Routines
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43447: Print Character
Used by the routines at PrintNewline, ProcessObject_Display, ProcessTextCommand, PrintCharacterAndReturnZero, PrintCharacterWithTimePeriod, PrintCharacterAndReturn, ExtractTokenFromText, PrintTextBasedOnFlag, ProcessLocationTokenDisplay, PrintFormattedObjectList, PrintObjectDescriptionText and 59068.
Input
A Character code to print
Print_Character 43447 PUSH AF Stash the character code on the stack.
43448 LD A,(40999) Jump to Print_Character_AlternateMode if *PrintModeFlag isn't set (not in direct print mode).
43451 AND A
43452 JR NZ,Print_Character_AlternateMode
Handle direct print mode - write character to buffer.
43454 POP AF Restore the character code from the stack.
43455 PUSH AF Stash the character code and HL on the stack.
43456 PUSH HL
43457 LD HL,(43445) HL=*BufferPointer (load the buffer pointer).
43460 CP 32 Jump to Print_Character_ScreenPrintMode if the character is a "SPACE" (ASCII 32).
43462 JR Z,Print_Character_ScreenPrintMode
43464 CP 13 Jump to Print_Character_ScreenPrintMode if the character is an "ENTER" (ASCII 13).
43466 JR Z,Print_Character_ScreenPrintMode
43468 CP 34 Jump to Print_Character_ScreenPrintMode if the character is a quotation mark (ASCII 34).
43470 JR Z,Print_Character_ScreenPrintMode
43472 CP 8 Jump to Print_Character_WriteToBuffer if the character is not a backspace (ASCII 8).
43474 JR NZ,Print_Character_WriteToBuffer
The character IS a backspace, so handle this.
43476 DEC HL Decrease HL by one (move buffer pointer back for backspace).
43477 JR Print_Character_UpdateBufferPointer Jump to Print_Character_UpdateBufferPointer (skip writing the character).
Write the character to the buffer.
Print_Character_WriteToBuffer 43479 LD (HL),A Write the character to the buffer.
43480 INC HL Increment the buffer pointer by one.
Print_Character_UpdateBufferPointer 43481 LD (43445),HL Write the buffer pointer back to *BufferPointer.
43484 POP HL Restore HL and the character code from the stack.
43485 POP AF
43486 RET Return.
Handle screen print mode - check if we need to scroll.
Print_Character_ScreenPrintMode 43487 PUSH DE Stash DE on the stack.
43488 LD DE,23563 Jump to Print_Character_ProcessChar if DEFADD is equal to HL.
43491 AND A
43492 SBC HL,DE
43494 JR Z,Print_Character_ProcessChar
Check if we need to scroll the screen.
43496 LD A,(49653) A=*ScreenWidth.
43499 CP L Compare *ScreenWidth with L (the screen offset).
43500 PUSH AF Stash the comparison result on the stack.
43501 JR NC,Print_Character_ScrollScreen Jump to Print_Character_ScrollScreen if we don't need to scroll (A is greater than or equal to L).
43503 LD A,13 A=13 (load carriage return character).
43505 CALL Print_Character_ProcessCharacter Call Print_Character_ProcessCharacter to process the carriage return.
Scroll the screen by clearing the first line.
Print_Character_ScrollScreen 43508 PUSH BC Stash BC on the stack.
43509 LD B,L B=L (store the line width in B).
43510 LD HL,23563 HL=DEFADD (reset to the start of the screen buffer).
43513 LD (43445),HL Write HL (the screen buffer pointer) to *BufferPointer.
Print_Character_ScrollLoop 43516 LD A,(HL) Load a character from the screen buffer into A.
43517 CALL Print_Character_ProcessCharacter Call Print_Character_ProcessCharacter to process the character (shift it up).
43520 INC HL Move to the next character.
43521 DJNZ Print_Character_ScrollLoop Decrease counter by one and loop back to Print_Character_ScrollLoop until counter is zero.
43523 POP BC Restore BC and AF from the stack.
43524 POP AF
43525 JR NZ,Print_Character_ProcessChar Jump to Print_Character_ProcessChar if we haven't finished scrolling (HL is not equal to L).
Clear the print position flag after scrolling is complete.
43527 XOR A Reset *PrintPositionFlag.
43528 LD (40997),A
Print_Character_ProcessChar 43531 POP DE Restore DE, HL and the character code from the stack.
