[mirror_ubuntu-artful-kernel.git] / arch / ia64 / lib / csum_partial_copy.c

/*
 * Network Checksum & Copy routine
 *
 * Copyright (C) 1999, 2003-2004 Hewlett-Packard Co
 *	Stephane Eranian <eranian@hpl.hp.com>
 *
 * Most of the code has been imported from Linux/Alpha
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>

#include <linux/uaccess.h>

/*
 * XXX Fixme: those 2 inlines are meant for debugging and will go away
 */
static inline unsigned
short from64to16(unsigned long x)
{
	/* add up 32-bit words for 33 bits */
	x = (x & 0xffffffff) + (x >> 32);
	/* add up 16-bit and 17-bit words for 17+c bits */
	x = (x & 0xffff) + (x >> 16);
	/* add up 16-bit and 2-bit for 16+c bit */
	x = (x & 0xffff) + (x >> 16);
	/* add up carry.. */
	x = (x & 0xffff) + (x >> 16);
	return x;
}

static inline
unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum)
{
	int odd, count;
	unsigned long result = (unsigned long)psum;

	if (len <= 0)
		goto out;
	odd = 1 & (unsigned long) buff;
	if (odd) {
		result = *buff << 8;
		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) {
			if (4 & (unsigned long) buff) {
				result += *(unsigned int *) buff;
				count--;
				len -= 4;
				buff += 4;
			}
			count >>= 1;	/* nr of 64-bit words.. */
			if (count) {
				unsigned long carry = 0;
				do {
					unsigned long w = *(unsigned long *) buff;
					count--;
					buff += 8;
					result += carry;
					result += w;
					carry = (w > result);
				} while (count);
				result += carry;
				result = (result & 0xffffffff) + (result >> 32);
			}
			if (len & 4) {
				result += *(unsigned int *) buff;
				buff += 4;
			}
		}
		if (len & 2) {
			result += *(unsigned short *) buff;
			buff += 2;
		}
	}
	if (len & 1)
		result += *buff;

	result = from64to16(result);

	if (odd)
		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);

out:
	return result;
}

/*
 * XXX Fixme
 *
 * This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS.
 * But it's very tricky to get right even in C.
 */
extern unsigned long do_csum(const unsigned char *, long);

__wsum
csum_partial_copy_from_user(const void __user *src, void *dst,
				int len, __wsum psum, int *errp)
{
	unsigned long result;

	/* XXX Fixme
	 * for now we separate the copy from checksum for obvious
	 * alignment difficulties. Look at the Alpha code and you'll be
	 * scared.
	 */

	if (__copy_from_user(dst, src, len) != 0 && errp)
		*errp = -EFAULT;

	result = do_csum(dst, len);

	/* add in old sum, and carry.. */
	result += (__force u32)psum;
	/* 32+c bits -> 32 bits */
	result = (result & 0xffffffff) + (result >> 32);
	return (__force __wsum)result;
}

EXPORT_SYMBOL(csum_partial_copy_from_user);

__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{
	return csum_partial_copy_from_user((__force const void __user *)src,
					   dst, len, sum, NULL);
}

