Routines
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A880: Extract Token From Text
Used by the routines at ProcessObject_Display and PrintObjectAttributeDescription.
Input
HL Pointer to text data
Output
DE Token value (word)
HL Updated pointer
Read the token value from the text data.
ExtractTokenFromText A880 LD E,(HL) E=*HL (load the first byte of the token into E).
A881 INC HL Increment HL by one (move to the second byte).
A882 LD A,(HL) A=*HL (load the second byte of the token into A).
A883 INC HL Increment HL by one (advance the text pointer past the token).
A884 AND %00001111 Keep only bits 0-3 (extract the low nibble from the second byte).
A886 LD D,A D=A (store the low nibble in D).
This entry point is used by the routines at ProcessObjectDisplay, ProcessObject_Display, ProcessTextCommand, PrintCharacterWithTimePeriod, PrintTokenBasedOnParameters, ProcessTextTokenWithAttributes, ProcessObjectOrPrintToken, ProcessTextTokenEntry, GetDisplayAddressBasedOnFlag, ProcessLocationTokenDisplay, PrintFormattedObjectList, PrintObjectAttributeDescription, PrintLocationExits and PrintLocationExitsWithFormatting.
PrintTextToken A887 LD A,($5C3C) Return if *TV-FLAG is not set.
A88A AND A
A88B RET Z
A88C LD ($A022),DE Write DE (the token value) to *TokenValueBuffer.
Check if this is a simple token that doesn't need further processing.
A890 LD A,D A=D (load the low nibble into A).
A891 AND %00001111 Keep only bits 0-3 (ensure we have just the low nibble).
A893 OR E Set the bits from E (merge with the first byte).
A894 RET Z Return if this is a simple token (HL equals E).
A895 PUSH IX Stash IX, HL, BC and DE on the stack.
A897 PUSH HL
A898 PUSH BC
A899 PUSH DE
Process the token format and prepare for dictionary lookup.
A89A LD A,$20 A=20 (load space character code).
A89C CALL Print_Character Call Print_Character to print the space character.
A89F LD A,D A=D (load the token byte).
A8A0 AND %11110000 Keep only bits 4-7 (extract the high nibble).
A8A2 LD C,A Compare C (the high nibble) with 70.
A8A3 CP $70
Prepare to set a flag if the token format is 70.
A8A5 LD A,$01 A=01.
A8A7 JR NZ,ExtractTokenFromText_ProcessToken Jump to ExtractTokenFromText_ProcessToken if the token format is not 70.
A8A9 LD ($A026),A Write A to *TokenFormatFlag (set a flag for this token format).
ExtractTokenFromText_ProcessToken A8AC LD A,D A=D (restore the token byte).
A8AD AND %00001111 Keep only bits 0-3 (extract the low nibble).
A8AF LD D,A D=A (store the low nibble in D).
A8B0 EX DE,HL Exchange the DE and HL registers (swap token and text pointer).
A8B1 PUSH HL Stash HL (the text pointer) on the stack.
A8B2 LD A,H A=H (load the high byte of the token).
A8B3 OR C Set the bits from C (merge with the format bits).
A8B4 LD H,A H=A (store the modified high byte).
A8B5 LD ($A022),HL Write HL (the modified token) to *TokenValueBuffer.
A8B8 POP HL Restore HL (the text pointer) from the stack.
A8B9 PUSH BC Stash BC on the stack.
Search the word index table for the token value.
A8BA LD IX,$5D80 IX=Table_WordIndex (load the address of the word index table).
A8BE LD B,$5F B=5F (initialise the search index).
ExtractTokenFromText_SearchLoop A8C0 INC B Increment B by one (move to the next entry).
A8C1 LD A,(IX+$01) Jump to ExtractTokenFromText_ContinueSearch if the high byte of the table entry is less than H (token high byte).
A8C4 CP H
A8C5 JR C,ExtractTokenFromText_ContinueSearch
A8C7 JR NZ,ExtractTokenFromText_FoundEntry Jump to ExtractTokenFromText_FoundEntry if the high byte doesn't match (IX+01 is not equal to H).
A8C9 LD A,(IX+$00) Jump to ExtractTokenFromText_FoundEntry if the low byte is too high (IX+00 is greater than or equal to L).
A8CC CP L
A8CD JR NC,ExtractTokenFromText_FoundEntry
ExtractTokenFromText_ContinueSearch A8CF INC IX Increment IX by two (move to the next table entry).
