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https://github.com/Klaus2m5/6502_EhBASIC_V2.22.git
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195 lines
7.7 KiB
Plaintext
195 lines
7.7 KiB
Plaintext
Tokenizer mixed case keyword recognition
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This modification is based on a patch by user ArnoldLayne and jbevren of the
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6502.org forum: http://forum.6502.org/viewtopic.php?f=5&t=4383
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In EhBasic keywords must be upper case. This may be inconvenient on computers
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with mixed case support. The modification below changes the tokenizer to match
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lower, upper or even mixed case keywords. However, the listing will still show
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keywords in upper case.
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; crunch keywords into Basic tokens
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; position independent buffer version ..
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; faster, dictionary search version ....
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LAB_13A6
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LDY #$FF ; set save index (makes for easy math later)
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SEC ; set carry for subtract
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LDA Bpntrl ; get basic execute pointer low byte
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SBC #<Ibuffs ; subtract input buffer start pointer
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TAX ; copy result to X (index past line # if any)
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STX Oquote ; clear open quote/DATA flag
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LAB_13AC
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LDA Ibuffs,X ; get byte from input buffer
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BEQ LAB_13EC ; if null save byte then exit
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; *** begin patch: lower case token recognition V2 ***
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; *** WARNING! changes documented behavior!
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; *** add
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CMP #'{' ; convert lower to upper case
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BCS LAB_13EC ; is above lower case
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CMP #'a'
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BCC PATCH_LC ; is below lower case
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AND #$DF ; mask lower case bit
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PATCH_LC
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; *** end
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CMP #'_' ; compare with "_"
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BCS LAB_13EC ; if >= go save byte then continue crunching
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CMP #'<' ; compare with "<"
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BCS LAB_13CC ; if >= go crunch now
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CMP #'0' ; compare with "0"
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BCS LAB_13EC ; if >= go save byte then continue crunching
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STA Scnquo ; save buffer byte as search character
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CMP #$22 ; is it quote character?
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BEQ LAB_1410 ; branch if so (copy quoted string)
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CMP #'*' ; compare with "*"
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BCC LAB_13EC ; if < go save byte then continue crunching
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; else crunch now
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LAB_13CC
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BIT Oquote ; get open quote/DATA token flag
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BVS LAB_13EC ; branch if b6 of Oquote set (was DATA)
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; go save byte then continue crunching
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STX TempB ; save buffer read index
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STY csidx ; copy buffer save index
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LDY #<TAB_1STC ; get keyword first character table low address
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STY ut2_pl ; save pointer low byte
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LDY #>TAB_1STC ; get keyword first character table high address
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STY ut2_ph ; save pointer high byte
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LDY #$00 ; clear table pointer
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LAB_13D0
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CMP (ut2_pl),Y ; compare with keyword first character table byte
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BEQ LAB_13D1 ; go do word_table_chr if match
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; *** replace
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; BCC LAB_13EA ; if < keyword first character table byte go restore
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; *** with
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BCC PATCH_LC2 ; if < keyword first character table byte go restore
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; *** end
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; Y and save to crunched
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INY ; else increment pointer
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BNE LAB_13D0 ; and loop (branch always)
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; have matched first character of some keyword
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LAB_13D1
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TYA ; copy matching index
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ASL ; *2 (bytes per pointer)
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TAX ; copy to new index
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LDA TAB_CHRT,X ; get keyword table pointer low byte
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STA ut2_pl ; save pointer low byte
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LDA TAB_CHRT+1,X ; get keyword table pointer high byte
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STA ut2_ph ; save pointer high byte
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LDY #$FF ; clear table pointer (make -1 for start)
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LDX TempB ; restore buffer read index
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LAB_13D6
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INY ; next table byte
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LDA (ut2_pl),Y ; get byte from table
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LAB_13D8
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BMI LAB_13EA ; all bytes matched so go save token
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INX ; next buffer byte
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; *** replace
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; CMP Ibuffs,X ; compare with byte from input buffer
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; *** with
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EOR Ibuffs,x ; check bits against table
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AND #$DF ; DF masks the upper/lower case bit
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; *** end
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BEQ LAB_13D6 ; go compare next if match
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BNE LAB_1417 ; branch if >< (not found keyword)
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LAB_13EA
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LDY csidx ; restore save index
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; save crunched to output
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LAB_13EC
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INX ; increment buffer index (to next input byte)
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INY ; increment save index (to next output byte)
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STA Ibuffs,Y ; save byte to output
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CMP #$00 ; set the flags, set carry
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BEQ LAB_142A ; do exit if was null [EOL]
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; A holds token or byte here
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SBC #':' ; subtract ":" (carry set by CMP #00)
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BEQ LAB_13FF ; branch if it was ":" (is now $00)
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; A now holds token-$3A
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CMP #TK_DATA-$3A ; compare with DATA token - $3A
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BNE LAB_1401 ; branch if not DATA
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; token was : or DATA
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LAB_13FF
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STA Oquote ; save token-$3A (clear for ":", TK_DATA-$3A for DATA)
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LAB_1401
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EOR #TK_REM-$3A ; effectively subtract REM token offset
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BNE LAB_13AC ; If wasn't REM then go crunch rest of line
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STA Asrch ; else was REM so set search for [EOL]
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; loop for REM, "..." etc.
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LAB_1408
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LDA Ibuffs,X ; get byte from input buffer
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BEQ LAB_13EC ; branch if null [EOL]
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CMP Asrch ; compare with stored character
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BEQ LAB_13EC ; branch if match (end quote)
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; entry for copy string in quotes, don't crunch
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LAB_1410
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INY ; increment buffer save index
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STA Ibuffs,Y ; save byte to output
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INX ; increment buffer read index
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BNE LAB_1408 ; loop while <> 0 (should never be 0!)
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; not found keyword this go
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LAB_1417
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LDX TempB ; compare has failed, restore buffer index (start byte!)
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; now find the end of this word in the table
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LAB_141B
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LDA (ut2_pl),Y ; get table byte
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PHP ; save status
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INY ; increment table index
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PLP ; restore byte status
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BPL LAB_141B ; if not end of keyword go do next
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LDA (ut2_pl),Y ; get byte from keyword table
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BNE LAB_13D8 ; go test next word if not zero byte (end of table)
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; reached end of table with no match
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; *** add label
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PATCH_LC2
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; *** end
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; *** end patch: lower case token recognition V2 ***
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LDA Ibuffs,X ; restore byte from input buffer
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BPL LAB_13EA ; branch always (all bytes in buffer are $00-$7F)
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; go save byte in output and continue crunching
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; reached [EOL]
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LAB_142A
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INY ; increment pointer
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INY ; increment pointer (makes it next line pointer high byte)
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STA Ibuffs,Y ; save [EOL] (marks [EOT] in immediate mode)
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INY ; adjust for line copy
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INY ; adjust for line copy
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INY ; adjust for line copy
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DEC Bpntrl ; allow for increment (change if buffer starts at $xxFF)
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RTS
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