intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 79 insertions, 0 deletions

diff --git a/library/cpp/monlib/encode/spack/varint.cpp b/library/cpp/monlib/encode/spack/varint.cpp
new file mode 100644
index 0000000000..051cf17380
--- /dev/null
+++ b/library/cpp/monlib/encode/spack/varint.cpp
@@ -0,0 +1,79 @@
+#include "varint.h"
+
+#include <util/generic/yexception.h>
+#include <util/stream/input.h>
+#include <util/stream/output.h>
+
+namespace NMonitoring {
+    ui32 WriteVarUInt32(IOutputStream* output, ui32 value) {
+        bool stop = false;
+        ui32 written = 0;
+        while (!stop) {
+            ui8 byte = static_cast<ui8>(value | 0x80);
+            value >>= 7;
+            if (value == 0) {
+                stop = true;
+                byte &= 0x7F;
+            }
+            output->Write(byte);
+            written++;
+        }
+        return written;
+    }
+
+    ui32 ReadVarUInt32(IInputStream* input) {
+        ui32 value = 0;
+        switch (TryReadVarUInt32(input, &value)) {
+            case EReadResult::OK:
+                return value;
+            case EReadResult::ERR_OVERFLOW:
+                ythrow yexception() << "the data is too long to read ui32";
+            case EReadResult::ERR_UNEXPECTED_EOF:
+                ythrow yexception() << "the data unexpectedly ended";
+            default:
+                ythrow yexception() << "unknown error while reading varint";
+        }
+    }
+
+    size_t ReadVarUInt32(const ui8* buf, size_t len, ui32* result) {
+        size_t count = 0;
+        ui32 value = 0;
+
+        ui8 byte = 0;
+        do {
+            if (7 * count > 8 * sizeof(ui32)) {
+                ythrow yexception() << "the data is too long to read ui32";
+            }
+            if (count == len) {
+                ythrow yexception() << "the data unexpectedly ended";
+            }
+            byte = buf[count];
+            value |= (static_cast<ui32>(byte & 0x7F)) << (7 * count);
+            ++count;
+        } while (byte & 0x80);
+
+        *result = value;
+        return count;
+    }
+
+EReadResult TryReadVarUInt32(IInputStream* input, ui32* value) {
+        size_t count = 0;
+        ui32 result = 0;
+
+        ui8 byte = 0;
+        do {
+            if (7 * count > 8 * sizeof(ui32)) {
+                return EReadResult::ERR_OVERFLOW;
+            }
+            if (input->Read(&byte, 1) != 1) {
+                return EReadResult::ERR_UNEXPECTED_EOF;
+            }
+            result |= (static_cast<ui32>(byte & 0x7F)) << (7 * count);
+            ++count;
+        } while (byte & 0x80);
+
+        *value = result;
+        return EReadResult::OK;
+    }
+
+}