Gitiles
Code Review Sign In
gerrit.nordix.org / codeaurora / cp-linux / 8d8f6542b666daf5e87de156590e635c2c4da0c0 / . / arch / x86 / um / checksum_32.S
blob: fa4b8b9841ff7071a993e61d2b55ca3bc8b35575 [file] [log] [blame]
Kyle Swenson8d8f6542021-03-15 11:02:55 -0600[diff] [blame^]1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * IP/TCP/UDP checksumming routines
7 *
8 * Authors: Jorge Cwik, <jorge@laser.satlink.net>
9 * Arnt Gulbrandsen, <agulbra@nvg.unit.no>
10 * Tom May, <ftom@netcom.com>
11 * Pentium Pro/II routines:
12 * Alexander Kjeldaas <astor@guardian.no>
13 * Finn Arne Gangstad <finnag@guardian.no>
14 * Lots of code moved from tcp.c and ip.c; see those files
15 * for more names.
16 *
17 * Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
18 * handling.
19 * Andi Kleen, add zeroing on error
20 * converted to pure assembler
21 *
22 * This program is free software; you can redistribute it and/or
23 * modify it under the terms of the GNU General Public License
24 * as published by the Free Software Foundation; either version
25 * 2 of the License, or (at your option) any later version.
26 */
27
28#include <asm/errno.h>
29#include <asm/asm.h>
30
31/*
32 * computes a partial checksum, e.g. for TCP/UDP fragments
33 */
34
35/*
36unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
37 */
38
39.text
40.align 4
41.globl csum_partial
42
43#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
44
45 /*
46 * Experiments with Ethernet and SLIP connections show that buff
47 * is aligned on either a 2-byte or 4-byte boundary. We get at
48 * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
49 * Fortunately, it is easy to convert 2-byte alignment to 4-byte
50 * alignment for the unrolled loop.
51 */
52csum_partial:
53 pushl %esi
54 pushl %ebx
55 movl 20(%esp),%eax # Function arg: unsigned int sum
56 movl 16(%esp),%ecx # Function arg: int len
57 movl 12(%esp),%esi # Function arg: unsigned char *buff
58 testl $2, %esi # Check alignment.
59 jz 2f # Jump if alignment is ok.
60 subl $2, %ecx # Alignment uses up two bytes.
61 jae 1f # Jump if we had at least two bytes.
62 addl $2, %ecx # ecx was < 2. Deal with it.
63 jmp 4f
641: movw (%esi), %bx
65 addl $2, %esi
66 addw %bx, %ax
67 adcl $0, %eax
682:
69 movl %ecx, %edx
70 shrl $5, %ecx
71 jz 2f
72 testl %esi, %esi
731: movl (%esi), %ebx
74 adcl %ebx, %eax
75 movl 4(%esi), %ebx
76 adcl %ebx, %eax
77 movl 8(%esi), %ebx
78 adcl %ebx, %eax
79 movl 12(%esi), %ebx
80 adcl %ebx, %eax
81 movl 16(%esi), %ebx
82 adcl %ebx, %eax
83 movl 20(%esi), %ebx
84 adcl %ebx, %eax
85 movl 24(%esi), %ebx
86 adcl %ebx, %eax
87 movl 28(%esi), %ebx
88 adcl %ebx, %eax
89 lea 32(%esi), %esi
90 dec %ecx
91 jne 1b
92 adcl $0, %eax
932: movl %edx, %ecx
94 andl $0x1c, %edx
95 je 4f
96 shrl $2, %edx # This clears CF
973: adcl (%esi), %eax
98 lea 4(%esi), %esi
99 dec %edx
100 jne 3b
101 adcl $0, %eax
1024: andl $3, %ecx
103 jz 7f
104 cmpl $2, %ecx
105 jb 5f
106 movw (%esi),%cx
107 leal 2(%esi),%esi
108 je 6f
109 shll $16,%ecx
1105: movb (%esi),%cl
1116: addl %ecx,%eax
112 adcl $0, %eax
1137:
114 popl %ebx
115 popl %esi
116 ret
117
118#else
119
120/* Version for PentiumII/PPro */
121
122csum_partial:
123 pushl %esi
124 pushl %ebx
125 movl 20(%esp),%eax # Function arg: unsigned int sum
126 movl 16(%esp),%ecx # Function arg: int len
127 movl 12(%esp),%esi # Function arg: const unsigned char *buf
128
129 testl $2, %esi
130 jnz 30f
13110:
132 movl %ecx, %edx
133 movl %ecx, %ebx
134 andl $0x7c, %ebx
135 shrl $7, %ecx
136 addl %ebx,%esi
137 shrl $2, %ebx
138 negl %ebx
139 lea 45f(%ebx,%ebx,2), %ebx
140 testl %esi, %esi
141 jmp *%ebx
142
143 # Handle 2-byte-aligned regions
14420: addw (%esi), %ax
145 lea 2(%esi), %esi
146 adcl $0, %eax
147 jmp 10b
148
14930: subl $2, %ecx
150 ja 20b
151 je 32f
152 movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
153 addl %ebx, %eax
154 adcl $0, %eax
155 jmp 80f
15632:
157 addw (%esi), %ax # csumming 2 bytes, 2-aligned
158 adcl $0, %eax
159 jmp 80f
160
16140:
162 addl -128(%esi), %eax
163 adcl -124(%esi), %eax
164 adcl -120(%esi), %eax
165 adcl -116(%esi), %eax
166 adcl -112(%esi), %eax
167 adcl -108(%esi), %eax
168 adcl -104(%esi), %eax
169 adcl -100(%esi), %eax
170 adcl -96(%esi), %eax
171 adcl -92(%esi), %eax
172 adcl -88(%esi), %eax
173 adcl -84(%esi), %eax
174 adcl -80(%esi), %eax
175 adcl -76(%esi), %eax
176 adcl -72(%esi), %eax
177 adcl -68(%esi), %eax
178 adcl -64(%esi), %eax
179 adcl -60(%esi), %eax
180 adcl -56(%esi), %eax
181 adcl -52(%esi), %eax
182 adcl -48(%esi), %eax
183 adcl -44(%esi), %eax
184 adcl -40(%esi), %eax
185 adcl -36(%esi), %eax
186 adcl -32(%esi), %eax
187 adcl -28(%esi), %eax
188 adcl -24(%esi), %eax
189 adcl -20(%esi), %eax
190 adcl -16(%esi), %eax
191 adcl -12(%esi), %eax
192 adcl -8(%esi), %eax
193 adcl -4(%esi), %eax
19445:
195 lea 128(%esi), %esi
196 adcl $0, %eax
197 dec %ecx
198 jge 40b
199 movl %edx, %ecx
20050: andl $3, %ecx
201 jz 80f
202
203 # Handle the last 1-3 bytes without jumping
204 notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
205 movl $0xffffff,%ebx # by the shll and shrl instructions
206 shll $3,%ecx
207 shrl %cl,%ebx
208 andl -128(%esi),%ebx # esi is 4-aligned so should be ok
209 addl %ebx,%eax
210 adcl $0,%eax
21180:
212 popl %ebx
213 popl %esi
214 ret
215
216#endif