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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 *
Chen, Kenneth W007d77d2006-11-10 13:17:50 -080011 * Copyright (C) 2002, 2006 Intel Corp.
12 * Copyright (C) 2002, 2006 Ken Chen <kenneth.w.chen@intel.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 */
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
Chen, Kenneth W007d77d2006-11-10 13:17:50 -080028#define in2 r34
29#define in3 r35
30#define in4 r36
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#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
Chen, Kenneth W6dbfc19b2006-11-08 16:29:25 -080071 mov r9=0xffff
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 ;;
Chen, Kenneth W6dbfc19b2006-11-08 16:29:25 -080073 andcm ret0=r9,r20
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 .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)
Chen, Kenneth W007d77d2006-11-10 13:17:50 -080095
96GLOBAL_ENTRY(csum_ipv6_magic)
97 ld4 r20=[in0],4
98 ld4 r21=[in1],4
99 dep r15=in3,in2,32,16
100 ;;
101 ld4 r22=[in0],4
102 ld4 r23=[in1],4
103 mux1 r15=r15,@rev
104 ;;
105 ld4 r24=[in0],4
106 ld4 r25=[in1],4
107 shr.u r15=r15,16
108 add r16=r20,r21
109 add r17=r22,r23
110 ;;
111 ld4 r26=[in0],4
112 ld4 r27=[in1],4
113 add r18=r24,r25
114 add r8=r16,r17
115 ;;
116 add r19=r26,r27
117 add r8=r8,r18
118 ;;
119 add r8=r8,r19
120 add r15=r15,in4
121 ;;
122 add r8=r8,r15
123 ;;
124 shr.u r10=r8,32 // now fold sum into short
125 zxt4 r11=r8
126 ;;
127 add r8=r10,r11
128 ;;
129 shr.u r10=r8,16 // yeah, keep it rolling
130 zxt2 r11=r8
131 ;;
132 add r8=r10,r11
133 ;;
134 shr.u r10=r8,16 // three times lucky
135 zxt2 r11=r8
136 ;;
137 add r8=r10,r11
138 mov r9=0xffff
139 ;;
140 andcm r8=r9,r8
141 br.ret.sptk.many b0
142END(csum_ipv6_magic)