1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * linux/arch/arm/lib/csumpartialcopygeneric.S
4 *
5 * Copyright (C) 1995-2001 Russell King
6 */
7 #include <asm/assembler.h>
8
9 /*
10 * unsigned int
11 * csum_partial_copy_xxx(const char *src, char *dst, int len, int sum, )
12 * r0 = src, r1 = dst, r2 = len, r3 = sum
13 * Returns : r0 = checksum
14 *
15 * Note that 'tst' and 'teq' preserve the carry flag.
16 */
17
18 src .req r0
19 dst .req r1
20 len .req r2
21 sum .req r3
22
23 .Lzero: mov r0, sum
24 load_regs
25
26 /*
27 * Align an unaligned destination pointer. We know that
28 * we have >= 8 bytes here, so we don't need to check
29 * the length. Note that the source pointer hasn't been
30 * aligned yet.
31 */
32 .Ldst_unaligned:
33 tst dst, #1
34 beq .Ldst_16bit
35
36 load1b ip
37 sub len, len, #1
38 adcs sum, sum, ip, put_byte_1 @ update checksum
39 strb ip, [dst], #1
40 tst dst, #2
41 reteq lr @ dst is now 32bit aligned
42
43 .Ldst_16bit: load2b r8, ip
44 sub len, len, #2
45 adcs sum, sum, r8, put_byte_0
46 strb r8, [dst], #1
47 adcs sum, sum, ip, put_byte_1
48 strb ip, [dst], #1
49 ret lr @ dst is now 32bit aligned
50
51 /*
52 * Handle 0 to 7 bytes, with any alignment of source and
53 * destination pointers. Note that when we get here, C = 0
54 */
55 .Lless8: teq len, #0 @ check for zero count
56 beq .Lzero
57
58 /* we must have at least one byte. */
59 tst dst, #1 @ dst 16-bit aligned
60 beq .Lless8_aligned
61
62 /* Align dst */
63 load1b ip
64 sub len, len, #1
65 adcs sum, sum, ip, put_byte_1 @ update checksum
66 strb ip, [dst], #1
67 tst len, #6
68 beq .Lless8_byteonly
69
70 1: load2b r8, ip
71 sub len, len, #2
72 adcs sum, sum, r8, put_byte_0
73 strb r8, [dst], #1
74 adcs sum, sum, ip, put_byte_1
75 strb ip, [dst], #1
76 .Lless8_aligned:
77 tst len, #6
78 bne 1b
79 .Lless8_byteonly:
80 tst len, #1
81 beq .Ldone
82 load1b r8
83 adcs sum, sum, r8, put_byte_0 @ update checksum
84 strb r8, [dst], #1
85 b .Ldone
86
87 FN_ENTRY
88 save_regs
89 mov sum, #-1
90
91 cmp len, #8 @ Ensure that we have at least
92 blo .Lless8 @ 8 bytes to copy.
93
94 adds sum, sum, #0 @ C = 0
95 tst dst, #3 @ Test destination alignment
96 blne .Ldst_unaligned @ align destination, return here
97
98 /*
99 * Ok, the dst pointer is now 32bit aligned, and we know
100 * that we must have more than 4 bytes to copy. Note
101 * that C contains the carry from the dst alignment above.
102 */
103
104 tst src, #3 @ Test source alignment
105 bne .Lsrc_not_aligned
106
107 /* Routine for src & dst aligned */
108
109 bics ip, len, #15
110 beq 2f
111
112 1: load4l r4, r5, r6, r7
113 stmia dst!, {r4, r5, r6, r7}
114 adcs sum, sum, r4
115 adcs sum, sum, r5
116 adcs sum, sum, r6
117 adcs sum, sum, r7
118 sub ip, ip, #16
119 teq ip, #0
120 bne 1b
121
122 2: ands ip, len, #12
123 beq 4f
124 tst ip, #8
125 beq 3f
126 load2l r4, r5
127 stmia dst!, {r4, r5}
128 adcs sum, sum, r4
129 adcs sum, sum, r5
130 tst ip, #4
131 beq 4f
132
133 3: load1l r4
134 str r4, [dst], #4
135 adcs sum, sum, r4
136
137 4: ands len, len, #3
138 beq .Ldone
139 load1l r4
140 tst len, #2
141 mov r5, r4, get_byte_0
142 beq .Lexit
143 adcs sum, sum, r4, lspush #16
144 strb r5, [dst], #1
145 mov r5, r4, get_byte_1
146 strb r5, [dst], #1
147 mov r5, r4, get_byte_2
148 .Lexit: tst len, #1
149 strbne r5, [dst], #1
150 andne r5, r5, #255
151 adcsne sum, sum, r5, put_byte_0
152
153 /*
154 * If the dst pointer was not 16-bit aligned, we
155 * need to rotate the checksum here to get around
156 * the inefficient byte manipulations in the
157 * architecture independent code.
