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9f36eaed MJ |
1 | /* SPDX-License-Identifier: MIT |
2 | * | |
9115fbdc MD |
3 | * BabelTrace |
4 | * | |
5 | * Bitfields read/write functions. | |
6 | * | |
7 | * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
9115fbdc MD |
8 | */ |
9 | ||
9f36eaed MJ |
10 | #ifndef _BABELTRACE_BITFIELD_H |
11 | #define _BABELTRACE_BITFIELD_H | |
12 | ||
5671a661 | 13 | #include <lttng-endian.h> |
9115fbdc MD |
14 | |
15 | #ifndef CHAR_BIT | |
16 | #define CHAR_BIT 8 | |
17 | #endif | |
18 | ||
19 | /* We can't shift a int from 32 bit, >> 32 and << 32 on int is undefined */ | |
20 | #define _bt_piecewise_rshift(_v, _shift) \ | |
21 | ({ \ | |
22 | typeof(_v) ___v = (_v); \ | |
23 | typeof(_shift) ___shift = (_shift); \ | |
24 | unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \ | |
25 | unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \ | |
26 | \ | |
27 | for (; sb; sb--) \ | |
28 | ___v >>= sizeof(___v) * CHAR_BIT - 1; \ | |
29 | ___v >>= final; \ | |
30 | }) | |
31 | ||
32 | #define _bt_piecewise_lshift(_v, _shift) \ | |
33 | ({ \ | |
34 | typeof(_v) ___v = (_v); \ | |
35 | typeof(_shift) ___shift = (_shift); \ | |
36 | unsigned long sb = (___shift) / (sizeof(___v) * CHAR_BIT - 1); \ | |
37 | unsigned long final = (___shift) % (sizeof(___v) * CHAR_BIT - 1); \ | |
38 | \ | |
39 | for (; sb; sb--) \ | |
40 | ___v <<= sizeof(___v) * CHAR_BIT - 1; \ | |
41 | ___v <<= final; \ | |
42 | }) | |
43 | ||
44 | #define _bt_is_signed_type(type) (((type)(-1)) < 0) | |
45 | ||
46 | #define _bt_unsigned_cast(type, v) \ | |
47 | ({ \ | |
48 | (sizeof(v) < sizeof(type)) ? \ | |
49 | ((type) (v)) & (~(~(type) 0 << (sizeof(v) * CHAR_BIT))) : \ | |
50 | (type) (v); \ | |
51 | }) | |
52 | ||
53 | /* | |
54 | * bt_bitfield_write - write integer to a bitfield in native endianness | |
55 | * | |
56 | * Save integer to the bitfield, which starts at the "start" bit, has "len" | |
57 | * bits. | |
58 | * The inside of a bitfield is from high bits to low bits. | |
59 | * Uses native endianness. | |
60 | * For unsigned "v", pad MSB with 0 if bitfield is larger than v. | |
61 | * For signed "v", sign-extend v if bitfield is larger than v. | |
62 | * | |
63 | * On little endian, bytes are placed from the less significant to the most | |
64 | * significant. Also, consecutive bitfields are placed from lower bits to higher | |
65 | * bits. | |
66 | * | |
67 | * On big endian, bytes are places from most significant to less significant. | |
68 | * Also, consecutive bitfields are placed from higher to lower bits. | |
69 | */ | |
70 | ||
71 | #define _bt_bitfield_write_le(_ptr, type, _start, _length, _v) \ | |
72 | do { \ | |
73 | typeof(_v) __v = (_v); \ | |
74 | type *__ptr = (void *) (_ptr); \ | |
75 | unsigned long __start = (_start), __length = (_length); \ | |
76 | type mask, cmask; \ | |
77 | unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \ | |
78 | unsigned long start_unit, end_unit, this_unit; \ | |
79 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
80 | \ | |
81 | if (!__length) \ | |
82 | break; \ | |
83 | \ | |
84 | end = __start + __length; \ | |
85 | start_unit = __start / ts; \ | |
86 | end_unit = (end + (ts - 1)) / ts; \ | |
87 | \ | |
88 | /* Trim v high bits */ \ | |
89 | if (__length < sizeof(__v) * CHAR_BIT) \ | |
90 | __v &= ~((~(typeof(__v)) 0) << __length); \ | |
91 | \ | |
92 | /* We can now append v with a simple "or", shift it piece-wise */ \ | |
93 | this_unit = start_unit; \ | |
94 | if (start_unit == end_unit - 1) { \ | |
95 | mask = ~((~(type) 0) << (__start % ts)); \ | |
96 | if (end % ts) \ | |
97 | mask |= (~(type) 0) << (end % ts); \ | |
98 | cmask = (type) __v << (__start % ts); \ | |
