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Diffstat (limited to '')
| -rw-r--r-- | src/basic/bitfield.h | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/src/basic/bitfield.h b/src/basic/bitfield.h new file mode 100644 index 0000000..25bc0eb --- /dev/null +++ b/src/basic/bitfield.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +#pragma once + +#include "macro.h" + +/* Bit index (0-based) to mask of specified type. Assertion failure if index is out of range. */ +#define _INDEX_TO_MASK(type, i, uniq) \ + ({ \ + int UNIQ_T(_i, uniq) = (i); \ + assert(UNIQ_T(_i, uniq) < (int)sizeof(type) * 8); \ + ((type)1) << UNIQ_T(_i, uniq); \ + }) +#define INDEX_TO_MASK(type, i) \ + ({ \ + assert_cc(sizeof(type) <= sizeof(unsigned long long)); \ + assert_cc(__builtin_choose_expr(__builtin_constant_p(i), i, 0) < (int)(sizeof(type) * 8)); \ + __builtin_choose_expr(__builtin_constant_p(i), \ + ((type)1) << (i), \ + _INDEX_TO_MASK(type, i, UNIQ)); \ + }) + +/* Builds a mask of specified type with multiple bits set. Note the result will not be constant, even if all + * indexes are constant. */ +#define INDEXES_TO_MASK(type, ...) \ + UNIQ_INDEXES_TO_MASK(type, UNIQ, ##__VA_ARGS__) +#define UNIQ_INDEXES_TO_MASK(type, uniq, ...) \ + ({ \ + typeof(type) UNIQ_T(_mask, uniq) = (type)0; \ + int UNIQ_T(_i, uniq); \ + VA_ARGS_FOREACH(UNIQ_T(_i, uniq), ##__VA_ARGS__) \ + UNIQ_T(_mask, uniq) |= INDEX_TO_MASK(type, UNIQ_T(_i, uniq)); \ + UNIQ_T(_mask, uniq); \ + }) + +/* Same as the FLAG macros, but accept a 0-based bit index instead of a mask. Results in assertion failure if + * index is out of range for the type. */ +#define SET_BIT(bits, i) SET_FLAG(bits, INDEX_TO_MASK(typeof(bits), i), true) +#define CLEAR_BIT(bits, i) SET_FLAG(bits, INDEX_TO_MASK(typeof(bits), i), false) +#define BIT_SET(bits, i) FLAGS_SET(bits, INDEX_TO_MASK(typeof(bits), i)) + +/* As above, but accepts multiple indexes. Note the result will not be constant, even if all indexes are + * constant. */ +#define SET_BITS(bits, ...) SET_FLAG(bits, INDEXES_TO_MASK(typeof(bits), ##__VA_ARGS__), true) +#define CLEAR_BITS(bits, ...) SET_FLAG(bits, INDEXES_TO_MASK(typeof(bits), ##__VA_ARGS__), false) +#define BITS_SET(bits, ...) FLAGS_SET(bits, INDEXES_TO_MASK(typeof(bits), ##__VA_ARGS__)) + +/* Iterate through each set bit. Index is 0-based and type int. */ +#define BIT_FOREACH(index, bits) _BIT_FOREACH(index, bits, UNIQ) +#define _BIT_FOREACH(index, bits, uniq) \ + for (int UNIQ_T(_last, uniq) = -1, index; \ + (index = BIT_NEXT_SET(bits, UNIQ_T(_last, uniq))) >= 0; \ + UNIQ_T(_last, uniq) = index) + +/* Find the next set bit after 0-based index 'prev'. Result is 0-based index of next set bit, or -1 if no + * more bits are set. */ +#define BIT_FIRST_SET(bits) BIT_NEXT_SET(bits, -1) +#define BIT_NEXT_SET(bits, prev) \ + UNIQ_BIT_NEXT_SET(bits, prev, UNIQ) +#define UNIQ_BIT_NEXT_SET(bits, prev, uniq) \ + ({ \ + typeof(bits) UNIQ_T(_bits, uniq) = (bits); \ + int UNIQ_T(_prev, uniq) = (prev); \ + int UNIQ_T(_next, uniq); \ + _BIT_NEXT_SET(UNIQ_T(_bits, uniq), \ + UNIQ_T(_prev, uniq), \ + UNIQ_T(_next, uniq)); \ + }) +#define _BIT_NEXT_SET(bits, prev, next) \ + ((int)(prev + 1) == (int)sizeof(bits) * 8 \ + ? -1 /* Prev index was msb. */ \ + : ((next = __builtin_ffsll(((unsigned long long)(bits)) >> (prev + 1))) == 0 \ + ? -1 /* No more bits set. */ \ + : prev + next)) |