/*
 *
 * IP checksum routines
 *
 * Copyright (C) Original authors of ../asm-i386/checksum.h
 * Copyright (C) 1996-1999 Russell King
 */

#include <net/checksum.h>

unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum);

/*
 *	This is a version of ip_compute_csum() optimized for IP headers,
 *	which always checksum on 4 octet boundaries.
 */
unsigned short ip_fast_csum(unsigned char * iph, unsigned int ihl)
{
	unsigned int sum, tmp1;

	
	__asm__ __volatile__(
	"	mov		%1, %%r2\n\t"
	"	ld		(%%r2, 0), %0\n\t"
	"	add		%%r2, 4, %%r2\n\t"
	"	ld		(%%r2, 0), %3\n\t"
	"	add		%%r2, 4, %%r2\n\t"
	"	sub		%2, 5, %2\n\t"
	"	add		%0, %3, %0\n\t"
	"	adc		%0, 0, %0\n\t"
	"	ld		(%%r2, 0), %3\n\t"
	"	add		%%r2, 4, %%r2\n\t"
	"	add		%0, %3, %0\n\t"
	"	adc		%0, 0, %0\n\t"
	"	ld		(%%r2, 0), %3\n\t"
	"	add		%%r2, 4, %%r2\n\t"
	"	add		%0, %3, %0\n\t"
	"	adc		%0, 0, %0\n\t"
	"1:	ld		(%%r2, 0), %3\n\t"
	"	add		%%r2, 4, %%r2\n\t"
	"	add		%0, %3, %0\n\t"
	"	adc		%0, 0, %0\n\t"
	"	tst		%2, 15\n\t"
	"	jz		2f\n\t"
	"	sub		%2, 1, %2\n\t"
	"	jmp		1b\n\t"
	"2:	mov		%0, %3\n\t"
	"	asl		16, %3\n\t"
	"	add		%0, %3, %0\n\t"
	"	jnc		3f\n\t"
	"	add		%0, 0x10000, %0\n\t"
	"3:	xor		%0, 0xFFFFFFFF, %0\n\t"
	"	lsr		16, %0\n\t"
	: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
	: "1" (iph), "2" (ihl)
	: "%r2" );
	
	return sum;
}

/*
 * 	Fold a partial checksum without adding pseudo headers
 */
unsigned int csum_fold(unsigned int sum)
{
	__asm__ __volatile__(
	"	mov		%0, %%r2\n\t"
	"	asl		16, %%r2\n\t"
	"	add		%%r2, %0, %0\n\t"
	"	jnc		1f\n\t"
	"	add		%0, 0x10000, %0\n\t"
	"1:	\n\t"
	: "=r" (sum)
	: "0" (sum)
	: "%r2" );

	return (~sum) >> 16;
}

unsigned int csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr, unsigned short len,
		   unsigned int proto, unsigned int sum)
{
	__asm__ __volatile__(
	"	add		%0, %2, %0\n\t"
	"	adc		%0, %3, %0\n\t"
	"	adc		%0, %4, %0\n\t"
	"	adc		%0, %5, %0\n\t"
	"	adc		%0, 0, %0\n\t"
	: "=&r"(sum)
	: "0" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len) << 16), "r" (proto << 8)
	);

	return sum;
}	

/*
 * computes the checksum of the TCP/UDP pseudo-header
 * returns a 16-bit checksum, already complemented
 */
unsigned short int
csum_tcpudp_magic(unsigned long saddr, unsigned long daddr, unsigned short len,
		  unsigned int proto, unsigned int sum)
{
	__asm__ __volatile__(
	"	add		%0, %2, %0\n\t"
	"	adc		%0, %3, %0\n\t"
	"	adc		%0, %4, %0\n\t"
	"	adc		%0, %5, %0\n\t"
	"	adc		%0, 0, %0\n\t"
	"	mov		%0, %%r2\n\t"
	"	asl		16, %%r2\n\t"
	"	add		%%r2, %0, %0\n\t"
	"	jnc		1f\n\t"
	"	add		%0, 0x10000, %0\n\t"
	"1:	xor		%0, 0xFFFFFFFF, %0\n\t"
	: "=&r"(sum)
	: "0" (sum), "r" (daddr), "r" (saddr), "r" (ntohs(len)<<16), "r" (proto << 8)
	: "%r2");

	return sum >> 16;
}

unsigned short int ip_compute_csum(unsigned char *buff,int len)
{
	return csum_fold(csum_partial(buff,len,0));
}

/* by lbh 2003/03/05  */