158 */
159 .Ldone: adc r0, sum, #0
160 ldr sum, [sp, #0] @ dst
161 tst sum, #1
162 movne r0, r0, ror #8
163 load_regs
164
165 .Lsrc_not_aligned:
166 adc sum, sum, #0 @ include C from dst alignment
167 and ip, src, #3
168 bic src, src, #3
169 load1l r5
170 cmp ip, #2
171 beq .Lsrc2_aligned
172 bhi .Lsrc3_aligned
173 mov r4, r5, lspull #8 @ C = 0
174 bics ip, len, #15
175 beq 2f
176 1: load4l r5, r6, r7, r8
177 orr r4, r4, r5, lspush #24
178 mov r5, r5, lspull #8
179 orr r5, r5, r6, lspush #24
180 mov r6, r6, lspull #8
181 orr r6, r6, r7, lspush #24
182 mov r7, r7, lspull #8
183 orr r7, r7, r8, lspush #24
184 stmia dst!, {r4, r5, r6, r7}
185 adcs sum, sum, r4
186 adcs sum, sum, r5
187 adcs sum, sum, r6
188 adcs sum, sum, r7
189 mov r4, r8, lspull #8
190 sub ip, ip, #16
191 teq ip, #0
192 bne 1b
193 2: ands ip, len, #12
194 beq 4f
195 tst ip, #8
196 beq 3f
197 load2l r5, r6
198 orr r4, r4, r5, lspush #24
199 mov r5, r5, lspull #8
200 orr r5, r5, r6, lspush #24
201 stmia dst!, {r4, r5}
202 adcs sum, sum, r4
203 adcs sum, sum, r5
204 mov r4, r6, lspull #8
205 tst ip, #4
206 beq 4f
207 3: load1l r5
208 orr r4, r4, r5, lspush #24
209 str r4, [dst], #4
210 adcs sum, sum, r4
211 mov r4, r5, lspull #8
212 4: ands len, len, #3
213 beq .Ldone
214 mov r5, r4, get_byte_0
215 tst len, #2
216 beq .Lexit
217 adcs sum, sum, r4, lspush #16
218 strb r5, [dst], #1
219 mov r5, r4, get_byte_1
220 strb r5, [dst], #1
221 mov r5, r4, get_byte_2
222 b .Lexit
223
224 .Lsrc2_aligned: mov r4, r5, lspull #16
225 adds sum, sum, #0
226 bics ip, len, #15
227 beq 2f
228 1: load4l r5, r6, r7, r8
229 orr r4, r4, r5, lspush #16
230 mov r5, r5, lspull #16
231 orr r5, r5, r6, lspush #16
232 mov r6, r6, lspull #16
233 orr r6, r6, r7, lspush #16
234 mov r7, r7, lspull #16
235 orr r7, r7, r8, lspush #16
236 stmia dst!, {r4, r5, r6, r7}
237 adcs sum, sum, r4
238 adcs sum, sum, r5
239 adcs sum, sum, r6
240 adcs sum, sum, r7
241 mov r4, r8, lspull #16
242 sub ip, ip, #16
243 teq ip, #0
244 bne 1b
245 2: ands ip, len, #12
246 beq 4f
247 tst ip, #8
248 beq 3f
249 load2l r5, r6
250 orr r4, r4, r5, lspush #16
251 mov r5, r5, lspull #16
252 orr r5, r5, r6, lspush #16
253 stmia dst!, {r4, r5}
254 adcs sum, sum, r4
255 adcs sum, sum, r5
256 mov r4, r6, lspull #16
257 tst ip, #4
258 beq 4f
259 3: load1l r5
260 orr r4, r4, r5, lspush #16
261 str r4, [dst], #4
262 adcs sum, sum, r4
263 mov r4, r5, lspull #16
264 4: ands len, len, #3
265 beq .Ldone
266 mov r5, r4, get_byte_0
267 tst len, #2
268 beq .Lexit
269 adcs sum, sum, r4
270 strb r5, [dst], #1
271 mov r5, r4, get_byte_1
272 strb r5, [dst], #1
273 tst len, #1
274 beq .Ldone
275 load1b r5
276 b .Lexit
277
278 .Lsrc3_aligned: mov r4, r5, lspull #24
279 adds sum, sum, #0
280 bics ip, len, #15
281 beq 2f
282 1: load4l r5, r6, r7, r8
283 orr r4, r4, r5, lspush #8
284 mov r5, r5, lspull #24
285 orr r5, r5, r6, lspush #8
286 mov r6, r6, lspull #24
287 orr r6, r6, r7, lspush #8
288 mov r7, r7, lspull #24
289 orr r7, r7, r8, lspush #8
290 stmia dst!, {r4, r5, r6, r7}
291 adcs sum, sum, r4
292 adcs sum, sum, r5
293 adcs sum, sum, r6
294 adcs sum, sum, r7
295 mov r4, r8, lspull #24
296 sub ip, ip, #16
297 teq ip, #0
298 bne 1b
299 2: ands ip, len, #12
300 beq 4f
301 tst ip, #8
302 beq 3f
303 load2l r5, r6
304 orr r4, r4, r5, lspush #8
305 mov r5, r5, lspull #24
306 orr r5, r5, r6, lspush #8
307 stmia dst!, {r4, r5}
308 adcs sum, sum, r4
309 adcs sum, sum, r5
310 mov r4, r6, lspull #24
311 tst ip, #4
312 beq 4f
313 3: load1l r5
314 orr r4, r4, r5, lspush #8
315 str r4, [dst], #4
316 adcs sum, sum, r4
317 mov r4, r5, lspull #24
318 4: ands len, len, #3
319 beq .Ldone
320 mov r5, r4, get_byte_0
321 tst len, #2
322 beq .Lexit
323 strb r5, [dst], #1
324 adcs sum, sum, r4
325 load1l r4
326 mov r5, r4, get_byte_0
327 strb r5, [dst], #1
328 adcs sum, sum, r4, lspush #24
329 mov r5, r4, get_byte_1
330 b .Lexit
331 FN_EXIT
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