reordered and size-optimized some screen routines

Makefile

@@ -3,7 +3,7 @@
 
 SRCDIR_COMMON            = c64/aliases
 SRCDIR_BASIC_COMMON      = $(SRCDIR_COMMON) c64/basic
-SRCDIR_KERNAL_COMMON     = $(SRCDIR_COMMON) c64/kernal c64/kernal/assets c64/kernal/jumptable c64/kernal/iec c64/kernal/interrupts c64/kernal/print
+SRCDIR_KERNAL_COMMON     = $(SRCDIR_COMMON) c64/kernal c64/kernal/assets c64/kernal/jumptable c64/kernal/iec c64/kernal/interrupts c64/kernal/print c64/kernal/screen
 
 SRCDIR_BASIC_generic     = $(SRCDIR_BASIC_COMMON) c64/basic/,target_generic
 SRCDIR_BASIC_mega65      = $(SRCDIR_BASIC_COMMON) c64/basic/,target_mega65

c64/kernal/blink_cursor.s

@@ -1,96 +0,0 @@
-// We have the following variables:
-// BLNSW (cursor blink switch)
-// BLNCT (cursor blink countdown)
-// GDBLN (cursor saved character)
-// BLNON (if cursor is visible)
-// GDCOL (colour under cursor)
-// USER  (current screen line colour pointer)
-// PNT   (current screen line pointer)
-// PNTR  (current screen x position)
-
-show_cursor_if_enabled:
-	lda BLNSW
-	beq !+
-	rts
-!:	lda BLNON
-	beq show_cursor
-	rts
-
-show_cursor:
-	// Set cursor as though it had just finished the off phase,
-	// so that the call to blink_cursor paints it
-	lda #$00
-	sta BLNCT
-	sta BLNON
-	jsr blink_cursor
-	// Then set the timeout to 1 frame, so that the cursor
-	// blinks under key repeat conditions, like on the original KERNAL
-	lda #$01
-	sta BLNCT
-	rts
-
-blink_cursor:
-	// Is the cursor enabled?
-	lda BLNSW
-	bne no_blink_cursor
-
-	// Do we need to redraw things?
-	dec BLNCT
-	bpl no_blink_cursor
-
-	// Check if cursor was visible or not, and toggle
-	lda BLNON
-	bne undraw_cursor
-draw_cursor:
-	jsr calculate_screen_line_pointer
-
-	ldy PNTR
-	lda (PNT),y
-	sta GDBLN
-	eor #$80
-	sta (PNT),y
-	// Also set cursor colour
-	lda (USER),y
-	sta GDCOL
-	lda COLOR
-	sta (USER),y
-
-	lda #1
-	sta BLNON
-
-	jmp reset_blink_timer
-
-undraw_cursor:
-	jsr calculate_screen_line_pointer
-
-	lda GDBLN
-	ldy PNTR
-	sta (PNT),y
-	lda GDCOL
-	sta (USER),y
-	
-	lda #0
-	sta BLNON
-	// Fall through
-reset_blink_timer:	
-	// Rest blink counter
-	// (Compute's Mapping the 64, p39-40)
-	lda #20
-	sta BLNCT
-no_blink_cursor:
-	rts
-
-disable_cursor:
-	lda #$80
-	sta BLNSW
-	// FALL THROUGH
-hide_cursor_if_visible:
-	lda BLNON
-	bne undraw_cursor
-	rts
-
-enable_cursor:
-	lda #$00
-	sta BLNSW
-	rts
-

c64/kernal/chrin_real.s

@@ -9,6 +9,7 @@
 //
 
 // XXX keyboard part currently does not preserve register Y, to be fixed!
+// XXX try to make chrin_real unnecessary (try to fit this into original location)
 
 // Reads a byte of input, unless from keyboard.
 // If from keyboard, then it gets a whole line of input, and returns the first char.
@@ -84,7 +85,7 @@ not_end_of_input:
 
 read_from_keyboard:
 
-	jsr enable_cursor
+	jsr cursor_enable
 
 	// Wait for a key
 	lda NDX
@@ -94,11 +95,11 @@ read_from_keyboard:
 	cmp #$0d
 	bne not_enter
 
-	jsr disable_cursor
+	jsr cursor_disable
 
 	jsr pop_keyboard_buffer
 
-	jsr hide_cursor_if_visible
+	jsr cursor_hide_if_visible
 
 	// It was enter.
 	// Note that we have a line of input to return, and return the first byte thereof
@@ -170,41 +171,3 @@ pop_keyboard_buffer:
 	cli
 
 	rts
-
-screen_code_to_petscii:
-	cmp #$1b
-	bcs not_alpha
-
-	clc
-	adc #$40
-	rts
-	
-not_alpha:
-	cmp #$40
-	bcs not_punctuation
-
-	rts
-
-not_punctuation:
-	cmp #$5b
-	bcs not_shifted
-
-	clc
-	adc #$80
-
-	rts
-
-not_shifted:
-
-	cmp #$80
-	bcs not_vendor
-
-	// $60-$7F -> $A0-$BF
-
-	clc
-	adc #$40
-	
-	// FALLTROUGH
-not_vendor:
-	rts
-

c64/kernal/chrout_screen.s

@@ -9,7 +9,7 @@ chrout_screen:
 	// Crude implementation of character output	
 	sei // XXX why do we need to disable interrupts?
 
