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ô > CRC32 ô CRC32 test code : (2Þ mem% &FFF:ÿ"LOAD CRCs/htm "+Ã~mem%:num%=&A6D 2ô mem%=PAGE:num%=TOP-PAGE <: F@%=&90A P8ñ"BASIC CRC-32:   ";:S%=-1:T%=‘:òcrc:T%=‘-T%:S%=¬ S% Zñ"&";~S%;" in ";T%/100;"s"' d: n@%=&2040A x	òAsm1 ‚EñA$;" CRC-32: ";:T%=‘:ã L%=1 ¸ N%:S%=-1:òcrcAsm:í:T%=‘-T%:S%=¬ S% Œ*ñ‰(7-©A$)"&";~S%;" in ";T%/100/N%;"s"' –:  	òAsm2 ªEñA$;" CRC-32: ";:T%=‘:ã L%=1 ¸ N%:S%=-1:òcrcAsm:í:T%=‘-T%:S%=¬ S% ´*ñ‰(7-©A$)"&";~S%;" in ";T%/100/N%;"s"' ¾à È: Ò
Ýòcopy Ü?S%=-1                            :ô CRC starts as &FFFFFFFF æõ ð?  num%=¢#in%-#in%           :ô Number of bytes to transfer ú  ç num%>max% Œ num%=max%7  ògbpb(rd%,in%,mem%,num%,0)  :ô Read block of data/  òcrc                        :ô Update CRC8  ògbpb(wr%,out%,mem%,num%,0) :ô Write block of data"7ý num%<max%                  :ô Loop until all done,;crc%=¬ S%                      :ô Final CRC is inverted6á@:Jô BASIC:TkÝòcrc:ãA%=mem%¸mem%+num%-1:S%=S%‚?A%:ãB%=1¸8:O%=S%:S%=(((S%+(S%<0))2)€&7FFFFFFF):çO%€1:S%=S%‚&EDB88320^	í:í:áh:rô Assembler:|:ÝòcrcAsm:!addr=mem%:!num=num%:!crc=S%:Ö Calc:S%=!crc:á†:1ô With CRC-32 code previously assembled with:š
ÝòAsm1¤3ç>&8000:ç¦-256=—"W":òcrc86:A$="80x86":N%=100:á®%ç>&8000:òcrcARM:A$="ARM":N%=10:á¸,ç?&FFF7=&6C:òcrc65v1:A$="6502 v1":N%=1:áÂ&ç?&FFF7=&C3:òcrc80:A$="Z80":N%=1:áÌáÖ:à
ÝòAsm2êç>&8000:àô,ç?&FFF7=&6C:òcrc65v2:A$="6502 v2":N%=1:áþàá:9Ýòcrc65v2:Þ Calcv2 63:addr=&70:num=&72:crc=&74:ãP=0¸1&P%=Calc:[OPT P*20.bytelp:@LDX #8                       :\ Prepare to rotate CRC 8 bitsD8LDA (addr-8 € &FF,X)       :\ Fetch byte from memoryN:XF\ The following code updates the CRC with the byte in A ---------+bF\ If used in isolation, requires LDX #8 here                     |lB‚ crc+0                    :\ ‚ byte into CRC bottom byte    |vF.rotlp                       :\                                  |€FLSR crc+3:ROR crc+2          :\ Rotate CRC clearing bit 31       |ŠFROR crc+1:ROR A              :\                                  |”FBCC clear                    :\ b0 was zero                      |žFTAY                          :\ Hold CRC low byte in Y           |¨DLDA crc+3:‚ #&ED:STA crc+3 :\ CRC=CRC ‚ &EDB88320, ZIP polynomic²DLDA crc+2:‚ #&B8:STA crc+2 :\                                  |¼DLDA crc+1:‚ #&83:STA crc+1 :\                                  |ÆDTYA:‚ #&20                 :\ Get CRC low byte back from Y     |ÐF.clear                       :\                                  |ÚFDEX:BNE rotlp                :\ Loop for 8 bits                  |äF\ If used in isolation, requires STA crc+0 here                  |îF\ ---------------------------------------------------------------+ø:5INC addr:BNE next:INC addr+1 :\ Step to next byte	.next9STA crc+0                    :\ Store CRC bottom byte :*\ Now do a 16-bit decrement4ILDA num+0:BNE skip           :\ num.lo<>0, not wrapping from 00 to FF>JDEC num+1                    :\ Wrapping from 00 to FF, dec. high byteH	.skipRFDEC num+0:BNE bytelp         :\ Dec. low byte, loop until num.lo=0\4LDA num+1:BNE bytelp         :\ Loop until num=0fRTSp	]:í:áz:„7Ýòcrc65v1:Þ Calc 79:addr=&70:num=&72:crc=&74:ãP=0¸1ŽP%=Calc:[OPT P*2˜7LDY #0                       :\ Point to first byte¢.bytelp¬=LDA (addr),Y:‚ crc:STA crc :\ ‚ byte into CRC bottom byte¶@LDX #8                       :\ Prepare to rotate CRC 8 bitsÀ
.rotlpÊ.LSR crc+3:ROR crc+2          :\ Rotate CRCÔROR crc+1:ROR crc+0Þ/BCC clear                    :\ b0 was zeroèDLDA crc+3:‚ #&ED:STA crc+3 :\ CRC=CRC ‚ &EDB88320, ZIP polynomicòLDA crc+2:‚ #&B8:STA crc+2üLDA crc+1:‚ #&83:STA crc+1LDA crc+0:‚ #&20:STA crc+0
