Drivers for the Epson Graphic LCD Controller (GLC) chip
-------------------------------------------------------

Document:	glcfns.doc	Version 3	1988-08-03

Based on:	glcinit.c	Version 5	1988-08-03
		glcdefs.h	Version 3	1988-08-03
		glcplot.s	Version 2	1987-04-23

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GLC Function synopsis:
----------------------

GLCcrc		unsigned	GLCcrc(row, col)
GLCcurs		void		GLCcurs(crs)
GLCcxy		unsigned	GLCcxy(x, y)
GLCdisp		void		GLCdisp(dsp, crs, blk1, blk2, blk3)
GLCinit		void		GLCinit()
GLCplot		void		GLCplot(x, y, val)
GLCtext		void		GLCtext(row, col, s)
GLCwrts		void		GLCwrts(s)


GLC Variable synopsis:
----------------------

lcdbase		unsigned	lcdbase;	LCD graphics base address
lcdbit		unsigned	lcdbit;		LCD graphics pixel bit mask
lcdcol		unsigned	lcdcol;		LCD text column
lcdctl1		unsigned	lcdctl1;	LCD display control -- command
lcdctl2		unsigned	lcdctl2;	LCD display control -- data
lcdcurs		unsigned	lcdcurs;	LCD graphics pixel byte address
lcdrow		unsigned	lcdrow;		LCD text row
lcdx		unsigned	lcdx;		LCD graphics x
lcdy		unsigned	lcdy;		LCD graphics y

GLC Constants:
--------------

#define	G_INIT		(char)0x40		initialize GLC
#define	G_MWRITE	(char)0x42		set memory write mode
#define	G_MREAD		(char)0x43		set memory read mode
#define	G_SETSAD	(char)0x44		set scroll addresses
#define	G_CRSWR		(char)0x46		write cursor address
#define	G_CRSRD		(char)0x47		read cursor address
#define	G_CRSMRT	(char)0x4C		set cursor direction - right
#define	G_CRSMLT	(char)0x4D		set cursor direction - left
#define	G_CRSMUP	(char)0x4E		set cursor direction - up
#define	G_CRSMDN	(char)0x4F		set cursor direction - down
#define	G_ERASE		(char)0x52		erase
#define	G_SLEEP		(char)0x53		set sleep mode
#define	G_DSPCTL	(char)0x58		set display controls
#define	G_HSCRL		(char)0x5A		set horizontal dot scroll
#define	G_OVRLAY	(char)0x5B		set overlay mode
#define	G_CGRAM		(char)0x5C		set CG RAM base
#define	G_CRSFRM	(char)0x5D		set cursor format

#define	LCD_WC		lcd_a1			write command address
#define	LCD_RS		lcd_a0			read status address
#define	LCD_WD		lcd_a0			write data address
#define	LCD_RD		lcd_a1			read data address

#define	G_PLANE1	(unsigned)0x0000	plane 1 base address
#define	G_PLANE2	(unsigned)0x2000	plane 2 base address

#define	G_OFF		0			off
#define	G_ON		1			on
#define	G_B2		2			blink - FR/32
#define	G_B1		3			blink - FR/64
GLC characteristics:
--------------------

	Graphics:

		510 pixels wide by 64 pixels high.
		Graphics are in plane 2.
		X = 0, Y = 0 is the lower left corner of the display.
	
	Text:

		8 rows by 85 columns
		Text is in plane 1.
		Row 0, Column 0 is the upper left corner of the display.

	Characters:

		Internal ASCII character generator.
		5 pixels wide by 7 pixels high, in a 6 by 8 block.

G_INIT parameters:
------------------

	0x12	P1	IV, M/S, W/S, M2, M1, M0
	0x05	P2	WF, FX
	0x07	P3	FY
	0x54	P4	C/R
	0x58	P5	TC/R
	0x3F	P6	L/F
	0x55	P7	APL
	0x00	P8	APH

G_SETSAD parameters:
--------------------

	0x00	P1	SAD1L
	0x00	P2	SAD1H
	0x3F	P3	SL1
	0x00	P4	SAD2L
	0x20	P5	SAD2H
	0x3F	P6	SL2
	0x00	P7	SAD3L
	0x00	P8	SAD3H

GLC initialization values:
--------------------------

	G_INIT:
	-------

	IV	0		correct screen to top line
	M/S	1		master mode
	W/S	0		single screen drive
	M2	0		8 pixel wide CG
	M1	0		32 character CG RAM area
	M0	0		internal CG

	WF	0		"line reversion" drive
	FX	0x05		6 pixel character block width

	FY	0x07		8 pixel character block height

	C/R	0x54		85 characters per line

	TC/R	0x58		89 scan times per line

	L/F	0x3F		64 lines

	APL,APH	0x0055		virtual screen size = 85 characters


	G_SETSAD:
	---------

	SAD1	0x0000		plane 1 (text plane) address = 0x0000

	SL1	0x3F		plane 1 height = 64 lines

	SAD2	0x2000		plane 2 (graphics plane) address = 0x2000

	SL2	0x3F		plane 2 height = 64 lines
Functions:
----------

	unsigned
	GLCcrc(row, col)
	unsigned row, col;

		Positions the GLC cursor at ('row', 'col') preparatory
		to writing text.  Returns the calculated cursor address.

	GLCcurs(crs)
	short crs;

		Turns the cursor on or off.

	unsigned
	GLCcxy(x, y)
	unsigned x, y;

		Positions the GLC cursor at ('x', 'y') preparatory to
		writing graphics.  Returns a bit mask for the pixel.
		Leaves the cursor address in lcdcurs.
		Limits:  0 LE x LE 511,  0 LE y LE 63.

	GLCdisp(dsp, crs, blk1, blk2, blk3)
	short dsp, crs, blk1, blk2, blk3;

		Sets the overall display, cursor and block status values.

	GLCinit()

		Initializes the GLC.

	GLCplot(x, y, val)
	unsigned x, y, val;

		Plots a dot at x, y.  The dot will be dark if val is non-zero.

	GLCtext(row, col, s)
	unsigned row, col;
	char *s;

		Sets the GLC cursor to ('row', 'col'), then writes the
		character string pointed to by 's'.
		Cursor must start and end on the same line.
		No error checks are done.

	GLCwrts(s)
	char *s;

		Writes the character string pointed to by 's' at the
		current cursor position on the LCD display.
		Cursor must start and end on the same line.
		No error checks are done.