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CRC32 in 68000 assembly

Discussion in 'Technical Discussion' started by Hivebrain, Apr 16, 2024.

  1. Hivebrain

    Hivebrain

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    I wrote a subroutine to calculate the CRC32 of a section of ROM/RAM. It can process a whole 512kB ROM in about 3 seconds. Not sure what anyone might use it for, it's just a fun mini-project I thought I'd share.

    https://github.com/cvghivebrain/CRC3268k

    Code (Text):
    1.  
    2. ; ---------------------------------------------------------------------------
    3. ; Subroutine to    calculate CRC32 of region of ROM/RAM
    4.  
    5. ; input:
    6. ;    a1 = start address
    7. ;    d0.l = length of data
    8.  
    9. ; output:
    10. ;    d1.l = CRC32
    11.  
    12. ;    uses d0.l, d2.l, a1, a2
    13.  
    14. ; usage:
    15. ;        lea    Address,a1
    16. ;        move.l    #length,d0
    17. ;        bsr.w    CalcCRC32
    18. ;        cmpi.l    #expected_value,d1
    19. ;        bne.w    Doesnt_match                ; branch if CRC32 doesn't match
    20. ; ---------------------------------------------------------------------------
    21.  
    22. CalcCRC32:
    23.         moveq    #-1,d1                    ; initial value
    24.         tst.l    d0                    ; check if size is valid
    25.         bmi.s    .exit                    ; branch if not
    26.         beq.s    .exit
    27.         lea    CRC32_Table(pc),a2
    28.        
    29.     .loop:
    30.         moveq    #0,d2
    31.         move.b    (a1)+,d2                ; get byte from source
    32.         eor.b    d1,d2
    33.         add.w    d2,d2
    34.         add.w    d2,d2                    ; multiply by 4
    35.         lsr.l    #8,d1                    ; shift right 1 byte
    36.         move.l    (a2,d2.w),d2
    37.         eor.l    d2,d1                    ; eor with value from table
    38.         subq.l    #1,d0                    ; subtract 1 from size
    39.         bne.s    .loop                    ; repeat if not 0
    40.        
    41.     .exit:
    42.         not.l    d1                    ; final result
    43.         rts
    44.  
    45. CRC32_Table:
    46.         dc.l $00000000, $77073096, $EE0E612C, $990951BA
    47.         dc.l $076DC419, $706AF48F, $E963A535, $9E6495A3
    48.         dc.l $0EDB8832, $79DCB8A4, $E0D5E91E, $97D2D988
    49.         dc.l $09B64C2B, $7EB17CBD, $E7B82D07, $90BF1D91
    50.         dc.l $1DB71064, $6AB020F2, $F3B97148, $84BE41DE
    51.         dc.l $1ADAD47D, $6DDDE4EB, $F4D4B551, $83D385C7
    52.         dc.l $136C9856, $646BA8C0, $FD62F97A, $8A65C9EC
    53.         dc.l $14015C4F, $63066CD9, $FA0F3D63, $8D080DF5
    54.         dc.l $3B6E20C8, $4C69105E, $D56041E4, $A2677172
    55.         dc.l $3C03E4D1, $4B04D447, $D20D85FD, $A50AB56B
    56.         dc.l $35B5A8FA, $42B2986C, $DBBBC9D6, $ACBCF940
    57.         dc.l $32D86CE3, $45DF5C75, $DCD60DCF, $ABD13D59
    58.         dc.l $26D930AC, $51DE003A, $C8D75180, $BFD06116
    59.         dc.l $21B4F4B5, $56B3C423, $CFBA9599, $B8BDA50F
