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fix file specification in comments
[linux-2.6-block.git] / arch / xtensa / lib / memcopy.S
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CZ		 1/*
2 * arch/xtensa/lib/hal/memcopy.S -- Core HAL library functions
3 * xthal_memcpy and xthal_bcopy
4 *
5 * This file is subject to the terms and conditions of the GNU General Public
6 * License. See the file "COPYING" in the main directory of this archive
7 * for more details.
8 *
9 * Copyright (C) 2002 - 2005 Tensilica Inc.
10 */
11
12#include <xtensa/coreasm.h>
13
14 .macro src_b r, w0, w1
15#ifdef __XTENSA_EB__
16 src \r, \w0, \w1
17#else
18 src \r, \w1, \w0
19#endif
20 .endm
21
22 .macro ssa8 r
23#ifdef __XTENSA_EB__
24 ssa8b \r
25#else
26 ssa8l \r
27#endif
28 .endm
29
30
31/*
32 * void *memcpy(void *dst, const void *src, size_t len);
33 * void *memmove(void *dst, const void *src, size_t len);
34 * void *bcopy(const void *src, void *dst, size_t len);
35 *
36 * This function is intended to do the same thing as the standard
37 * library function memcpy() (or bcopy()) for most cases.
38 * However, where the source and/or destination references
39 * an instruction RAM or ROM or a data RAM or ROM, that
40 * source and/or destination will always be accessed with
41 * 32-bit load and store instructions (as required for these
42 * types of devices).
43 *
44 * !!!!!!! XTFIXME:
45 * !!!!!!! Handling of IRAM/IROM has not yet
46 * !!!!!!! been implemented.
47 *
48 * The bcopy version is provided here to avoid the overhead
49 * of an extra call, for callers that require this convention.
50 *
51 * The (general case) algorithm is as follows:
52 * If destination is unaligned, align it by conditionally
53 * copying 1 and 2 bytes.
54 * If source is aligned,
55 * do 16 bytes with a loop, and then finish up with
56 * 8, 4, 2, and 1 byte copies conditional on the length;
57 * else (if source is unaligned),
58 * do the same, but use SRC to align the source data.
59 * This code tries to use fall-through branches for the common
60 * case of aligned source and destination and multiple
61 * of 4 (or 8) length.
62 *
63 * Register use:
64 * a0/ return address
65 * a1/ stack pointer
66 * a2/ return value
67 * a3/ src
68 * a4/ length
69 * a5/ dst
70 * a6/ tmp
71 * a7/ tmp
72 * a8/ tmp
73 * a9/ tmp
74 * a10/ tmp
75 * a11/ tmp
76 */
77
78 .text
79 .align 4
80 .global bcopy
81 .type bcopy,@function
82bcopy:
83 entry sp, 16 # minimal stack frame
84 # a2=src, a3=dst, a4=len
85 mov a5, a3 # copy dst so that a2 is return value
86 mov a3, a2
87 mov a2, a5
88 j .Lcommon # go to common code for memcpy+bcopy
89
90
91/*
92 * Byte by byte copy
93 */
94 .align 4
95 .byte 0 # 1 mod 4 alignment for LOOPNEZ
96 # (0 mod 4 alignment for LBEG)
97.Lbytecopy:
98#if XCHAL_HAVE_LOOPS
99 loopnez a4, .Lbytecopydone
100#else /* !XCHAL_HAVE_LOOPS */
101 beqz a4, .Lbytecopydone
102 add a7, a3, a4 # a7 = end address for source
103#endif /* !XCHAL_HAVE_LOOPS */
104.Lnextbyte:
105 l8ui a6, a3, 0
106 addi a3, a3, 1
107 s8i a6, a5, 0
108 addi a5, a5, 1
109#if !XCHAL_HAVE_LOOPS
110 blt a3, a7, .Lnextbyte
111#endif /* !XCHAL_HAVE_LOOPS */
112.Lbytecopydone:
113 retw
114
115/*
116 * Destination is unaligned
117 */
118
119 .align 4
120.Ldst1mod2: # dst is only byte aligned
121 _bltui a4, 7, .Lbytecopy # do short copies byte by byte
122
123 # copy 1 byte
124 l8ui a6, a3, 0
125 addi a3, a3, 1
126 addi a4, a4, -1
127 s8i a6, a5, 0
128 addi a5, a5, 1
129 _bbci.l a5, 1, .Ldstaligned # if dst is now aligned, then
130 # return to main algorithm
131.Ldst2mod4: # dst 16-bit aligned
132 # copy 2 bytes
133 _bltui a4, 6, .Lbytecopy # do short copies byte by byte
134 l8ui a6, a3, 0
135 l8ui a7, a3, 1
136 addi a3, a3, 2
137 addi a4, a4, -2
138 s8i a6, a5, 0
139 s8i a7, a5, 1
140 addi a5, a5, 2
141 j .Ldstaligned # dst is now aligned, return to main algorithm
142
143 .align 4
144 .global memcpy
145 .type memcpy,@function
146memcpy:
147 .global memmove
148 .type memmove,@function
149memmove:
150
151 entry sp, 16 # minimal stack frame
152 # a2/ dst, a3/ src, a4/ len
153 mov a5, a2 # copy dst so that a2 is return value
154.Lcommon:
155 _bbsi.l a2, 0, .Ldst1mod2 # if dst is 1 mod 2
156 _bbsi.l a2, 1, .Ldst2mod4 # if dst is 2 mod 4
157.Ldstaligned: # return here from .Ldst?mod? once dst is aligned
158 srli a7, a4, 4 # number of loop iterations with 16B
159 # per iteration
160 movi a8, 3 # if source is not aligned,
161 _bany a3, a8, .Lsrcunaligned # then use shifting copy
162 /*
163 * Destination and source are word-aligned, use word copy.
