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1 | #ifndef _CTF_BITFIELD_H |
2 | #define _CTF_BITFIELD_H | |
3 | ||
4 | /* | |
5 | * Common Trace Format | |
6 | * | |
7 | * Bitfields read/write functions. | |
8 | * | |
9 | * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * | |
11 | * Permission is hereby granted, free of charge, to any person obtaining a copy | |
12 | * of this software and associated documentation files (the "Software"), to deal | |
13 | * in the Software without restriction, including without limitation the rights | |
14 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell | |
15 | * copies of the Software, and to permit persons to whom the Software is | |
16 | * furnished to do so, subject to the following conditions: | |
17 | * | |
18 | * The above copyright notice and this permission notice shall be included in | |
19 | * all copies or substantial portions of the Software. | |
20 | */ | |
21 | ||
22 | #include <stdint.h> /* C99 5.2.4.2 Numerical limits */ | |
23 | #include <limits.h> /* C99 5.2.4.2 Numerical limits */ | |
24 | #include <endian.h> /* Non-standard BIG_ENDIAN, LITTLE_ENDIAN, BYTE_ORDER */ | |
25 | #include <assert.h> | |
26 | ||
27 | /* We can't shift a int from 32 bit, >> 32 on int is undefined */ | |
28 | #define _ctf_piecewise_rshift(v, shift) \ | |
29 | ({ \ | |
30 | unsigned long sb = (shift) / (sizeof(v) * CHAR_BIT - 1); \ | |
31 | unsigned long final = (shift) % (sizeof(v) * CHAR_BIT - 1); \ | |
32 | typeof(v) _v = (v); \ | |
33 | \ | |
34 | for (; sb; sb--) \ | |
35 | _v >>= sizeof(v) * CHAR_BIT - 1; \ | |
36 | _v >>= final; \ | |
37 | }) | |
38 | ||
39 | /* | |
40 | * ctf_bitfield_write - write integer to a bitfield in native endianness | |
41 | * | |
42 | * Save integer to the bitfield, which starts at the "start" bit, has "len" | |
43 | * bits. | |
44 | * The inside of a bitfield is from high bits to low bits. | |
45 | * Uses native endianness. | |
46 | * For unsigned "v", pad MSB with 0 if bitfield is larger than v. | |
47 | * For signed "v", sign-extend v if bitfield is larger than v. | |
48 | * | |
49 | * On little endian, bytes are placed from the less significant to the most | |
50 | * significant. Also, consecutive bitfields are placed from lower bits to higher | |
51 | * bits. | |
52 | * | |
53 | * On big endian, bytes are places from most significant to less significant. | |
54 | * Also, consecutive bitfields are placed from higher to lower bits. | |
55 | */ | |
56 | ||
57 | #define _ctf_bitfield_write_le(ptr, _start, _length, _v) \ | |
58 | do { \ | |
59 | typeof(*(ptr)) mask, cmask; \ | |
60 | unsigned long start = (_start), length = (_length); \ | |
61 | typeof(_v) v = (_v); \ | |
62 | unsigned long start_unit, end_unit, this_unit; \ | |
63 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
64 | unsigned long ts = sizeof(typeof(*(ptr))) * CHAR_BIT; /* type size */ \ | |
65 | \ | |
66 | if (!length) \ | |
67 | break; \ | |
68 | \ | |
69 | end = start + length; \ | |
70 | start_unit = start / ts; \ | |
71 | end_unit = (end + (ts - 1)) / ts; \ | |
72 | \ | |
73 | /* Trim v high bits */ \ | |
74 | if (length < sizeof(v) * CHAR_BIT) \ | |
75 | v &= ~((~(typeof(v)) 0) << length); \ | |
76 | \ | |