    60.         dc.l $2802B89E, $5F058808, $C60CD9B2, $B10BE924
    61.         dc.l $2F6F7C87, $58684C11, $C1611DAB, $B6662D3D
    62.         dc.l $76DC4190, $01DB7106, $98D220BC, $EFD5102A
    63.         dc.l $71B18589, $06B6B51F, $9FBFE4A5, $E8B8D433
    64.         dc.l $7807C9A2, $0F00F934, $9609A88E, $E10E9818
    65.         dc.l $7F6A0DBB, $086D3D2D, $91646C97, $E6635C01
    66.         dc.l $6B6B51F4, $1C6C6162, $856530D8, $F262004E
    67.         dc.l $6C0695ED, $1B01A57B, $8208F4C1, $F50FC457
    68.         dc.l $65B0D9C6, $12B7E950, $8BBEB8EA, $FCB9887C
    69.         dc.l $62DD1DDF, $15DA2D49, $8CD37CF3, $FBD44C65
    70.         dc.l $4DB26158, $3AB551CE, $A3BC0074, $D4BB30E2
    71.         dc.l $4ADFA541, $3DD895D7, $A4D1C46D, $D3D6F4FB
    72.         dc.l $4369E96A, $346ED9FC, $AD678846, $DA60B8D0
    73.         dc.l $44042D73, $33031DE5, $AA0A4C5F, $DD0D7CC9
    74.         dc.l $5005713C, $270241AA, $BE0B1010, $C90C2086
    75.         dc.l $5768B525, $206F85B3, $B966D409, $CE61E49F
    76.         dc.l $5EDEF90E, $29D9C998, $B0D09822, $C7D7A8B4
    77.         dc.l $59B33D17, $2EB40D81, $B7BD5C3B, $C0BA6CAD
    78.         dc.l $EDB88320, $9ABFB3B6, $03B6E20C, $74B1D29A
    79.         dc.l $EAD54739, $9DD277AF, $04DB2615, $73DC1683
    80.         dc.l $E3630B12, $94643B84, $0D6D6A3E, $7A6A5AA8
    81.         dc.l $E40ECF0B, $9309FF9D, $0A00AE27, $7D079EB1
    82.         dc.l $F00F9344, $8708A3D2, $1E01F268, $6906C2FE
    83.         dc.l $F762575D, $806567CB, $196C3671, $6E6B06E7
    84.         dc.l $FED41B76, $89D32BE0, $10DA7A5A, $67DD4ACC
    85.         dc.l $F9B9DF6F, $8EBEEFF9, $17B7BE43, $60B08ED5
    86.         dc.l $D6D6A3E8, $A1D1937E, $38D8C2C4, $4FDFF252
    87.         dc.l $D1BB67F1, $A6BC5767, $3FB506DD, $48B2364B
    88.         dc.l $D80D2BDA, $AF0A1B4C, $36034AF6, $41047A60
    89.         dc.l $DF60EFC3, $A867DF55, $316E8EEF, $4669BE79
    90.         dc.l $CB61B38C, $BC66831A, $256FD2A0, $5268E236
    91.         dc.l $CC0C7795, $BB0B4703, $220216B9, $5505262F
    92.         dc.l $C5BA3BBE, $B2BD0B28, $2BB45A92, $5CB36A04
    93.         dc.l $C2D7FFA7, $B5D0CF31, $2CD99E8B, $5BDEAE1D
    94.         dc.l $9B64C2B0, $EC63F226, $756AA39C, $026D930A
    95.         dc.l $9C0906A9, $EB0E363F, $72076785, $05005713
    96.         dc.l $95BF4A82, $E2B87A14, $7BB12BAE, $0CB61B38
    97.         dc.l $92D28E9B, $E5D5BE0D, $7CDCEFB7, $0BDBDF21
    98.         dc.l $86D3D2D4, $F1D4E242, $68DDB3F8, $1FDA836E
    99.         dc.l $81BE16CD, $F6B9265B, $6FB077E1, $18B74777
    100.         dc.l $88085AE6, $FF0F6A70, $66063BCA, $11010B5C
    101.         dc.l $8F659EFF, $F862AE69, $616BFFD3, $166CCF45
    102.         dc.l $A00AE278, $D70DD2EE, $4E048354, $3903B3C2
    103.         dc.l $A7672661, $D06016F7, $4969474D, $3E6E77DB
    104.         dc.l $AED16A4A, $D9D65ADC, $40DF0B66, $37D83BF0
    105.         dc.l $A9BCAE53, $DEBB9EC5, $47B2CF7F, $30B5FFE9
    106.         dc.l $BDBDF21C, $CABAC28A, $53B39330, $24B4A3A6
    107.         dc.l $BAD03605, $CDD70693, $54DE5729, $23D967BF
    108.         dc.l $B3667A2E, $C4614AB8, $5D681B02, $2A6F2B94
    109.         dc.l $B40BBE37, $C30C8EA1, $5A05DF1B, $2D02EF8D