From c524b9a0ca51805ddda716363c14c9d8acadbdd0 Mon Sep 17 00:00:00 2001
From: Christian Bender <christianbender89@web.de>
Date: Sun, 31 Dec 2017 22:58:30 +0100
Subject: [PATCH] Add files via upload

---
 Hash/README.md      |  7 +++++
 Hash/hash.c         | 63 +++++++++++++++++++++++++++++++++++++++++++++
 Hash/hash.h         | 43 +++++++++++++++++++++++++++++++
 Hash/test_program.c | 20 ++++++++++++++
 4 files changed, 133 insertions(+)
 create mode 100644 Hash/README.md
 create mode 100644 Hash/hash.c
 create mode 100644 Hash/hash.h
 create mode 100644 Hash/test_program.c

diff --git a/Hash/README.md b/Hash/README.md
new file mode 100644
index 00000000..1bf23b8f
--- /dev/null
+++ b/Hash/README.md
@@ -0,0 +1,7 @@
+# Hash algorithms
+
+Overview files **hash.h** and **hash.c**
+* sdbm
+* djb2
+* xor8 (8 bit)
+* adler_32 (32 bit)
\ No newline at end of file
diff --git a/Hash/hash.c b/Hash/hash.c
new file mode 100644
index 00000000..220bb5ca
--- /dev/null
+++ b/Hash/hash.c
@@ -0,0 +1,63 @@
+/*
+    author: Christian Bender
+    This is the implementation unit of the hash-functions.
+
+    Overview about hash-functions:
+
+    - sdbm
+    - djb2
+    - xor8 (8 bits)
+    - adler_32 (32 bits)
+*/
+
+long long sdbm(char s[])
+{
+    long long hash = 0;
+    int i = 0;
+    while (s[i] != '\0')
+    {
+        hash = s[i] + (hash << 6) + (hash << 16) - hash;
+        i++;
+    }
+    return hash;
+}
+
+long long djb2(char s[])
+{
+    long long hash = 5381; /* init value */
+    int i = 0;
+    while (s[i] != '\0')
+    {
+        hash = ((hash << 5) + hash) + s[i];
+        i++;
+    }
+    return hash;
+}
+
+char xor8(char s[])
+{
+    int hash = 0;
+    int i = 0;
+    while (s[i] != '\0')
+    {
+        hash = (hash + s[i]) & 0xff;
+        i++;
+    }
+    return (((hash ^ 0xff) + 1) & 0xff);
+}
+
+int adler_32(char s[])
+{
+    int a = 1;
+    int b = 0;
+    const int MODADLER = 65521;
+
+    int i = 0;
+    while (s[i] != '\0')
+    {
+        a = (a + s[i]) % MODADLER;
+        b = (b + a) % MODADLER;
+        i++;
+    }
+    return (b << 16) | a;
+}
\ No newline at end of file
diff --git a/Hash/hash.h b/Hash/hash.h
new file mode 100644
index 00000000..7497b1b2
--- /dev/null
+++ b/Hash/hash.h
@@ -0,0 +1,43 @@
+/*
+    author: Christian Bender
+    This file contains the public interface
+
+    Overview about hash-functions:
+
+    - sdbm
+    - djb2
+    - xor8 (8 bit)
+    - adler_32 (32 bits)
+*/
+
+#ifndef __HASH__H
+#define __HASH__H
+
+/*
+    sdbm: implements the sdbm hash-algorithm
+    returns a whole number of type long long.
+*/
+long long sdbm(char[]);
+
+/*
+    djb2: implements the djb2 hash-algorithm
+    returns a whole number of type long long.
+*/
+long long djb2(char[]);
+
+/*
+    xor8: implements the xor8 hash-algorithm
+    returns a whole number of type char.
+    length: 8 bit
+*/
+char xor8(char[]);
+
+/*
+    adler_32: implements the adler-32 hash-algorithm
+    returns a whole number of type int.
+    length: 32 bit
+    assumes: int has a length of 32 bits.
+*/
+int adler_32(char[]);
+
+#endif
\ No newline at end of file
diff --git a/Hash/test_program.c b/Hash/test_program.c
new file mode 100644
index 00000000..f9dcd299
--- /dev/null
+++ b/Hash/test_program.c
@@ -0,0 +1,20 @@
+/*
+    author: Christian Bender
+    This file contains a simple test program for each hash-function.
+*/
+
+#include <stdio.h>
+#include "hash.h"
+
+int main(void)
+{
+    char s[] = "name";
+
+    /* actual tests */
+    printf("sdbm: %s --> %lld\n", s, sdbm(s));
+    printf("djb2: %s --> %lld\n", s, djb2(s));
+    printf("xor8: %s --> %i\n", s, xor8(s)); /* 8 bit */
+    printf("adler_32: %s --> %i\n", s, adler_32(s)); /* 32 bit */
+
+    return 0;
+}
\ No newline at end of file