intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 71 insertions, 0 deletions

diff --git a/library/cpp/yson/varint.cpp b/library/cpp/yson/varint.cpp
new file mode 100644
index 0000000000..d538ee3cff
--- /dev/null
+++ b/library/cpp/yson/varint.cpp
@@ -0,0 +1,71 @@
+#include "varint.h"
+
+#include "zigzag.h"
+
+#include <util/generic/yexception.h>
+
+namespace NYson {
+    ////////////////////////////////////////////////////////////////////////////////
+
+    int WriteVarUInt64(IOutputStream* output, ui64 value) {
+        bool stop = false;
+        int bytesWritten = 0;
+        while (!stop) {
+            ++bytesWritten;
+            ui8 byte = static_cast<ui8>(value | 0x80);
+            value >>= 7;
+            if (value == 0) {
+                stop = true;
+                byte &= 0x7F;
+            }
+            output->Write(byte);
+        }
+        return bytesWritten;
+    }
+
+    int WriteVarInt32(IOutputStream* output, i32 value) {
+        return WriteVarUInt64(output, static_cast<ui64>(ZigZagEncode32(value)));
+    }
+
+    int WriteVarInt64(IOutputStream* output, i64 value) {
+        return WriteVarUInt64(output, static_cast<ui64>(ZigZagEncode64(value)));
+    }
+
+    int ReadVarUInt64(IInputStream* input, ui64* value) {
+        size_t count = 0;
+        ui64 result = 0;
+
+        ui8 byte = 0;
+        do {
+            if (7 * count > 8 * sizeof(ui64)) {
+                ythrow yexception() << "The data is too long to read ui64";
+            }
+            if (input->Read(&byte, 1) != 1) {
+                ythrow yexception() << "The data is too long to read ui64";
+            }
+            result |= (static_cast<ui64>(byte & 0x7F)) << (7 * count);
+            ++count;
+        } while (byte & 0x80);
+
+        *value = result;
+        return count;
+    }
+
+    int ReadVarInt32(IInputStream* input, i32* value) {
+        ui64 varInt;
+        int bytesRead = ReadVarUInt64(input, &varInt);
+        if (varInt > Max<ui32>()) {
+            ythrow yexception() << "The data is too long to read ui64";
+        }
+        *value = ZigZagDecode32(static_cast<ui32>(varInt));
+        return bytesRead;
+    }
+
+    int ReadVarInt64(IInputStream* input, i64* value) {
+        ui64 varInt;
+        int bytesRead = ReadVarUInt64(input, &varInt);
+        *value = ZigZagDecode64(varInt);
+        return bytesRead;
+    }
+
+} // namespace NYson