99 | cmask &= ~mask; \ | |
100 | __ptr[this_unit] &= mask; \ | |
101 | __ptr[this_unit] |= cmask; \ | |
102 | break; \ | |
103 | } \ | |
104 | if (__start % ts) { \ | |
105 | cshift = __start % ts; \ | |
106 | mask = ~((~(type) 0) << cshift); \ | |
107 | cmask = (type) __v << cshift; \ | |
108 | cmask &= ~mask; \ | |
109 | __ptr[this_unit] &= mask; \ | |
110 | __ptr[this_unit] |= cmask; \ | |
111 | __v = _bt_piecewise_rshift(__v, ts - cshift); \ | |
112 | __start += ts - cshift; \ | |
113 | this_unit++; \ | |
114 | } \ | |
115 | for (; this_unit < end_unit - 1; this_unit++) { \ | |
116 | __ptr[this_unit] = (type) __v; \ | |
117 | __v = _bt_piecewise_rshift(__v, ts); \ | |
118 | __start += ts; \ | |
119 | } \ | |
120 | if (end % ts) { \ | |
121 | mask = (~(type) 0) << (end % ts); \ | |
122 | cmask = (type) __v; \ | |
123 | cmask &= ~mask; \ | |
124 | __ptr[this_unit] &= mask; \ | |
125 | __ptr[this_unit] |= cmask; \ | |
126 | } else \ | |
127 | __ptr[this_unit] = (type) __v; \ | |
128 | } while (0) | |
129 | ||
130 | #define _bt_bitfield_write_be(_ptr, type, _start, _length, _v) \ | |
131 | do { \ | |
132 | typeof(_v) __v = (_v); \ | |
133 | type *__ptr = (void *) (_ptr); \ | |
134 | unsigned long __start = (_start), __length = (_length); \ | |
135 | type mask, cmask; \ | |
136 | unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \ | |
137 | unsigned long start_unit, end_unit, this_unit; \ | |
138 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
139 | \ | |
140 | if (!__length) \ | |
141 | break; \ | |
142 | \ | |
143 | end = __start + __length; \ | |
144 | start_unit = __start / ts; \ | |
145 | end_unit = (end + (ts - 1)) / ts; \ | |
146 | \ | |
147 | /* Trim v high bits */ \ | |
148 | if (__length < sizeof(__v) * CHAR_BIT) \ | |
149 | __v &= ~((~(typeof(__v)) 0) << __length); \ | |
150 | \ | |
151 | /* We can now append v with a simple "or", shift it piece-wise */ \ | |
152 | this_unit = end_unit - 1; \ | |
153 | if (start_unit == end_unit - 1) { \ | |
154 | mask = ~((~(type) 0) << ((ts - (end % ts)) % ts)); \ | |
155 | if (__start % ts) \ | |
156 | mask |= (~((type) 0)) << (ts - (__start % ts)); \ | |
157 | cmask = (type) __v << ((ts - (end % ts)) % ts); \ | |
158 | cmask &= ~mask; \ | |
159 | __ptr[this_unit] &= mask; \ | |
160 | __ptr[this_unit] |= cmask; \ | |
161 | break; \ | |
162 | } \ | |
163 | if (end % ts) { \ | |
164 | cshift = end % ts; \ | |
165 | mask = ~((~(type) 0) << (ts - cshift)); \ | |
166 | cmask = (type) __v << (ts - cshift); \ | |
167 | cmask &= ~mask; \ | |
168 | __ptr[this_unit] &= mask; \ | |
169 | __ptr[this_unit] |= cmask; \ | |
170 | __v = _bt_piecewise_rshift(__v, cshift); \ | |
171 | end -= cshift; \ | |
172 | this_unit--; \ | |
173 | } \ | |
174 | for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \ | |
175 | __ptr[this_unit] = (type) __v; \ | |
176 | __v = _bt_piecewise_rshift(__v, ts); \ | |
177 | end -= ts; \ | |
178 | } \ | |
179 | if (__start % ts) { \ | |
180 | mask = (~(type) 0) << (ts - (__start % ts)); \ | |
181 | cmask = (type) __v; \ | |
182 | cmask &= ~mask; \ | |
183 | __ptr[this_unit] &= mask; \ | |
184 | __ptr[this_unit] |= cmask; \ | |
185 | } else \ | |
186 | __ptr[this_unit] = (type) __v; \ | |
187 | } while (0) | |
188 | ||
189 | /* | |
190 | * bt_bitfield_write - write integer to a bitfield in native endianness | |
191 | * bt_bitfield_write_le - write integer to a bitfield in little endian | |
192 | * bt_bitfield_write_be - write integer to a bitfield in big endian | |
193 | */ | |
194 | ||
195 | #if (__BYTE_ORDER == __LITTLE_ENDIAN) | |
196 | ||
197 | #define bt_bitfield_write(ptr, type, _start, _length, _v) \ | |
198 | _bt_bitfield_write_le(ptr, type, _start, _length, _v) | |
199 | ||