77 | /* We can now append v with a simple "or", shift it piece-wise */ \ | |
78 | this_unit = start_unit; \ | |
79 | if (start_unit == end_unit - 1) { \ | |
80 | mask = ~((~(typeof(*(ptr))) 0) << (start % ts)); \ | |
81 | if (end % ts) \ | |
82 | mask |= (~(typeof(*(ptr))) 0) << (end % ts); \ | |
83 | cmask = (typeof(*(ptr))) v << (start % ts); \ | |
84 | (ptr)[this_unit] &= mask; \ | |
85 | (ptr)[this_unit] |= cmask; \ | |
86 | break; \ | |
87 | } \ | |
88 | if (start % ts) { \ | |
89 | cshift = start % ts; \ | |
90 | mask = ~((~(typeof(*(ptr))) 0) << cshift); \ | |
91 | cmask = (typeof(*(ptr))) v << cshift; \ | |
92 | (ptr)[this_unit] &= mask; \ | |
93 | (ptr)[this_unit] |= cmask; \ | |
94 | v = _ctf_piecewise_rshift(v, ts - cshift); \ | |
95 | start += ts - cshift; \ | |
96 | this_unit++; \ | |
97 | } \ | |
98 | for (; this_unit < end_unit - 1; this_unit++) { \ | |
99 | (ptr)[this_unit] = (typeof(*(ptr))) v; \ | |
100 | v = _ctf_piecewise_rshift(v, ts); \ | |
101 | start += ts; \ | |
102 | } \ | |
103 | if (end % ts) { \ | |
104 | mask = (~(typeof(*(ptr))) 0) << (end % ts); \ | |
105 | cmask = (typeof(*(ptr))) v; \ | |
106 | (ptr)[this_unit] &= mask; \ | |
107 | (ptr)[this_unit] |= cmask; \ | |
108 | } else \ | |
109 | (ptr)[this_unit] = (typeof(*(ptr))) v; \ | |
110 | } while (0) | |
111 | ||
112 | #define _ctf_bitfield_write_be(ptr, _start, _length, _v) \ | |
113 | do { \ | |
114 | typeof(_v) v = (_v); \ | |
115 | unsigned long start = _start, length = _length; \ | |
116 | unsigned long start_unit, end_unit, this_unit; \ | |
117 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
118 | typeof(*(ptr)) mask, cmask; \ | |
119 | unsigned long ts = sizeof(typeof(*(ptr))) * CHAR_BIT; /* type size */ \ | |
120 | \ | |
121 | if (!length) \ | |
122 | break; \ | |
123 | \ | |
124 | end = start + length; \ | |
125 | start_unit = start / ts; \ | |
126 | end_unit = (end + (ts - 1)) / ts; \ | |
127 | \ | |
128 | /* Trim v high bits */ \ | |
129 | if (length < sizeof(v) * CHAR_BIT) \ | |
130 | v &= ~((~(typeof(v)) 0) << length); \ | |
131 | \ | |
132 | /* We can now append v with a simple "or", shift it piece-wise */ \ | |
133 | this_unit = end_unit - 1; \ | |
134 | if (start_unit == end_unit - 1) { \ | |
135 | mask = ~((~(typeof(*(ptr))) 0) << ((ts - (end % ts)) % ts)); \ | |
136 | if (start % ts) \ | |
137 | mask |= (~((typeof(*(ptr))) 0)) << (ts - (start % ts)); \ | |
138 | cmask = (typeof(*(ptr))) v << ((ts - (end % ts)) % ts); \ | |
139 | (ptr)[this_unit] &= mask; \ | |
140 | (ptr)[this_unit] |= cmask; \ | |
141 | break; \ | |
142 | } \ | |
143 | if (end % ts) { \ | |
144 | cshift = end % ts; \ | |
145 | mask = ~((~(typeof(*(ptr))) 0) << (ts - cshift)); \ | |
146 | cmask = (typeof(*(ptr))) v << (ts - cshift); \ | |
147 | (ptr)[this_unit] &= mask; \ | |
148 | (ptr)[this_unit] |= cmask; \ | |
149 | v = _ctf_piecewise_rshift(v, cshift); \ | |
150 | end -= cshift; \ | |
151 | this_unit--; \ | |
152 | } \ | |
153 | for (; (long)this_unit >= (long)start_unit + 1; this_unit--) { \ | |
154 | (ptr)[this_unit] = (typeof(*(ptr))) v; \ | |
155 | v = _ctf_piecewise_rshift(v, ts); \ | |
156 | end -= ts; \ | |
157 | } \ | |
158 | if (start % ts) { \ | |
159 | mask = (~(typeof(*(ptr))) 0) << (ts - (start % ts)); \ | |
