Routines
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82F7: Command: Follow The Grammar Flag
Used by the routine at CommandDispatchAControl.
Follows the grammar flag for a special key. A clear bit 7 copies ten grammar bytes, otherwise four, and the replay path is then scored.
Command_FollowTheGrammarFlag 82F7 JP Z,Inglish_CopyTenGrammarBytes Jump back to Inglish_CopyTenGrammarBytes if bit 7 of the grammar flag is clear.
82FA JP Inglish_CopyFourGrammarBytes Jump to Inglish_CopyFourGrammarBytes to clear bit 6 and copy the grammar bytes.
Command_FollowTheGrammarFlag_Loop 82FD LD A,D Use the class being matched again.
82FE LD ($824F),A Store the result at 824F.
8301 PUSH DE Save DE, BC and IY, and read *B706.
8302 PUSH BC
8303 PUSH IY
8305 LD A,($B706)
8308 LD ($8250),A Remember the replay flag from B706 at 8250.
830B LD DE,$FFE8 Step back one 18-byte parser record.
830E ADD IY,DE Add FFE8 onto this record.
8310 LD A,$01 Pass 01 on to the grammar scorer at InglishPrepareTheClause_1.
8312 JP InglishPrepareTheClause_1 Jump back to InglishPrepareTheClause_1 to update the conjunction count.
Test the conjunction count. Reached through the special-key table at 8271, dispatched from Command_MatchASpecialKey.
8315 LD A,($B71B) Jump to Command_FollowTheGrammarFlag_Loop if *B71B is zero.
8318 AND A
8319 JR Z,Command_FollowTheGrammarFlag_Loop
831B DEC A Step the conjunction count down by one.
831C LD ($B71B),A Update *B71B.
831F LD A,($8250) Read the saved class.
8322 LD B,A Copy the result into B.
8323 LD A,($B706) Read *B706.
8326 SUB B Clear C and jump to Command_FollowTheGrammarFlag_ClearTheMatcherPhase if the replay flag equals the saved class.
8327 AND A
8328 LD C,$00
832A JR Z,Command_FollowTheGrammarFlag_ClearTheMatcherPhase
832C POP IY Restore the parser pointer from the stack, keeping a copy there.
832E PUSH IY
8330 LD DE,$FFE8 Step back one 18-byte parser record.
8333 ADD IY,DE Add FFE8 onto this record.
8335 LD B,A Use the difference as the record count in B.
Command_FollowTheGrammarFlag_PointAtTheSlots 8336 LD IX,$B738 Point at the first character slot at B738.
833A PUSH DE Each character slot at B738 is 19 bytes.
833B PUSH BC
833C LD DE,$0019
833F LD B,$08 Count 08 passes.
Command_FollowTheGrammarFlag_SkipAUsedSlot 8341 LD A,(IX+$00) Jump to Command_FollowTheGrammarFlag_ClaimTheSlot if this character slot is empty.
8344 AND A
8345 JR Z,Command_FollowTheGrammarFlag_ClaimTheSlot
8347 ADD IX,DE Step to the next 19-byte character slot.
8349 DJNZ Command_FollowTheGrammarFlag_SkipAUsedSlot Loop back to Command_FollowTheGrammarFlag_SkipAUsedSlot until 08 runs out.
Command_FollowTheGrammarFlag_ClaimTheSlot 834B LD (IX+$00),$FF Claim this free slot with FF.
834F INC IX Step to the next byte of this character slot.
8351 POP BC Jump to Command_FollowTheGrammarFlag_ClearTheMatcherPhase if every character slot is in use.
8352 POP DE
8353 JR NZ,Command_FollowTheGrammarFlag_ClearTheMatcherPhase
8355 BIT 6,(IY+$01) Jump to Command_FollowTheGrammarFlag_CopyTheRecord if bit 6 of byte 1 of this record is clear.
8359 JR Z,Command_FollowTheGrammarFlag_CopyTheRecord
835B LD (IX-$01),$00 Clear the previous byte of this entry.
835F JR Command_FollowTheGrammarFlag_StepBackOneRecord Jump to Command_FollowTheGrammarFlag_StepBackOneRecord to update the matcher phase.
Command_FollowTheGrammarFlag_CopyTheRecord 8361 PUSH BC Count 18 passes.
8362 LD B,$18
Command_FollowTheGrammarFlag_CopyTheNextByte 8364 LD A,(IY+$00) Copy the next byte into this entry.
8367 LD (IX+$00),A
836A INC IY Step to the next byte of this record.
836C INC IX Step to the next byte of this character slot.
836E DJNZ Command_FollowTheGrammarFlag_CopyTheNextByte Loop back to Command_FollowTheGrammarFlag_CopyTheNextByte until 18 runs out.
8370 POP BC Restore the record count, and step IY back 18 bytes to the start of this record.
8371 ADD IY,DE
Command_FollowTheGrammarFlag_StepBackOneRecord 8373 ADD IY,DE Step IY back 18 bytes to the previous record.
8375 INC C Count one more character slot.
8376 DJNZ Command_FollowTheGrammarFlag_PointAtTheSlots Decrease the record count in B and loop back to Command_FollowTheGrammarFlag_PointAtTheSlots until it is zero.
Command_FollowTheGrammarFlag_ClearTheMatcherPhase 8378 XOR A Clear *B719.
8379 LD ($B719),A
837C LD A,C Copy the count in C into A.
837D LD ($B737),A Store the number of claimed slots at B737.
8380 POP IY Restore the parser pointer from the stack and restore the replay flag from 8250.
8382 LD A,($8250)
8385 LD ($B706),A Update *B706.
8388 POP BC Restore the saved pair from the stack and read the class from 824F.
8389 POP DE
838A LD A,($824F)
838D LD D,A Keep the saved class.
838E JP InglishPrepareTheClause_3 Jump back to InglishPrepareTheClause_3 to clear the matcher scratch.
Reached through the special-key table at 8271, dispatched from Command_MatchASpecialKey.
8391 CALL GameOver_Start Call GameOver_Start to print the score.
Command_FollowTheGrammarFlag_WaitForAKey 8394 XOR A Select every keyboard row (A=00).
8395 IN A,($FE) Read port FE into A.
8397 AND %00011111 Jump back to Command_FollowTheGrammarFlag_WaitForAKey while the low five bits are all set.
8399 CP %00011111
839B JR Z,Command_FollowTheGrammarFlag_WaitForAKey
839D JP Restart Jump back to Restart to restart the game.
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