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Add cursor processing

This commit is contained in:
Karri Kaksonen 2022-04-04 10:51:43 +03:00
parent 0e6b490c8b
commit 04a13cf949

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;
; 2022-04-03, Karri Kaksonen
;
; setcursor (unsigned char on);
;
; The Atari 7800 does not have a hw cursor.
; This module emulates a cursor to be used with the conio
; implementation.
;
; The actual cursor display is included in the conio dll
; but every scanline has the element silenced by default
; at the end of every zone.
;
; The way the cursor works is to silence it before the cursor
; position changes and enable it afterwards.
;
; In order to get some performance we have a pointer to the
; cursor header structure. This structure is always at the
; end of the zone. So the pointer changes when CURS_Y changes.
;
; There is so many dependencies that it makes sense to
; deal with all CURS_X, CURS_Y stuff in this file and
; definitely not allow direct access to the variables.
;
.export _cursor_visible
.export _cursorzone
.export _gotoxy, _gotox, _gotoy, wherex, wherey
.constructor init_cursor
.importzp ptr1, sp
.import _zones
.import pusha, incsp1, pusha0, pushax, popax, tosumula0, incax5
.include "atari7800.inc"
.macpack generic
.data
CURS_X:
.byte 0
CURS_Y:
.byte 0
_cursor_visible:
.byte 1
.bss
_cursorzone:
.res 2
.code
;-----------------------------------------------------------------------------
; Calculate cursorzone address
; You also need to set the cursorzone to point to the correct cursor Header
; at the end of line CURS_Y.
; Offset to cursor zone 5. To next line offset 11
; cursorzone points to _zones + CURS_Y * 11 + 5
; A = CURS_Y
calccursorzone:
jsr pusha0
lda #11
jsr tosumula0
jsr incax5
clc
adc #<_zones
sta _cursorzone ; calculate new cursorzone
sta ptr1
txa
adc #>_zones
sta _cursorzone+1
sta ptr1+1
rts
;-----------------------------------------------------------------------------
; Set cursor to Y position.
; You also need to set the cursorzone to point to the correct cursor Header
; at the end of line CURS_Y.
; Offset to cursor zone 5. To next line offset 11
; cursorzone points to _zones + CURS_Y * 11 + 5
;
; cursorzone[1] = 0 when not CURS_Y, 30 if CURS_Y
;
; Disable cursor
; cursorzone[1] = 0
;
; Enable cursor
; if showcursor cursorzone[1] = 30
;
_gotoy: pha
lda CURS_Y
jsr calccursorzone
ldy #1
lda #0
sta (ptr1),y ; disable cursor
pla
sta CURS_Y
jsr calccursorzone
lda _cursor_visible
beq L2
lda #30 ; enable cursor
L2: ldy #1
sta (ptr1),y
rts
;-----------------------------------------------------------------------------
; Set cursor to X position.
; You also need to set the hpos offset to the correct value on this line
; cursorzone[3] = 8 * CURS_X
;
_gotox: tay
lda _cursorzone
ldx _cursorzone+1
sta ptr1
stx ptr1+1
tya
ldy #3
clc
rol
rol
rol
sta (ptr1),y
rts
;-----------------------------------------------------------------------------
; Set cursor to desired position (X,Y)
;
.proc _gotoxy
jsr _gotoy
jsr popax
jsr _gotox
rts
.endproc
;-----------------------------------------------------------------------------
; Get cursor X position
;
.proc wherex
lda CURS_X
jsr pusha0
rts
.endproc
;-----------------------------------------------------------------------------
; Get cursor Y position
;
.proc wherey
lda CURS_Y
jsr pusha0
rts
.endproc
;-----------------------------------------------------------------------------
; Initialize cursorzone at startup
; Offset to cursor zone 5.
;
; .segment "ONCE"
init_cursor:
lda #0
jsr calccursorzone
rts
;-----------------------------------------------------------------------------
; force the init constructor to be imported
.import initconio
conio_init = initconio