171 lines
3.7 KiB
C
171 lines
3.7 KiB
C
/* bit vector utility routines */
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/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <errno.h>
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#include <sys/types.h>
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#include <osmocore/bitvec.h>
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#define BITNUM_FROM_COMP(byte, bit) ((byte*8)+bit)
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static inline unsigned int bytenum_from_bitnum(unsigned int bitnum)
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{
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unsigned int bytenum = bitnum / 8;
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return bytenum;
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}
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/* convert ZERO/ONE/L/H to a bitmask at given pos in a byte */
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static u_int8_t bitval2mask(enum bit_value bit, u_int8_t bitnum)
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{
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int bitval;
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switch (bit) {
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case ZERO:
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bitval = (0 << bitnum);
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break;
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case ONE:
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bitval = (1 << bitnum);
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break;
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case L:
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bitval = ((0x2b ^ (0 << bitnum)) & (1 << bitnum));
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break;
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case H:
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bitval = ((0x2b ^ (1 << bitnum)) & (1 << bitnum));
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break;
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default:
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return 0;
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}
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return bitval;
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}
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/* check if the bit is 0 or 1 for a given position inside a bitvec */
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enum bit_value bitvec_get_bit_pos(struct bitvec *bv, unsigned int bitnr)
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{
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unsigned int bytenum = bytenum_from_bitnum(bitnr);
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unsigned int bitnum = 7 - (bitnr % 8);
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u_int8_t bitval;
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if (bytenum >= bv->data_len)
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return -EINVAL;
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bitval = bitval2mask(ONE, bitnum);
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if (bv->data[bytenum] & bitval)
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return ONE;
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return ZERO;
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}
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/* get the Nth set bit inside the bit vector */
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unsigned int bitvec_get_nth_set_bit(struct bitvec *bv, unsigned int n)
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{
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unsigned int i, k = 0;
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for (i = 0; i < bv->data_len*8; i++) {
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if (bitvec_get_bit_pos(bv, i) == ONE) {
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k++;
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if (k == n)
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return i;
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}
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}
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return 0;
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}
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/* set the bit at a given position inside a bitvec */
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int bitvec_set_bit_pos(struct bitvec *bv, unsigned int bitnr,
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enum bit_value bit)
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{
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unsigned int bytenum = bytenum_from_bitnum(bitnr);
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unsigned int bitnum = 7 - (bitnr % 8);
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u_int8_t bitval;
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if (bytenum >= bv->data_len)
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return -EINVAL;
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/* first clear the bit */
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bitval = bitval2mask(ONE, bitnum);
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bv->data[bytenum] &= ~bitval;
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/* then set it to desired value */
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bitval = bitval2mask(bit, bitnum);
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bv->data[bytenum] |= bitval;
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return 0;
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}
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/* set the next bit inside a bitvec */
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int bitvec_set_bit(struct bitvec *bv, enum bit_value bit)
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{
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int rc;
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rc = bitvec_set_bit_pos(bv, bv->cur_bit, bit);
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if (!rc)
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bv->cur_bit++;
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return rc;
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}
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/* set multiple bits (based on array of bitvals) at current pos */
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int bitvec_set_bits(struct bitvec *bv, enum bit_value *bits, int count)
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{
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int i, rc;
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for (i = 0; i < count; i++) {
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rc = bitvec_set_bit(bv, bits[i]);
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if (rc)
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return rc;
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}
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return 0;
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}
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/* set multiple bits (based on numeric value) at current pos */
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int bitvec_set_uint(struct bitvec *bv, unsigned int ui, int num_bits)
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{
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int i, rc;
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for (i = 0; i < num_bits; i++) {
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int bit = 0;
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if (ui & (1 << (num_bits - i - 1)))
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bit = 1;
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rc = bitvec_set_bit(bv, bit);
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if (rc)
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return rc;
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}
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return 0;
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}
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/* pad all remaining bits up to num_bits */
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int bitvec_spare_padding(struct bitvec *bv, unsigned int up_to_bit)
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{
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unsigned int i;
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for (i = bv->cur_bit; i <= up_to_bit; i++)
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bitvec_set_bit(bv, L);
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return 0;
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}
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