/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from tahoe: in_cksum.c 1.2 86/01/05
* from: @(#)in_cksum.c 1.3 (Berkeley) 1/19/91
* $FreeBSD: src/sys/i386/i386/in_cksum.c,v 1.17.2.3 2002/07/02 04:03:00 jdp Exp $
* $DragonFly: src/sys/i386/i386/Attic/in_cksum.c,v 1.3 2003/07/26 19:07:47 rob Exp $
*/
#include
#include
#include
#include
#include
#include
#include
/*
* Checksum routine for Internet Protocol family headers.
*
* This routine is very heavily used in the network
* code and should be modified for each CPU to be as fast as possible.
*
* This implementation is 386 version.
*/
#undef ADDCARRY
#define ADDCARRY(x) if ((x) > 0xffff) (x) -= 0xffff
#define REDUCE {sum = (sum & 0xffff) + (sum >> 16); ADDCARRY(sum);}
/*
* These asm statements require __volatile because they pass information
* via the condition codes. GCC does not currently provide a way to specify
* the condition codes as an input or output operand.
*
* The LOAD macro below is effectively a prefetch into cache. GCC will
* load the value into a register but will not use it. Since modern CPUs
* reorder operations, this will generally take place in parallel with
* other calculations.
*/
#define ADD(n) __asm __volatile \
("addl %1, %0" : "+r" (sum) : \
"g" (((const u_int32_t *)w)[n / 4]))
#define ADDC(n) __asm __volatile \
("adcl %1, %0" : "+r" (sum) : \
"g" (((const u_int32_t *)w)[n / 4]))
#define LOAD(n) __asm __volatile \
("" : : "r" (((const u_int32_t *)w)[n / 4]))
#define MOP __asm __volatile \
("adcl $0, %0" : "+r" (sum))
int
in_cksum(m, len)
struct mbuf *m;
int len;
{
u_short *w;
unsigned sum = 0;
int mlen = 0;
int byte_swapped = 0;
union { char c[2]; u_short s; } su;
for (;m && len; m = m->m_next) {
if (m->m_len == 0)
continue;
w = mtod(m, u_short *);
if (mlen == -1) {
/*
* The first byte of this mbuf is the continuation
* of a word spanning between this mbuf and the
* last mbuf.
*/
/* su.c[0] is already saved when scanning previous
* mbuf. sum was REDUCEd when we found mlen == -1
*/
su.c[1] = *(u_char *)w;
sum += su.s;
w = (u_short *)((char *)w + 1);
mlen = m->m_len - 1;
len--;
} else
mlen = m->m_len;
if (len < mlen)
mlen = len;
len -= mlen;
/*
* Force to long boundary so we do longword aligned
* memory operations
*/
if (3 & (int) w) {
REDUCE;
if ((1 & (int) w) && (mlen > 0)) {
sum <<= 8;
su.c[0] = *(char *)w;
w = (u_short *)((char *)w + 1);
mlen--;
byte_swapped = 1;
}
if ((2 & (int) w) && (mlen >= 2)) {
sum += *w++;
mlen -= 2;
}
}
/*
* Advance to a 486 cache line boundary.
*/
if (4 & (int) w && mlen >= 4) {
ADD(0);
MOP;
w += 2;
mlen -= 4;
}
if (8 & (int) w && mlen >= 8) {
ADD(0);
ADDC(4);
MOP;
w += 4;
mlen -= 8;
}
/*
* Do as much of the checksum as possible 32 bits at at time.
* In fact, this loop is unrolled to make overhead from
* branches &c small.
*/
mlen -= 1;
while ((mlen -= 32) >= 0) {
/*
* Add with carry 16 words and fold in the last
* carry by adding a 0 with carry.
*
* The early ADD(16) and the LOAD(32) are to load
* the next 2 cache lines in advance on 486's. The
* 486 has a penalty of 2 clock cycles for loading
* a cache line, plus whatever time the external
* memory takes to load the first word(s) addressed.
* These penalties are unavoidable. Subsequent
* accesses to a cache line being loaded (and to
* other external memory?) are delayed until the
* whole load finishes. These penalties are mostly
* avoided by not accessing external memory for
* 8 cycles after the ADD(16) and 12 cycles after
* the LOAD(32). The loop terminates when mlen
* is initially 33 (not 32) to guaranteed that
* the LOAD(32) is within bounds.
