;  Tank Battle Game for the XGameStation Micro Edition
;  by Jeff Tranter
;  Copyright (c) 2006 Jeff Tranter 
;
;  This program is free software; you can redistribute it and/or modify
;  it under the terms of the GNU General Public License as published by
;  the Free Software Foundation; either version 2 of the License, or
;  (at your option) any later version.
; 
;  This program is distributed in the hope that it will be useful,
;  but WITHOUT ANY WARRANTY; without even the implied warranty of
;  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;  GNU General Public License for more details.
; 
;  You should have received a copy of the GNU General Public License
;  along with this program; if not, write to the Free Software
;  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
; 
; Tank Battle revision history:
;
; 3 Mar 2006 - version 1.0 - basic game is working


; XGS-ME TILE GRAPHICS ENGINE

; Version 1.3.1
; Alex Varanese

; 1.5.2005

; **** NOTES ******************************************************************

; ---- OVERVIEW ---------------------------------------------------------------

; This is a tile-based graphics system that makes it easy to create complex,
; graphically-detailed games on the XGameStation Micro Edition. Instead of
; directly generating the TV signal, client programs manipulate a framebuffer
; stored in SRAM.
;
; The framebuffer consists of 16x24 tiles. Each tile is 8x8 pixels and has its
; own foreground and background color. The system supports up to 64 unique
; tiles.

; ---- WRITING CLIENT PROGRAMS ------------------------------------------------

; Client programs can be written easily by filling in the empty Game_Init()
; and Game_Update() subroutines. Game_Init() is called once before the TV signal
; is generated, and Game_Update() is called once per frame.
;
; Game_Update() is given a timeslice of about 60,672 clocks, after which the TV
; signal will be corrupted. As long as the subroutine does not exceed this time
; limit, timing issues will be handled automatically and client programs need
; not worry about stalling for the remainder of the timeslice.
;
; The easiest way to draw graphics to the screen is with the following macros:
;
; M_SET_TILE x, y, tile_index, fg_color, bg_color
;
;	Sets a tile at any place on the screen. This macro allows control over
;	the tile's foreground and background colors as well.  specifies
;	the location of the tile to set.  can range from 0-15, and  can
;	range from 0-23. Clipping is automatically performed to the screen
; 	boundaries.
;
; M_FILL_ROW y, tile_index, fg_color, bg_color
;
; 	Fills an entire horizontal row of tiles to the specified tile graphic
; 	and colors.  specifies which screen row to fill (0-23).
;
; M_FILL_SCREEN tile_index, fg_color, bg_color
;
;	Fills the entire screen with the specified tile graphic and colors.
; 	Most useful for laying down a full-screen background pattern or color
;	at the start of the program.
;
; A better way is to create screen-sized maps in program memory which reference
; a TAT (tile attribute table) to save memory by using a limited palette of
; tiles:
;
; M_LOAD_MAP map, tat
;
;	Loads the map located at label 

    Source: geocities.com/jefftranter@rogers.com/xgs

               ( geocities.com/jefftranter@rogers.com)