;===========================================================================; Copyright (c) 1990-2000 Info-ZIP.  All rights reserved.;; See the accompanying file LICENSE, version 2000-Apr-09 or later; (the contents of which are also included in zip.h) for terms of use.; If, for some reason, all these files are missing, the Info-ZIP license; also may be found at:  ftp://ftp.info-zip.org/pub/infozip/license.html;===========================================================================; crc_68 created by Paul Kienitz, last modified 04 Jan 96.;; Return an updated 32 bit CRC value, given the old value and a block of data.; The CRC table used to compute the value is gotten by calling get_crc_table().; This replaces the older updcrc() function used in Zip and fUnZip.  The; prototype of the function is:;;    ulg crc32(ulg crcval, uch *text, extent textlen);;; On the Amiga, type extent is always unsigned long, not unsigned int, because; int can be short or long at whim, but size_t is long.;; If using this source on a non-Amiga 680x0 system, note that we treat; a0/a1/d0/d1 as scratch registers not preserved across function calls.; We do not bother to support registerized arguments for crc32() -- the; textlen parm is usually large enough so that savings outside the loop; are pointless.;; Define NO_UNROLLED_LOOPS to use a simple short loop which might be more; efficient on certain machines with dinky instruction caches ('020?), or for; processing short strings.  If loops are unrolled, the textlen parm must be; less than 512K; if not unrolled, it must be less than 64K.        xdef    _crc32          ; (ulg val, uch *buf, extent bufsize)DO_CRC0 MACRO        moveq  #0,ltemp        move.b (textbuf)+,ltemp        eor.b  crcval,ltemp        lsl.w  #2,ltemp        move.l (crc_table,ltemp.w),ltemp        lsr.l  #8,crcval        eor.l  ltemp,crcval        ENDM        machine mc68020DO_CRC2 MACRO        move.b (textbuf)+,btemp        eor.b  crcval,btemp        lsr.l  #8,crcval        move.l (crc_table,btemp.w*4),ltemp        eor.l  ltemp,crcval        ENDMcrc_table       equr    a0      array of unsigned longcrcval          equr    d0      unsigned long initial valuetextbuf         equr    a1      array of unsigned chartextbufsize     equr    d1      unsigned long (count of bytes in textbuf)btemp           equr    d2ltemp           equr    d3        xref    _get_crc_table  ; ulg *get_crc_table(void)        NOLIST        INCLUDE 'exec/execbase.i'        LIST        xref    _SysBase        ; struct ExecBase *_crc32:        move.l  8(sp),d0        bne.s   valid         moveq  #0,d0         rtsvalid:  movem.l btemp/ltemp,-(sp)        jsr     _get_crc_table        move.l  d0,ltemp        move.l  12(sp),crcval        move.l  16(sp),textbuf        move.l  20(sp),textbufsize        not.l   crcval        move.l  _SysBase,crc_table        move.w  AttnFlags(crc_table),btemp        move.l  ltemp,crc_table        btst    #AFB_68020,btemp        bne     twenty    IFD     NO_UNROLLED_LOOPS        bra.s   decrloop:    DO_CRC0decr:    dbra   textbufsize,loop        bra.s   donetwenty: moveq   #0,btemp        bra.s   decr2loop2:   DO_CRC2decr2:   dbra   textbufsize,loop2    ELSE    ; !NO_UNROLLED_LOOPS        move.l  textbufsize,btemp        lsr.l   #3,textbufsize        bra     decr8loop8:   DO_CRC0         DO_CRC0         DO_CRC0         DO_CRC0         DO_CRC0         DO_CRC0         DO_CRC0         DO_CRC0decr8:   dbra   textbufsize,loop8        and.w   #7,btemp        bra.s   decr1loop1:   DO_CRC0decr1:   dbra   btemp,loop1        bra     donetwenty: moveq   #0,btemp        move.l  textbufsize,-(sp)        lsr.l   #3,textbufsize        bra     decr82loop82:  DO_CRC2         DO_CRC2         DO_CRC2         DO_CRC2         DO_CRC2         DO_CRC2         DO_CRC2         DO_CRC2decr82:  dbra   textbufsize,loop82        move.l  (sp)+,textbufsize        and.w   #7,textbufsize        bra.s   decr12loop12:  DO_CRC2decr12:  dbra   textbufsize,loop12    ENDC    ; ?NO_UNROLLED_LOOPSdone:   movem.l (sp)+,btemp/ltemp        not.l   crcval;;;;;   move.l  crcval,d0               ; crcval already is d0        rts