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/*

 * csum_partial_copy - do IP checksumming and copy

 *

 * (C) Copyright 1996 Linus Torvalds

 *

 * Don't look at this too closely - you'll go mad. The things

 * we do for performance..

 */

#define ldq_u(x,y) \

__asm__ __volatile__("ldq_u %0,%1":"=r" (x):"m" (*(unsigned long *)(y)))

#define stq_u(x,y) \

__asm__ __volatile__("stq_u %1,%0":"=m" (*(unsigned long *)(y)):"r" (x))

#define extql(x,y,z) \

__asm__ __volatile__("extql %1,%2,%0":"=r" (z):"r" (x),"r" (y))

#define extqh(x,y,z) \

__asm__ __volatile__("extqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))

#define mskql(x,y,z) \

__asm__ __volatile__("mskql %1,%2,%0":"=r" (z):"r" (x),"r" (y))

#define mskqh(x,y,z) \

__asm__ __volatile__("mskqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))

#define insql(x,y,z) \

__asm__ __volatile__("insql %1,%2,%0":"=r" (z):"r" (x),"r" (y))

#define insqh(x,y,z) \

__asm__ __volatile__("insqh %1,%2,%0":"=r" (z):"r" (x),"r" (y))

/*

 * Ok. This isn't fun, but this is the EASY case.

 */

static inline unsigned long csum_partial_copy_aligned(

        unsigned long *src, unsigned long *dst,

        long len, unsigned long checksum)

{

        unsigned long carry = 0;

        while (len >= 0) {

                unsigned long word = *src;

                checksum += carry;

                src++;

                checksum += word;

                len -= 8;

                carry = checksum < word;

                *dst = word;

                dst++;

        }

        len += 8;

        checksum += carry;

        if (len) {

                unsigned long word, tmp;

                word = *src;

                tmp = *dst;

                mskql(word, len, word);

                checksum += word;

                mskqh(tmp, len, tmp);

                carry = checksum < word;

                *dst = word | tmp;

                checksum += carry;

        }

        return checksum;

}

/*

 * This is even less fun, but this is still reasonably

 * easy.

 */

static inline unsigned long csum_partial_copy_dest_aligned(

        unsigned long *src, unsigned long *dst,

        unsigned long soff,

        long len, unsigned long checksum)

{

        unsigned long first;

        unsigned long word, carry;

        unsigned long lastsrc = 7+len+(unsigned long)src;

        ldq_u(first,src);

        carry = 0;

        while (len >= 0) {

                unsigned long second;

                ldq_u(second, src+1);

                extql(first, soff, word);

                len -= 8;

                src++;

                extqh(second, soff, first);

                checksum += carry;

                word |= first;

                first = second;

                checksum += word;

                *dst = word;

                dst++;

                carry = checksum < word;

        }

        len += 8;

        checksum += carry;

        if (len) {

                unsigned long tmp;

                unsigned long second;

                ldq_u(second, lastsrc);

                tmp = *dst;

                extql(first, soff, word);

                extqh(second, soff, first);

                word |= first;

                mskql(word, len, word);

                checksum += word;

                mskqh(tmp, len, tmp);

                carry = checksum < word;

                *dst = word | tmp;

                checksum += carry;

        }

        return checksum;

}

/*

 * This is slightly less fun than the above..

 */

static inline unsigned long csum_partial_copy_src_aligned(

        unsigned long *src, unsigned long *dst,

        unsigned long doff,

        long len, unsigned long checksum,

        unsigned long partial_dest)

{

        unsigned long carry = 0;

        unsigned long word;

        mskql(partial_dest, doff, partial_dest);

        while (len >= 0) {

                unsigned long second_dest;

                word = *src;

                len -= 8;

                insql(word, doff, second_dest);

                checksum += carry;

                stq_u(partial_dest | second_dest, dst);

                src++;

                checksum += word;

                insqh(word, doff, partial_dest);

                carry = checksum < word;

                dst++;

        }

        len += doff;

        checksum += carry;

        if (len >= 0) {

                unsigned long second_dest;

                word = *src;

                mskql(word, len-doff, word);

                checksum += word;

                insql(word, doff, second_dest);

                stq_u(partial_dest | second_dest, dst);

                carry = checksum < word;

                if (len) {

                        ldq_u(second_dest, dst+1);

                        insqh(word, doff, partial_dest);

                        mskqh(second_dest, len, second_dest);

                        stq_u(partial_dest | second_dest, dst+1);

                }

                checksum += carry;

        } else if (len & 7) {

                unsigned long second_dest;

                word = *src;

                ldq_u(second_dest, dst);

                mskql(word, len-doff, word);

                checksum += word;

                mskqh(second_dest, len, second_dest);

                carry = checksum < word;

                insql(word, doff, word);

                stq_u(partial_dest | word | second_dest, dst);

                checksum += carry;

        }

        return checksum;

}

/*

 * This is so totally un-fun that it's frightening. Don't

 * look at this too closely, you'll go blind.

