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/*
* Optmized version of the ip_fast_csum() function
* Used for calculating IP header checksum
*
* Return: 16bit checksum, complemented
*
* Inputs:
* in0: address of buffer to checksum (char *)
* in1: length of the buffer (int)
*
* Copyright (C) 2002, 2006 Intel Corp.
* Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com>
*/
#include <asm/asmmacro.h>
/*
* Since we know that most likely this function is called with buf aligned
* on 4-byte boundary and 20 bytes in length, we can execution rather quickly
* versus calling generic version of do_csum, which has lots of overhead in
* handling various alignments and sizes. However, due to lack of constrains
* put on the function input argument, cases with alignment not on 4-byte or
* size not equal to 20 bytes will be handled by the generic do_csum function.
*/
#define in0 r32
#define in1 r33
#define in2 r34
#define in3 r35
#define in4 r36
#define ret0 r8
GLOBAL_ENTRY(ip_fast_csum)
.prologue
.body
cmp.ne p6,p7=5,in1 // size other than 20 byte?
and r14=3,in0 // is it aligned on 4-byte?
add r15=4,in0 // second source pointer
;;
cmp.ne.or.andcm p6,p7=r14,r0
;;
(p7) ld4 r20=[in0],8
(p7) ld4 r21=[r15],8
(p6) br.spnt .generic
;;
ld4 r22=[in0],8
ld4 r23=[r15],8
;;
ld4 r24=[in0]
add r20=r20,r21
add r22=r22,r23
;;
add r20=r20,r22
;;
add r20=r20,r24
;;
shr.u ret0=r20,16 // now need to add the carry
zxt2 r20=r20
;;
add r20=ret0,r20
;;
shr.u ret0=r20,16 // add carry again
zxt2 r20=r20
;;
add r20=ret0,r20
;;
shr.u ret0=r20,16
zxt2 r20=r20
;;
add r20=ret0,r20
;;
andcm ret0=-1,r20
.restore sp // reset frame state
br.ret.sptk.many b0
;;
.generic:
.prologue
.save ar.pfs, r35
alloc r35=ar.pfs,2,2,2,0
.save rp, r34
mov r34=b0
.body
dep.z out1=in1,2,30
mov out0=in0
;;
br.call.sptk.many b0=do_csum
;;
andcm ret0=-1,ret0
mov ar.pfs=r35
mov b0=r34
br.ret.sptk.many b0
END(ip_fast_csum)
GLOBAL_ENTRY(csum_ipv6_magic)
ld4 r20=[in0],4
ld4 r21=[in1],4
dep r15=in3,in2,32,16
;;
ld4 r22=[in0],4
ld4 r23=[in1],4
mux1 r15=r15,@rev
;;
ld4 r24=[in0],4
ld4 r25=[in1],4
shr.u r15=r15,16
add r16=r20,r21
add r17=r22,r23
;;
ld4 r26=[in0],4
ld4 r27=[in1],4
add r18=r24,r25
add r8=r16,r17
;;
add r19=r26,r27
add r8=r8,r18
;;
add r8=r8,r19
add r15=r15,in4
;;
add r8=r8,r15
;;
shr.u r10=r8,32 // now fold sum into short
zxt4 r11=r8
;;
add r8=r10,r11
;;
shr.u r10=r8,16 // yeah, keep it rolling
zxt2 r11=r8
;;
add r8=r10,r11
;;
shr.u r10=r8,16 // three times lucky
zxt2 r11=r8
;;
add r8=r10,r11
mov r9=0xffff
;;
andcm r8=r9,r8
br.ret.sptk.many b0
END(csum_ipv6_magic)
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