*/
ADD(16);
ADDC(0);
ADDC(4);
ADDC(8);
ADDC(12);
LOAD(32);
ADDC(20);
ADDC(24);
ADDC(28);
MOP;
w += 16;
}
mlen += 32 + 1;
if (mlen >= 32) {
ADD(16);
ADDC(0);
ADDC(4);
ADDC(8);
ADDC(12);
ADDC(20);
ADDC(24);
ADDC(28);
MOP;
w += 16;
mlen -= 32;
}
if (mlen >= 16) {
ADD(0);
ADDC(4);
ADDC(8);
ADDC(12);
MOP;
w += 8;
mlen -= 16;
}
if (mlen >= 8) {
ADD(0);
ADDC(4);
MOP;
w += 4;
mlen -= 8;
}
if (mlen == 0 && byte_swapped == 0)
continue; /* worth 1% maybe ?? */
REDUCE;
while ((mlen -= 2) >= 0) {
sum += *w++;
}
if (byte_swapped) {
sum <<= 8;
byte_swapped = 0;
if (mlen == -1) {
su.c[1] = *(char *)w;
sum += su.s;
mlen = 0;
} else
mlen = -1;
} else if (mlen == -1)
/*
* This mbuf has odd number of bytes.
* There could be a word split betwen
* this mbuf and the next mbuf.
* Save the last byte (to prepend to next mbuf).
*/
su.c[0] = *(char *)w;
}
if (len)
printf("%s: out of data by %d\n", __func__, len);
if (mlen == -1) {
/* The last mbuf has odd # of bytes. Follow the
standard (the odd byte is shifted left by 8 bits) */
su.c[1] = 0;
sum += su.s;
}
REDUCE;
return (~sum & 0xffff);
}
u_short
in_cksum_skip(m, len, skip)
struct mbuf *m;
int len;
int skip;
{
u_short *w;
unsigned sum = 0;
int mlen = 0;
int byte_swapped = 0;
union { char c[2]; u_short s; } su;
len -= skip;
for (; skip && m; m = m->m_next) {
if (m->m_len > skip) {
mlen = m->m_len - skip;
w = (u_short *)(mtod(m, u_char *) + skip);
goto skip_start;
} else {
skip -= m->m_len;
}
}
for (;m && len; m = m->m_next) {
if (m->m_len == 0)
continue;
w = mtod(m, u_short *);
if (mlen == -1) {
/*
* The first byte of this mbuf is the continuation
* of a word spanning between this mbuf and the
* last mbuf.
*/
/* su.c[0] is already saved when scanning previous
* mbuf. sum was REDUCEd when we found mlen == -1
*/
su.c[1] = *(u_char *)w;
sum += su.s;
w = (u_short *)((char *)w + 1);
mlen = m->m_len - 1;
len--;
} else
mlen = m->m_len;
skip_start:
if (len < mlen)
mlen = len;
len -= mlen;
/*
* Force to long boundary so we do longword aligned
* memory operations
*/
if (3 & (int) w) {
REDUCE;
if ((1 & (int) w) && (mlen > 0)) {
sum <<= 8;
su.c[0] = *(char *)w;
w = (u_short *)((char *)w + 1);
mlen--;
byte_swapped = 1;
}
if ((2 & (int) w) && (mlen >= 2)) {
sum += *w++;
mlen -= 2;
}
}
/*
* Advance to a 486 cache line boundary.
*/
if (4 & (int) w && mlen >= 4) {
ADD(0);
MOP;
w += 2;
mlen -= 4;
}
if (8 & (int) w && mlen >= 8) {
ADD(0);
ADDC(4);
MOP;
w += 4;
mlen -= 8;
}
/*
* Do as much of the checksum as possible 32 bits at at time.
* In fact, this loop is unrolled to make overhead from
* branches &c small.
*/
mlen -= 1;
while ((mlen -= 32) >= 0) {
/*
* Add with carry 16 words and fold in the last
* carry by adding a 0 with carry.
*
* The early ADD(16) and the LOAD(32) are to load
* the next 2 cache lines in advance on 486's. The
* 486 has a penalty of 2 clock cycles for loading
* a cache line, plus whatever time the external
* memory takes to load the first word(s) addressed.
* These penalties are unavoidable. Subsequent
* accesses to a cache line being loaded (and to
* other external memory?) are delayed until the
* whole load finishes. These penalties are mostly
* avoided by not accessing external memory for
* 8 cycles after the ADD(16) and 12 cycles after
* the LOAD(32). The loop terminates when mlen
* is initially 33 (not 32) to guaranteed that
* the LOAD(32) is within bounds.
*/
ADD(16);
ADDC(0);
ADDC(4);
ADDC(8);
ADDC(12);
LOAD(32);
ADDC(20);
ADDC(24);
ADDC(28);
MOP;
w += 16;
}
mlen += 32 + 1;
if (mlen >= 32) {
ADD(16);
ADDC(0);
ADDC(4);
ADDC(8);
ADDC(12);
ADDC(20);
ADDC(24);
ADDC(28);
MOP;
w += 16;
mlen -= 32;
}
if (mlen >= 16) {
ADD(0);
ADDC(4);
ADDC(8);
ADDC(12);
MOP;
w += 8;
mlen -= 16;
}
if (mlen >= 8) {
ADD(0);
ADDC(4);
MOP;
w += 4;
mlen -= 8;
}
if (mlen == 0 && byte_swapped == 0)
continue; /* worth 1% maybe ?? */
REDUCE;
while ((mlen -= 2) >= 0) {
sum += *w++;
}
if (byte_swapped) {
sum <<= 8;
byte_swapped = 0;
if (mlen == -1) {
su.c[1] = *(char *)w;
sum += su.s;
mlen = 0;
} else
mlen = -1;
} else if (mlen == -1)
/*
* This mbuf has odd number of bytes.