200 | #define bt_bitfield_write_le(ptr, type, _start, _length, _v) \ | |
201 | _bt_bitfield_write_le(ptr, type, _start, _length, _v) | |
202 | ||
203 | #define bt_bitfield_write_be(ptr, type, _start, _length, _v) \ | |
204 | _bt_bitfield_write_be(ptr, unsigned char, _start, _length, _v) | |
205 | ||
206 | #elif (__BYTE_ORDER == __BIG_ENDIAN) | |
207 | ||
208 | #define bt_bitfield_write(ptr, type, _start, _length, _v) \ | |
209 | _bt_bitfield_write_be(ptr, type, _start, _length, _v) | |
210 | ||
211 | #define bt_bitfield_write_le(ptr, type, _start, _length, _v) \ | |
212 | _bt_bitfield_write_le(ptr, unsigned char, _start, _length, _v) | |
213 | ||
214 | #define bt_bitfield_write_be(ptr, type, _start, _length, _v) \ | |
215 | _bt_bitfield_write_be(ptr, type, _start, _length, _v) | |
216 | ||
217 | #else /* (BYTE_ORDER == PDP_ENDIAN) */ | |
218 | ||
219 | #error "Byte order not supported" | |
220 | ||
221 | #endif | |
222 | ||
223 | #define _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \ | |
224 | do { \ | |
225 | typeof(*(_vptr)) *__vptr = (_vptr); \ | |
226 | typeof(*__vptr) __v; \ | |
227 | type *__ptr = (void *) (_ptr); \ | |
228 | unsigned long __start = (_start), __length = (_length); \ | |
229 | type mask, cmask; \ | |
230 | unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \ | |
231 | unsigned long start_unit, end_unit, this_unit; \ | |
232 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
233 | \ | |
234 | if (!__length) { \ | |
235 | *__vptr = 0; \ | |
236 | break; \ | |
237 | } \ | |
238 | \ | |
239 | end = __start + __length; \ | |
240 | start_unit = __start / ts; \ | |
241 | end_unit = (end + (ts - 1)) / ts; \ | |
242 | \ | |
243 | this_unit = end_unit - 1; \ | |
244 | if (_bt_is_signed_type(typeof(__v)) \ | |
245 | && (__ptr[this_unit] & ((type) 1 << ((end % ts ? : ts) - 1)))) \ | |
246 | __v = ~(typeof(__v)) 0; \ | |
247 | else \ | |
248 | __v = 0; \ | |
249 | if (start_unit == end_unit - 1) { \ | |
250 | cmask = __ptr[this_unit]; \ | |
251 | cmask >>= (__start % ts); \ | |
252 | if ((end - __start) % ts) { \ | |
253 | mask = ~((~(type) 0) << (end - __start)); \ | |
254 | cmask &= mask; \ | |
255 | } \ | |
256 | __v = _bt_piecewise_lshift(__v, end - __start); \ | |
257 | __v |= _bt_unsigned_cast(typeof(__v), cmask); \ | |
258 | *__vptr = __v; \ | |
259 | break; \ | |
260 | } \ | |
261 | if (end % ts) { \ | |
262 | cshift = end % ts; \ | |
263 | mask = ~((~(type) 0) << cshift); \ | |
264 | cmask = __ptr[this_unit]; \ | |
265 | cmask &= mask; \ | |
266 | __v = _bt_piecewise_lshift(__v, cshift); \ | |
267 | __v |= _bt_unsigned_cast(typeof(__v), cmask); \ | |
268 | end -= cshift; \ | |
269 | this_unit--; \ | |
270 | } \ | |
271 | for (; (long) this_unit >= (long) start_unit + 1; this_unit--) { \ | |
272 | __v = _bt_piecewise_lshift(__v, ts); \ | |
273 | __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\ | |
274 | end -= ts; \ | |
275 | } \ | |
276 | if (__start % ts) { \ | |
277 | mask = ~((~(type) 0) << (ts - (__start % ts))); \ | |
278 | cmask = __ptr[this_unit]; \ | |
279 | cmask >>= (__start % ts); \ | |
280 | cmask &= mask; \ | |
281 | __v = _bt_piecewise_lshift(__v, ts - (__start % ts)); \ | |
282 | __v |= _bt_unsigned_cast(typeof(__v), cmask); \ | |
283 | } else { \ | |
284 | __v = _bt_piecewise_lshift(__v, ts); \ | |
285 | __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\ | |
286 | } \ | |
287 | *__vptr = __v; \ | |
288 | } while (0) | |
289 | ||
290 | #define _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \ | |
291 | do { \ | |
292 | typeof(*(_vptr)) *__vptr = (_vptr); \ | |
293 | typeof(*__vptr) __v; \ | |
294 | type *__ptr = (void *) (_ptr); \ | |
295 | unsigned long __start = (_start), __length = (_length); \ | |
