Routines
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34317: Print: Scroll The Line Buffer
Used by the routine at Print_Character.
Scrolls the line buffer up by four rows of 32 bytes and fills the vacated row with spaces.
Print_ScrollTheLineBuffer 34317 PUSH HL Save HL, DE, BC and AF, and point HL at the screen line 20608.
34318 PUSH DE
34319 PUSH BC
34320 PUSH AF
34321 LD HL,20608
34324 LD DE,20576 Point DE at the line buffer.
34327 LD A,4 Load 4 before the day and night test.
34329 LD B,0 Start the token count at zero.
Print_ScrollTheLineBuffer_ScrollOneCharacterRow 34331 PUSH HL Save the screen pointers and count 8 pixel rows.
34332 PUSH DE
34333 LD C,8
Print_ScrollTheLineBuffer_Loop 34335 PUSH HL Copy the prepared bytes.
34336 PUSH DE
34337 PUSH BC
34338 LD C,32
34340 LDIR
34342 POP BC Restore the screen pointers from the stack, step to the next pixel row, and jump back to Print_ScrollTheLineBuffer_Loop until the count in C reaches zero.
34343 POP DE
34344 POP HL
34345 INC H
34346 INC D
34347 DEC C
34348 JR NZ,Print_ScrollTheLineBuffer_Loop
34350 POP DE Restore the saved screen pointers from the stack and set BC to 32, one screen row.
34351 POP HL
34352 LD C,32
34354 ADD HL,BC Step one screen row, 32 bytes.
34355 EX DE,HL Swap the two screen pointers.
34356 ADD HL,BC Step the other pointer one screen row, 32 bytes.
34357 EX DE,HL Swap the two screen pointers.
34358 DEC A Jump back to Print_ScrollTheLineBuffer_ScrollOneCharacterRow until the row count in A reaches zero.
34359 JR NZ,Print_ScrollTheLineBuffer_ScrollOneCharacterRow
34361 LD B,32 Count 32 passes.
34363 LD HL,20704 Point HL at the attribute line.
34366 LD A,32 Use the character ' '.
Blank the new line with spaces.
Print_ScrollTheLineBuffer_BlankTheNewLine 34368 CALL Print_RomFont Call Print_RomFont to draw this character with the ROM font.
34371 DJNZ Print_ScrollTheLineBuffer_BlankTheNewLine Loop back to Print_ScrollTheLineBuffer_BlankTheNewLine until 32 runs out.
34373 POP AF Restore AF, BC, DE and HL from the stack.
34374 POP BC
34375 POP DE
34376 POP HL
34377 RET Return.
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