Forest At World's End: Routine at BFD8

BFD8: Parser: Match Input Word

Split the command into words and look each one up in the vocabulary.
Blank the four-character word buffer.
Parser_MatchInputWord	BFD8	LD DE,$BB41	Start at the word buffer (BB41).
	BFDB	LD B,$04	Prepare a space and a counter of 04 characters.
	BFDD	LD A,$20	Prepare a space and a counter of 04 characters.
MatchInputWord_Clear	BFDF	LD (DE),A	Write spaces through the word buffer.
	BFE0	INC DE
	BFE1	DJNZ MatchInputWord_Clear
	BFE3	XOR A	Jump to Handler_UnknownWord when no token slots remain, or the command has ended.
	BFE4	OR C
	BFE5	JP Z,Handler_UnknownWord
	BFE8	LD A,(HL)
	BFE9	CP $0D
	BFEB	JP Z,Handler_UnknownWord
Copy the next word, up to 04 characters, stopping at a space, a comma or ENTER.
	BFEE	LD B,$04	Copy up to 04 characters into the word buffer.
	BFF0	LD DE,$BB41	Copy up to 04 characters into the word buffer.
MatchInputWord_Copy	BFF3	LD A,(HL)	Jump to MatchInputWord_IgnoreThe when the character is ENTER.
	BFF4	CP $0D
	BFF6	JR Z,MatchInputWord_IgnoreThe
	BFF8	CP $20	Jump to MatchInputWord_Delimiter when the character is a space or a comma.
	BFFA	JR Z,MatchInputWord_Delimiter
	BFFC	CP $2C
	BFFE	JR Z,MatchInputWord_Delimiter
	C000	LD (DE),A	Copy the character into the word buffer and advance both pointers.
	C001	INC HL
	C002	INC DE
	C003	DJNZ MatchInputWord_Copy	Repeat from MatchInputWord_Copy until four characters have been copied.
A longer word is skipped up to the next delimiter.
MatchInputWord_Skip	C005	LD A,(HL)	Jump to MatchInputWord_IgnoreThe on ENTER, or to MatchInputWord_Delimiter on a space or a comma.
	C006	CP $0D
	C008	JR Z,MatchInputWord_IgnoreThe
	C00A	CP $20
	C00C	JR Z,MatchInputWord_Delimiter
	C00E	CP $2C
	C010	JR Z,MatchInputWord_Delimiter
	C012	INC HL	Skip this character and keep looking for a delimiter.
	C013	JR MatchInputWord_Skip	Skip this character and keep looking for a delimiter.
MatchInputWord_Delimiter	C015	INC HL	Skip consecutive spaces and commas.
	C016	LD A,(HL)
	C017	CP $20
	C019	JR Z,MatchInputWord_Delimiter
	C01B	CP $2C
	C01D	JR Z,MatchInputWord_Delimiter
Ignore the word "THE ".
MatchInputWord_IgnoreThe	C01F	EXX	Switch in the spare registers and point them at "THE " and the word.
	C020	LD HL,$BB5C
	C023	LD DE,$BB41
	C026	LD B,$04
MatchInputWord_The	C028	LD A,(DE)	Compare the four characters.
	C029	CP (HL)
	C02A	JR NZ,MatchInputWord_AfterThe
	C02C	INC DE
	C02D	INC HL
	C02E	DJNZ MatchInputWord_The
MatchInputWord_AfterThe	C030	EXX	Switch back to the main registers to act on the comparison.
	C031	JR Z,Parser_MatchInputWord	Jump back to Parser_MatchInputWord when the word was THE, so it is not tokenised.
	C033	DEC C	Use up one token slot.
	C034	EXX	Use up one token slot.
Look the word up in the vocabulary. A comma separates synonyms.
	C035	LD HL,($BADC)	Start at the vocabulary, with the token index at zero.
	C038	LD C,$00	Start at the vocabulary, with the token index at zero.
