From 4cd99e3fa5cda1655da226d6abd562f902d67fcc Mon Sep 17 00:00:00 2001
From: Max <msuraev@sysmocom.de>
Date: Tue, 26 Jan 2016 18:53:45 +0100
Subject: [PATCH] Expand bitvec interface
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(-)
@@ -4,6 +4,7 @@
/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
* (C) 2012 Ivan Klyuchnikov
+ * (C) 2015 Sysmocom s.f.m.c. GmbH by Max <msuraev@sysmocom.de>
*
* 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);
/*! @} */
@@ -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