ti/kbd: add alpha support

no a-lock or lowercase yet.

ref #41

kernel/ti/kbd.asm

@@ -24,11 +24,17 @@ kbdGetC:
 	push	bc
 	push	hl
 
-; loop until a digit is pressed
+	; During this GetC loop, register C holds the modificators (Alpha, 2nd)
+	ld	c, 0
+	; loop until a digit is pressed
 .loop:
 	ld	hl, .dtbl
 	; we go through the 7 rows of the table
 	ld	b, 7
+	; is alpha mod enabled?
+	bit	0, c
+	jr	z, .inner	; unset? skip next
+	ld	hl, .atbl	; set? we're in alpha mode
 .inner:
 	ld	a, (hl)		; group mask
 	call	.get
@@ -54,6 +60,11 @@ kbdGetC:
 	ld	a, (hl)
 	or	a		; is char 0?
 	jr	z, .loop	; yes? unsupported. loop.
+	cp	0x80		; is it alpha?
+	jr	nz, .notalpha
+	set	0, c
+	jr	.loop
+.notalpha:
 	
 	; wait until all keys are de-pressed
 	push	af		; --> lvl 1
@@ -81,11 +92,22 @@ kbdGetC:
 
 ; digits table. each row represents a group. first item is group mask.
 ; 0 means unsupported. no group 7 because it has no keys.
+; 0x80 is a special value for ALPHA key which is never returned directly.
 .dtbl:
 	.db	0xfe, 0, 0, 0, 0, 0, 0, 0, 0
 	.db	0xfd, 0x0d, '+' ,'-' ,'*', '/', '^', 0, 0
 	.db	0xfb, 0, '3', '6', '9', ')', 0, 0, 0
 	.db	0xf7, '.', '2', '5', '8', '(', 0, 0, 0
 	.db	0xef, '0', '1', '4', '7', ',', 0, 0, 0
-	.db	0xdf, 0, 0, 0, 0, 0, 0, 0, 0
+	.db	0xdf, 0, 0, 0, 0, 0, 0, 0, 0x80
+	.db	0xbf, 0, 0, 0, 0, 0, 0, 0, 0x7f
+
+; alpha table. same as .dtbl, for when we're in alpha mode.
+.atbl:
+	.db	0xfe, 0, 0, 0, 0, 0, 0, 0, 0
+	.db	0xfd, 0x0d, '"' ,'W' ,'R', 'M', 'H', 0, 0
+	.db	0xfb, '?', 0, 'V', 'Q', 'L', 'G', 0, 0
+	.db	0xf7, ':', 'Z', 'U', 'P', 'K', 'F', 'C', 0
+	.db	0xef, '_', 'Y', 'T', 'O', 'J', 'E', 'B', 0
+	.db	0xdf, 0, 'X', 'S', 'N', 'I', 'D', 'A', 0x80
 	.db	0xbf, 0, 0, 0, 0, 0, 0, 0, 0x7f