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Diffstat (limited to 'libosmocore/src/bitvec.c')
| -rw-r--r-- | libosmocore/src/bitvec.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/libosmocore/src/bitvec.c b/libosmocore/src/bitvec.c new file mode 100644 index 000000000..eb83ac667 --- /dev/null +++ b/libosmocore/src/bitvec.c @@ -0,0 +1,170 @@ +/* bit vector utility routines */ + +/* (C) 2009 by Harald Welte <laforge@gnumonks.org> + * + * All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + * + */ + + +#include <errno.h> +#include <stdint.h> + +#include <osmocore/bitvec.h> + +#define BITNUM_FROM_COMP(byte, bit) ((byte*8)+bit) + +static inline unsigned int bytenum_from_bitnum(unsigned int bitnum) +{ + unsigned int bytenum = bitnum / 8; + + return bytenum; +} + +/* convert ZERO/ONE/L/H to a bitmask at given pos in a byte */ +static uint8_t bitval2mask(enum bit_value bit, uint8_t bitnum) +{ + int bitval; + + switch (bit) { + case ZERO: + bitval = (0 << bitnum); + break; + case ONE: + bitval = (1 << bitnum); + break; + case L: + bitval = ((0x2b ^ (0 << bitnum)) & (1 << bitnum)); + break; + case H: + bitval = ((0x2b ^ (1 << bitnum)) & (1 << bitnum)); + break; + default: + return 0; + } + return bitval; +} + +/* check if the bit is 0 or 1 for a given position inside a bitvec */ +enum bit_value bitvec_get_bit_pos(const struct bitvec *bv, unsigned int bitnr) +{ + unsigned int bytenum = bytenum_from_bitnum(bitnr); + unsigned int bitnum = 7 - (bitnr % 8); + uint8_t bitval; + + if (bytenum >= bv->data_len) + return -EINVAL; + + bitval = bitval2mask(ONE, bitnum); + + if (bv->data[bytenum] & bitval) + return ONE; + + return ZERO; +} + +/* get the Nth set bit inside the bit vector */ +unsigned int bitvec_get_nth_set_bit(const struct bitvec *bv, unsigned int n) +{ + unsigned int i, k = 0; + + for (i = 0; i < bv->data_len*8; i++) { + if (bitvec_get_bit_pos(bv, i) == ONE) { + k++; + if (k == n) + return i; + } + } + + return 0; +} + +/* set the bit at a given position inside a bitvec */ +int bitvec_set_bit_pos(struct bitvec *bv, unsigned int bitnr, + enum bit_value bit) +{ + unsigned int bytenum = bytenum_from_bitnum(bitnr); + unsigned int bitnum = 7 - (bitnr % 8); + uint8_t bitval; + + if (bytenum >= bv->data_len) + return -EINVAL; + + /* first clear the bit */ + bitval = bitval2mask(ONE, bitnum); + bv->data[bytenum] &= ~bitval; + + /* then set it to desired value */ + bitval = bitval2mask(bit, bitnum); + bv->data[bytenum] |= bitval; + + return 0; +} + +/* set the next bit inside a bitvec */ +int bitvec_set_bit(struct bitvec *bv, enum bit_value bit) +{ + int rc; + + rc = bitvec_set_bit_pos(bv, bv->cur_bit, bit); + if (!rc) + bv->cur_bit++; + + return rc; +} + +/* set multiple bits (based on array of bitvals) at current pos */ +int bitvec_set_bits(struct bitvec *bv, enum bit_value *bits, int count) +{ + int i, rc; + + for (i = 0; i < count; i++) { + rc = bitvec_set_bit(bv, bits[i]); + if (rc) + return rc; + } + + return 0; +} + +/* set multiple bits (based on numeric value) at current pos */ +int bitvec_set_uint(struct bitvec *bv, unsigned int ui, int num_bits) +{ + int i, rc; + + for (i = 0; i < num_bits; i++) { + int bit = 0; + if (ui & (1 << (num_bits - i - 1))) + bit = 1; + rc = bitvec_set_bit(bv, bit); + if (rc) + return rc; + } + + return 0; +} + +/* pad all remaining bits up to num_bits */ +int bitvec_spare_padding(struct bitvec *bv, unsigned int up_to_bit) +{ + unsigned int i; + + for (i = bv->cur_bit; i <= up_to_bit; i++) + bitvec_set_bit(bv, L); + + return 0; +} |