Routines
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42160: Handler: User Input
Used by the routine at GameStart.
Handles keyboard input, tokenises commands and validates the vocabulary.
Reset the screen position to defaults.
Handler_UserInput 42160 CALL PrintPrompt Call PrintPrompt.
42163 LD HL,41225 HL=CommandBuffer.
Initialise the command buffer.
42166 LD B,0 Initialise a letter counter in B.
42168 JR UserInput_Next Jump to UserInput_Next.
Main input loop - process each keypress.
UserInput_Loop 42170 INC HL Move to the next byte of the command buffer.
42171 INC B Increment the letter counter by one.
UserInput_Next 42172 CALL Print_Cursor Call Print_Cursor.
42175 CALL GetUserInput Call GetUserInput.
42178 CP 12 Jump to ValidateUserInput if "DELETE" was not pressed.
42180 JR NZ,ValidateUserInput
The user pressed "DELETE".
42182 XOR A Jump back to UserInput_Next if there hasn't been any input yet (nothing to delete).
42183 OR B
42184 JR Z,UserInput_Next
There is input which can be deleted, so action a delete!
42186 EX DE,HL Temporarily stash the command buffer pointer in DE.
Print "SPACE BACKSPACE BACKSPACE SPACE BACKSPACE" to move the current print position on the screen to the previous character, and to delete the character present using a space.
42187 LD HL,42055 HL=Messaging_SpaceBackspaceBackspaceSpaceBackspace.
42190 CALL PrintString Call PrintString.
Adjust the command buffer position and letter counter.
42193 EX DE,HL Restore the command buffer pointer from DE.
42194 DEC HL Decrease the command buffer pointer by one.
42195 DEC B Decrease the letter counter by one.
42196 JR UserInput_Next Jump to UserInput_Next.
Check which key the user pressed:
ValidateUserInput 42198 LD C,A Jump to UserInput_WriteKeypress if "ENTER" was pressed.
42199 CP 13
42201 JR Z,UserInput_WriteKeypress
42203 CP 32 If the keypress was any other control key (the value being under 32 ASCII "SPACE"), it's not valid input so jump back to UserInput_Next.
42205 JR C,UserInput_Next
42207 CP 128 If the keypress was higher than 128 it's also not valid input so jump back to UserInput_Next.
42209 JR NC,UserInput_Next
Is the command buffer full?
42211 LD A,B Jump to UserInput_Next if the letter counter is 49 (so the buffer is full).
42212 CP 49
42214 JR Z,UserInput_Next
Writes the keypress into the command buffer and print it to the screen.
UserInput_WriteKeypress 42216 LD A,C Write the user input key to *HL.
42217 LD (HL),A
42218 CALL Print_UserInputToScreen Call Print_UserInputToScreen.
Did the user press "ENTER"?
42221 LD A,C Jump to UserInput_Loop if "ENTER" was not pressed.
42222 CP 13
42224 JR NZ,UserInput_Loop
The player pressed "ENTER" so begin to process the user input.
Clear down the user input tokens.
42226 LD HL,41275 HL=UserInput_Token_1.
42229 LD B,10 Set a counter in B for all 10 user input tokens.
EmptyUserInputTokens_Loop 42231 LD (HL),255 Write a termination byte (255) to *HL.
42233 INC HL Increment HL by one.
42234 DJNZ EmptyUserInputTokens_Loop Decrease the user input tokens counter by one and loop back to EmptyUserInputTokens_Loop until all the tokens have been set to termination bytes (255).
Set up pointers for the command buffer, the user input tokens and the count of the number of user input tokens.
42236 LD HL,41225 HL=CommandBuffer.
42239 LD IX,41275 IX=UserInput_Token_1.
42243 LD C,10 Set a counter in C for the 10 user input tokens.
42245 JR EmptyFourLetterBuffer Jump to EmptyFourLetterBuffer.
Print "Give me a command!".
Handler_UserInput_0 42247 LD HL,1 HL=Messaging_GiveMeACommand.
42250 CALL PrintCompressedStringAndNewline Call PrintCompressedStringAndNewline.
42253 JP Handler_UserInput Jump to Handler_UserInput.
Handler_UserInput_1 42256 PUSH HL
42257 PUSH DE
42258 PUSH BC
42259 LD HL,(42051)
42262 LD DE,41285
42265 LD BC,4
42268 LD A,(42053)
42271 CP C
42272 JR NC,Handler_UserInput_2
42274 LD C,A
Handler_UserInput_2 42275 LDIR
42277 POP BC
42278 POP DE
42279 POP HL
42280 PUSH HL
42281 LD HL,40402
42284 LD (42111),HL
42287 CALL Handler_MatchItem
42290 LD HL,45293
42293 LD (42111),HL
42296 POP HL
42297 JR C,EmptyFourLetterBuffer
42299 CALL Handler_MatchItem
42302 JR C,StoreTokenAndContinue
42304 LD HL,2
42307 CALL PrintCompressedStringAndNewline
42310 JP Handler_UserInput
StoreTokenAndContinue 42313 LD (IX+0),A
42316 INC IX
42318 DEC C
42319 JR Z,Handler_UserInput_9
EmptyFourLetterBuffer 42321 PUSH HL
42322 PUSH BC
42323 LD HL,41285
42326 LD B,4
Handler_UserInput_3 42328 LD (HL),32
42330 INC HL
42331 DJNZ Handler_UserInput_3
42333 POP BC
42334 POP HL
42335 PUSH DE
42336 JR Handler_UserInput_5
Handler_UserInput_4 42338 INC HL
Handler_UserInput_5 42339 LD A,(HL)
42340 CP 13
42342 JR Z,Handler_UserInput_8
42344 CALL IsDelimiter
42347 JR Z,Handler_UserInput_4
42349 LD (42051),HL
42352 LD DE,0
Handler_UserInput_6 42355 INC HL
42356 INC DE
42357 LD A,(HL)
42358 CP 13
42360 JR Z,Handler_UserInput_7
42362 CALL IsDelimiter
42365 JR NZ,Handler_UserInput_6
Handler_UserInput_7 42367 LD (42053),DE
42371 SCF
Handler_UserInput_8 42372 POP DE
42373 JP C,Handler_UserInput_1
Handler_UserInput_9 42376 LD A,(41275)
42379 CP 255
42381 JP Z,Handler_UserInput_0
42384 RET
View the equivalent code in;
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