1/*
2 * Optmized version of the ip_fast_csum() function
3 * Used for calculating IP header checksum
4 *
5 * Return: 16bit checksum, complemented
6 *
7 * Inputs:
8 *      in0: address of buffer to checksum (char *)
9 *      in1: length of the buffer (int)
10 *
11 * Copyright (C) 2002, 2006 Intel Corp.
12 * Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com>
13 */
14
15#include <asm/asmmacro.h>
16
17/*
18 * Since we know that most likely this function is called with buf aligned
19 * on 4-byte boundary and 20 bytes in length, we can execution rather quickly
20 * versus calling generic version of do_csum, which has lots of overhead in
21 * handling various alignments and sizes.  However, due to lack of constrains
22 * put on the function input argument, cases with alignment not on 4-byte or
23 * size not equal to 20 bytes will be handled by the generic do_csum function.
24 */
25
26#define in0	r32
27#define in1	r33
28#define in2	r34
29#define in3	r35
30#define in4	r36
31#define ret0	r8
32
33GLOBAL_ENTRY(ip_fast_csum)
34	.prologue
35	.body
36	cmp.ne	p6,p7=5,in1	// size other than 20 byte?
37	and	r14=3,in0	// is it aligned on 4-byte?
38	add	r15=4,in0	// second source pointer
39	;;
40	cmp.ne.or.andcm p6,p7=r14,r0
41	;;
42(p7)	ld4	r20=[in0],8
43(p7)	ld4	r21=[r15],8
44(p6)	br.spnt	.generic
45	;;
46	ld4	r22=[in0],8
47	ld4	r23=[r15],8
48	;;
49	ld4	r24=[in0]
50	add	r20=r20,r21
51	add	r22=r22,r23
52	;;
53	add	r20=r20,r22
54	;;
55	add	r20=r20,r24
56	;;
57	shr.u	ret0=r20,16	// now need to add the carry
58	zxt2	r20=r20
59	;;
60	add	r20=ret0,r20
61	;;
62	shr.u	ret0=r20,16	// add carry again
63	zxt2	r20=r20
64	;;
65	add	r20=ret0,r20
66	;;
67	shr.u	ret0=r20,16
68	zxt2	r20=r20
69	;;
70	add	r20=ret0,r20
71	mov	r9=0xffff
72	;;
73	andcm	ret0=r9,r20
74	.restore sp		// reset frame state
75	br.ret.sptk.many b0
76	;;
77
78.generic:
79	.prologue
80	.save ar.pfs, r35
81	alloc	r35=ar.pfs,2,2,2,0
82	.save rp, r34
83	mov	r34=b0
84	.body
85	dep.z	out1=in1,2,30
86	mov	out0=in0
87	;;
88	br.call.sptk.many b0=do_csum
89	;;
90	andcm	ret0=-1,ret0
91	mov	ar.pfs=r35
92	mov	b0=r34
93	br.ret.sptk.many b0
94END(ip_fast_csum)
95
96GLOBAL_ENTRY(csum_ipv6_magic)
97	ld4	r20=[in0],4
98	ld4	r21=[in1],4
99	zxt4	in2=in2
100	;;
101	ld4	r22=[in0],4
102	ld4	r23=[in1],4
103	dep	r15=in3,in2,32,16
104	;;
105	ld4	r24=[in0],4
106	ld4	r25=[in1],4
107	mux1	r15=r15,@rev
108	add	r16=r20,r21
109	add	r17=r22,r23
110	zxt4	in4=in4
111	;;
112	ld4	r26=[in0],4
113	ld4	r27=[in1],4
114	shr.u	r15=r15,16
115	add	r18=r24,r25
116	add	r8=r16,r17
117	;;
118	add	r19=r26,r27
119	add	r8=r8,r18
120	;;
121	add	r8=r8,r19
122	add	r15=r15,in4
123	;;
124	add	r8=r8,r15
125	;;
126	shr.u	r10=r8,32	// now fold sum into short
127	zxt4	r11=r8
128	;;
129	add	r8=r10,r11
130	;;
131	shr.u	r10=r8,16	// yeah, keep it rolling
132	zxt2	r11=r8
133	;;
134	add	r8=r10,r11
135	;;
136	shr.u	r10=r8,16	// three times lucky
137	zxt2	r11=r8
138	;;
139	add	r8=r10,r11
140	mov	r9=0xffff
141	;;
142	andcm	r8=r9,r8
143	br.ret.sptk.many b0
144END(csum_ipv6_magic)
145