--- /dev/null
+/*
+ * 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:
+ */
Code Review / vpp.git / blobdiff