# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.

include	<mach.h>
include	<ctype.h>
include	<gki.h>
include	"gkt.h"

# GKT_INIT -- Initialize the gkt data structures from the graphcap entry
# for the device.  Called once, at OPENWS time, with the TTY pointer already
# set in the common.  The companion routine GKT_RESET initializes the attribute
# packets when the frame is flushed.

procedure gkt_init (tty, devname)

pointer	tty			# graphcap descriptor
char	devname[ARB]		# device name

pointer	nextch
int	maxch, i
real	char_height, char_width, char_size

bool	ttygetb()
real	ttygetr()
int	ttygeti(), btoi(), gstrcpy()
include	"gkt.com"
include	"nspp.com"
int	pow2()

begin
	# Allocate the gkt descriptor and the string buffer.
	if (g_kt == NULL) {
	    call calloc (g_kt, LEN_GKT, TY_STRUCT)
	    call malloc (GKT_SBUF(g_kt), SZ_SBUF, TY_CHAR)
	}

	# Get the maximum frame count and the flags controlling frame advance
	# at start and end of metafile (NSPP parameters).

	g_maxframes = ttygeti (tty, "MF")
	if (g_maxframes == 0)
	    g_maxframes = DEF_MAXFRAMES
	GKT_STARTFRAME(g_kt) = btoi (ttygetb (tty, "FS"))
	GKT_ENDFRAME(g_kt)   = btoi (ttygetb (tty, "FE"))

	# Init string buffer parameters.  The first char of the string buffer
	# is reserved as a null string, used for graphcap control strings
	# omitted from the graphcap entry for the device.

	GKT_SZSBUF(g_kt) = SZ_SBUF
	GKT_NEXTCH(g_kt) = GKT_SBUF(g_kt) + 1
	Memc[GKT_SBUF(g_kt)] = EOS

	# Get the device resolution from the graphcap entry.

	g_xres = ttygeti (tty, "xr")
	if (g_xres <= 0)
	    g_xres = 1024
	g_yres = ttygeti (tty, "yr")
	if (g_yres <= 0)
	    g_yres = 1024

	# Set up coordinate transformations.

	call seti (pow2(g_xres), pow2(g_yres))
	call set (0., 1., 0., 1., 0., 1., 0., 1., 1)
	call z8zpii()

	# Set byteswap flag for output metacode.
	mbswap = btoi (ttygetb (tty, "BS"))

	# Initialize the character scaling parameters, required for text
	# generation.  The heights are given in NDC units in the graphcap
	# file, which we convert to GKI units.  Estimated values are
	# supplied if the parameters are missing in the graphcap entry.

	char_height = ttygetr (tty, "ch")
	if (char_height < EPSILON)
	    char_height = 1.0 / 35.0
	char_height = char_height * GKI_MAXNDC

	char_width = ttygetr (tty, "cw")
	if (char_width < EPSILON)
	    char_width = 1.0 / 80.0
	char_width = char_width * GKI_MAXNDC

	# If the device has a set of discreet character sizes, get the
	# size of each by fetching the parameter "tN", where the N is
	# a digit specifying the text size index.  Compute the height and
	# width of each size character from the "ch" and "cw" parameters
	# and the relative scale of character size I.
	# ... not relevant for nspp, but leave here anyway for now

	GKT_NCHARSIZES(g_kt) = min (MAX_CHARSIZES, ttygeti (tty, "th"))
	nextch = GKT_NEXTCH(g_kt)

	if (GKT_NCHARSIZES(g_kt) <= 0) {
	    GKT_NCHARSIZES(g_kt) = 1
	    GKT_CHARSIZE(g_kt,1) = 1.0
	    GKT_CHARHEIGHT(g_kt,1) = char_height
	    GKT_CHARWIDTH(g_kt,1)  = char_width
	} else {
	    Memc[nextch+2] = EOS
	    for (i=1;  i <= GKT_NCHARSIZES(g_kt);  i=i+1) {
		Memc[nextch] = 't'
		Memc[nextch+1] = TO_DIGIT(i)
		char_size = ttygetr (tty, Memc[nextch])
		GKT_CHARSIZE(g_kt,i)   = char_size
		GKT_CHARHEIGHT(g_kt,i) = char_height * char_size
		GKT_CHARWIDTH(g_kt,i)  = char_width  * char_size
	    }
	}

	# Initialize the output parameters.  All boolean parameters are stored
	# as integer flags.  All string valued parameters are stored in the
	# string buffer, saving a pointer to the string in the gkt
	# descriptor.  If the capability does not exist the pointer is set to
	# point to the null string at the beginning of the string buffer.

	GKT_POLYLINE(g_kt)   = btoi (ttygetb (tty, "pl"))
	GKT_POLYMARKER(g_kt) = btoi (ttygetb (tty, "pm"))
	GKT_FILLAREA(g_kt)   = btoi (ttygetb (tty, "fa"))
	GKT_FILLSTYLE(g_kt)  =       ttygeti (tty, "fs")
	GKT_ROAM(g_kt)	     = btoi (ttygetb (tty, "ro"))
	GKT_ZOOM(g_kt)	     = btoi (ttygetb (tty, "zo"))
	GKT_ZRES(g_kt)	     =       ttygeti (tty, "zr")
	GKT_CELLARRAY(g_kt)  = btoi (ttygetb (tty, "ca"))
	GKT_SELERASE(g_kt)   = btoi (ttygetb (tty, "se"))
	GKT_PIXREP(g_kt)     = btoi (ttygetb (tty, "pr"))

	# Initialize the input parameters.

	GKT_CURSOR(g_kt)     = 1

	# Save the device string in the descriptor.
	nextch = GKT_NEXTCH(g_kt)
	GKT_DEVNAME(g_kt) = nextch
	maxch = GKT_SBUF(g_kt) + SZ_SBUF - nextch + 1
	nextch = nextch + gstrcpy (devname, Memc[nextch], maxch) + 1
	GKT_NEXTCH(g_kt) = nextch
end


# GKT_GSTRING -- Get a string value parameter from the graphcap table,
# placing the string at the end of the string buffer.  If the device does
# not have the named capability return a pointer to the null string,
# otherwise return a pointer to the string.  Since pointers are used,
# rather than indices, the string buffer is fixed in size.  The additional
# degree of indirection required with an index was not considered worthwhile
# in this application since the graphcap entries are never very large.

pointer procedure gkt_gstring (cap)

char	cap[ARB]		# device capability to be fetched
pointer	strp, nextch
int	maxch, nchars
int	ttygets()
include	"gkt.com"

begin
	nextch = GKT_NEXTCH(g_kt)
	maxch = GKT_SBUF(g_kt) + SZ_SBUF - nextch + 1

	nchars = ttygets (g_tty, cap, Memc[nextch], maxch)
	if (nchars > 0) {
	    strp = nextch
	    nextch = nextch + nchars + 1
	} else
	    strp = GKT_SBUF(g_kt)

	GKT_NEXTCH(g_kt) = nextch
	return (strp)
end


# POW2 -- Return the integer base two exponent of the first power of two
# greater than the argument.  The technique is to use successive one bit
# shift rights to determine the index of the leftmost one-bit.

int procedure pow2 (num)

int	num
int	bitshift, n, pow

begin
	bitshift = 0
	for (n=max(1,num);  n > 0;  n=n/2)
	    bitshift = bitshift + 1
	pow = bitshift - 1

	if (num > 2 ** pow)
	    return (pow + 1)
	else
	    return (pow)
end