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#include <u.h>
#include <libc.h>
#include <draw.h>
#include "sokoban.h"
static int dirlist[] = { Up, Down, Left, Right, Up, Down, Left, Right, };
static int ndir = 4;
static Point
dir2point(int dir)
{
switch(dir) {
case Up:
return Pt(0, -1);
case Down:
return Pt(0, 1);
case Left:
return Pt(-1, 0);
case Right:
return Pt(1, 0);
}
return Pt(0,0);
}
int
validpush(Point g, Step *s, Point *t)
{
int i;
Point m;
if (s == nil)
return 0;
m = dir2point(s->dir);
// first test for Cargo next to us (in direction dir)
if (s->count > 0) {
g = addpt(g, m);
if (!ptinrect(g, Rpt(Pt(0,0), level.max)))
return 0;
switch (level.board[g.x][g.y]) {
case Wall:
case Empty:
case Goal:
return 0;
}
}
// then test for enough free space for us _and_ Cargo
for (i=0; i < s->count; i++) {
g = addpt(g, m);
if (!ptinrect(g, Rpt(Pt(0,0), level.max)))
return 0;
switch (level.board[g.x][g.y]) {
case Wall:
case Cargo:
case GoalCargo:
return 0;
}
}
if (t != nil)
*t = g;
return 1;
}
int
isvalid(Point s, Route* r, int (*isallowed)(Point, Step*, Point*))
{
Point m;
Step *p;
if (r == nil)
return 0;
m = s;
for (p = r->step; p < r->step + r->nstep; p++)
if (!isallowed(m, p, &m))
return 0;
return 1;
}
static Walk*
newwalk(void)
{
Walk *w;
w = mallocz(sizeof *w, 1);
if (w == nil)
sysfatal("cannot allocate walk");
return w;
}
static void
resetwalk(Walk *w)
{
Route **p;
if (w == nil || w->route == nil)
return;
for (p=w->route; p < w->route + w->nroute; p++)
freeroute(*p);
w->nroute = 0;
}
static void
freewalk(Walk *w)
{
if (w == nil)
return;
resetwalk(w);
if(w->route)
free(w->route);
free(w);
}
static void
addroute(Walk *w, Route *r)
{
if (w == nil || r == nil)
return;
if (w->beyond < w->nroute+1) {
w->beyond = w->nroute+1;
w->route = realloc(w->route, sizeof(Route*)*w->beyond);
}
if (w->route == nil)
sysfatal("cannot allocate route in addroute");
w->route[w->nroute] = r;
w->nroute++;
}
void
freeroute(Route *r)
{
if (r == nil)
return;
free(r->step);
free(r);
}
Route*
extend(Route *rr, int dir, int count, Point dest)
{
Route *r;
r = mallocz(sizeof *r, 1);
if (r == nil)
sysfatal("cannot allocate route in extend");
r->dest = dest;
if (count > 0) {
r->nstep = 1;
if (rr != nil)
r->nstep += rr->nstep;
r->step = malloc(sizeof(Step)*r->nstep);
if (r->step == nil)
sysfatal("cannot allocate step in extend");
if (rr != nil)
memmove(r->step, rr->step, sizeof(Step)*rr->nstep);
r->step[r->nstep-1].dir = dir;
r->step[r->nstep-1].count = count;
}
return r;
}
static Step*
laststep(Route*r)
{
if (r != nil && r->nstep > 0)
return &r->step[r->nstep-1];
return nil;
}
static int*
startwithdirfromroute(Route *r, int* dl, int n)
{
Step *s;
int *p;
if (r == nil || dl == nil)
return dl;
s = laststep(r);
if (s == nil || s->count == 0)
return dl;
for (p=dl; p < dl + n; p++)
if (*p == s->dir)
break;
return p;
}
static Route*
bfstrydir(Route *r, int dir, Visited *v)
{
Point m, p, n;
if (r == nil)
return nil;
m = r->dest;
p = dir2point(dir);
n = addpt(m, p);
if (ptinrect(n, Rpt(Pt(0,0), level.max)) && v->board[n.x][n.y] == 0) {
v->board[n.x][n.y] = 1;
switch (level.board[n.x][n.y]) {
case Empty:
case Goal:
return extend(r, dir, 1, n);
}
}
return nil;
}
static Route*
bfs(Point src, Point dst, Visited *v)
{
Walk *cur, *new, *tmp;
Route *r, **p;
int progress, *dirs, *dirp;
Point n;
if (v == nil)
return nil;
cur = newwalk();
new = newwalk();
v->board[src.x][src.y] = 1;
r = extend(nil, 0, 0, src);
if (eqpt(src, dst)) {
freewalk(cur);
freewalk(new);
return r;
}
addroute(cur, r);
progress = 1;
while (progress) {
progress = 0;
for (p=cur->route; p < cur->route + cur->nroute; p++) {
dirs = startwithdirfromroute(*p, dirlist, ndir);
for (dirp=dirs; dirp < dirs + ndir; dirp++) {
r = bfstrydir(*p, *dirp, v);
if (r != nil) {
progress = 1;
n = r->dest;
if (eqpt(n, dst)) {
freewalk(cur);
freewalk(new);
return(r);
}
addroute(new, r);
}
}
}
resetwalk(cur);
tmp = cur;
cur = new;
new = tmp;
}
freewalk(cur);
freewalk(new);
return nil;
}
Route*
findroute(Point src, Point dst)
{
Visited v;
Route* r;
memset(&v, 0, sizeof(Visited));
r = bfs(src, dst, &v);
return r;
}
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