From 14104ebb5411db03edf6a337f19de6678b9c8596 Mon Sep 17 00:00:00 2001
From: Gabriel Tofvesson <gabto095@student.liu.se>
Date: Sun, 25 Nov 2018 17:08:53 +0100
Subject: [PATCH] Finalized varint implementation along with zigzag
 implementation

---
 .gitignore |  3 +++
 bits.h     |  6 ++---
 varint.c   | 65 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 66 insertions(+), 8 deletions(-)

diff --git a/.gitignore b/.gitignore
index c6127b3..e2b0ce8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,3 +50,6 @@ modules.order
 Module.symvers
 Mkfile.old
 dkms.conf
+
+# Output build artifacts
+bin/
diff --git a/bits.h b/bits.h
index 50a360b..d0dc910 100644
--- a/bits.h
+++ b/bits.h
@@ -12,7 +12,7 @@ union sig_ll {
     signed long long value : SIZE_LL;
     struct {
         unsigned long long value : SIZE_LL - 1;
-        unsigned char sig : 1;
+        signed char sig : 1;
     } signature;
 };
 
@@ -21,7 +21,7 @@ union sig_l {
     signed long value : SIZE_L;
     struct {
         unsigned long value : SIZE_L - 1;
-        unsigned char sig : 1;
+        signed char sig : 1;
     } signature;
 };
 
@@ -29,7 +29,7 @@ union sig_i {
     signed int value : SIZE_I;
     struct {
         unsigned int value : SIZE_I - 1;
-        unsigned char sig : 1;
+        signed char sig : 1;
     } signature;
 };
 
diff --git a/varint.c b/varint.c
index 13c2d6d..70c7bfe 100644
--- a/varint.c
+++ b/varint.c
@@ -1,18 +1,73 @@
 #include "varint.h"
-
+#include <stdlib.h>
 
 varint varint_encode(unsigned long long value){
-    
+    varint result;
+
+    if (value <= 240){
+        result = (varint)malloc(1);
+        result[0] = (char)value;
+    }
+    else if (value <= 2287)
+    {
+        result = (varint)malloc(2);
+        result[0] = (char)(((value - 240) >> 8) + 241);
+        result[1] = (char)(value - 240);
+    }
+    else if (value <= 67823)
+    {
+        result = (varint)malloc(3);
+        result[0] = 249;
+        result[1] = (char)((value - 2288) >> 8);
+        result[2] = (char)(value - 2288);
+    }
+    else
+    {
+        unsigned long long header = 255;
+        unsigned long long match = 0x00FFFFFFFFFFFFFFUL;
+        while (value <= match)
+        {
+            --header;
+            match >>= 8;
+        }
+        int max = (int)(header - 247);
+
+        result = (varint)malloc(max + 1);
+        result[0] = (char) header;
+        for (int i = 0; i < max; ++i)
+                result[i+1] = (char)(value >> (i << 3));
+    }
+    return result;
 }
 
 unsigned long long varint_decode(varint varint){
-
+    unsigned long long header = (unsigned char)varint[0];
+    if(header <= 240){
+            free(varint);
+            return header;
+    }
+    if(header <= 248){
+            free(varint);
+            return 240UL + ((header - 241) << 8) + (unsigned char)varint[1];
+    }
+    if(header == 249){
+            free(varint);
+            return 2288UL + ((unsigned char)varint[1] << 8) + (unsigned char)varint[2];
+    }
+    unsigned long result = (unsigned char)varint[1] | ((unsigned char)varint[2] << 8) | ((unsigned char)varint[3]);
+    int compare = 2;
+    int head = (int)(header - 247);
+    while(head > ++compare) result |= (unsigned char)varint[compare + 2] << (compare << 3);
+    free(varint);
+    return result;
 }
 
 unsigned long long zigzag_encode(signed long long value){
-    return ((unsigned long long)value << 1) ^ (value >> 63);
+    union sig_ll convert = {value};
+    return (convert.signature.value << 1) ^ (unsigned long long)convert.signature.sig;
 }
 
 signed long long zigzag_decode(unsigned long long value){
-
+    union sig_ll convert = {value << 63};
+    return (signed long long)((value >> 1) ^ (unsigned long long)convert.signature.sig);
 }