160 | cmask = (typeof(*(ptr))) v; \ | |
161 | (ptr)[this_unit] &= mask; \ | |
162 | (ptr)[this_unit] |= cmask; \ | |
163 | } else \ | |
164 | (ptr)[this_unit] = (typeof(*(ptr))) v; \ | |
165 | } while (0) | |
166 | ||
167 | /* | |
168 | * ctf_bitfield_write - write integer to a bitfield in native endianness | |
169 | * ctf_bitfield_write_le - write integer to a bitfield in little endian | |
170 | * ctf_bitfield_write_be - write integer to a bitfield in big endian | |
171 | */ | |
172 | ||
173 | #if (BYTE_ORDER == LITTLE_ENDIAN) | |
174 | ||
175 | #define ctf_bitfield_write(ptr, _start, _length, _v) \ | |
176 | _ctf_bitfield_write_le(ptr, _start, _length, _v) | |
177 | ||
178 | #define ctf_bitfield_write_le(ptr, _start, _length, _v) \ | |
179 | _ctf_bitfield_write_le(ptr, _start, _length, _v) | |
180 | ||
181 | #define ctf_bitfield_write_be(ptr, _start, _length, _v) \ | |
182 | _ctf_bitfield_write_be((uint8_t *) (ptr), _start, _length, _v) | |
183 | ||
184 | #elif (BYTE_ORDER == BIG_ENDIAN) | |
185 | ||
186 | #define ctf_bitfield_write(ptr, _start, _length, _v) \ | |
187 | _ctf_bitfield_write_be(ptr, _start, _length, _v) | |
188 | ||
189 | #define ctf_bitfield_write_le(ptr, _start, _length, _v) \ | |
190 | _ctf_bitfield_write_le((uint8_t *) (ptr), _start, _length, _v) | |
191 | ||
192 | #define ctf_bitfield_write_be(ptr, _start, _length, _v) \ | |
193 | _ctf_bitfield_write_be(ptr, _start, _length, _v) | |
194 | ||
195 | #else /* (BYTE_ORDER == PDP_ENDIAN) */ | |
196 | ||
197 | #error "Byte order not supported" | |
198 | ||
199 | #endif | |
200 | ||
201 | #if 0 | |
202 | #define _ctf_bitfield_read_le(ptr, _start, _length, _vptr) \ | |
203 | do { \ | |
204 | typeof(_vptr) vptr = (_vptr); \ | |
205 | unsigned long start = _start, length = _length; \ | |
206 | unsigned long start_unit, end_unit, this_unit; \ | |
207 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
208 | typeof(*(ptr)) mask, cmask; \ | |
209 | unsigned long ts = sizeof(typeof(*(ptr))) * CHAR_BIT; /* type size */ \ | |
210 | \ | |
211 | if (!length) \ | |
212 | break; \ | |
213 | \ | |
214 | end = start + length; \ | |
215 | start_unit = start / ts; \ | |
216 | end_unit = (end + (ts - 1)) / ts; \ | |
217 | } while (0) | |
218 | ||
219 | #endif //0 | |
220 | ||
221 | /* | |
222 | * Read a bitfield byte-wise. This function is arch-agnostic. | |
223 | */ | |
224 | ||
225 | static inline | |
226 | uint64_t _ctf_bitfield_read_64(const unsigned char *ptr, | |
227 | unsigned long start, unsigned long len, | |
228 | int byte_order, int signedness) | |
229 | { | |
230 | long start_unit, end_unit, this_unit; | |
231 | unsigned long end, cshift; /* cshift is "complement shift" */ | |
232 | unsigned long ts = sizeof(unsigned char) * CHAR_BIT; | |
233 | unsigned char mask, cmask; | |
234 | uint64_t v = 0; | |
235 | ||
236 | if (!len) | |
237 | return 0; | |
238 | end = start + len; | |
239 | start_unit = start / ts; | |
240 | end_unit = (end + (ts - 1)) / ts; | |
241 | ||
242 | /* | |
243 | * We can now fill v piece-wise, from lower bits to upper bits. | |
244 | * We read the bitfield in the opposite direction it was written. | |
245 | */ | |
246 | switch (byte_order) { | |
247 | case LITTLE_ENDIAN: | |
