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/*
* 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.
*
* 1998/8/31 Andreas Schwab:
* Zero out rest of buffer on exception in
* csum_partial_copy_from_user.
*/
#include <net/checksum.h>
/*
* computes a partial checksum, e.g. for TCP/UDP fragments
*/
unsigned int
csum_partial (const unsigned char *buff, int len, unsigned int sum)
{
unsigned long tmp1, tmp2;
/*
* Experiments with ethernet and slip connections show that buff
* is aligned on either a 2-byte or 4-byte boundary.
*/
__asm__("movel %2,%3\n\t"
"btst #1,%3\n\t" /* Check alignment */
"jeq 2f\n\t"
"subql #2,%1\n\t" /* buff%4==2: treat first word */
"jgt 1f\n\t"
"addql #2,%1\n\t" /* len was == 2, treat only rest */
"jra 4f\n"
"1:\t"
"addw %2@+,%0\n\t" /* add first word to sum */
"clrl %3\n\t"
"addxl %3,%0\n" /* add X bit */
"2:\t"
/* unrolled loop for the main part: do 8 longs at once */
"movel %1,%3\n\t" /* save len in tmp1 */
"lsrl #5,%1\n\t" /* len/32 */
"jeq 2f\n\t" /* not enough... */
"subql #1,%1\n"
"1:\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"dbra %1,1b\n\t"
"clrl %4\n\t"
"addxl %4,%0\n\t" /* add X bit */
"clrw %1\n\t"
"subql #1,%1\n\t"
"jcc 1b\n"
"2:\t"
"movel %3,%1\n\t" /* restore len from tmp1 */
"andw #0x1c,%3\n\t" /* number of rest longs */
"jeq 4f\n\t"
"lsrw #2,%3\n\t"
"subqw #1,%3\n"
"3:\t"
/* loop for rest longs */
"movel %2@+,%4\n\t"
"addxl %4,%0\n\t"
"dbra %3,3b\n\t"
"clrl %4\n\t"
"addxl %4,%0\n" /* add X bit */
"4:\t"
/* now check for rest bytes that do not fit into longs */
"andw #3,%1\n\t"
"jeq 7f\n\t"
"clrl %4\n\t" /* clear tmp2 for rest bytes */
"subqw #2,%1\n\t"
"jlt 5f\n\t"
"movew %2@+,%4\n\t" /* have rest >= 2: get word */
"swap %4\n\t" /* into bits 16..31 */
"tstw %1\n\t" /* another byte? */
"jeq 6f\n"
"5:\t"
"moveb %2@,%4\n\t" /* have odd rest: get byte */
"lslw #8,%4\n\t" /* into bits 8..15; 16..31 untouched */
"6:\t"
"addl %4,%0\n\t" /* now add rest long to sum */
"clrl %4\n\t"
"addxl %4,%0\n" /* add X bit */
"7:\t"
: "=d" (sum), "=d" (len), "=a" (buff),
"=&d" (tmp1), "=&d" (tmp2)
: "0" (sum), "1" (len), "2" (buff)
);
return(sum);
}
/*
* copy from user space while checksumming, with exception handling.
*/
unsigned int
csum_partial_copy_from_user(const char *src, char *dst, int len,
int sum, int *csum_err)
{
/*
* GCC doesn't like more than 10 operands for the asm
* statements so we have to use tmp2 for the error
* code.
*/
unsigned long tmp1, tmp2;
__asm__("movel %2,%4\n\t"
"btst #1,%4\n\t" /* Check alignment */
"jeq 2f\n\t"
"subql #2,%1\n\t" /* buff%4==2: treat first word */
"jgt 1f\n\t"
"addql #2,%1\n\t" /* len was == 2, treat only rest */
"jra 4f\n"
"1:\n"
"10:\t"
"movesw %2@+,%4\n\t" /* add first word to sum */
"addw %4,%0\n\t"
"movew %4,%3@+\n\t"
"clrl %4\n\t"
"addxl %4,%0\n" /* add X bit */
"2:\t"
/* unrolled loop for the main part: do 8 longs at once */
"movel %1,%4\n\t" /* save len in tmp1 */
"lsrl #5,%1\n\t" /* len/32 */
"jeq 2f\n\t" /* not enough... */
"subql #1,%1\n"
"1:\n"
"11:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"12:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"13:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"14:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"15:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"16:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"17:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"18:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"dbra %1,1b\n\t"
"clrl %5\n\t"
"addxl %5,%0\n\t" /* add X bit */
"clrw %1\n\t"
"subql #1,%1\n\t"
"jcc 1b\n"
"2:\t"
"movel %4,%1\n\t" /* restore len from tmp1 */
"andw #0x1c,%4\n\t" /* number of rest longs */
"jeq 4f\n\t"
"lsrw #2,%4\n\t"
"subqw #1,%4\n"
"3:\n"
/* loop for rest longs */
"19:\t"
"movesl %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"dbra %4,3b\n\t"
"clrl %5\n\t"
"addxl %5,%0\n" /* add X bit */
"4:\t"
/* now check for rest bytes that do not fit into longs */
"andw #3,%1\n\t"
"jeq 7f\n\t"
"clrl %5\n\t" /* clear tmp2 for rest bytes */
"subqw #2,%1\n\t"
"jlt 5f\n\t"
"20:\t"
"movesw %2@+,%5\n\t" /* have rest >= 2: get word */
"movew %5,%3@+\n\t"
"swap %5\n\t" /* into bits 16..31 */
"tstw %1\n\t" /* another byte? */
"jeq 6f\n"
"5:\n"
"21:\t"
"movesb %2@,%5\n\t" /* have odd rest: get byte */
"moveb %5,%3@+\n\t"
"lslw #8,%5\n\t" /* into bits 8..15; 16..31 untouched */
"6:\t"
"addl %5,%0\n\t" /* now add rest long to sum */
"clrl %5\n\t"
"addxl %5,%0\n\t" /* add X bit */
"7:\t"
"clrl %5\n" /* no error - clear return value */
"8:\n"
".section .fixup,\"ax\"\n"
".even\n"
/* If any execption occurs zero out the rest.
