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/arch/parisc/lib/checksum.c

https://github.com/aicjofs/android_kernel_lge_v500_20d_f2fs
C | 149 lines | 102 code | 12 blank | 35 comment | 11 complexity | f988b6817a155e2dc2d17c9885d364e0 MD5 | raw file
  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 *		MIPS specific IP/TCP/UDP checksumming routines
  7 *
  8 * Authors:	Ralf Baechle, <ralf@waldorf-gmbh.de>
  9 *		Lots of code moved from tcp.c and ip.c; see those files
 10 *		for more names.
 11 *
 12 *		This program is free software; you can redistribute it and/or
 13 *		modify it under the terms of the GNU General Public License
 14 *		as published by the Free Software Foundation; either version
 15 *		2 of the License, or (at your option) any later version.
 16 */
 17#include <linux/module.h>
 18#include <linux/types.h>
 19
 20#include <net/checksum.h>
 21#include <asm/byteorder.h>
 22#include <asm/string.h>
 23#include <asm/uaccess.h>
 24
 25#define addc(_t,_r)                     \
 26	__asm__ __volatile__ (          \
 27"       add             %0, %1, %0\n"   \
 28"       addc            %0, %%r0, %0\n" \
 29	: "=r"(_t)                      \
 30	: "r"(_r), "0"(_t));
 31
 32static inline unsigned short from32to16(unsigned int x)
 33{
 34	/* 32 bits --> 16 bits + carry */
 35	x = (x & 0xffff) + (x >> 16);
 36	/* 16 bits + carry --> 16 bits including carry */
 37	x = (x & 0xffff) + (x >> 16);
 38	return (unsigned short)x;
 39}
 40
 41static inline unsigned int do_csum(const unsigned char * buff, int len)
 42{
 43	int odd, count;
 44	unsigned int result = 0;
 45
 46	if (len <= 0)
 47		goto out;
 48	odd = 1 & (unsigned long) buff;
 49	if (odd) {
 50		result = be16_to_cpu(*buff);
 51		len--;
 52		buff++;
 53	}
 54	count = len >> 1;		/* nr of 16-bit words.. */
 55	if (count) {
 56		if (2 & (unsigned long) buff) {
 57			result += *(unsigned short *) buff;
 58			count--;
 59			len -= 2;
 60			buff += 2;
 61		}
 62		count >>= 1;		/* nr of 32-bit words.. */
 63		if (count) {
 64			while (count >= 4) {
 65				unsigned int r1, r2, r3, r4;
 66				r1 = *(unsigned int *)(buff + 0);
 67				r2 = *(unsigned int *)(buff + 4);
 68				r3 = *(unsigned int *)(buff + 8);
 69				r4 = *(unsigned int *)(buff + 12);
 70				addc(result, r1);
 71				addc(result, r2);
 72				addc(result, r3);
 73				addc(result, r4);
 74				count -= 4;
 75				buff += 16;
 76			}
 77			while (count) {
 78				unsigned int w = *(unsigned int *) buff;
 79				count--;
 80				buff += 4;
 81				addc(result, w);
 82			}
 83			result = (result & 0xffff) + (result >> 16);
 84		}
 85		if (len & 2) {
 86			result += *(unsigned short *) buff;
 87			buff += 2;
 88		}
 89	}
 90	if (len & 1)
 91		result += le16_to_cpu(*buff);
 92	result = from32to16(result);
 93	if (odd)
 94		result = swab16(result);
 95out:
 96	return result;
 97}
 98
 99/*
100 * computes a partial checksum, e.g. for TCP/UDP fragments
101 */
102/*
103 * why bother folding?
104 */
105__wsum csum_partial(const void *buff, int len, __wsum sum)
106{
107	unsigned int result = do_csum(buff, len);
108	addc(result, sum);
109	return (__force __wsum)from32to16(result);
110}
111
112EXPORT_SYMBOL(csum_partial);
113
114/*
115 * copy while checksumming, otherwise like csum_partial
116 */
117__wsum csum_partial_copy_nocheck(const void *src, void *dst,
118				       int len, __wsum sum)
119{
120	/*
121	 * It's 2:30 am and I don't feel like doing it real ...
122	 * This is lots slower than the real thing (tm)
123	 */
124	sum = csum_partial(src, len, sum);
125	memcpy(dst, src, len);
126
127	return sum;
128}
129EXPORT_SYMBOL(csum_partial_copy_nocheck);
130
131/*
132 * Copy from userspace and compute checksum.  If we catch an exception
133 * then zero the rest of the buffer.
134 */
135__wsum csum_partial_copy_from_user(const void __user *src,
136					void *dst, int len,
137					__wsum sum, int *err_ptr)
138{
139	int missing;
140
141	missing = copy_from_user(dst, src, len);
142	if (missing) {
143		memset(dst + len - missing, 0, missing);
144		*err_ptr = -EFAULT;
145	}
146		
147	return csum_partial(dst, len, sum);
148}
149EXPORT_SYMBOL(csum_partial_copy_from_user);