43532 POP HL
43533 POP AF
43534 JR Print_Character_ProcessCharacter Jump to Print_Character_ProcessCharacter to process the character.
Use alternate print method (direct screen printing).
Print_Character_AlternateMode 43536 POP AF Restore the character code from the stack.
43537 JP CheckTVFlagAndProcess Jump to CheckTVFlagAndProcess to print using alternate method.
Convert uppercase letters to lowercase if needed.
Print_Character_ProcessCharacter 43540 CP 65 Jump to Print_Character_CheckSpace if the character is not uppercase.
43542 JR C,Print_Character_CheckSpace
43544 CP 91
43546 JR NC,Print_Character_CheckSpace
43548 OR %00100000 Set bit 5 (convert to lowercase).
Print_Character_CheckSpace 43550 PUSH AF Stash the character code on the stack.
43551 LD A,(40997) Jump to Print_Character_MarkPrintStarted if we're not at the start of a line (load print position flag from *PrintPositionFlag, set flags, jump if not zero).
43554 AND A
43555 JR NZ,Print_Character_MarkPrintStarted
43557 POP AF Restore the character code from the stack.
43558 CP 32 Return if the character is a "SPACE".
43560 RET Z
43561 PUSH AF Stash the character code on the stack.
Mark that we've started printing on this line.
Print_Character_MarkPrintStarted 43562 LD A,1 Set *PrintPositionFlag.
43564 LD (40997),A
43567 POP AF Restore the character code from the stack.
43568 PUSH AF Stash the character code on the stack.
43569 CP 13 Jump to Print_Character_CheckQuote if the character is not a carriage return (compare with 13 jump if not equal).
43571 JR NZ,Print_Character_CheckQuote
Reset the print position flag for a carriage return.
43573 XOR A Clear *PrintPositionFlag.
43574 LD (40997),A
43577 JR Print_Character_Print Jump to Print_Character_Print (skip further processing).
Check if the character is a quotation mark (needs special handling).
Print_Character_CheckQuote 43579 CP 34 Jump to Print_Character_CheckPeriod if the character is not a quote mark (compare with 34 jump if not equal).
43581 JR NZ,Print_Character_CheckPeriod
43583 LD A,32 A=32 (replace quote with space).
43585 CALL CheckTVFlagAndProcess Call CheckTVFlagAndProcess to print the space.
43588 JR Print_Character_SetTokenFormatFlag Jump to Print_Character_SetTokenFormatFlag (continue processing).
Check if the character is a period (sets token format flag if it is).
Print_Character_CheckPeriod 43590 CP 46 Jump to Print_Character_CheckLowercase if the character is not a period (compare with 46 jump if not equal).
43592 JR NZ,Print_Character_CheckLowercase
Print_Character_SetTokenFormatFlag 43594 LD A,1 Set *TokenFormatFlag.
43596 LD (40998),A
43599 JR Print_Character_Print Jump to Print_Character_Print (skip further processing).
Handle lowercase letters (dictionary word characters).
Print_Character_CheckLowercase 43601 CP 97 Jump to Print_Character_Print if the character is less than 97 (ASCII "a").
43603 JR C,Print_Character_Print
43605 CP 123 Jump to Print_Character_Print if the character is greater than or equal to 123 (ASCII "z"+1).
43607 JR NC,Print_Character_Print
43609 LD A,(43089) Check the lowercase handling flag and jump to Print_Character_ResetTokenFormatFlag if it's not set (load flag from *LowercaseHandlingFlag, set flags, jump if not set).
43612 AND A
43613 JR NZ,Print_Character_ResetTokenFormatFlag
43615 LD A,(40998) Jump to Print_Character_Print if *TokenFormatFlag the token format flag is not set.
43618 AND A
43619 JR Z,Print_Character_Print
Reset the token format flag before converting to uppercase.
Print_Character_ResetTokenFormatFlag 43621 XOR A Reset *TokenFormatFlag.
43622 LD (40998),A
43625 POP AF Restore the character code from the stack.
Clear bit 5 from the character code (convert to uppercase).
43626 AND %01011111 Keep only bits 0-4, 6 (clear bit 5 to convert lowercase to uppercase).
43628 PUSH AF Stash the modified character code on the stack.
Print_Character_Print 43629 POP AF Restore the character code from the stack.
43630 JP CheckTVFlagAndProcess Jump to CheckTVFlagAndProcess to print the character.
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