Files
open-roms/c64/kernal/screen/chrout_screen_del.s
T

79 lines
1.3 KiB
ArmAsm

//
// CHROUT routine - screen support, DEL key handling
//
chrout_screen_DEL:
// In insert mode it embeds control character
ldx INSRT
beq !+
jmp chrout_screen_quote
!:
ldy PNTR
bne chrout_screen_del_column_non_0
// FALLTROUGH
chrout_screen_del_column_0:
ldy TBLX
beq chrout_screen_del_done // delete from row 0, col 0 does nothing
// Move cursor to end of previous line
dec TBLX
lda #39
sta PNTR
// Update PNT and USER pointers
jsr screen_calculate_PNT_USER
// Put space character at the current cursor position (do not clear the color!)
ldy #39
lda #$20
sta (PNT),y
// Finish with recalculating all the variables
jmp chrout_screen_calc_lptr_done
chrout_screen_del_column_non_0:
// We need to scroll back the rest of the logical line
// YYY does not work properly when cursor crosses physical line boundary
// YYY possibly it should remove the 'continuaed line' mark in some cases, test on original ROMs
jsr screen_get_logical_line_end_ptr
tya
tax
ldy PNTR
dey
!:
iny
lda (PNT),y
dey
sta (PNT),y
iny
lda (USER),y
dey
sta (USER),y
iny
dex
cpx PNTR
bne !-
!:
// Clear char at end of line (just the character - not color!)
jsr screen_get_logical_line_end_ptr
lda #$20
sta (PNT),y
dec PNTR
// FALLTROUGH
chrout_screen_del_done:
jmp chrout_screen_done