Repo created

3party/succinct/vbyte.hpp

@@ -0,0 +1,41 @@
+#pragma once
+
+#include "broadword.hpp"
+
+namespace succinct {
+
+    inline size_t vbyte_size(size_t val)
+    {
+        unsigned long bits;
+        if (!broadword::msb(val, bits)) bits = 0;
+        return util::ceil_div(bits + 1, 7);
+    }
+
+    template <typename Vector>
+    inline size_t append_vbyte(Vector& v, size_t val)
+    {
+        size_t chunks = vbyte_size(val);
+        for (size_t b = chunks - 1; b + 1 > 0; --b) {
+            uint8_t chunk = (val >> (b * 7)) & 0x7F;
+            chunk |= b ? 0x80 : 0;
+            v.push_back(chunk);
+        }
+        return chunks;
+    }
+
+    template <typename Vector>
+    inline size_t decode_vbyte(Vector const& v, size_t offset, size_t& val)
+    {
+        size_t pos = offset;
+        val = 0;
+        uint8_t chunk;
+        do {
+            chunk = v[pos++];
+            val <<= 7;
+            val |= chunk & 0x7F;
+        } while (chunk & 0x80);
+
+        return pos - offset;
+    }
+
+}