A8D1 INC IX
A8D3 LD A,B Jump to ExtractTokenFromText_SearchLoop if we haven't reached the end of the table (B is not equal to 7B).
A8D4 CP $7B
A8D6 JR NZ,ExtractTokenFromText_SearchLoop
A8D8 INC B Increment B by one (adjust for end of table).
ExtractTokenFromText_FoundEntry A8D9 JR Z,ExtractTokenFromText_GetWordAddress Jump to ExtractTokenFromText_GetWordAddress if no matching entry was found (B is zero).
ExtractTokenFromText_BackupEntry A8DB DEC IX Decrease IX by two (back up to the matching entry).
A8DD DEC IX
A8DF DEC B Decrease B by one (adjust the index).
ExtractTokenFromText_GetWordAddress A8E0 LD E,(IX+$00) Load the word address from the table entry into DE.
A8E3 LD D,(IX+$01)
A8E6 LD A,D Jump to ExtractTokenFromText_BackupEntry until we find a non-zero word address (DE is zero).
A8E7 OR E
A8E8 JR Z,ExtractTokenFromText_BackupEntry
Print the word from the dictionary.
A8EA LD A,B A=B (load the word index).
A8EB CALL Print_Character Call Print_Character to print the word character.
A8EE LD BC,$5DBF HL+=5DBF (add the dictionary base address to get the word data pointer).
A8F1 ADD HL,BC
A8F2 PUSH HL Stash HL (the word data pointer) on the stack.
A8F3 EX DE,HL Exchange the DE and HL registers (swap word address and word data pointer).
A8F4 ADD HL,BC HL+=BC (add the offset to the word data).
ExtractTokenFromText_PrintWordContinue A8F5 PUSH HL Stash HL (the calculated word data address) on the stack.
ExtractTokenFromText_PrintWordLoop A8F6 AND A HL-=DE (with carry) (calculate the remaining length).
A8F7 SBC HL,DE
A8F9 POP HL Restore HL (the word data address) from the stack.
A8FA PUSH AF Stash AF (the length comparison result) on the stack.
A8FB CALL ProcessFormatDataByte Call ProcessFormatDataByte to print characters from the word.
A8FE POP AF Restore AF (the length comparison result) from the stack.
A8FF JR NZ,ExtractTokenFromText_PrintWordContinue Jump to ExtractTokenFromText_PrintWordContinue if there are more characters to print (B is not equal to A).
A901 POP HL Restore HL and BC from the stack.
A902 POP BC
Handle special token format cases.
A903 LD A,C Jump to ExtractTokenFromText_PrintRemainingText if the token format is 50.
A904 CP $50
A906 JR Z,ExtractTokenFromText_PrintRemainingText
A908 CP $40 Jump to ExtractTokenFromText_ProcessFormat if the token format is 40.
A90A JR Z,ExtractTokenFromText_ProcessFormat
Check if the token format is 10 (requires special handling).
A90C CP $10 Compare C (the token format) with 10.
A90E LD A,($A034) A=*RoomDisplayParameter (load the room display parameter).
A911 JR Z,ExtractTokenFromText_Format10 Jump to ExtractTokenFromText_Format10 if the token format is 10.
A913 LD A,($A036) Load A with *CurrentCharacter_ID.
ExtractTokenFromText_Format10 A916 AND A Jump to ExtractTokenFromText_PrintRemainingText (skip format processing for format 10).
A917 JR Z,ExtractTokenFromText_PrintRemainingText
ExtractTokenFromText_ProcessFormat A919 CALL ProcessTextTokenFormat Call ProcessTextTokenFormat to process the text token format.
ExtractTokenFromText_PrintRemainingText A91C LD HL,$5C42 HL=NEWPPC.
ExtractTokenFromText_PrintLoop A91F LD A,(HL) Load a byte from *NEWPPC.
A920 AND A Jump to ExtractTokenFromText_End if we've reached the end of the text (A is zero).
A921 JR Z,ExtractTokenFromText_End
A923 CALL Print_Character Call Print_Character to print the character.
A926 INC HL Increment HL by one (move to the next character).
A927 JR ExtractTokenFromText_PrintLoop Jump to ExtractTokenFromText_PrintLoop to continue printing.
All text printed - restore registers and return.
ExtractTokenFromText_End A929 POP DE Restore DE, BC, HL and IX from the stack.
A92A POP BC
A92B POP HL
A92C POP IX
A92E RET Return.
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