.clear3DEX:BNE rotlp                :\ Loop for 8 bits$5INY:BNE next:INC addr+1      :\ Step to next byte.	.next8SECB-LDA num+0:SBC #1:STA num+0   :\ num=num-1LLDA num+1:SBC #0:STA num+1V3„A num:BNE bytelp           :\ Loop until num=0`RTSj	]:í:át:~5Ýòcrc80:Þ Calc 79:addr=&70:num=&72:crc=&74:ãP=0¸1ˆP%=Calc:[OPT P*2’/LD IX,(addr):LD BC,(num)  :\ Address, Countœ-LD DE,(crc):LD HL,(crc+2) :\ Incoming CRC¦:°;\ Enter here with IX=>data, BC=count, HLDE=incoming CRCº.bytelpÄ+PUSH BC                   :\ Save countÎ7LD A,(IX)                 :\ Fetch byte from memoryØ:âF\ The following code updates the CRC with the byte in A ---------+ìFXOR E                     :\ XOR byte into CRC bottom byte       |öFLD B,8                    :\ Prepare to rotate 8 bits            | F.rotlp                    :\                                     |
FSRL H:RR L:RR D:RRA       :\ Rotate CRC                          |FJP NC,clear               :\ b0 was zero                         |FLD E,A                    :\ Put CRC low byte back into E        |(FLD A,H:XOR &ED:LD H,A     :\ CRC=CRC XOR &EDB88320, ZIP polynomic|2FLD A,L:XOR &B8:LD L,A     :\                                     |<FLD A,D:XOR &83:LD D,A     :\                                     |FFLD A,E:XOR &20            :\ And get CRC low byte back into A    |PF.clear                    :\                                     |ZFDEC B:JP NZ,rotlp         :\ Loop for 8 bits                     |dFLD E,A                    :\ Put CRC low byte back into E        |nF\ ---------------------------------------------------------------+x:‚2INC IX                    :\ Step to next byteŒ*POP BC:DEC BC             :\ num=num-1–0LD A,B:„ C:JP NZ,bytelp  :\ Loop until num=0 3LD (crc),DE:LD (crc+2),HL :\ Store outgoing CRCªRET´]:í:ñP%-Calc:á¾:ÈÝòcrcARM:Þ Calc 79:ãP=0¸1ÒP%=Calc:[OPT P*2Ü/LDR R0,addr:LDR R1,num    :\ Address, Countæ-LDR R2,crc                :\ Incoming CRCð\ú-\ Enter here with R0=addr, R1=num, R2=crc\.crc32reg.LDR R3,xor                :\ ZIP polynomic".bytelp,6LDRB R4,[R0],#1           :\ Get byte, inc address6:@F\ The following code updates the CRC with the byte in R4 --------+JF\ If used in isolation, requires LDR R3,xor here                 |TB‚ R2,R2,R4              :\ ‚ byte into CRC bottom byte       |^FMOV R4,#8                 :\ Prepare to rotate 8 bits            |hF.rotlp                    :\                                     |rFMOVS R2,R2,LSR #1         :\ Rotate CRC                          ||B‚CS R2,R2,R3            :\ If b0 was set, ‚ with ZIP polynomic†FSUBS R4,R4,#1:BNE rotlp   :\ Loop for 8 bits                     |F\ ---------------------------------------------------------------+š:¤1SUBS R1,R1,#1:BNE bytelp  :\ Loop until num=0®>STR R2,crc:MOV R15,R14    :\ Store outgoing CRC and return¸..xor:EQUD &EDB88320       :\ ZIP polynomicÂ.addr:EQUD 0:.num:EQUD 0Ì.crc:EQUD 0Ö	]:í:áà:êÝòcrc86:Þ Calc 63:ãP=0¸1ôP%=Calc:[OPT P*2þ
.crc32,MOV ESI,[addr]      ; ESI=>start of data-MOV EBX,[num]       ; EBX= length of data+MOV ECX,[crc]       ; ECX= incoming CRC&;0.bytelp:0MOV AL,[ESI]        ; Fetch byte from memoryD;NC; The following code updates the CRC with the byte in AL -----+XCXOR CL,AL           ; XOR byte into bottom of CRC             |bCMOV AL,8            ; Prepare to rotate 8 bits                |lC.rotlp              ;                                         |vCSHR ECX,1           ; Rotate CRC                              |€CJNC clear           ; b0 was zero                             |ŠCXOR ECX,&EDB88320   ; If b0 was set, XOR with ZIP polymonic   |”C.clear              ;                                         |žCDEC AL:JNZ rotlp    ; Loop for 8 bits                         |¨C; ------------------------------------------------------------+²;¼,INC SI              ; Point to next byteÆ5DEC EBX:JNE bytelp  ; num=num-1, loop until num=0Ð,MOV [crc],ECX       ; Store outgoing CRCÚRETFä.addr:DD 0î.num:DD 0ø.crc:DD 0	]:í:á:ÿ