[deliverable/linux.git] / arch / m68knommu / lib / checksum.c

/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		IP/TCP/UDP checksumming routines
 *
 * Authors:	Jorge Cwik, <jorge@laser.satlink.net>
 *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
 *		Tom May, <ftom@netcom.com>
 *		Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
 *		Lots of code moved from tcp.c and ip.c; see those files
 *		for more names.
 *
 * 03/02/96	Jes Sorensen, Andreas Schwab, Roman Hodek:
 *		Fixed some nasty bugs, causing some horrible crashes.
 *		A: At some points, the sum (%0) was used as
 *		length-counter instead of the length counter
 *		(%1). Thanks to Roman Hodek for pointing this out.
 *		B: GCC seems to mess up if one uses too many
 *		data-registers to hold input values and one tries to
 *		specify d0 and d1 as scratch registers. Letting gcc choose these
 *      registers itself solves the problem.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */
 
/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access kills, so most
   of the assembly has to go. */

#include <linux/module.h>
#include <net/checksum.h>

static inline unsigned short from32to16(unsigned long x)
{
	/* add up 16-bit and 16-bit for 16+c bit */
	x = (x & 0xffff) + (x >> 16);
	/* add up carry.. */
	x = (x & 0xffff) + (x >> 16);
	return x;
}

static unsigned long do_csum(const unsigned char * buff, int len)
{
	int odd, count;
	unsigned long result = 0;

	if (len <= 0)
		goto out;
	odd = 1 & (unsigned long) buff;
	if (odd) {
		result = *buff;
		len--;
		buff++;
	}
	count = len >> 1;		/* nr of 16-bit words.. */
	if (count) {
		if (2 & (unsigned long) buff) {
			result += *(unsigned short *) buff;
			count--;
			len -= 2;
			buff += 2;
		}
		count >>= 1;		/* nr of 32-bit words.. */
		if (count) {
		        unsigned long carry = 0;
			do {
				unsigned long w = *(unsigned long *) buff;
				count--;
				buff += 4;
				result += carry;
				result += w;
				carry = (w > result);
			} while (count);
			result += carry;
			result = (result & 0xffff) + (result >> 16);
		}
		if (len & 2) {
			result += *(unsigned short *) buff;
			buff += 2;
		}
	}
	if (len & 1)
		result += (*buff << 8);
	result = from32to16(result);
	if (odd)
		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
out:
	return result;
}

#ifdef CONFIG_COLDFIRE
/*
 *	This is a version of ip_compute_csum() optimized for IP headers,
 *	which always checksum on 4 octet boundaries.
 */
__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
	return (__force __sum16)~do_csum(iph,ihl*4);
}
#endif

/*
 * computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * returns a 32-bit number suitable for feeding into itself
 * or csum_tcpudp_magic
 *
 * this function must be called with even lengths, except
 * for the last fragment, which may be odd
 *
 * it's best to have buff aligned on a 32-bit boundary
 */
__wsum csum_partial(const void *buff, int len, __wsum sum)
{
	unsigned int result = do_csum(buff, len);

	/* add in old sum, and carry.. */
	result += (__force u32)sum;
	if ((__force u32)sum > result)
		result += 1;
	return (__force __wsum)result;
}

EXPORT_SYMBOL(csum_partial);

/*
 * copy from fs while checksumming, otherwise like csum_partial
 */

__wsum
csum_partial_copy_from_user(const void __user *src, void *dst,
			    int len, __wsum sum, int *csum_err)
{
	if (csum_err) *csum_err = 0;
	memcpy(dst, (__force const void *)src, len);
	return csum_partial(dst, len, sum);
}