164 */
165 # copy 16 bytes per iteration for word-aligned dst and word-aligned src
166#if XCHAL_HAVE_LOOPS
167 loopnez a7, .Loop1done
168#else /* !XCHAL_HAVE_LOOPS */
169 beqz a7, .Loop1done
170 slli a8, a7, 4
171 add a8, a8, a3 # a8 = end of last 16B source chunk
172#endif /* !XCHAL_HAVE_LOOPS */
173.Loop1:
174 l32i a6, a3, 0
175 l32i a7, a3, 4
176 s32i a6, a5, 0
177 l32i a6, a3, 8
178 s32i a7, a5, 4
179 l32i a7, a3, 12
180 s32i a6, a5, 8
181 addi a3, a3, 16
182 s32i a7, a5, 12
183 addi a5, a5, 16
184#if !XCHAL_HAVE_LOOPS
185 blt a3, a8, .Loop1
186#endif /* !XCHAL_HAVE_LOOPS */
187.Loop1done:
188 bbci.l a4, 3, .L2
189 # copy 8 bytes
190 l32i a6, a3, 0
191 l32i a7, a3, 4
192 addi a3, a3, 8
193 s32i a6, a5, 0
194 s32i a7, a5, 4
195 addi a5, a5, 8
196.L2:
197 bbsi.l a4, 2, .L3
198 bbsi.l a4, 1, .L4
199 bbsi.l a4, 0, .L5
200 retw
201.L3:
202 # copy 4 bytes
203 l32i a6, a3, 0
204 addi a3, a3, 4
205 s32i a6, a5, 0
206 addi a5, a5, 4
207 bbsi.l a4, 1, .L4
208 bbsi.l a4, 0, .L5
209 retw
210.L4:
211 # copy 2 bytes
212 l16ui a6, a3, 0
213 addi a3, a3, 2
214 s16i a6, a5, 0
215 addi a5, a5, 2
216 bbsi.l a4, 0, .L5
217 retw
218.L5:
219 # copy 1 byte
220 l8ui a6, a3, 0
221 s8i a6, a5, 0
222 retw
223
224/*
225 * Destination is aligned, Source is unaligned
226 */
227
228 .align 4
229.Lsrcunaligned:
230 _beqz a4, .Ldone # avoid loading anything for zero-length copies
231 # copy 16 bytes per iteration for word-aligned dst and unaligned src
232 ssa8 a3 # set shift amount from byte offset
233#define SIM_CHECKS_ALIGNMENT 1 /* set to 1 when running on ISS (simulator) with the
234 lint or ferret client, or 0 to save a few cycles */
235#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
236 and a11, a3, a8 # save unalignment offset for below
237 sub a3, a3, a11 # align a3
238#endif
239 l32i a6, a3, 0 # load first word
240#if XCHAL_HAVE_LOOPS
241 loopnez a7, .Loop2done
242#else /* !XCHAL_HAVE_LOOPS */
243 beqz a7, .Loop2done
244 slli a10, a7, 4
245 add a10, a10, a3 # a10 = end of last 16B source chunk
246#endif /* !XCHAL_HAVE_LOOPS */
247.Loop2:
248 l32i a7, a3, 4
249 l32i a8, a3, 8
250 src_b a6, a6, a7
251 s32i a6, a5, 0
252 l32i a9, a3, 12
253 src_b a7, a7, a8
254 s32i a7, a5, 4
255 l32i a6, a3, 16
256 src_b a8, a8, a9
257 s32i a8, a5, 8
258 addi a3, a3, 16
259 src_b a9, a9, a6
260 s32i a9, a5, 12
261 addi a5, a5, 16
262#if !XCHAL_HAVE_LOOPS
263 blt a3, a10, .Loop2
264#endif /* !XCHAL_HAVE_LOOPS */
265.Loop2done:
266 bbci.l a4, 3, .L12
267 # copy 8 bytes
268 l32i a7, a3, 4
269 l32i a8, a3, 8
270 src_b a6, a6, a7
271 s32i a6, a5, 0
272 addi a3, a3, 8
273 src_b a7, a7, a8
274 s32i a7, a5, 4
275 addi a5, a5, 8
276 mov a6, a8
277.L12:
278 bbci.l a4, 2, .L13
279 # copy 4 bytes
280 l32i a7, a3, 4
281 addi a3, a3, 4
282 src_b a6, a6, a7
283 s32i a6, a5, 0
284 addi a5, a5, 4
285 mov a6, a7
286.L13:
287#if XCHAL_UNALIGNED_LOAD_EXCEPTION || SIM_CHECKS_ALIGNMENT
288 add a3, a3, a11 # readjust a3 with correct misalignment
289#endif
290 bbsi.l a4, 1, .L14
291 bbsi.l a4, 0, .L15
292.Ldone: retw
293.L14:
294 # copy 2 bytes
295 l8ui a6, a3, 0
296 l8ui a7, a3, 1
297 addi a3, a3, 2
298 s8i a6, a5, 0
299 s8i a7, a5, 1
300 addi a5, a5, 2
301 bbsi.l a4, 0, .L15
302 retw
303.L15:
304 # copy 1 byte
305 l8ui a6, a3, 0
306 s8i a6, a5, 0
307 retw
308\f
309/*
310 * Local Variables:
311 * mode:fundamental
312 * comment-start: "# "
313 * comment-start-skip: "# *"
314 * End:
315 */
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