From d5e33fb20918d3dfb9e3707ec7a5a31994f158c1 Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Tue, 26 Mar 2024 15:13:23 +0100
Subject: [PATCH] added some support functions

---
 client/src/util.c | 25 +++++++++++++++++++++++++
 client/src/util.h |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/client/src/util.c b/client/src/util.c
index d409d2292..577a790e9 100644
--- a/client/src/util.c
+++ b/client/src/util.c
@@ -1145,6 +1145,12 @@ void binstr_2_bytes(uint8_t *target, size_t *targetlen, const char *src) {
     }
 }
 
+void hex_xor(uint8_t *d, uint8_t *x, int n) {
+    while(n--) {
+        d[n] ^= x[n];
+    }
+}
+
 // return parity bit required to match type
 uint8_t GetParity(const uint8_t *bits, uint8_t type, int length) {
     int x;
@@ -1474,3 +1480,22 @@ void sb_append_char(smartbuf *sb, unsigned char c) {
     sb->ptr[sb->idx] = c;
     sb->idx++;
 }
+
+uint8_t get_highest_frequency(const uint8_t *d, uint8_t n) {
+
+    uint8_t frequency[256] = {0};
+    uint8_t highest = 0;
+    uint8_t v = 0;
+
+    // Count the frequency of each byte
+    for(uint8_t i = 0; i < n; i++) {
+        frequency[d[i]]++;
+
+        if (frequency[d[i]] > highest) {
+            highest = frequency[d[i]];
+            v = d[i];
+        }
+    }
+    PrintAndLogEx(DEBUG, "highest occurance... %u  xor byte... 0x%02X", highest, v);
+    return v;
+}
\ No newline at end of file
diff --git a/client/src/util.h b/client/src/util.h
index 226443dab..eedd409f8 100644
--- a/client/src/util.h
+++ b/client/src/util.h
@@ -133,6 +133,8 @@ int binstr_2_binarray(uint8_t *target, char *source, int length);
 void bytes_2_binstr(char *target,  const uint8_t *source, size_t sourcelen);
 void binstr_2_bytes(uint8_t *target, size_t *targetlen, const char *src);
 
+void hex_xor(uint8_t *d, uint8_t *x, int n);
+
 uint8_t GetParity(const uint8_t *bits, uint8_t type, int length);
 void wiegand_add_parity(uint8_t *target, uint8_t *source, uint8_t length);
 void wiegand_add_parity_swapped(uint8_t *target, uint8_t *source, uint8_t length);
@@ -179,4 +181,6 @@ struct smartbuf {
     size_t idx;
 } typedef smartbuf;
 void sb_append_char(smartbuf *sb, unsigned char c);
+
+uint8_t get_highest_frequency(const uint8_t *d, uint8_t n);
 #endif