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#include "distance.h"
int process_left (int from_row, int to_row, int start_col, int first_zone)
{
register int i,col,cur_zone;
register MAPTYPE *to_ptr, *from_ptr;
register int ncols,incr,farthest;
/* find cells to the left
* stop at left edge, or when ncols is bigger than the last zone,
* or when we see a 1 in the map
*/
col = start_col;
from_ptr = map + MAPINDEX(from_row, col);
to_ptr = map + MAPINDEX(to_row, col);
farthest = distances[ndist-1].ncols;
/* planimetric grids will look for ncols^2
* and can use fact that (n+1)^2 = n^2 + 2n + 1
*/
if (window.proj != PROJECTION_LL)
incr = 1;
else
incr = 0;
ncols = 0;
while(1)
{
if (col == 0)
{ /* global wrap-around */
if (!wrap_ncols) break; /* only can happen with lat-lon */
col = window.cols;
ncols += wrap_ncols-1;
from_ptr = map + MAPINDEX(from_row, col);
to_ptr = map + MAPINDEX(to_row, col);
}
col--;
if (incr)
{
ncols += incr;
incr += 2;
}
else
ncols++;
if(ncols > farthest) break;
if (*--from_ptr == 1) break;
/* convert 1,2,3,4 to -1,0,1,2 etc. 0 becomes ndist */
if(cur_zone = *--to_ptr)
cur_zone -= ZONE_INCR;
else
cur_zone = ndist;
/* find the first zone that is closer than the current value */
for (i = first_zone; i < cur_zone; i++)
{
if (distances[i].ncols >= ncols)
{
*to_ptr = (first_zone=i) + ZONE_INCR;
break;
}
}
}
return 0;
}
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