Routines
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6DD6: Read The Input Line
Used by the routine at TurnReadAndTokeniseTheCommand.
Reads one line into the input buffer. Cursor keys become the compass letters, and a quote or full stop ends a word.
ReadTheInputLine 6DD6 LD HL,$0BB8 Store 0BB8 in *B714.
6DD9 LD ($B714),HL
Update the action countdown.
6DDC LD A,$01 Write 01 to *WaitCountdown and *B6FA.
6DDE LD ($B701),A
6DE1 LD ($B6FA),A
Print the ">" prompt.
6DE4 LD A,$3E Print '>'.
6DE6 CALL Print_Character
Print a space.
6DE9 LD A,$20 Print a space.
6DEB CALL Print_Character
6DEE LD HL,$6FF9 Point at the input buffer.
6DF1 LD B,$80 Start the free-space count at 80.
ReadTheInputLine_Loop 6DF3 LD C,$00 No characters have been rubbed out yet.
This entry point is used by the routine at Input_MapACursorKey.
Read the next key.
ReadTheInputLine_WaitForAKey 6DF5 CALL Input_WaitForAKey Call Input_WaitForAKey to wait for a key.
6DF8 BIT 7,B Jump to ReadTheInputLine_TestTheRubOutKey if bit 7 of the free-space count in B is clear.
6DFA JR Z,ReadTheInputLine_TestTheRubOutKey
6DFC CP $40 Jump to Input_MapACursorKey_ReadAnotherKeyWhenTheFlagIsSet when the character is 40.
6DFE JP Z,Input_MapACursorKey_ReadAnotherKeyWhenTheFlagIsSet
ReadTheInputLine_TestTheRubOutKey 6E01 BIT 0,C Call Input_MapACursorKey if bit 0 of C (set once a character has been rubbed out) is clear.
6E03 CALL Z,Input_MapACursorKey
6E06 LD C,$01 Set the rubbed-out flag and jump to ReadTheInputLine_TestForABackspace unless the key is 18.
6E08 CP $18
6E0A JR NZ,ReadTheInputLine_TestForABackspace
Rub out the whole line.
6E0C CALL Input_RubOutCharacters Call Input_RubOutCharacters to rub out characters.
6E0F JR ReadTheInputLine_Loop Jump back to ReadTheInputLine_Loop to read the next character.
ReadTheInputLine_TestForABackspace 6E11 CP $08 Jump to ReadTheInputLine_TestForALetter unless the key is 08.
6E13 JR NZ,ReadTheInputLine_TestForALetter
6E15 BIT 7,B Jump back to ReadTheInputLine_WaitForAKey if bit 7 of the free-space count in B is set.
6E17 JR NZ,ReadTheInputLine_WaitForAKey
Print character 08.
6E19 LD A,$08 Print a backspace.
6E1B CALL Print_Character
6E1E INC B One more byte of the line is free.
6E1F DEC HL Step back one byte through 6FF9.
6E20 JR ReadTheInputLine_WaitForAKey Jump back to ReadTheInputLine_WaitForAKey to read the next key.
ReadTheInputLine_TestForALetter 6E22 CP $40 Jump to ReadTheInputLine_RememberTheAcceptedKey if the key is not below 40.
6E24 JR NC,ReadTheInputLine_RememberTheAcceptedKey
6E26 CP $22 Jump to ReadTheInputLine_RememberTheAcceptedKey if the key is a quote.
6E28 JR Z,ReadTheInputLine_RememberTheAcceptedKey
6E2A CP $20 Jump to ReadTheInputLine_RememberTheAcceptedKey if the key is a space.
6E2C JR Z,ReadTheInputLine_RememberTheAcceptedKey
6E2E CP $0D Jump to ReadTheInputLine_RememberTheAcceptedKey if the key is ENTER.
6E30 JR Z,ReadTheInputLine_RememberTheAcceptedKey
6E32 CP $2E Jump to ReadTheInputLine_RememberTheAcceptedKey if the key is a full stop.
6E34 JR Z,ReadTheInputLine_RememberTheAcceptedKey
6E36 CP $2C Jump back to ReadTheInputLine_WaitForAKey if the key is not a comma.
6E38 JR NZ,ReadTheInputLine_WaitForAKey
ReadTheInputLine_RememberTheAcceptedKey 6E3A LD ($B704),A Remember this key at B704 so the next letter is capitalised.
6E3D DEC B Jump to ReadTheInputLine_FinishWhenTheKeyIsEnter if the free-space count in B is zero.
6E3E INC B
6E3F JR Z,ReadTheInputLine_FinishWhenTheKeyIsEnter
Print the character in A.
6E41 CALL Print_Character Call Print_Character to print one character.
6E44 LD (HL),A Store it at 6FF9 and step on.
6E45 INC HL
6E46 DEC B One fewer byte of the line is free.
ReadTheInputLine_FinishWhenTheKeyIsEnter 6E47 CP $0D Jump back to ReadTheInputLine_WaitForAKey if the key is not ENTER.
6E49 JP NZ,ReadTheInputLine_WaitForAKey
6E4C OR $01 Clear the zero flag so ENTER ends the line.
6E4E RET Return.
View the equivalent code in;
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