ti-84+: wip

I need RSHIFT and LSHIFT first...

blk/001

@@ -9,7 +9,7 @@ MASTER INDEX
 370 SD Card driver            390 Inner core
 420 Core words                480 AT28 Driver
 490 TRS-80 Recipe             520 Fonts
-
+550 TI-84+ Recipe
 
 
 

blk/550

@@ -0,0 +1,6 @@
+TI-84+ Recipe
+
+Support code for the TI-84+ recipe. Contains drivers for the
+keyboard and LCD.
+
+551 LCD

blk/551

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+TI-84+ LCD driver
+
+Implement (emit) on TI-84+ (for now)'s LCD screen. Load with
+"555 LOAD".
+
+The screen is 96x64 pixels. The 64 rows are addressed directly
+with CMD_ROW but columns are addressed in chunks of 6 or 8 bits
+(there are two modes).
+
+In 6-bit mode, there are 16 visible columns. In 8-bit mode,
+there are 12.
+
+Note that "X-increment" and "Y-increment" work in the opposite
+way than what most people expect. Y moves left and right, X
+moves up and down.
+                                                        (cont.)

blk/552

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+# Z-Offset
+
+This LCD has a "Z-Offset" parameter, allowing to offset rows on
+the screen however we wish. This is handy because it allows us
+to scroll more efficiently. Instead of having to copy the LCD
+ram around at each linefeed (or instead of having to maintain
+an in-memory buffer), we can use this feature.
+
+The Z-Offet goes upwards, with wrapping. For example, if we
+have an 8 pixels high line at row 0 and if our offset is 8,
+that line will go up 8 pixels, wrapping itself to the bottom of
+the screen.
+
+The principle is this: The active line is always the bottom
+one. Therefore, when active row is 0, Z is FNT_HEIGHT+1, when
+row is 1, Z is (FNT_HEIGHT+1)*2, When row is 8, Z is 0. (cont.)

blk/553

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+# 6/8 bit columns and smaller fonts
+
+If your glyphs, including padding, are 6 or 8 pixels wide,
+you're in luck because pushing them to the LCD can be done in a
+very efficient manner.  Unfortunately, this makes the LCD
+unsuitable for a Collapse OS shell: 6 pixels per glyph gives us
+only 16 characters per line, which is hardly usable.
+
+This is why we have this buffering system. How it works is that
+we're always in 8-bit mode and we hold the whole area (8 pixels
+wide by FNT_HEIGHT high) in memory. When we want to put a glyph
+to screen, we first read the contents of that area, then add
+our new glyph, offsetted and masked, to that buffer, then push
+the buffer back to the LCD. If the glyph is split, move to the
+next area and finish the job.
+                                                        (cont.)

blk/554

@@ -0,0 +1,3 @@
+That being said, it's important to define clearly what CURX and
+CURY variable mean. Those variable keep track of the current
+position *in pixels*, in both axes.

blk/555

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+( Required config: TI_MEM )
+: TI_MEM+ [ TI_MEM LITN ] + ;
+: LCD_PORT_CMD 0x10 ;
+: LCD_PORT_DATA 0x11 ;
+: FNT_WIDTH 3 ;
+: FNT_HEIGHT 5 ;
+( Current Y position on the LCD, that is, where we're going to
+  spit our next glyph. )
+: LCD_CURY 0 TI_MEM+ ;
+: LCD_CURX 1 TI_MEM+ ;
+( two pixel buffers that are 8 pixels wide (1b) by FNT_HEIGHT
+  pixels high. This is where we compose our resulting pixels
+  blocks when spitting a glyph. )
+: LCD_BUF 2 TI_MEM+ ;
+
+1 2 LOADR+

blk/556

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+: _wait ( Wait until the lcd is ready to receive a command )
+	( When 7th bit is cleared, we can send a new command )
+    BEGIN LCD_PORT_CMD PC@ 0x80 AND NOT UNTIL ;
+: _cmd LCD_PORT_CMD PC! _wait ;
+: _data! LCD_PORT_DATA PC! _wait ;
+: _data@ LCD_PORT_DATA PC@ _wait ;
+: LCDOFF 0x02 ( CMD_DISABLE ) _cmd ;
+: _col! ( col -- )
+    0x20 ( CMD_COL ) + _cmd ;
+: _row! ( row -- )
+    0x80 ( CMD_ROW ) + _cmd ;

blk/557

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+( Load a "glyph line" from buffer, left part being in MSB and
+  right part being in LSB. )
+: _gl@

blk/558

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+: _glyph> ( a -- )
+    LCD_CURY C@ _row! LCD_CURX C@ 8 /MOD _col! ( a coff )
+    0x05 ( XINC ) _cmd _data@ DROP
+    FNT_HEIGHT 0 DO LOOP
+