* There could be a word split betwen
* this mbuf and the next mbuf.
* Save the last byte (to prepend to next mbuf).
*/
su.c[0] = *(char *)w;
}
if (len)
printf("%s: out of data by %d\n", __func__, len);
if (mlen == -1) {
/* The last mbuf has odd # of bytes. Follow the
standard (the odd byte is shifted left by 8 bits) */
su.c[1] = 0;
sum += su.s;
}
REDUCE;
return (~sum & 0xffff);
}
/*
* This is the exact same algorithm as above with a few exceptions:
* (1) it is designed to operate on buffers, not mbufs
* (2) it returns an intermediate form of the sum which has to be
* explicitly finalized (but this can be delayed)
* (3) it accepts an intermediate sum
*
* This is particularly useful when building packets quickly,
* since one can compute the checksum of the pseudoheader ahead of
* time and then use this function to complete the work. That way,
* the pseudoheader never actually has to exist in the packet buffer,
* which avoids needless duplication of work.
*/
in_psum_t
in_cksum_partial(psum, w, len)
in_psum_t psum;
const u_short *w;
int len;
{
in_psum_t sum = psum;
int byte_swapped = 0;
union { char c[2]; u_short s; } su;
/*
* Force to long boundary so we do longword aligned
* memory operations
*/
if (3 & (int) w) {
REDUCE;
if ((1 & (int) w) && (len > 0)) {
sum <<= 8;
su.c[0] = *(const char *)w;
w = (const u_short *)((const char *)w + 1);
len--;
byte_swapped = 1;
}
if ((2 & (int) w) && (len >= 2)) {
sum += *w++;
len -= 2;
}
}
/*
* Advance to a 486 cache line boundary.
*/
if (4 & (int) w && len >= 4) {
ADD(0);
MOP;
w += 2;
len -= 4;
}
if (8 & (int) w && len >= 8) {
ADD(0);
ADDC(4);
MOP;
w += 4;
len -= 8;
}
/*
* Do as much of the checksum as possible 32 bits at at time.
* In fact, this loop is unrolled to make overhead from
* branches &c small.
*/
len -= 1;
while ((len -= 32) >= 0) {
/*
* Add with carry 16 words and fold in the last
* carry by adding a 0 with carry.
*
* The early ADD(16) and the LOAD(32) are to load
* the next 2 cache lines in advance on 486's. The
* 486 has a penalty of 2 clock cycles for loading
* a cache line, plus whatever time the external
* memory takes to load the first word(s) addressed.
* These penalties are unavoidable. Subsequent
* accesses to a cache line being loaded (and to
* other external memory?) are delayed until the
* whole load finishes. These penalties are mostly
* avoided by not accessing external memory for
* 8 cycles after the ADD(16) and 12 cycles after
* the LOAD(32). The loop terminates when len
* is initially 33 (not 32) to guaranteed that
* the LOAD(32) is within bounds.
*/
ADD(16);
ADDC(0);
ADDC(4);
ADDC(8);
ADDC(12);
LOAD(32);
ADDC(20);
ADDC(24);
ADDC(28);
MOP;
w += 16;
}
len += 32 + 1;
if (len >= 32) {
ADD(16);
ADDC(0);
ADDC(4);
ADDC(8);
ADDC(12);
ADDC(20);
ADDC(24);
ADDC(28);
MOP;
w += 16;
len -= 32;
}
if (len >= 16) {
ADD(0);
ADDC(4);
ADDC(8);
ADDC(12);
MOP;
w += 8;
len -= 16;
}
if (len >= 8) {
ADD(0);
ADDC(4);
MOP;
w += 4;
len -= 8;
}
if (len == 0 && byte_swapped == 0)
goto out;
REDUCE;
while ((len -= 2) >= 0) {
sum += *w++;
}
if (byte_swapped) {
sum <<= 8;
byte_swapped = 0;
if (len == -1) {
su.c[1] = *(const char *)w;
sum += su.s;
len = 0;
} else
len = -1;
} else if (len == -1) {
/*
* This buffer has odd number of bytes.
* There could be a word split betwen
* this buffer and the next.
*/
su.c[0] = *(const char *)w;
}
out:
if (len == -1) {
/* The last buffer has odd # of bytes. Follow the
standard (the odd byte is shifted left by 8 bits) */
su.c[1] = 0;
sum += su.s;
}
return sum;
}
int
in_cksum_finalize(psum)
in_psum_t psum;
{
in_psum_t sum = psum;
REDUCE;
return (~sum & 0xffff);
}