-	jsr hide_cursor_if_visible
+	jsr cursor_hide_if_visible
 
 	lda SCHAR
 	tax
@@ -620,7 +620,7 @@ line_not_linked_del:
 
 screen_advance_to_next_line:
 
-	// jsr hide_cursor_if_visible
+	// jsr cursor_hide_if_visible
 	
 	//  Go to start of line
 	lda #0

c64/kernal/e544.clear_screen.s

@@ -3,6 +3,8 @@
 
 clear_screen:
 
+	// XXX it is probably a good idea to hide cursor first
+
 	// Clear line link table 
 	// (Compute's Mapping the 64 p215)
 
@@ -57,4 +59,4 @@ clearscreen_l3:
 	bne clearscreen_l3
 
 	// (Compute's Mapping the 64 p216)
-	jmp home_cursor
+	jmp cursor_home

c64/kernal/f1ca.chrout.s

@@ -41,7 +41,7 @@ chrout_iec:
 	// FALLTROUGH
 
 chrout_done_fail:
-	jsr show_cursor_if_enabled
+	jsr cursor_show_if_enabled
 
 	plp
 
@@ -54,7 +54,7 @@ chrout_done_fail:
 	rts
 
 chrout_done_unknown_device:
-	jsr show_cursor_if_enabled
+	jsr cursor_show_if_enabled
 
 	plp
 
@@ -68,7 +68,7 @@ chrout_done_unknown_device:
 	jmp lvs_device_not_found_error
 
 chrout_done:
-	jsr show_cursor_if_enabled
+	jsr cursor_show_if_enabled
 
 	plp
 

c64/kernal/interrupts/ea31.default_irq_handler.s

@@ -1,7 +1,7 @@
 
 default_irq_handler:
 
-	jsr blink_cursor
+	jsr cursor_blink
 	jsr JSCNKEY
 	jsr JUDTIM // update jiffy clock
 

c64/kernal/screen/cursor.s

@@ -0,0 +1,81 @@
+
+//
+// Variables used:
+// - BLNSW (cursor blink switch)
+// - BLNCT (cursor blink countdown)
+// - GDBLN (cursor saved character)
+// - BLNON (if cursor is visible)
+// - GDCOL (colour under cursor)
+// - USER  (current screen line colour pointer)
+// - PNT   (current screen line pointer)
+// - PNTR  (current screen x position)
+//
+
+
+cursor_blink:
+	// Is the cursor enabled?
+	lda BLNSW
+	bne cursor_blink_end
+
+	// Do we need to redraw things?
+	dec BLNCT
+	bpl cursor_blink_end
+
+	// Check if cursor was visible or not, and toggle
+	lda BLNON
+	bne cursor_undraw
+
+	// FALLTROUGH
+
+cursor_draw:
+	jsr calculate_screen_line_pointer // XXX make sure this is not needed and remove the call
+
+	ldy PNTR
+	lda (PNT),y
+	sta GDBLN
+	eor #$80
+	sta (PNT),y
+	// Also set cursor colour
+	lda (USER),y
+	sta GDCOL
+	lda COLOR
+	sta (USER),y
+
+	lda #1
+	sta BLNON
+
+	bne cursor_blink_timer_reset // branches always
+
+cursor_disable:
+	lda #$80
+	sta BLNSW
+
+	// FALLTHROUGH
+
+cursor_hide_if_visible:
+	lda BLNON
+	beq cursor_blink_end
+
+cursor_undraw:
+
+	lda GDBLN
+	ldy PNTR
+	sta (PNT),y
+	lda GDCOL
+	sta (USER),y
+	
+	lda #0
+	sta BLNON
+
+	// FALLTROUGH
+
+cursor_blink_timer_reset:
+
+	// Rest blink counter (Mapping the 64, p39-40)
+	lda #20
+	sta BLNCT
+
+	// FALLTROUGH
+
+cursor_blink_end:
+	rts

c64/kernal/screen/cursor_enable.s

@@ -0,0 +1,10 @@
+
+//
+// Variables used:
+// - BLNSW (cursor blink switch)
+//
+
+cursor_enable:
+	lda #$00
+	sta BLNSW
+	rts

c64/kernal/screen/cursor_home.s

@@ -1,7 +1,9 @@
-// Home the cursor
-// (Compute's Mapping the 64 p216)
 
-home_cursor:
+//
+// Home the cursor (Compute's Mapping the 64 p216)
+//
+
+cursor_home:
 
 	lda #$00
 	sta PNTR // x position

c64/kernal/screen/cursor_show.s

@@ -0,0 +1,34 @@
+
+//
+// Variables used:
+// - BLNSW (cursor blink switch)
+// - BLNON (if cursor is visible)
+// - BLNCT (cursor blink countdown)
+//
+
+cursor_show_if_enabled:
+	lda BLNSW
+	bne cursor_show_end
+	lda BLNON
+	bne cursor_show_end
+
+	// FALLTROUGH
+
+cursor_show:
+
+	// Set cursor as though it had just finished the off phase,
+	// so that the call to cursor_blink paints it
+	lda #$00
+	sta BLNCT
+	sta BLNON
+	jsr cursor_blink
+
+	// Then set the timeout to 1 frame, so that the cursor
+	// blinks under key repeat conditions, like on the original KERNAL
+	lda #$01
+	sta BLNCT
+
+	// FALLTROUGH
+
+cursor_show_end:
+	rts

c64/kernal/screen/screen_code_to_petscii.s

@@ -0,0 +1,36 @@
+
+screen_code_to_petscii:
+	cmp #$1B
+	bcc s2p_adc_40
+	
+s2p_not_alpha:
+	cmp #$40
+	bcc s2p_end
+
+	// FALLTROUGH
+
+s2p_not_punctuation:
+	cmp #$5B
+	bcs s2p_not_shifted
+
+	// carry already clear here
+	adc #$80
+
+	rts
+
+s2p_not_shifted:
+
+	cmp #$80
+	bcs s2p_end // not vendor
+
+	// $60-$7F -> $A0-$BF
+
+s2p_adc_40:
+
+	clc
+	adc #$40
+	
+	// FALLTROUGH
+
+s2p_end:
+	rts