checksum.h

Boot code for ADM5120 with serial console for Edimax router.

/*****************************************************************************
;
;   (C) Unpublished Work of ADMtek Incorporated.  All Rights Reserved.
;
;       THIS WORK IS AN UNPUBLISHED WORK AND CONTAINS CONFIDENTIAL,
;       PROPRIETARY AND TRADESECRET INFORMATION OF ADMTEK INCORPORATED.
;       ACCESS TO THIS WORK IS RESTRICTED TO (I) ADMTEK EMPLOYEES WHO HAVE A
;       NEED TO KNOW TO PERFORM TASKS WITHIN THE SCOPE OF THEIR ASSIGNMENTS
;       AND (II) ENTITIES OTHER THAN ADMTEK WHO HAVE ENTERED INTO APPROPRIATE
;       LICENSE AGREEMENTS.  NO PART OF THIS WORK MAY BE USED, PRACTICED,
;       PERFORMED, COPIED, DISTRIBUTED, REVISED, MODIFIED, TRANSLATED,
;       ABBRIDGED, CONDENSED, EXPANDED, COLLECTED, COMPILED, LINKED, RECAST,
;       TRANSFORMED OR ADAPTED WITHOUT THE PRIOR WRITTEN CONSENT OF ADMTEK.
;       ANY USE OR EXPLOITATION OF THIS WORK WITHOUT AUTHORIZATION COULD
;       SUBJECT THE PERPERTRATOR TO CRIMINAL AND CIVIL LIABILITY.
;
;------------------------------------------------------------------------------
;
;    Project : Common Plateform
;    Creator : 
;    File    : checksum.h
;    Abstract: defines the specific items that loader nedded.
;
;Modification History:
;       By              Date     Ver.   Modification Description
;       --------------- -------- -----  --------------------------------------
;
;*****************************************************************************/
#include <asm.h>
/*
 *	Fold a partial checksum without adding pseudo headers
 */
static inline unsigned short int csum_fold(unsigned int sum)
{
	__asm__(
	".set\tnoat\t\t\t# csum_fold\n\t"
	"sll\t$1,%0,16\n\t"
	"addu\t%0,$1\n\t"
	"sltu\t$1,%0,$1\n\t"
	"srl\t%0,%0,16\n\t"
	"addu\t%0,$1\n\t"
	"xori\t%0,0xffff\n\t"
	".set\tat"
	: "=r" (sum)
	: "0" (sum));

	return sum;
}
 
/*
 *	This is a version of ip_compute_csum() optimized for IP headers,
 *	which always checksum on 4 octet boundaries.
 *
 *	By Jorge Cwik <[e-mail]>, adapted for linux by
 *	Arnt Gulbrandsen.
 */
static inline unsigned short ip_fast_csum(unsigned char *iph,
					  unsigned int ihl)
{
	unsigned int sum;
	unsigned long dummy;

	/*
	 * This is for 32-bit MIPS processors.
	 */
	__asm__ __volatile__(
	".set\tnoreorder\t\t\t# ip_fast_csum\n\t"
	".set\tnoat\n\t"
	"lw\t%0, (%1)\n\t"
	"subu\t%2, 4\n\t"
	"#blez\t%2, 2f\n\t"
	" sll\t%2, 2\n\t"
	"lw\t%3, 4(%1)\n\t"
	"addu\t%2, %1\n\t"
	"addu\t%0, %3\n\t"
	"sltu\t$1, %0, %3\n\t"
	"lw\t%3, 8(%1)\n\t"
	"addu\t%0, $1\n\t"
	"addu\t%0, %3\n\t"
	"sltu\t$1, %0, %3\n\t"
	"lw\t%3, 12(%1)\n\t"
	"addu\t%0, $1\n\t"
	"addu\t%0, %3\n\t"
	"sltu\t$1, %0, %3\n\t"
	"addu\t%0, $1\n"

	"1:\tlw\t%3, 16(%1)\n\t"
	"addiu\t%1, 4\n\t"
	"addu\t%0, %3\n\t"
	"sltu\t$1, %0, %3\n\t"
	"bne\t%2, %1, 1b\n\t"
	" addu\t%0, $1\n"

	"2:\t.set\tat\n\t"
	".set\treorder"
	: "=&r" (sum), "=&r" (iph), "=&r" (ihl), "=&r" (dummy)
	: "1" (iph), "2" (ihl));

	return csum_fold(sum);
}