248 | this_unit = end_unit - 1; | |
249 | if (signedness) { | |
250 | if (ptr[this_unit] & (1U << ((end % ts ? : ts) - 1))) | |
251 | v = ~(uint64_t) 0; | |
252 | } | |
253 | if (start_unit == end_unit - 1) { | |
254 | mask = (~(unsigned char) 0) << (end % ts ? : ts); | |
255 | mask |= ~((~(unsigned char) 0) << (start % ts)); | |
256 | cmask = ptr[this_unit]; | |
257 | cmask &= ~mask; | |
258 | cmask >>= (start % ts); | |
259 | v <<= end - start; | |
260 | v |= cmask; | |
261 | break; | |
262 | } | |
263 | if (end % ts) { | |
264 | cshift = (end % ts ? : ts); | |
265 | mask = (~(unsigned char) 0) << cshift; | |
266 | cmask = ptr[this_unit]; | |
267 | cmask &= ~mask; | |
268 | v <<= cshift; | |
269 | v |= (uint64_t) cmask; | |
270 | end -= cshift; | |
271 | this_unit--; | |
272 | } | |
273 | for (; this_unit >= start_unit + 1; this_unit--) { | |
274 | v <<= ts; | |
275 | v |= (uint64_t) ptr[this_unit]; | |
276 | end -= ts; | |
277 | } | |
278 | if (start % ts) { | |
279 | cmask = ptr[this_unit] >> (start % ts); | |
280 | v <<= ts - (start % ts); | |
281 | v |= (uint64_t) cmask; | |
282 | } else { | |
283 | v <<= ts; | |
284 | v |= (uint64_t) ptr[this_unit]; | |
285 | } | |
286 | break; | |
287 | case BIG_ENDIAN: | |
288 | this_unit = start_unit; | |
289 | if (signedness) { | |
290 | if (ptr[this_unit] & (1U << (ts - (start % ts) - 1))) | |
291 | v = ~(uint64_t) 0; | |
292 | } | |
293 | if (start_unit == end_unit - 1) { | |
294 | mask = (~(unsigned char) 0) << (ts - (start % ts)); | |
295 | mask |= ~((~(unsigned char) 0) << ((ts - (end % ts)) % ts)); | |
296 | cmask = ptr[this_unit]; | |
297 | cmask &= ~mask; | |
298 | cmask >>= (ts - (end % ts)) % ts; | |
299 | v <<= end - start; | |
300 | v |= (uint64_t) cmask; | |
301 | break; | |
302 | } | |
303 | if (start % ts) { | |
304 | mask = (~(unsigned char) 0) << (ts - (start % ts)); | |
305 | cmask = ptr[this_unit]; | |
306 | cmask &= ~mask; | |
307 | v <<= ts - (start % ts); | |
308 | v |= (uint64_t) cmask; | |
309 | start += ts - (start % ts); | |
310 | this_unit++; | |
311 | } | |
312 | for (; this_unit < end_unit - 1; this_unit++) { | |
313 | v <<= ts; | |
314 | v |= (uint64_t) ptr[this_unit]; | |
315 | start += ts; | |
316 | } | |
317 | if (end % ts) { | |
318 | cmask = ptr[this_unit]; | |
319 | cmask >>= (ts - (end % ts)) % ts; | |
320 | v <<= (end % ts); | |
321 | v |= (uint64_t) cmask; | |
322 | } else { | |
323 | v <<= ts; | |
324 | v |= (uint64_t) ptr[this_unit]; | |
325 | } | |
326 | break; | |
327 | default: | |
328 | assert(0); /* TODO: support PDP_ENDIAN */ | |
329 | } | |
330 | return v; | |
331 | } | |
332 | ||
333 | static inline | |
334 | uint64_t ctf_bitfield_unsigned_read(const uint8_t *ptr, | |
335 | unsigned long start, unsigned long len, | |
336 | int byte_order) | |
337 | { | |
338 | return (uint64_t) _ctf_bitfield_read_64(ptr, start, len, byte_order, 0); | |
339 | } | |
340 | ||
341 | static inline | |
342 | int64_t ctf_bitfield_signed_read(const uint8_t *ptr, | |
343 | unsigned long start, unsigned long len, | |
344 | int byte_order) | |
345 | { | |
346 | return (int64_t) _ctf_bitfield_read_64(ptr, start, len, byte_order, 1); | |
347 | } | |
348 | ||
349 | #endif /* _CTF_BITFIELD_H */ |