Similarities with the code above are intentional :-) */
"90:\t"
"clrw %3@+\n\t"
"movel %1,%4\n\t"
"lsrl #5,%1\n\t"
"jeq 1f\n\t"
"subql #1,%1\n"
"91:\t"
"clrl %3@+\n"
"92:\t"
"clrl %3@+\n"
"93:\t"
"clrl %3@+\n"
"94:\t"
"clrl %3@+\n"
"95:\t"
"clrl %3@+\n"
"96:\t"
"clrl %3@+\n"
"97:\t"
"clrl %3@+\n"
"98:\t"
"clrl %3@+\n\t"
"dbra %1,91b\n\t"
"clrw %1\n\t"
"subql #1,%1\n\t"
"jcc 91b\n"
"1:\t"
"movel %4,%1\n\t"
"andw #0x1c,%4\n\t"
"jeq 1f\n\t"
"lsrw #2,%4\n\t"
"subqw #1,%4\n"
"99:\t"
"clrl %3@+\n\t"
"dbra %4,99b\n\t"
"1:\t"
"andw #3,%1\n\t"
"jeq 9f\n"
"100:\t"
"clrw %3@+\n\t"
"tstw %1\n\t"
"jeq 9f\n"
"101:\t"
"clrb %3@+\n"
"9:\t"
#define STR(X) STR1(X)
#define STR1(X) #X
"moveq #-" STR(EFAULT) ",%5\n\t"
"jra 8b\n"
".previous\n"
".section __ex_table,\"a\"\n"
".long 10b,90b\n"
".long 11b,91b\n"
".long 12b,92b\n"
".long 13b,93b\n"
".long 14b,94b\n"
".long 15b,95b\n"
".long 16b,96b\n"
".long 17b,97b\n"
".long 18b,98b\n"
".long 19b,99b\n"
".long 20b,100b\n"
".long 21b,101b\n"
".previous"
: "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
"=&d" (tmp1), "=d" (tmp2)
: "0" (sum), "1" (len), "2" (src), "3" (dst)
);
*csum_err = tmp2;
return(sum);
}
/*
* copy from kernel space while checksumming, otherwise like csum_partial
*/
unsigned int
csum_partial_copy(const char *src, char *dst, int len, int sum)
{
unsigned long tmp1, tmp2;
__asm__("movel %2,%4\n\t"
"btst #1,%4\n\t" /* Check alignment */
"jeq 2f\n\t"
"subql #2,%1\n\t" /* buff%4==2: treat first word */
"jgt 1f\n\t"
"addql #2,%1\n\t" /* len was == 2, treat only rest */
"jra 4f\n"
"1:\t"
"movew %2@+,%4\n\t" /* add first word to sum */
"addw %4,%0\n\t"
"movew %4,%3@+\n\t"
"clrl %4\n\t"
"addxl %4,%0\n" /* add X bit */
"2:\t"
/* unrolled loop for the main part: do 8 longs at once */
"movel %1,%4\n\t" /* save len in tmp1 */
"lsrl #5,%1\n\t" /* len/32 */
"jeq 2f\n\t" /* not enough... */
"subql #1,%1\n"
"1:\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"dbra %1,1b\n\t"
"clrl %5\n\t"
"addxl %5,%0\n\t" /* add X bit */
"clrw %1\n\t"
"subql #1,%1\n\t"
"jcc 1b\n"
"2:\t"
"movel %4,%1\n\t" /* restore len from tmp1 */
"andw #0x1c,%4\n\t" /* number of rest longs */
"jeq 4f\n\t"
"lsrw #2,%4\n\t"
"subqw #1,%4\n"
"3:\t"
/* loop for rest longs */
"movel %2@+,%5\n\t"
"addxl %5,%0\n\t"
"movel %5,%3@+\n\t"
"dbra %4,3b\n\t"
"clrl %5\n\t"
"addxl %5,%0\n" /* add X bit */
"4:\t"
/* now check for rest bytes that do not fit into longs */
"andw #3,%1\n\t"
"jeq 7f\n\t"
"clrl %5\n\t" /* clear tmp2 for rest bytes */
"subqw #2,%1\n\t"
"jlt 5f\n\t"
"movew %2@+,%5\n\t" /* have rest >= 2: get word */
"movew %5,%3@+\n\t"
"swap %5\n\t" /* into bits 16..31 */
"tstw %1\n\t" /* another byte? */
"jeq 6f\n"
"5:\t"
"moveb %2@,%5\n\t" /* have odd rest: get byte */
"moveb %5,%3@+\n\t"
"lslw #8,%5\n" /* into bits 8..15; 16..31 untouched */
"6:\t"
"addl %5,%0\n\t" /* now add rest long to sum */
"clrl %5\n\t"
"addxl %5,%0\n" /* add X bit */
"7:\t"
: "=d" (sum), "=d" (len), "=a" (src), "=a" (dst),
"=&d" (tmp1), "=&d" (tmp2)
: "0" (sum), "1" (len), "2" (src), "3" (dst)
);
return(sum);
}
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