Routines
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BF73: Handler: User Input
Used by the routines at Handler_UnknownWord and GameLoop.
Read a line of text, then turn it into vocabulary tokens.
Reset the cursor to the top of the text window.
Handler_UserInput BF73 CALL SetDefaultScreenPosition Call SetDefaultScreenPosition to park the cursor at the top of the text.
Clear the command buffer.
BF76 LD HL,$BB04 Start at the command buffer (CommandBuffer).
BF79 LD A,$20 Prepare a space (20) and a counter of 32 bytes.
BF7B LD B,$32
EmptyCommandBuffer_Loop BF7D LD (HL),A Write spaces through the whole command buffer.
BF7E INC HL
BF7F DJNZ EmptyCommandBuffer_Loop
Print the ">" prompt.
BF81 CALL PrintInputPrompt Call PrintInputPrompt.
Collect keypresses.
BF84 LD HL,$BB04 Start again at the beginning of the command.
This entry point is used by the routine at UserInput_Delete.
Wait for the next key.
UserInput_Loop BF87 CALL GetUserInput Call GetUserInput.
DELETE rubs out a character. ENTER finishes the line. Any other control key is ignored.
BF8A CP $0C Jump to UserInput_Delete if DELETE was pressed.
BF8C JR Z,UserInput_Delete
BF8E CP $0D Jump to UserInput_Enter if ENTER was pressed.
BF90 JR Z,UserInput_Enter
BF92 CP $20 Jump back to UserInput_Loop when the key is below SPACE.
BF94 JR C,UserInput_Loop
Is the command buffer full?
BF96 EX DE,HL Jump back to UserInput_Loop once the pointer has reached the sentinel at BB35.
BF97 LD HL,$BB35
BF9A AND A
BF9B SBC HL,DE
BF9D EX DE,HL
BF9E JR Z,UserInput_Loop
The key is valid, so store it and print it.
BFA0 LD (HL),A Write the key into the command buffer.
BFA1 CALL SwitchNormalScreenOutput Call SwitchNormalScreenOutput to select the screen channel.
BFA4 CALL PrintCharacter Call PrintCharacter to echo the key.
BFA7 INC HL Advance to the next space in the buffer.
BFA8 JR UserInput_Loop Jump back to UserInput_Loop for the next key.
View the equivalent code in;
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