+ * information for execute_move() to reconstruct it from the
+ * previous one.
+ */
+ for (i = 1; i < me->nstates; i++) {
+ assert(me->states[i].movetype != NEWGAME); /* only state 0 */
+ switch (me->states[i].movetype) {
+ case MOVE:
+ wr("MOVE", me->states[i].movestr);
+ break;
+ case SOLVE:
+ wr("SOLVE", me->states[i].movestr);
+ break;
+ case RESTART:
+ wr("RESTART", me->states[i].movestr);
+ break;
+ }
+ }
+
+#undef wr
+}
+
+/*
+ * This function returns NULL on success, or an error message.
+ */
+char *midend_deserialise(midend *me,
+ int (*read)(void *ctx, void *buf, int len),
+ void *rctx)
+{
+ int nstates = 0, statepos = -1, gotstates = 0;
+ int started = FALSE;
+ int i;
+
+ char *val = NULL;
+ /* Initially all errors give the same report */
+ char *ret = "Data does not appear to be a saved game file";
+
+ /*
+ * We construct all the new state in local variables while we
+ * check its sanity. Only once we have finished reading the
+ * serialised data and detected no errors at all do we start
+ * modifying stuff in the midend passed in.
+ */
+ char *seed = NULL, *parstr = NULL, *desc = NULL, *privdesc = NULL;
+ char *auxinfo = NULL, *uistr = NULL, *cparstr = NULL;
+ float elapsed = 0.0F;
+ game_params *params = NULL, *cparams = NULL;
+ game_ui *ui = NULL;
+ struct midend_state_entry *states = NULL;
+
+ /*
+ * Loop round and round reading one key/value pair at a time
+ * from the serialised stream, until we have enough game states
+ * to finish.
+ */
+ while (nstates <= 0 || statepos < 0 || gotstates < nstates-1) {
+ char key[9], c;
+ int len;
+
+ do {
+ if (!read(rctx, key, 1)) {
+ /* unexpected EOF */
+ goto cleanup;
+ }
+ } while (key[0] == '\r' || key[0] == '\n');
+
+ if (!read(rctx, key+1, 8)) {
+ /* unexpected EOF */
+ goto cleanup;
+ }
+
+ if (key[8] != ':') {
+ if (started)
+ ret = "Data was incorrectly formatted for a saved game file";
+ goto cleanup;
+ }
+ len = strcspn(key, ": ");
+ assert(len <= 8);
+ key[len] = '\0';
+
+ len = 0;
+ while (1) {
+ if (!read(rctx, &c, 1)) {
+ /* unexpected EOF */
+ goto cleanup;
+ }