;=========================================================================== ; Copyright (c) 1990-1999 Info-ZIP. All rights reserved. ; ; See the accompanying file LICENSE, version 1999-Oct-05 or later ; (the contents of which are also included in zip.h) for terms of use. ; If, for some reason, both of these files are missing, the Info-ZIP license ; also may be found at: ftp://ftp.cdrom.com/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. ; ; 1999/09/23: for Human68k: Modified by Shimazaki Ryo. 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 DO_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 ENDM crc_table reg a0 array of unsigned long crcval reg d0 unsigned long initial value textbuf reg a1 array of unsigned char textbufsize reg d1 unsigned long (count of bytes in textbuf) btemp reg d2 ltemp reg d3 xref _get_crc_table ; ulg *get_crc_table(void) quad _crc32: move.l 8(sp),d0 bne.s valid ;;;;; moveq #0,d0 rts valid: movem.l btemp/ltemp,-(sp) jsr _get_crc_table movea.l d0,crc_table move.l 12(sp),crcval move.l 16(sp),textbuf move.l 20(sp),textbufsize not.l crcval ifdef NO_UNROLLED_LOOPS if CPU==68000 bra.s decr loop: DO_CRC0 decr: dbra textbufsize,loop bra.s done else twenty: moveq #0,btemp bra.s decr2 loop2: DO_CRC2 decr2: dbra textbufsize,loop2 endif ELSE ; !NO_UNROLLED_LOOPS if CPU==68000 moveq #7,btemp and textbufsize,btemp lsr.l #3,textbufsize bra decr8 loop8: DO_CRC0 DO_CRC0 DO_CRC0 DO_CRC0 DO_CRC0 DO_CRC0 DO_CRC0 DO_CRC0 decr8: dbra textbufsize,loop8 bra.s decr1 loop1: DO_CRC0 decr1: dbra btemp,loop1 bra done else twenty: moveq #0,btemp move.l textbufsize,-(sp) lsr.l #3,textbufsize bra decr82 quad loop82: DO_CRC2 DO_CRC2 DO_CRC2 DO_CRC2 DO_CRC2 DO_CRC2 DO_CRC2 DO_CRC2 decr82: dbra textbufsize,loop82 moveq #7,textbufsize and.l (sp)+,textbufsize bra.s decr12 loop12: DO_CRC2 decr12: dbra textbufsize,loop12 endif ENDC ; ?NO_UNROLLED_LOOPS done: movem.l (sp)+,btemp/ltemp not.l crcval ;;;;; move.l crcval,d0 ; crcval already is d0 rts