# Semicode for the IRAF image to text file converter.

procedure t_wtextimage (input, output)

begin
	input = expand template of input image file names
	if (output hasn't been redirected)
	    get name of output file from cl

	# Get hidden parameters from cl
	header = is header to be written?
	maxlinelen = max number of characters per line of text
	if (format not user specified)
	    format = NOT_SET

	for (each file name in input) {
	    im = open image file
	    generate output file name
	    text = open text file
	    call convert_image (im, text, header, maxlinelen, format)
	    close image file
	    close text file
	}
end


# CONVERT_IMAGE -- called once for each image to be converted.  Directs
# the processing depending on user request.

procedure convert_image (im, text, header, maxlinelen, format)

begin
	if (format = NOT_SET)
	    format = appropriate value for data type of image

	# Calculate number of pixels per line of text
	npix_line = maxlinelen / (field width of pixel output format)
	output_format = "npix_line.pixel_format"

	if (header is to be written)
	    call write_header (im, text, output_format, maxlinelen)

	call convert_pixels (im, text, output_format)
end


# WRITE_HEADER -- write information from IRAF image header in
# "keyword = value" format, one keyword per line of text.

procedure convert_header (image, text, output_format, maxlinelen)

begin
	# Write header information to text file
	SIMPLE  = T
	BITPIX  = 8
	NAXIS   = 0
	ORIGIN  = NOAO
	IRAF-MAX= IM_MAX
	IRAF-MIN= IM_MIN
	IRAF-B/P= 
	IRAFTYPE=
	OBJECT  = IM_TITLE
	NDIM    = IM_NDIM
	LEN1    = IM_LEN(1)
	FILENAME= IM_HDRFILE
	FORMAT  = output_format

	# Write any information stored in image user area
	if (user area contains information) {
	    COMMENT = "Copying user area"
	    KEYWORD = copy user area to text file
	}

	# Final header line is END
	END = last line of header

	Pad with blank lines until multiple of 36 lines is output
end


# CONVERT_IMAGE -- write pixel values from IRAF image into text file.  The
# pixels are output in "leftmost subscript varying most rapidly" order.

procedure convert_image (image, text, format)

begin
	get next line of image
	for each pixel in line 
	    convert pixel to character
	put out line to text file according to format
end