Routines
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25596: Plot Character
Used by the routines at ObeyCommand, DescribeLocation, PrintCharacter and PrintFlag.
Puts A on the screen. 12 rubs out the previous character. 13 moves to the next row, pausing and scrolling when the text hits the bottom of the window.
DELETE is printed as a space and then another DELETE, so the cursor steps back.
PlotCharacter 25596 CP 12 DELETE prints a space and then rubs it out.
25598 JR NZ,PlotCharacter_Byte
25600 CALL PlotCharacter_Byte Plot the space, then pass DELETE on.
25603 LD A,32
25605 CALL PlotCharacter_Byte
25608 LD A,12 DELETE is the character that falls through.
PlotCharacter_Byte 25610 PUSH HL Save the screen address and the character.
25611 PUSH BC
25612 PUSH DE
25613 PUSH AF
25614 CP 13 ENTER starts a new row.
25616 JP Z,PlotCharacter_Newline
25619 CP 12 Anything except DELETE is a glyph.
25621 JR NZ,PlotGlyph
25623 LD A,(23434) Column 0 wraps to the previous row.
25626 OR A
25627 JR NZ,PlotCharacter_Back
25629 LD A,41 Column 41 of the row above.
25631 LD (23434),A
25634 LD A,(23433) The previous row, then the pixel address moves back.
25637 DEC A
25638 LD (23433),A
25641 JR PlotCharacter_Pixel
PlotCharacter_Back 25643 DEC A Step one column left.
25644 LD (23434),A
25647 AND 3 A column whose low bits are 2 does not move the pixel address.
25649 CP 2
25651 JP Z,PlotGlyph_Done
PlotCharacter_Pixel 25654 LD HL,(23431) Otherwise the pixel address moves back one byte.
25657 DEC HL
25658 LD (23431),HL
25661 JP PlotGlyph_Done
This entry point is used by the routine at PlotGlyph.
ENTER on row 19 while a description is on screen waits for a key. Below the window, the text scrolls.
PlotCharacter_Newline 25664 LD A,(23433) Row 19 is the pause row while a description is on screen.
25667 CP 19
25669 JR NZ,PlotCharacter_Low
25671 LD A,(24966) The pause only happens when PauseFlag is set.
25674 OR A
25675 JR Z,PlotCharacter_Low
25677 LD A,13 The pause row's bottom is 13.
25679 LD (23447),A
25682 CALL WaitKeyDown Wait for a key and scroll.
25685 CALL ScrollWindow
25688 LD A,19 Stay on row 19.
25690 JR PlotCharacter_Stay
PlotCharacter_Low 25692 CP 23 A row below 23 simply advances.
25694 JR C,PlotCharacter_Down
25696 CALL ScrollWindow Row 23 scrolls and stays put.
25699 LD A,23
PlotCharacter_Stay 25701 LD (23433),A Home the cursor on that row.
25704 CALL HomeRow
25707 XOR A
25708 LD (23434),A
25711 JP PlotGlyph_Done Return to the plotter.
PlotCharacter_Down 25714 LD A,(23433) Advance one row.
25717 INC A
25718 LD (23433),A
25721 CALL HomeRow Home the cursor on it.
25724 XOR A
25725 LD (23434),A
25728 JP PlotGlyph_Done Return to the plotter.
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