/* * 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 Intel Corp. * Copyright (C) 2002 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 ret0	r8GLOBAL_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 b0END(ip_fast_csum)