implemented routine pointed by KEYTAB

STATUS.md

@@ -98,7 +98,7 @@ NOTE: Even the 'DONE' routines won't support features described as missing in on
 
 | Address   | Unofficial | Name        | Status   |  Remarks                                           |
 | :-------: | :--------: | :---------- | :------: | :------------------------------------------------: |
-| `($028F)` |            | `KEYLOG`    | NOT DONE |                                                    |
+| `($028F)` |            | `KEYLOG`    | DONE     |                                                    |
 | `$FF81`   | `$FF5B`    | `CINT`      | DONE     |                                                    |
 | `$FF84`   | `$FDA3`    | `IOINIT`    | PARTIAL  | CIA initialization incomplete                      |
 | `$FF87`   | `$FD50`    | `RAMTAS`    | DONE     |                                                    |

c64/aliases/,aliases_ram_lowmem.s

@@ -153,7 +153,7 @@
 	.label INSRT     = $D8  //          insert mode flag/counter
 	.label LDTBL     = $D9  // $D9-$F2  screen line link table, [!] our usage is different  XXX give more details
 	.label USER      = $F3  // $F3-$F4  pointer to current color RAM location
-	.label KEYTAB    = $F5  // $F5-$F6  -- NOT IMPLEMENTED --
+	.label KEYTAB    = $F5  // $F5-$F6  pointer to keyboard lookup table
 	.label RIBUF     = $F7  // $F7-$F8  -- NOT IMPLEMENTED --
 	.label ROBUF     = $F9  // $F9-$FA  -- NOT IMPLEMENTED --
 	//                 $FB     $FB-$FE  -- UNUSED --          free for user software

c64/kernal/cint_real.s

@@ -58,9 +58,9 @@ cint_pal:
 
 	// Setup KEYLOG vector - XXX is it proper place?
 
-	lda #<setup_keydecode
+	lda #<scnkey_set_keytab
 	sta KEYLOG+0
-	lda #>setup_keydecode
+	lda #>scnkey_set_keytab
 	sta KEYLOG+1
 
 cint_brk: // entry for BRK and STOP+RESTORE - XXX, where should it start?

c64/kernal/scnkey.s

@@ -0,0 +1,83 @@
+
+//
+// Official Kernal routine, described in:
+//
+// - [RG64] C64 Programmer's Reference Guide   - page 295
+// - [CM64] Compute's Mapping the Commodore 64 - page 220
+//
+// CPU registers that has to be preserved (see [RG64]): none
+//
+
+// Variables used:
+// - KEYTAB  - keyboard matrix pointer
+// - DELAY   - counter for first delay between key repeats
+// - KOUNT   - counter for next delays between key repeats
+// - SHFLAG  - SHIFT / CTRL / VENDOR keypress status
+// - NDX     - number of characters in keyboard buffer
+// - XMAX    - maximum size of keyboard buffer
+// - LSTX    - matrix coordinate of last pressed key
+// - LSTSHF  - previous status of SHFLAG
+// - MODE    - flag, whether charset toggle (SHIFT+VENDOR) is allowed
+
+
+#if !CONFIG_SCNKEY_TWW_CTR
+
+// Routine is heavily inspired by TWW/CTR proposal, see here:
+// - http://codebase64.org/doku.php?id=base:scanning_the_keyboard_the_correct_and_non_kernal_way
+
+
+SCNKEY:
+
+	// Handle repeat timer
+
+	ldx KOUNT
+	beq sk_start
+	dec KOUNT
+
+	// Setup the CIA registers
+
+	ldx #$FF
+	stx CIA1_DDRA  // output
+	ldy #$00
+	sty CIA1_DDRB  // input
+
+	// Prepare for SHFLAG update
+
+	lda SHFLAG
+	sta LSTSHF
+	sty SHFLAG
+
+	// XXX retrieve ALT and NO_SCRL status for C128/C65 keyboards
+
+	// Check for any activity
+
+	sty CIA1_PRA  // connect all the lines
+	cpx CIA1_PRB
+	beq scnkey_no_keys
+
+	// XXX retrieve SHIFT / CTRL / VENDOR status
+
+	// Set pointer in KEYTAB
+	jsr scnkey_via_keytab
+
+	// XXX scan the keyboard matrix
+
+
+
+
+
+
+
+	// XXX
+
+scnkey_no_keys:
+
+	// ldx #$FF
+	stx LSTX
+
+	rts
+
+scnkey_via_keytab:
+	jmp (KEYTAB)
+
+#endif // No CONFIG_SCNKEY_TWW_CTR

c64/kernal/scnkey_set_keytab.s

@@ -0,0 +1,53 @@
+
+//
+// Well-known Kernal routine, described in:
+//
+// - [CM64] Compute's Mapping the Commodore 64 - pages 220, 221
+//
+
+scnkey_set_keytab:
+
+	// Set initial KEYTAB value
+
+	lda #<keyboard_matrix
+	sta KEYTAB+0
+	lda #>keyboard_matrix
+	sta KEYTAB+1
+
+	// Calculate table index
+
+	lda SHFLAG
+	and #$07 // we are only interested in SHIFT / CTRL / VENDOR keys
+	tax
+
+	// Retrieve table offset
+	lda keyboard_matrix_lookup, x
+
+	// Add offset to the vector
+	sec
+	adc KEYTAB+0
+	sta KEYTAB+0
+	lda #$00
+	adc KEYTAB+1
+	sta KEYTAB+1
+
+	// Check if we should toggle the character set
+
+	lda MODE
+	bne !+ // not allowed to toggle
+	lda SHFLAG
+	and #$03
+	cmp #$03
+	bne !+ // no SHIFT + VENDOR pressed
+	lda LSTSHF
+	and #$03
+	cmp #$03
+	beq !+ // alreeady toggled
+
+	// Toggle char set
+
+	lda VIC_YMCSB
+	eor #$02
+	sta VIC_YMCSB
+!:
+	rts

c64/kernal/setup_keydecode.s

@@ -1,5 +0,0 @@
-
-// XXX provide documentation and implementation
-
-setup_keydecode:
-    STUB_IMPLEMENTATION()