EXPORT_SYMBOL(csum_partial_copy_nocheck);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Network Checksum & Copy routine
	3	*
	4	* Copyright (C) 1999, 2003-2004 Hewlett-Packard Co
	5	* Stephane Eranian <eranian@hpl.hp.com>
	6	*
	7	* Most of the code has been imported from Linux/Alpha
	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/types.h>
	12	#include <linux/string.h>
	13
7c0f6ba6	14	#include <linux/uaccess.h>
1da177e4 LT	15
	16	/*
	17	* XXX Fixme: those 2 inlines are meant for debugging and will go away
	18	*/
	19	static inline unsigned
	20	short from64to16(unsigned long x)
	21	{
	22	/* add up 32-bit words for 33 bits */
	23	x = (x & 0xffffffff) + (x >> 32);
	24	/* add up 16-bit and 17-bit words for 17+c bits */
	25	x = (x & 0xffff) + (x >> 16);
	26	/* add up 16-bit and 2-bit for 16+c bit */
	27	x = (x & 0xffff) + (x >> 16);
	28	/* add up carry.. */
	29	x = (x & 0xffff) + (x >> 16);
	30	return x;
	31	}
	32
	33	static inline
	34	unsigned long do_csum_c(const unsigned char * buff, int len, unsigned int psum)
	35	{
	36	int odd, count;
	37	unsigned long result = (unsigned long)psum;
	38
	39	if (len <= 0)
	40	goto out;
	41	odd = 1 & (unsigned long) buff;
	42	if (odd) {
	43	result = *buff << 8;
	44	len--;
	45	buff++;
	46	}
	47	count = len >> 1; /* nr of 16-bit words.. */
	48	if (count) {
	49	if (2 & (unsigned long) buff) {
	50	result += (unsigned short ) buff;
	51	count--;
	52	len -= 2;
	53	buff += 2;
	54	}
	55	count >>= 1; /* nr of 32-bit words.. */
	56	if (count) {
	57	if (4 & (unsigned long) buff) {
	58	result += (unsigned int ) buff;
	59	count--;
	60	len -= 4;
	61	buff += 4;
	62	}
	63	count >>= 1; /* nr of 64-bit words.. */
	64	if (count) {
	65	unsigned long carry = 0;
	66	do {
	67	unsigned long w = (unsigned long ) buff;
	68	count--;
	69	buff += 8;
	70	result += carry;
	71	result += w;
	72	carry = (w > result);
	73	} while (count);
	74	result += carry;
	75	result = (result & 0xffffffff) + (result >> 32);
	76	}
	77	if (len & 4) {
	78	result += (unsigned int ) buff;
79	buff += 4;
80	}
81	}
82	if (len & 2) {
83	result += (unsigned short ) buff;
84	buff += 2;
85	}
86	}
87	if (len & 1)
88	result += *buff;
89
90	result = from64to16(result);
91
92	if (odd)
93	result = ((result >> 8) & 0xff) \| ((result & 0xff) << 8);
94
95	out:
96	return result;
97	}
98
99	/*
100	* XXX Fixme
101	*
102	* This is very ugly but temporary. THIS NEEDS SERIOUS ENHANCEMENTS.
103	* But it's very tricky to get right even in C.
104	*/
105	extern unsigned long do_csum(const unsigned char *, long);
106
32252996 AV	107	__wsum
	108	csum_partial_copy_from_user(const void __user src, void dst,
	109	int len, __wsum psum, int *errp)
1da177e4 LT	110	{
	111	unsigned long result;
	112
	113	/* XXX Fixme
	114	* for now we separate the copy from checksum for obvious
	115	* alignment difficulties. Look at the Alpha code and you'll be
	116	* scared.
	117	*/
	118
	119	if (__copy_from_user(dst, src, len) != 0 && errp)
	120	*errp = -EFAULT;
	121
	122	result = do_csum(dst, len);
	123
	124	/* add in old sum, and carry.. */
32252996	125	result += (__force u32)psum;
1da177e4 LT	126	/* 32+c bits -> 32 bits */
1da177e4 LT	127	result = (result & 0xffffffff) + (result >> 32);
32252996	128	return (__force __wsum)result;
1da177e4 LT	129	}
1da177e4 LT	130
b1bdb691 DH	131	EXPORT_SYMBOL(csum_partial_copy_from_user);
b1bdb691 DH	132
32252996 AV	133	__wsum
32252996 AV	134	csum_partial_copy_nocheck(const void src, void dst, int len, __wsum sum)
1da177e4	135	{
32252996 AV	136	return csum_partial_copy_from_user((__force const void __user *)src,
32252996 AV	137	dst, len, sum, NULL);
1da177e4 LT	138	}
	139
	140	EXPORT_SYMBOL(csum_partial_copy_nocheck);