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/ Aminet 4 / Aminet 4 - November 1994.iso / aminet / comm / net / plip38src.lha / plip / crc16.asm < prev    next >
Assembly Source File  |  1994-03-02  |  2KB  |  74 lines
  1. *
  2. * fast table driven crc16 routine
  3. *
  4. *
  5.     section    "text",code
  6.  
  7. ;
  8. ; crc16 = CRC16(dataptr,datalen)
  9. ;  d0[0:16]       a0      d0
  10.  
  11.     xdef    _CRC16
  12.  
  13. _CRC16:
  14.     movem.l    d2/d3/d4,-(sp)
  15.     moveq    #0,d1    ; init crc
  16. ;    moveq    #0,d4
  17.     lea    crctab(pc),a1
  18.     bra.s    crcloop2
  19. crcloop:
  20.     move.l    d1,d2
  21.     move.l    d1,d3
  22.     asl.w    #8,d3           ; crc <<8
  23.     lsr.w    #8,d2            ; crc >>8
  24.     add.w    d2,d2            ; fuer 020+
  25.     move.w    0(a1,d2.w),d1        ; move.w (a1,d2.w*2),d1
  26.     eor.w    d3,d1
  27.     move.b    (a0)+,d4
  28.     eor.b    d4,d1
  29.  
  30. ;    subq.l    #1,d0
  31. ;    bne.s    crcloop
  32. crcloop2:
  33.     dbf    d0,crcloop
  34.  
  35.     movem.l    (sp)+,d2/d3/d4
  36.     move.l    d1,d0
  37.     rts
  38.  
  39. crctab:
  40.     dc.w $0000,$1021,$2042,$3063,$4084,$50a5,$60c6,$70e7
  41.     dc.w $8108,$9129,$a14a,$b16b,$c18c,$d1ad,$e1ce,$f1ef
  42.     dc.w $1231,$0210,$3273,$2252,$52b5,$4294,$72f7,$62d6
  43.     dc.w $9339,$8318,$b37b,$a35a,$d3bd,$c39c,$f3ff,$e3de
  44.     dc.w $2462,$3443,$0420,$1401,$64e6,$74c7,$44a4,$5485
  45.     dc.w $a56a,$b54b,$8528,$9509,$e5ee,$f5cf,$c5ac,$d58d
  46.     dc.w $3653,$2672,$1611,$0630,$76d7,$66f6,$5695,$46b4
  47.     dc.w $b75b,$a77a,$9719,$8738,$f7df,$e7fe,$d79d,$c7bc
  48.     dc.w $48c4,$58e5,$6886,$78a7,$0840,$1861,$2802,$3823
  49.     dc.w $c9cc,$d9ed,$e98e,$f9af,$8948,$9969,$a90a,$b92b
  50.     dc.w $5af5,$4ad4,$7ab7,$6a96,$1a71,$0a50,$3a33,$2a12
  51.     dc.w $dbfd,$cbdc,$fbbf,$eb9e,$9b79,$8b58,$bb3b,$ab1a
  52.     dc.w $6ca6,$7c87,$4ce4,$5cc5,$2c22,$3c03,$0c60,$1c41
  53.     dc.w $edae,$fd8f,$cdec,$ddcd,$ad2a,$bd0b,$8d68,$9d49
  54.     dc.w $7e97,$6eb6,$5ed5,$4ef4,$3e13,$2e32,$1e51,$0e70
  55.     dc.w $ff9f,$efbe,$dfdd,$cffc,$bf1b,$af3a,$9f59,$8f78
  56.     dc.w $9188,$81a9,$b1ca,$a1eb,$d10c,$c12d,$f14e,$e16f
  57.     dc.w $1080,$00a1,$30c2,$20e3,$5004,$4025,$7046,$6067
  58.     dc.w $83b9,$9398,$a3fb,$b3da,$c33d,$d31c,$e37f,$f35e
  59.     dc.w $02b1,$1290,$22f3,$32d2,$4235,$5214,$6277,$7256
  60.     dc.w $b5ea,$a5cb,$95a8,$8589,$f56e,$e54f,$d52c,$c50d
  61.     dc.w $34e2,$24c3,$14a0,$0481,$7466,$6447,$5424,$4405
  62.     dc.w $a7db,$b7fa,$8799,$97b8,$e75f,$f77e,$c71d,$d73c
  63.     dc.w $26d3,$36f2,$0691,$16b0,$6657,$7676,$4615,$5634
  64.     dc.w $d94c,$c96d,$f90e,$e92f,$99c8,$89e9,$b98a,$a9ab
  65.     dc.w $5844,$4865,$7806,$6827,$18c0,$08e1,$3882,$28a3
  66.     dc.w $cb7d,$db5c,$eb3f,$fb1e,$8bf9,$9bd8,$abbb,$bb9a
  67.     dc.w $4a75,$5a54,$6a37,$7a16,$0af1,$1ad0,$2ab3,$3a92
  68.     dc.w $fd2e,$ed0f,$dd6c,$cd4d,$bdaa,$ad8b,$9de8,$8dc9
  69.     dc.w $7c26,$6c07,$5c64,$4c45,$3ca2,$2c83,$1ce0,$0cc1
  70.     dc.w $ef1f,$ff3e,$cf5d,$df7c,$af9b,$bfba,$8fd9,$9ff8
  71.     dc.w $6e17,$7e36,$4e55,$5e74,$2e93,$3eb2,$0ed1,$1ef0
  72.  
  73.     end
  74.