Merge branch 'stable/1710' of https://gerrit.fd.io/r/vpp into 17101710

1 files changed, 166 insertions, 0 deletions

diff --git a/src/vppinfra/zvec.h b/src/vppinfra/zvec.h
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+++ b/src/vppinfra/zvec.h
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+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+  Copyright (c) 2001, 2002, 2003 Eliot Dresselhaus
+
+  Permission is hereby granted, free of charge, to any person obtaining
+  a copy of this software and associated documentation files (the
+  "Software"), to deal in the Software without restriction, including
+  without limitation the rights to use, copy, modify, merge, publish,
+  distribute, sublicense, and/or sell copies of the Software, and to
+  permit persons to whom the Software is furnished to do so, subject to
+  the following conditions:
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software.
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#ifndef included_zvec_h
+#define included_zvec_h
+
+#include <vppinfra/clib.h>
+#include <vppinfra/error.h>	/* for ASSERT */
+#include <vppinfra/format.h>
+
+/* zvec: compressed vectors.
+
+   Data is entropy coded with 32 bit "codings".
+
+   Consider coding as bitmap, coding = 2^c_0 + 2^c_1 + ... + 2^c_n
+   With c_0 < c_1 < ... < c_n.  coding == 0 represents c_n = BITS (uword).
+
+   Unsigned integers i = 0 ... are represented as follows:
+
+       0 <= i < 2^c_0       	(i << 1) | (1 << 0) binary:   i 1
+   2^c_0 <= i < 2^c_0 + 2^c_1   (i << 2) | (1 << 1) binary: i 1 0
+   ...                                              binary: i 0 ... 0
+
+   Smaller numbers use less bits.  Coding is chosen so that encoding
+   of given histogram of typical values gives smallest number of bits.
+   The number and position of coding bits c_i are used to best fit the
+   histogram of typical values.
+*/
+
+typedef struct
+{
+  /* Smallest coding for given histogram of typical data. */
+  u32 coding;
+
+  /* Number of data in histogram. */
+  u32 n_data;
+
+  /* Number of codes (unique values) in histogram. */
+  u32 n_codes;
+
+  /* Number of bits in smallest coding of data. */
+  u32 min_coding_bits;
+
+  /* Average number of bits per code. */
+  f64 ave_coding_bits;
+} zvec_coding_info_t;
+
+/* Encode/decode data. */
+uword zvec_encode (uword coding, uword data, uword * n_result_bits);
+uword zvec_decode (uword coding, uword zdata, uword * n_zdata_bits);
+
+format_function_t format_zvec_coding;
+
+typedef u32 zvec_histogram_count_t;
+
+#define zvec_coding_from_histogram(h,count_field,len,max_value_to_encode,zc) \
+  _zvec_coding_from_histogram ((h), (len),				\
+			       STRUCT_OFFSET_OF_VAR (h, count_field),	\
+			       sizeof (h[0]),				\
+			       max_value_to_encode,			\
+			       (zc))
+
+uword
+_zvec_coding_from_histogram (void *_histogram,
+			     uword histogram_len,
+			     uword histogram_elt_count_offset,
+			     uword histogram_elt_bytes,
+			     uword max_value_to_encode,
+			     zvec_coding_info_t * coding_info_return);
+
+#define _(TYPE,IS_SIGNED)						\
+  uword * zvec_encode_##TYPE (uword * zvec, uword * zvec_n_bits, uword coding, \
+			   void * data, uword data_stride, uword n_data);
+
+_(u8, /* is_signed */ 0);
+_(u16, /* is_signed */ 0);
+_(u32, /* is_signed */ 0);
+_(u64, /* is_signed */ 0);
+_(i8, /* is_signed */ 1);
+_(i16, /* is_signed */ 1);
+_(i32, /* is_signed */ 1);
+_(i64, /* is_signed */ 1);
+
+#undef _
+
+#define _(TYPE,IS_SIGNED)			\
+  void zvec_decode_##TYPE (uword * zvec,	\
+			   uword * zvec_n_bits,	\
+			   uword coding,	\
+			   void * data,		\
+			   uword data_stride,	\
+			   uword n_data)
+
+_(u8, /* is_signed */ 0);
+_(u16, /* is_signed */ 0);
+_(u32, /* is_signed */ 0);
+_(u64, /* is_signed */ 0);
+_(i8, /* is_signed */ 1);
+_(i16, /* is_signed */ 1);
+_(i32, /* is_signed */ 1);
+_(i64, /* is_signed */ 1);
+
+#undef _
+
+/* Signed <=> unsigned conversion.
+      -1, -2, -3, ... =>    1, 3, 5, ... odds
+   0, +1, +2, +3, ... => 0, 2, 4, 6, ... evens */
+always_inline uword
+zvec_signed_to_unsigned (word s)
+{
+  uword a = s < 0;
+  s = 2 * s + a;
+  return a ? -s : s;
+}
+
+always_inline word
+zvec_unsigned_to_signed (uword u)
+{
+  uword a = u & 1;
+  u >>= 1;
+  return a ? -u : u;
+}
+
+#endif /* included_zvec_h */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */