[comp.sys.m68k] crc32 algorithm

larimer@ncrcam.Cambridge.NCR.COM (Fred Larimer) (10/24/90)

I hope somebody can help me with this. 

I need to write a routine to generate a crc32 frame check sequence in software. 

I've read the description of the Autodin II CRC32 frame check sequence in the
IEEE 802.3 Standard 1988, but so far I haven't been able to convert that 
description to an algorithm that I can code to.

So, if anybody can help me with an algorithm, a routine, a function or a
source reference for any of the above I would appreciate it.

Fred.

rbt@cernvax.UUCP (roberto divia) (10/25/90)

Fred Larimer asked for an implementation of the Autodin II CRC32 cheker.
This is written using CERN macros. Hope it will be readable...

	IDENT	CHIFC_CRC_CHECK
	TTL	'CHIFC CRC Generator/Checker'
	STTL	'Module history'
********************************************************************************
*
*	CHIFC CRC Generator/Checker
*	===========================
*
* Modification history:
*	 5 Sep 89	Created (RD)
*
* General comment: this code is completely reentrant and it should be extremely
* fast since the kernel is small enough to be cached in the program cache of the
* 68020/68030. The data cache should not make a big difference.
*
********************************************************************************
	STTL	'EQU Declarations'
	PAGE
********************************************************************************
*
*	EQU Declarations
*	================
*
PROGRAM	SECTION	R
*
	OPT	P=68020
*
	NOLIST
	SYSTEXT
	LIST	CREF
*
* CRC polynomial term:
* --------------------
*
POLY	EQU	%00000100110000010001110110110111	As for Ethernet prot.
*
EXPECT	EQU	%11000111000001001101110101111011	As before, this is the
*							expected value by the
*							CRC checker.
*
********************************************************************************
	STTL	'CRC Generator initialisation'
	PAGE
********************************************************************************
*
* CRC Generator initialisation
* ----------------------------
*
*	procedure initialise_CRC;
*
* This entry must be called before using the CRC generator/checker, to "warm up"
* the table of CRC constants.
*
	S_Entry	initialise_CRC		Main entry point
	S_Entry	_initialise_CRC		For C programs
	S_Entry	iniCRC			For FORTRAN programs
*
	lea	CRC_t,a0		Load the CRC table base address (low b)
	clr.l	d1			Initial byte value
	move.l	#POLY,d7		Load the polynomial term
IextL	move.b	d1,d2			Load the current byte value
	moveq.l	#7,d3			Initialise the bit counter (7 + 1)
	clr.l	d0			Initial CRC value (all zeros)
IintL	rol.b	#1,d2			Get the top bit (# 7) in position 0
	lsl.l	#1,d0			Prepare the next CRC
	roxl.b	#1,d4			Get the top bit of the CRC into d4 bit 0
	eor.b	d2,d4			Xor the patterns
	btst.b	#0,d4			Bit 0 is zero?
	beq.b	IdivZ			Skip if true
	eor.l	d7,d0			Otherwise xor the CRC with the POLY...
	or.b	#1,d0			...and set bit 0
IdivZ	dbra.w	d3,IintL		Loop on all bits
	move.l	d0,(a0)+		Done: save the generated CRC value
	addq.b	#1,d1			Increment the byte count
	bne.b	IextL			And loop on all the possible patterns
	rts
*
********************************************************************************
	STTL	'CRC Generator'
	PAGE
********************************************************************************
*
* CRC Generator
* -------------
*
*	procedure generate_CRC(	VAR data_buffer : INTEGER [1..num_longwords];
*				VAR num_longwords : INTEGER );
*
* The data_buffer is scanned and the generated CRC is appended after
* num_longwords + 1.
*
* All input parameters are passed by ADDRESS for FORTRAN compatibility.
*
	S_Entry	generate_CRC		Main entry point
	S_Entry	_generate_CRC		For C programs
	S_Entry	genCRC			For FORTRAN programs
*
	bsr.b	do_CRC			Generate the CRC
	eor.l	#-1,d0			Negate the pattern...
	move.l	d0,(a0)			...and save it
	rts
*
********************************************************************************
	STTL	'CRC Checker'
	PAGE
********************************************************************************
*
* CRC Checker
* -----------
*
*	function check_CRC (	VAR data_buffer : INTEGER [1..num_longwords];
*				VAR num_longwords : INTEGER ) : UNSIGNED;
*
* The data_buffer is scanned for num_longwords and the CRC is checked. The
* function returns 0 if the check succedes. This procedure assumes that the
* last longword if the data_buffer contains the CRC generated by generate_CRC.
*
* All input parameters are passed by ADDRESS for FORTRAN compatibility.
*
	S_Entry	check_CRC		Main entry point
	S_Entry	_check_CRC		For C programs
	S_Entry	chkCRC			For FORTRAN programs
*
	bsr.b	do_CRC			Generate the expected CRC
	sub.l	#EXPECT,d0		Expected value? d0 MUST be = 0
	rts
*
********************************************************************************
	STTL	'CRC generator'
	PAGE
********************************************************************************
*
*	CRC generator
*	=============
*
* This procedure is called with this stack organisation:
*
* a7 ->	"internal" return address
* +4 ->	"external" return address
* +8 -> buffer address
* +C -> number of longwords in the buffer
*
* It returns in d0 the generated CRC and in a0 the address of the first
* unused longword.
*
do_CRC	move.l	8(a7),a0		Fetch the data array address
	move.l	([$C,a7]),d1		Fetch the number of longwords counter
	asl.l	#2,d1			Compute the byte count
	moveq.l	#-1,d0			Preload the Remainder
	lea	CRC_t,a1		Fetch the CRC table base address
	moveq.l	#0,d2
	bra	endOfL			Start looping
*
* Here starts the Main Loop
*
mainL	rol.l	#8,d0			Get the top remainder byte in low byte
	move.b	(a0)+,d3		Get current data pattern
	move.b	d0,d2			Move the bottom CRC byte into d2
	move.b	#0,d0			Clear the remainder bottom byte
	eor.b	d3,d2			Compute the table index
	move.l	(a1,d2.W*4),d4		Retrieve the remainder from the table...
	eor.l	d4,d0			...and compute the current CRC
endOfL	dbra.w	d1,mainL		Loop on all the bytes
	rts
*
********************************************************************************
	STTL	'CRC Generator (Bit oriented)'
	PAGE
********************************************************************************
*
* CRC Generator (Bit oriented)
* ----------------------------
*
*	procedure Bgenerate_CRC(VAR data_buffer : INTEGER [1..num_longwords];
*				VAR num_longwords : INTEGER );
*
* The data_buffer is scanned and the generated CRC is appended after
* num_longwords + 1.
*
* All input parameters are passed by ADDRESS for FORTRAN compatibility.
*
	S_Entry	Bgenerate_CRC		Main entry point
*
	bsr.b	private			Generate the CRC
	eor.l	#-1,d0			Negate the pattern...
	move.l	d0,(a0)			...and save it
	rts
*
********************************************************************************
	STTL	'CRC Checker (Bit oriented)'
	PAGE
********************************************************************************
*
* CRC Checker (Bit oriented)
* --------------------------
*
*	function Bcheck_CRC (	VAR data_buffer : INTEGER [1..num_longwords];
*				VAR num_longwords : INTEGER ) : UNSIGNED;
*
* The data_buffer is scanned for num_longwords and the CRC is checked. The
* function returns 0 if the check succedes. This procedure assumes that the
* last longword if the data_buffer contains the CRC generated by generate_CRC.
*
* All input parameters are passed by ADDRESS for FORTRAN compatibility.
*
	S_Entry	Bcheck_CRC		Main entry point
*
	bsr.b	private			Generate the expected CRC
	sub.l	#EXPECT,d0		Expected value? d0 MUST be = 0
	rts
*
********************************************************************************
	STTL	'CRC generator (Bit oriented)'
	PAGE
********************************************************************************
*
*	CRC generator (Bit oriented)
*	============================
*
* This procedure is called with this stack organisation:
*
* a7 ->	"internal" return address
* +4 ->	"external" return address
* +8 -> buffer address
* +C -> number of longwords in the buffer
*
* It returns in d0 the generated CRC and in a0 the address of the first
* unused longword.
*
private	move.l	8(a7),a0		Fetch the data array address
	move.l	([$C,a7]),d1		Fetch the number of longwords counter
	moveq.l	#-1,d0			Preload the CRC accumulator to all 1s
	move.l	#POLY,d7		d7 contains the polynomial term
	bra	BendOfL			Start looping
*
* Here starts the Main Loop
*
BmainL	move.l	(a0)+,d2		Fetch the current Lw
	moveq.l	#31,d3			Load the bits count - 1
BbitsL	rol.l	#1,d2			Get the current bit in position 0
	lsl.l	#1,d0			Start making the next CRC
	roxl.b	#1,d4			Get into d4 bit 0 the Shift out
	eor.b	d2,d4			Exor (only bit 0 is interesting)
	btst.b	#0,d4			Bit is zero?
	beq.b	BdivZ			If true, skip next phase
	eor.l	d7,d0			Otherwise xor CRC with the POLY...
	or.b	#1,d0			...and set bit 0
BdivZ	dbra.w	d3,BbitsL		Loop on all the data bits
BendOfL	dbra.w	d1,BmainL		Loop on all the Lws in the buffer
	rts
*
********************************************************************************
	STTL	'Data area'
	PAGE
********************************************************************************
*
* Data area
* ---------
*
UNINDATA	SECTION	R
*
	ENTRY	CRC_t		For debugging...
CRC_t	DS.L	256		CRC table (loaded by initialise_CRC)
*
********************************************************************************
	STTL	''
	PAGE
	END
-- 
|   Roberto Divia`      | Love at  first sight  is one of the greatest |
|   =============       | labor-saving devices the world has ever seen |
|  CERN :  European Laboratory for Particle Physics,  1211  Geneva  23 |
|  Switzerland (CH)                                                    |