MatchInputWord_Vocabulary	C03A	LD A,(HL)	Jump to MatchInputWord_Unknown when the vocabulary is exhausted.
	C03B	CP $FF
	C03D	JR Z,MatchInputWord_Unknown
MatchInputWord_CompareWord	C03F	LD DE,$BB41	Compare the next vocabulary word with the word buffer.
	C042	LD B,$04	Compare the next vocabulary word with the word buffer.
MatchInputWord_CompareChar	C044	LD A,(DE)	Compare the next character.
	C045	CP (HL)	Compare the next character.
	C046	JR NZ,MatchInputWord_NextWord	Jump to MatchInputWord_NextWord when it does not match.
	C048	INC DE
	C049	INC HL
	C04A	DJNZ MatchInputWord_CompareChar
	C04C	EXX	Turn the vocabulary index into a token-slot offset.
	C04D	LD A,$09
	C04F	SUB C
	C050	EXX
	C051	LD D,$00
	C053	LD E,A
	C054	LD HL,$BB36	Store that token in its slot at BB36 and parse the next word.
	C057	ADD HL,DE
	C058	LD (HL),C
	C059	EXX
	C05A	JP Parser_MatchInputWord
MatchInputWord_NextWord	C05D	LD E,B	Step to the end of this vocabulary word.
	C05E	LD D,$00
	C060	ADD HL,DE
	C061	LD A,(HL)	Jump back to MatchInputWord_CompareWord to try the synonym after a comma.
	C062	CP $2C
	C064	JR NZ,MatchInputWord_NextEntry
	C066	INC HL
	C067	JR MatchInputWord_CompareWord
MatchInputWord_NextEntry	C069	INC C	Try the next vocabulary word.
	C06A	JR MatchInputWord_Vocabulary	Try the next vocabulary word.
The word is not in the vocabulary, so quote it and ask again.
MatchInputWord_Unknown	C06C	EXX	Find the unknown word in the command buffer.
	C06D	LD A,$0A
	C06F	SUB C
	C070	LD C,A
	C071	LD HL,$BB04
MatchInputWord_SeekWord	C074	DEC C	Step back through the copied word count.
	C075	JR Z,MatchInputWord_PrintUnknown	Step back through the copied word count.
MatchInputWord_FindWord	C077	LD A,(HL)	Skip characters until a space or a comma.
	C078	CP $20
	C07A	JR Z,MatchInputWord_FindDelimiter
	C07C	CP $2C
	C07E	JR Z,MatchInputWord_FindDelimiter
	C080	INC HL
	C081	JR MatchInputWord_FindWord
MatchInputWord_FindDelimiter	C083	INC HL	Skip spaces and commas, then look for the next word.
	C084	LD A,(HL)
	C085	CP $20
	C087	JR Z,MatchInputWord_FindDelimiter
	C089	CP $2C
	C08B	JR Z,MatchInputWord_FindDelimiter
	C08D	JR MatchInputWord_SeekWord
MatchInputWord_PrintUnknown	C08F	PUSH HL	Print "I don't know the word:-".
	C090	LD HL,$BB75
	C093	CALL PrintStringAndANewline
	C096	POP HL	Restore the command pointer from the stack.
	C097	LD A,$22	Print a quote.
	C099	CALL PrintCharacter	Print a quote.
MatchInputWord_Quote	C09C	LD A,(HL)	Print the unknown word up to the next space.
	C09D	CP $21
	C09F	JR C,MatchInputWord_CloseQuote
	C0A1	INC HL
	C0A2	CALL PrintCharacter
	C0A5	JR MatchInputWord_Quote
MatchInputWord_CloseQuote	C0A7	LD A,$22	Print a closing quote.
	C0A9	CALL PrintCharacter	Print a closing quote.
	C0AC	LD HL,$BCF9	Print "." and read another command.
	C0AF	CALL PrintStringAndANewline
	C0B2	JR Handler_UnknownWord_Retry
View the equivalent code in; Heroes Of Karn Message From Andromeda The Jewels Of Babylon