From 7108e71b9608002435fab0fe44a2d46506235972 Mon Sep 17 00:00:00 2001
From: BodgeMaster <>
Date: Tue, 20 Dec 2022 04:41:09 +0100
Subject: [PATCH] lib/varint: Add toVarN() functions

---
 src/lib/varint.hpp  | 53 +++++++++++++++++++++++++++++++
 src/test/varint.cpp | 76 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)

diff --git a/src/lib/varint.hpp b/src/lib/varint.hpp
index 4e4382e..8feb23e 100644
--- a/src/lib/varint.hpp
+++ b/src/lib/varint.hpp
@@ -83,4 +83,57 @@ namespace VarInt {
 
         return ErrorOr<int64_t>(returnValue);
     }
+
+    // appends to the vector
+    void toVar32(int32_t value, std::vector<uint8_t> &data) {
+        uint8_t nextByte;
+        uint8_t shift = 0;
+        // do something else after the 4th shift
+        while (shift < 4) {
+            if (shift>0 && value==0) {
+                return;
+            }
+
+            nextByte = value & 0b01111111;
+
+            value = (value >> 7) & 0x01FFFFFF;
+            shift++;
+
+
+            if (value>0) {
+                nextByte = nextByte + 0b10000000;
+            }
+            data.push_back(nextByte);
+
+        }
+        if (value>0) {
+            data.push_back(value & 0b00001111);
+        }
+    }
+
+    // appends to the vector
+    void toVar64(int64_t value, std::vector<uint8_t> &data) {
+        uint8_t nextByte;
+        uint8_t shift = 0;
+        // do something else after the 4th shift
+        while (shift < 9) {
+            if (shift>0 && value==0) {
+                return;
+            }
+
+            nextByte = value & 0b01111111;
+
+            value = (value >> 7) & 0x01FFFFFFFFFFFFFF;
+            shift++;
+
+            if (value>0) {
+                nextByte = nextByte + 0b10000000;
+            }
+            data.push_back(nextByte);
+
+        }
+        if (value>0) {
+            data.push_back(value & 0b00000001);
+        }
+    }
 }
diff --git a/src/test/varint.cpp b/src/test/varint.cpp
index 90e70a7..2902f39 100644
--- a/src/test/varint.cpp
+++ b/src/test/varint.cpp
@@ -158,6 +158,82 @@ int main() {
 
     std::cout << "Passed fromVar64 test." << std::endl;
 
+    // reversing all the previous tests
+    std::vector<uint8_t> dataDump;
+
+    VarInt::toVar32(0, dataDump);
+    ASSERT(dataDump[0] == 0);
+
+    VarInt::toVar32(-1, dataDump);
+    ASSERT(
+        dataDump[1]==255 &&
+        dataDump[2]==255 &&
+        dataDump[3]==255 &&
+        dataDump[4]==255 &&
+        dataDump[5]==15
+    );
+
+    VarInt::toVar32(4369, dataDump);
+    ASSERT(
+        dataDump[6]==0b10010001 &&
+        dataDump[7]==0b00100010
+    );
+
+    VarInt::toVar32(2375101, dataDump);
+    ASSERT(
+        dataDump[8]==0b10111101 &&
+        dataDump[9]==0b11111011 &&
+        dataDump[10]==0b10010000 &&
+        dataDump[11]==0b00000001
+    );
+
+    std::cout << "Passed toVar32 test." << std::endl;
+
+    VarInt::toVar64(0, dataDump);
+    ASSERT(dataDump[12]==0);
+
+    VarInt::toVar64(-1, dataDump);
+    ASSERT(
+        dataDump[13]==255 &&
+        dataDump[14]==255 &&
+        dataDump[15]==255 &&
+        dataDump[16]==255 &&
+        dataDump[17]==255 &&
+        dataDump[18]==255 &&
+        dataDump[19]==255 &&
+        dataDump[20]==255 &&
+        dataDump[21]==255 &&
+        dataDump[22]==1
+    );
+
+    VarInt::toVar64(2310347307446489235, dataDump);
+    ASSERT(
+        dataDump[23]==0b10010011 &&
+        dataDump[24]==0b10100001 &&
+        dataDump[25]==0b10000011 &&
+        dataDump[26]==0b11000001 &&
+        dataDump[27]==0b10101010 &&
+        dataDump[28]==0b10010100 &&
+        dataDump[29]==0b10000000 &&
+        dataDump[30]==0b10001000 &&
+        dataDump[31]==0b00100000
+    );
+
+    VarInt::toVar64(-9205322385119247871, dataDump);
+    ASSERT(
+        dataDump[32]==0b10000001 &&
+        dataDump[33]==0b10000100 &&
+        dataDump[34]==0b10010000 &&
+        dataDump[35]==0b11000000 &&
+        dataDump[36]==0b10000000 &&
+        dataDump[37]==0b10000010 &&
+        dataDump[38]==0b10001000 &&
+        dataDump[39]==0b10100000 &&
+        dataDump[40]==0b10000000 &&
+        dataDump[41]==0b00000001
+    )
+
+    std::cout << "Passed toVar64 test." << std::endl;
 
     return 0;
 }