/*
 * copy from ds while checksumming, otherwise like csum_partial
 */

__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{
	memcpy(dst, src, len);
	return csum_partial(dst, len, sum);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* INET An implementation of the TCP/IP protocol suite for the LINUX
	3	* operating system. INET is implemented using the BSD Socket
	4	* interface as the means of communication with the user level.
	5	*
	6	* IP/TCP/UDP checksumming routines
	7	*
	8	* Authors: Jorge Cwik, <jorge@laser.satlink.net>
	9	* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
	10	* Tom May, <ftom@netcom.com>
	11	* Andreas Schwab, <schwab@issan.informatik.uni-dortmund.de>
	12	* Lots of code moved from tcp.c and ip.c; see those files
	13	* for more names.
	14	*
	15	* 03/02/96 Jes Sorensen, Andreas Schwab, Roman Hodek:
	16	* Fixed some nasty bugs, causing some horrible crashes.
	17	* A: At some points, the sum (%0) was used as
	18	* length-counter instead of the length counter
	19	* (%1). Thanks to Roman Hodek for pointing this out.
	20	* B: GCC seems to mess up if one uses too many
	21	* data-registers to hold input values and one tries to
	22	* specify d0 and d1 as scratch registers. Letting gcc choose these
	23	* registers itself solves the problem.
	24	*
	25	* This program is free software; you can redistribute it and/or
	26	* modify it under the terms of the GNU General Public License
	27	* as published by the Free Software Foundation; either version
	28	* 2 of the License, or (at your option) any later version.
	29	*/
	30
	31	/* Revised by Kenneth Albanowski for m68knommu. Basic problem: unaligned access kills, so most
	32	of the assembly has to go. */
	33
	34	#include <linux/module.h>
	35	#include <net/checksum.h>
	36
	37	static inline unsigned short from32to16(unsigned long x)
	38	{
	39	/* add up 16-bit and 16-bit for 16+c bit */
	40	x = (x & 0xffff) + (x >> 16);
	41	/* add up carry.. */
	42	x = (x & 0xffff) + (x >> 16);
	43	return x;
	44	}
	45
	46	static unsigned long do_csum(const unsigned char * buff, int len)
	47	{
	48	int odd, count;
	49	unsigned long result = 0;
	50
	51	if (len <= 0)
	52	goto out;
	53	odd = 1 & (unsigned long) buff;
	54	if (odd) {
	55	result = *buff;
	56	len--;
	57	buff++;
	58	}
	59	count = len >> 1; /* nr of 16-bit words.. */
	60	if (count) {
	61	if (2 & (unsigned long) buff) {
	62	result += (unsigned short ) buff;
	63	count--;
	64	len -= 2;
65	buff += 2;
66	}
67	count >>= 1; /* nr of 32-bit words.. */
68	if (count) {
69	unsigned long carry = 0;
70	do {
71	unsigned long w = (unsigned long ) buff;
72	count--;
73	buff += 4;
74	result += carry;
75	result += w;
76	carry = (w > result);
77	} while (count);
78	result += carry;
79	result = (result & 0xffff) + (result >> 16);
80	}
81	if (len & 2) {
82	result += (unsigned short ) buff;
83	buff += 2;
84	}
85	}
86	if (len & 1)
87	result += (*buff << 8);
88	result = from32to16(result);
89	if (odd)
90	result = ((result >> 8) & 0xff) \| ((result & 0xff) << 8);
91	out:
92	return result;
93	}
94
6192c1ea	95	#ifdef CONFIG_COLDFIRE
1da177e4 LT	96	/*
	97	* This is a version of ip_compute_csum() optimized for IP headers,
	98	* which always checksum on 4 octet boundaries.
	99	*/
59ed05a7	100	__sum16 ip_fast_csum(const void *iph, unsigned int ihl)
1da177e4	101	{
59ed05a7	102	return (__force __sum16)~do_csum(iph,ihl*4);
1da177e4	103	}
6192c1ea	104	#endif
1da177e4 LT	105
	106	/*
	107	* computes the checksum of a memory block at buff, length len,
	108	* and adds in "sum" (32-bit)
	109	*
	110	* returns a 32-bit number suitable for feeding into itself
	111	* or csum_tcpudp_magic
	112	*
	113	* this function must be called with even lengths, except
	114	* for the last fragment, which may be odd
	115	*
	116	* it's best to have buff aligned on a 32-bit boundary
	117	*/
59ed05a7	118	__wsum csum_partial(const void *buff, int len, __wsum sum)
1da177e4 LT	119	{
	120	unsigned int result = do_csum(buff, len);
	121
	122	/* add in old sum, and carry.. */
59ed05a7 AV	123	result += (__force u32)sum;
59ed05a7 AV	124	if ((__force u32)sum > result)
1da177e4	125	result += 1;
59ed05a7	126	return (__force __wsum)result;
1da177e4 LT	127	}
	128
	129	EXPORT_SYMBOL(csum_partial);
	130
1da177e4 LT	131	/*
	132	* copy from fs while checksumming, otherwise like csum_partial
	133	*/
	134
59ed05a7 AV	135	__wsum
	136	csum_partial_copy_from_user(const void __user src, void dst,
	137	int len, __wsum sum, int *csum_err)
1da177e4 LT	138	{
1da177e4 LT	139	if (csum_err) *csum_err = 0;
59ed05a7	140	memcpy(dst, (__force const void *)src, len);
1da177e4 LT	141	return csum_partial(dst, len, sum);
	142	}
	143
	144	/*
	145	* copy from ds while checksumming, otherwise like csum_partial
	146	*/
	147
59ed05a7 AV	148	__wsum
59ed05a7 AV	149	csum_partial_copy_nocheck(const void src, void dst, int len, __wsum sum)
1da177e4 LT	150	{
	151	memcpy(dst, src, len);
	152	return csum_partial(dst, len, sum);
	153	}