296 | type mask, cmask; \ | |
297 | unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */ \ | |
298 | unsigned long start_unit, end_unit, this_unit; \ | |
299 | unsigned long end, cshift; /* cshift is "complement shift" */ \ | |
300 | \ | |
301 | if (!__length) { \ | |
302 | *__vptr = 0; \ | |
303 | break; \ | |
304 | } \ | |
305 | \ | |
306 | end = __start + __length; \ | |
307 | start_unit = __start / ts; \ | |
308 | end_unit = (end + (ts - 1)) / ts; \ | |
309 | \ | |
310 | this_unit = start_unit; \ | |
311 | if (_bt_is_signed_type(typeof(__v)) \ | |
312 | && (__ptr[this_unit] & ((type) 1 << (ts - (__start % ts) - 1)))) \ | |
313 | __v = ~(typeof(__v)) 0; \ | |
314 | else \ | |
315 | __v = 0; \ | |
316 | if (start_unit == end_unit - 1) { \ | |
317 | cmask = __ptr[this_unit]; \ | |
318 | cmask >>= (ts - (end % ts)) % ts; \ | |
319 | if ((end - __start) % ts) { \ | |
320 | mask = ~((~(type) 0) << (end - __start)); \ | |
321 | cmask &= mask; \ | |
322 | } \ | |
323 | __v = _bt_piecewise_lshift(__v, end - __start); \ | |
324 | __v |= _bt_unsigned_cast(typeof(__v), cmask); \ | |
325 | *__vptr = __v; \ | |
326 | break; \ | |
327 | } \ | |
328 | if (__start % ts) { \ | |
329 | cshift = __start % ts; \ | |
330 | mask = ~((~(type) 0) << (ts - cshift)); \ | |
331 | cmask = __ptr[this_unit]; \ | |
332 | cmask &= mask; \ | |
333 | __v = _bt_piecewise_lshift(__v, ts - cshift); \ | |
334 | __v |= _bt_unsigned_cast(typeof(__v), cmask); \ | |
335 | __start += ts - cshift; \ | |
336 | this_unit++; \ | |
337 | } \ | |
338 | for (; this_unit < end_unit - 1; this_unit++) { \ | |
339 | __v = _bt_piecewise_lshift(__v, ts); \ | |
340 | __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\ | |
341 | __start += ts; \ | |
342 | } \ | |
343 | if (end % ts) { \ | |
344 | mask = ~((~(type) 0) << (end % ts)); \ | |
345 | cmask = __ptr[this_unit]; \ | |
346 | cmask >>= ts - (end % ts); \ | |
347 | cmask &= mask; \ | |
348 | __v = _bt_piecewise_lshift(__v, end % ts); \ | |
349 | __v |= _bt_unsigned_cast(typeof(__v), cmask); \ | |
350 | } else { \ | |
351 | __v = _bt_piecewise_lshift(__v, ts); \ | |
352 | __v |= _bt_unsigned_cast(typeof(__v), __ptr[this_unit]);\ | |
353 | } \ | |
354 | *__vptr = __v; \ | |
355 | } while (0) | |
356 | ||
357 | /* | |
358 | * bt_bitfield_read - read integer from a bitfield in native endianness | |
359 | * bt_bitfield_read_le - read integer from a bitfield in little endian | |
360 | * bt_bitfield_read_be - read integer from a bitfield in big endian | |
361 | */ | |
362 | ||
363 | #if (__BYTE_ORDER == __LITTLE_ENDIAN) | |
364 | ||
365 | #define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \ | |
366 | _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) | |
367 | ||
368 | #define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \ | |
369 | _bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) | |
370 | ||
371 | #define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \ | |
372 | _bt_bitfield_read_be(_ptr, unsigned char, _start, _length, _vptr) | |
373 | ||
374 | #elif (__BYTE_ORDER == __BIG_ENDIAN) | |
375 | ||
376 | #define bt_bitfield_read(_ptr, type, _start, _length, _vptr) \ | |
377 | _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) | |
378 | ||
379 | #define bt_bitfield_read_le(_ptr, type, _start, _length, _vptr) \ | |
380 | _bt_bitfield_read_le(_ptr, unsigned char, _start, _length, _vptr) | |
381 | ||
382 | #define bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) \ | |
383 | _bt_bitfield_read_be(_ptr, type, _start, _length, _vptr) | |
384 | ||
385 | #else /* (__BYTE_ORDER == __PDP_ENDIAN) */ | |
386 | ||
387 | #error "Byte order not supported" | |
388 | ||
389 | #endif | |
390 | ||
391 | #endif /* _BABELTRACE_BITFIELD_H */ |