; link with PIOxxx.OBJ

        sectionbss

crctable.d:     resd 256

        sectiondata

havetable.b:    db 0
string:         db "The quick brown fox jumps over the lazy dog"
stringend:
                db 13,10,0        ; carriage return and null terminator

        sectioncode

start!
        gosub initplatform

        beginfunc
        localvar crc.d

        callex ,printnt,"input = ".a
        callex ,printnt,string

        callex ,printnt,"The CRC-32 checksum = ".a
        callex crc,crc32,string,stringend
        callex ,printhexr,crc

        endfunc
        end

crc32:
        beginfunc bufend.d,buf.d
        localvar i.d,j.d,k.d,k2.d,crc.d

        ifunequal havetable,0,tabledone
        i=0
        whileless i,256

        k=i > j=8
        countdown j
        k2=k > k=_ shr 1
        ifequal k2 and 1,0,noxor > k=_ xor $EDB88320
noxor:
        nextcount

        crctable(i shl 2)=k
        i=_+1
        wend

        havetable=1
tabledone:

        crc=-1

        whileless buf,bufend
        crc=_ shr 8 xor crctable(crc and $FF xor [buf].b shl 2)
        buf=_+1
        wend

        crc=_ xor -1
        endfunc crc
        returnex 8                        ; clean off 2 parameters from the stack