 */

static inline unsigned long csum_partial_copy_unaligned(

        unsigned long * src, unsigned long * dst,

        unsigned long soff, unsigned long doff,

        long len, unsigned long checksum,

        unsigned long partial_dest)

{

        unsigned long carry = 0;

        unsigned long first;

        unsigned long lastsrc;

        ldq_u(first, src);

        lastsrc = 7+len+(unsigned long)src;

        mskql(partial_dest, doff, partial_dest);

        while (len >= 0) {

                unsigned long second, word;

                unsigned long second_dest;

                ldq_u(second, src+1);

                extql(first, soff, word);

                checksum += carry;

                len -= 8;

                extqh(second, soff, first);

                src++;

                word |= first;

                first = second;

                insql(word, doff, second_dest);

                checksum += word;

                stq_u(partial_dest | second_dest, dst);

                carry = checksum < word;

                insqh(word, doff, partial_dest);

                dst++;

        }

        len += doff;

        checksum += carry;

        if (len >= 0) {

                unsigned long second, word;

                unsigned long second_dest;

                ldq_u(second, lastsrc);

                extql(first, soff, word);

                extqh(second, soff, first);

                word |= first;

                first = second;

                mskql(word, len-doff, word);

                checksum += word;

                insql(word, doff, second_dest);

                carry = checksum < word;

                stq_u(partial_dest | second_dest, dst);

                if (len) {

                        ldq_u(second_dest, dst+1);

                        insqh(word, doff, partial_dest);

                        mskqh(second_dest, len, second_dest);

                        stq_u(partial_dest | second_dest, dst+1);

                }

                checksum += carry;

        } else if (len & 7) {

                unsigned long second, word;

                unsigned long second_dest;

                ldq_u(second, lastsrc);

                extql(first, soff, word);

                extqh(second, soff, first);

                word |= first;

                ldq_u(second_dest, dst);

                mskql(word, len-doff, word);

                checksum += word;

                mskqh(second_dest, len, second_dest);

                carry = checksum < word;

                insql(word, doff, word);

                stq_u(partial_dest | word | second_dest, dst);

                checksum += carry;

        }

        return checksum;

}

unsigned int csum_partial_copy(char *src, char *dst, int len, int sum)

{

        unsigned long checksum = (unsigned) sum;

        unsigned long soff = 7 & (unsigned long) src;

        unsigned long doff = 7 & (unsigned long) dst;

        if (len) {

                if (!doff) {

                        if (!soff)

                                checksum = csum_partial_copy_aligned(

                                        (unsigned long *) src,

                                        (unsigned long *) dst,

                                        len-8, checksum);

                        else

                                checksum = csum_partial_copy_dest_aligned(

                                        (unsigned long *) src,

                                        (unsigned long *) dst,

                                        soff, len-8, checksum);

                } else {

                        unsigned long partial_dest;

                        ldq_u(partial_dest, dst);

                        if (!soff)

                                checksum = csum_partial_copy_src_aligned(

                                        (unsigned long *) src,

                                        (unsigned long *) dst,

                                        doff, len-8, checksum,

                                        partial_dest);

                        else

                                checksum = csum_partial_copy_unaligned(

                                        (unsigned long *) src,

                                        (unsigned long *) dst,

                                        soff, doff, len-8, checksum,

                                        partial_dest);

                }

                /* 64 -> 33 bits */

                checksum = (checksum & 0xffffffff) + (checksum >> 32);

                /* 33 -> < 32 bits */

                checksum = (checksum & 0xffff) + (checksum >> 16);

                /* 32 -> 16 bits */

                checksum = (checksum & 0xffff) + (checksum >> 16);

                checksum = (checksum & 0xffff) + (checksum >> 16);

        }

        return checksum;

}