syackey@secola.Columbia.NCR.COM (Steve Yackey) (10/26/90)

In article <2117@ncrcam.Cambridge.NCR.COM> larimer@ncrcam.Cambridge.NCR.COM (Fred Larimer) writes:
>I hope somebody can help me with this. 
>
>I need to write a routine to generate a crc32 frame check sequence in software. 
>
>I've read the description of the Autodin II CRC32 frame check sequence in the
>IEEE 802.3 Standard 1988, but so far I haven't been able to convert that 
>description to an algorithm that I can code to.
>
>So, if anybody can help me with an algorithm, a routine, a function or a
>source reference for any of the above I would appreciate it.
>
>Fred.
/*
 * This code implements the AUTODIN II polynomial used by Ethernet,
 * and can be used to calculate multicast address hash indices.
 * It assumes that the low order bits will be transmitted first,
 * and consequently the low byte should be sent first when
 * the crc computation is finished.  The crc should be complemented
 * before transmission.
 * The variable corresponding to the macro argument "crc" should
 * be an unsigned long and should be preset to all ones for Ethernet
 * use.  An error-free packet will leave 0xDEBB20E3 in the crc.
 *			Spencer Garrett <srg@quick.com>
 */

#define CRC(crc, ch)	 (crc = (crc >> 8) ^ crctab[(crc ^ (ch)) & 0xff])

/* generated using the AUTODIN II polynomial
 *	x^32 + x^26 + x^23 + x^22 + x^16 +
 *	x^12 + x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + 1
 */
unsigned long crctab[256] = {
	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
	0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
	0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
	0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
	0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
	0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
	0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
	0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
	0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
	0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
	0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
	0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
	0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
	0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
	0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
	0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
	0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
	0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
	0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
	0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
	0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
	0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
	0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
	0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
	0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
	0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
	0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
	0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
	0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
	0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
	0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
	0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
	0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
	0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
	0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
	0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
	0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
	0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
	0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
	0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
	0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
	0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
};

#include <stdio.h>

main()
{
	unsigned long crc = 0xFFFFFFFF;

	int i;

	while (scanf(" %x", &i) == 1)
		CRC(crc, i);
	printf("crc 0x%08x comp 0x%08x\n", crc, ~crc);
}

sasrer@unx.sas.com (Rodney Radford) (11/06/90)

In article <2117@ncrcam.Cambridge.NCR.COM> larimer@ncrcam.Cambridge.NCR.COM (Fred Larimer) writes:
>I hope somebody can help me with this. 
>
>I need to write a routine to generate a crc32 frame check sequence in software. 
>
>I've read the description of the Autodin II CRC32 frame check sequence in the
>IEEE 802.3 Standard 1988, but so far I haven't been able to convert that 
>description to an algorithm that I can code to.
>
>So, if anybody can help me with an algorithm, a routine, a function or a
>source reference for any of the above I would appreciate it.
>
>Fred.

An article in Steve Ciarcia's magazine "Circuit Cellar" showed just such an
algorithm coded in C. I am currently at work so I don't have my magazines 
handy, but if you want more information, I can get the actual issue number
later....

-- 
Rodney E. Radford        SAS Institute, Inc.        sasrer@unx.sas.com
DG/UX AViiON developer   Box 8000, Cary, NC 27512   (919) 677-8000 x7703