Linux-2.6.33.2/arch/powerpc/lib/checksum_64.S
/*
* This file contains assembly-language implementations
* of IP-style 1's complement checksum routines.
*
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* 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.
*
* Severely hacked about by Paul Mackerras (paulus@cs.anu.edu.au).
*/
#include <linux/sys.h>
#include <asm/processor.h>
#include <asm/errno.h>
#include <asm/ppc_asm.h>
/*
* ip_fast_csum(r3=buf, r4=len) -- Optimized for IP header
* len is in words and is always >= 5.
*
* In practice len == 5, but this is not guaranteed. So this code does not
* attempt to use doubleword instructions.
*/
_GLOBAL(ip_fast_csum)
lwz r0,0(r3)
lwzu r5,4(r3)
addic. r4,r4,-2
addc r0,r0,r5
mtctr r4
blelr-
1: lwzu r4,4(r3)
adde r0,r0,r4
bdnz 1b
addze r0,r0 /* add in final carry */
rldicl r4,r0,32,0 /* fold two 32-bit halves together */
add r0,r0,r4
srdi r0,r0,32
rlwinm r3,r0,16,0,31 /* fold two halves together */
add r3,r0,r3
not r3,r3
srwi r3,r3,16
blr
/*
* Compute checksum of TCP or UDP pseudo-header:
* csum_tcpudp_magic(r3=saddr, r4=daddr, r5=len, r6=proto, r7=sum)
* No real gain trying to do this specially for 64 bit, but
* the 32 bit addition may spill into the upper bits of
* the doubleword so we still must fold it down from 64.
*/
_GLOBAL(csum_tcpudp_magic)
rlwimi r5,r6,16,0,15 /* put proto in upper half of len */
addc r0,r3,r4 /* add 4 32-bit words together */
adde r0,r0,r5
adde r0,r0,r7
rldicl r4,r0,32,0 /* fold 64 bit value */
add r0,r4,r0
srdi r0,r0,32
rlwinm r3,r0,16,0,31 /* fold two halves together */
add r3,r0,r3
not r3,r3
srwi r3,r3,16
blr
/*
* Computes the checksum of a memory block at buff, length len,
* and adds in "sum" (32-bit).
*
* This code assumes at least halfword alignment, though the length
* can be any number of bytes. The sum is accumulated in r5.
*
* csum_partial(r3=buff, r4=len, r5=sum)
*/
_GLOBAL(csum_partial)
subi r3,r3,8 /* we'll offset by 8 for the loads */
srdi. r6,r4,3 /* divide by 8 for doubleword count */
addic r5,r5,0 /* clear carry */
beq 3f /* if we're doing < 8 bytes */
andi. r0,r3,2 /* aligned on a word boundary already? */
beq+ 1f
lhz r6,8(r3) /* do 2 bytes to get aligned */
addi r3,r3,2
subi r4,r4,2
addc r5,r5,r6
srdi. r6,r4,3 /* recompute number of doublewords */
beq 3f /* any left? */
1: mtctr r6
2: ldu r6,8(r3) /* main sum loop */
adde r5,r5,r6
bdnz 2b
andi. r4,r4,7 /* compute bytes left to sum after doublewords */
3: cmpwi 0,r4,4 /* is at least a full word left? */
blt 4f
lwz r6,8(r3) /* sum this word */
addi r3,r3,4
subi r4,r4,4
adde r5,r5,r6
4: cmpwi 0,r4,2 /* is at least a halfword left? */
blt+ 5f
lhz r6,8(r3) /* sum this halfword */
addi r3,r3,2
subi r4,r4,2
adde r5,r5,r6
5: cmpwi 0,r4,1 /* is at least a byte left? */
bne+ 6f
lbz r6,8(r3) /* sum this byte */
slwi r6,r6,8 /* this byte is assumed to be the upper byte of a halfword */
adde r5,r5,r6
6: addze r5,r5 /* add in final carry */
rldicl r4,r5,32,0 /* fold two 32-bit halves together */
add r3,r4,r5
srdi r3,r3,32
blr
/*
* Computes the checksum of a memory block at src, length len,
* and adds in "sum" (32-bit), while copying the block to dst.
* If an access exception occurs on src or dst, it stores -EFAULT
* to *src_err or *dst_err respectively, and (for an error on
* src) zeroes the rest of dst.
*
* This code needs to be reworked to take advantage of 64 bit sum+copy.
* However, due to tokenring halfword alignment problems this will be very
* tricky. For now we'll leave it until we instrument it somehow.
*
* csum_partial_copy_generic(r3=src, r4=dst, r5=len, r6=sum, r7=src_err, r8=dst_err)
*/
_GLOBAL(csum_partial_copy_generic)
addic r0,r6,0
subi r3,r3,4
subi r4,r4,4
srwi. r6,r5,2
beq 3f /* if we're doing < 4 bytes */
andi. r9,r4,2 /* Align dst to longword boundary */
beq+ 1f
81: lhz r6,4(r3) /* do 2 bytes to get aligned */
addi r3,r3,2
subi r5,r5,2
91: sth r6,4(r4)
addi r4,r4,2
addc r0,r0,r6
srwi. r6,r5,2 /* # words to do */
beq 3f
1: mtctr r6
82: lwzu r6,4(r3) /* the bdnz has zero overhead, so it should */
92: stwu r6,4(r4) /* be unnecessary to unroll this loop */
adde r0,r0,r6
bdnz 82b
andi. r5,r5,3
3: cmpwi 0,r5,2
blt+ 4f
83: lhz r6,4(r3)
addi r3,r3,2
subi r5,r5,2
93: sth r6,4(r4)
addi r4,r4,2
adde r0,r0,r6
4: cmpwi 0,r5,1
bne+ 5f
84: lbz r6,4(r3)
94: stb r6,4(r4)
slwi r6,r6,8 /* Upper byte of word */
adde r0,r0,r6
5: addze r3,r0 /* add in final carry (unlikely with 64-bit regs) */
rldicl r4,r3,32,0 /* fold 64 bit value */
add r3,r4,r3
srdi r3,r3,32
blr
/* These shouldn't go in the fixup section, since that would
cause the ex_table addresses to get out of order. */
.globl src_error_1
src_error_1:
li r6,0
subi r5,r5,2
95: sth r6,4(r4)
addi r4,r4,2
srwi. r6,r5,2
beq 3f
mtctr r6
.globl src_error_2
src_error_2:
li r6,0
96: stwu r6,4(r4)
bdnz 96b
3: andi. r5,r5,3
beq src_error
.globl src_error_3
src_error_3:
li r6,0
mtctr r5
addi r4,r4,3
97: stbu r6,1(r4)
bdnz 97b
.globl src_error
src_error:
cmpdi 0,r7,0
beq 1f
li r6,-EFAULT
stw r6,0(r7)
1: addze r3,r0
blr
.globl dst_error
dst_error:
cmpdi 0,r8,0
beq 1f
li r6,-EFAULT
stw r6,0(r8)
1: addze r3,r0
blr
.section __ex_table,"a"
.align 3
.llong 81b,src_error_1
.llong 91b,dst_error
.llong 82b,src_error_2
.llong 92b,dst_error
.llong 83b,src_error_3
.llong 93b,dst_error
.llong 84b,src_error_3
.llong 94b,dst_error
.llong 95b,dst_error
.llong 96b,dst_error
.llong 97b,dst_error