Add bit filling, shifting and oter functions necessary for bit compression implementation.
Sponsored-by: On-Waves ehf --- include/osmocom/core/bitvec.h | 9 +++ src/bitvec.c | 132 ++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 136 insertions(+), 5 deletions(-) diff --git a/include/osmocom/core/bitvec.h b/include/osmocom/core/bitvec.h index d64d69d..774272f 100644 --- a/include/osmocom/core/bitvec.h +++ b/include/osmocom/core/bitvec.h @@ -4,6 +4,7 @@ /* (C) 2009 by Harald Welte <[email protected]> * (C) 2012 Ivan Klyuchnikov + * (C) 2015 Sysmocom s.f.m.c. GmbH by Max <[email protected]> * * All Rights Reserved * @@ -41,6 +42,7 @@ #include <stdint.h> #include <talloc.h> +#include <stdbool.h> /*! \brief A single GSM bit * @@ -82,5 +84,12 @@ unsigned int bitvec_pack(const struct bitvec *bv, uint8_t *buffer); unsigned int bitvec_unpack(struct bitvec *bv, const uint8_t *buffer); uint64_t bitvec_read_field(struct bitvec *bv, unsigned int read_index, unsigned int len); int bitvec_write_field(struct bitvec *bv, unsigned int write_index, uint64_t val, unsigned int len); +int bitvec_fill(struct bitvec *bv, unsigned int num_bits, enum bit_value fill); +char bit_value_to_char(enum bit_value v); +void bitvec_to_string_r(const struct bitvec *bv, char *str); +void bitvec_zero(struct bitvec *bv); +unsigned bitvec_rl(const struct bitvec *bv, bool b); +void bitvec_shiftl(struct bitvec *bv, unsigned int n); +int16_t bitvec_get_int16_msb(const struct bitvec *bv, unsigned int num_bits); /*! @} */ diff --git a/src/bitvec.c b/src/bitvec.c index f9341b7..09281d4 100644 --- a/src/bitvec.c +++ b/src/bitvec.c @@ -34,7 +34,9 @@ #include <stdint.h> #include <string.h> #include <stdio.h> +#include <stdbool.h> +#include <osmocom/core/bits.h> #include <osmocom/core/bitvec.h> #define BITNUM_FROM_COMP(byte, bit) ((byte*8)+bit) @@ -222,6 +224,20 @@ int bitvec_set_uint(struct bitvec *bv, unsigned int ui, unsigned int num_bits) return 0; } +/*! \brief get multiple bits (num_bits) from beginning of vector (MSB side) */ +int16_t bitvec_get_int16_msb(const struct bitvec *bv, unsigned int num_bits) +{ + uint8_t tmp[2]; + if (num_bits > 15 || bv->cur_bit < num_bits) + return -EINVAL; + + if (num_bits < 9) + return bv->data[0] >> (8 - num_bits); + + memcpy(tmp, bv->data, 2); + return osmo_load16be(tmp) >> (16 - num_bits); +} + /*! \brief get multiple bits (based on numeric value) from current pos */ int bitvec_get_uint(struct bitvec *bv, unsigned int num_bits) { @@ -240,15 +256,27 @@ int bitvec_get_uint(struct bitvec *bv, unsigned int num_bits) return ui; } +/*! \brief fill num_bits with \fill starting from the current position + * returns 0 on success, negative otherwise (out of vector boundary) + */ +int bitvec_fill(struct bitvec *bv, unsigned int num_bits, enum bit_value fill) +{ + unsigned i, stop = bv->cur_bit + num_bits; + for (i = bv->cur_bit; i < stop; i++) + if (bitvec_set_bit(bv, fill) < 0) + return -EINVAL; + + return 0; +} + /*! \brief 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); + int n = up_to_bit - bv->cur_bit + 1; + if (n < 1) + return 0; - return 0; + return bitvec_fill(bv, n, L); } /*! \brief find first bit set in bit vector */ @@ -431,4 +459,98 @@ int bitvec_write_field(struct bitvec *bv, unsigned int write_index, uint64_t val return 0; } +/*! \brief convert enum to corresponding character */ +char bit_value_to_char(enum bit_value v) +{ + switch (v) { + case ZERO: return '0'; + case ONE: return '1'; + case L: return 'L'; + case H: return 'H'; + } + /* make compiler happy - "avoid control reaches end of non-void function" warning: */ + return '?'; +} + +/*! \brief prints bit vector to provided string + * It's caller's responcibility to ensure that we won't shoot him in the foot. + */ +void bitvec_to_string_r(const struct bitvec *bv, char *str) +{ + unsigned i, pos = 0; + char *cur = str; + for (i = 0; i < bv->cur_bit; i++) { + if (0 == i % 8) + *cur++ = ' '; + *cur++ = bit_value_to_char(bitvec_get_bit_pos(bv, i)); + pos++; + } + *cur = 0; +} + +/* we assume that x have at least 1 non-b bit */ +static inline unsigned _leading_bits(uint8_t x, bool b) +{ + if (b) { + if (x < 0x80) return 0; + if (x < 0xC0) return 1; + if (x < 0xE0) return 2; + if (x < 0xF0) return 3; + if (x < 0xF8) return 4; + if (x < 0xFC) return 5; + if (x < 0xFE) return 6; + } else { + if (x > 0x7F) return 0; + if (x > 0x3F) return 1; + if (x > 0x1F) return 2; + if (x > 0xF) return 3; + if (x > 7) return 4; + if (x > 3) return 5; + if (x > 1) return 6; + } + return 7; +} +/*! \brief force bit vector to all 0 and current bit to the beginnig of the vector */ +void bitvec_zero(struct bitvec *bv) +{ + bv->cur_bit = 0; + memset(bv->data, 0, bv->data_len); +} + +/*! \brief Return number (bits) of uninterrupted run of \b in \bv starting from the MSB */ +unsigned bitvec_rl(const struct bitvec *bv, bool b) +{ + unsigned i; + for (i = 0; i < (bv->cur_bit % 8 ? bv->cur_bit / 8 + 1 : bv->cur_bit / 8); i++) { + if ( (b ? 0xFF : 0) != bv->data[i]) + return i * 8 + _leading_bits(bv->data[i], b); + } + + return bv->cur_bit; +} + +/*! \brief Shifts bitvec to the left, n MSB bits lost */ +void bitvec_shiftl(struct bitvec *bv, unsigned n) +{ + if (0 == n) + return; + if (n >= bv->cur_bit) { + bitvec_zero(bv); + return; + } + + memmove(bv->data, bv->data + n / 8, bv->data_len - n / 8); + + uint8_t tmp[2]; + unsigned i; + for (i = 0; i < bv->data_len - 2; i++) { + uint16_t t = osmo_load16be(bv->data + i); + osmo_store16be(t << (n % 8), &tmp); + bv->data[i] = tmp[0]; + } + + bv->data[bv->data_len - 1] <<= (n % 8); + bv->cur_bit -= n; +} + /*! @} */ -- 2.5.0 --------------050604090307060803070706--
