include "register.h"

procedure expixv (input, dim, rcentr, rwidth,x, y, status)

#     expixv -- Extracts locations and values of good pixels from data window
#  
#     Description:
#     ------------
#     This subroutine accepts the input vector and window mask,
#     and will, for a specified subvector size, return the locations
#     and the values of pixels within the data window. This version
#     does not handle data windows.
#
#              27-JAN-1993  R. Williamson Converted to SPP
#         5    22-FEB-1984  Pat Murphy   Bug removed: wrong indices in loop!
#         4     9-JAN-1984  Pat Murphy   Eliminate un-necessary loop
#         3    30-AUG-1983  PAT MURPHY   Cleverer way of scanning mask
#         2    22-AUG-1983  PAT MURPHY   add PDL and fortran
#         1    22-AUG-1983  PAT MURPHY   Prolog Generation
#
#
#

int dim	    	    	    	    	#  (I) Size of input vector
int rwidth  	    	    	    	#  (I) Size of output vectors
int x[rwidth]	    	    	    	#  (O) Output positions vector
int i, j, first, last, nn   	    	#  (L) Local variables
int status	    	    	    	#  (O) Returned status
real input[dim]	    	    	    	#  (I) Input vector
real rcentr 	    	    	    	#  (I) Location of center of range
real y[rwidth]	    	    	    	#  (O) Output values vector

begin

	#  Assume all is ok

	   status = OK

	#  If width is larger than vector,

        if (rwidth > dim) {

	#  then user is asking too much of this
	#  poor under-rated subroutine, so
	#  quit now on the unscrupulous cretin

	status = FATAL
	return
        }

	#  Get the nearest neighbor pixel
        nn = int (rcentr + .5)
	#  Figure where to start
        first = max (1, nn - rwidth/2)
	#  and where we would like to finish
        last  = first + rwidth - 1

	#  If finish point is beyond bounds then
        if (last > dim) {
	    #  move range down until last point is
	    first = first - (last - dim)

	#  just within the array bounds
	    last  = dim
        }

#  For each pixel in range of input
        do i = first, last {
	    #  Get position in sub-vectors
	    j = i + 1 - first
	    #Store the position of the pixel
	    x [j] = float [i]
	    #and its value in the sub-vectors
	    y [j] = input [i]
	}

end