From acf683b91b4d9e9e6f3df00ed24f053a903a18bf Mon Sep 17 00:00:00 2001
From: jgromes <jan.gromes@gmail.com>
Date: Sat, 13 May 2023 16:40:01 +0200
Subject: [PATCH] [CRC] Reworked for non-standard CRC lengths

---
 src/utils/CRC.cpp | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/src/utils/CRC.cpp b/src/utils/CRC.cpp
index f6cbfa23..4422942b 100644
--- a/src/utils/CRC.cpp
+++ b/src/utils/CRC.cpp
@@ -6,25 +6,24 @@ RadioLibCRC::RadioLibCRC() {
 
 uint32_t RadioLibCRC::checksum(uint8_t* buff, size_t len) {
   uint32_t crc = this->init;
-  for(size_t i = 0; i < len; i+=this->size/8) {
-    uint32_t window = 0;
-    for(uint8_t j = 0; j < this->size/8; j++) {
-      uint8_t inByte = buff[i + j];
+  size_t pos = 0;
+  for(size_t i = 0; i < 8*len; i++) {
+    if(i % 8 == 0) {
+      uint32_t in = buff[pos++];
       if(this->refIn) {
-        inByte = Module::reflect(inByte, 8);
+        in = Module::reflect(in, 8);
       }
-      window |= (inByte << ((this->size - 8) - 8*j));
+      crc ^= (in << (this->size - 8));
     }
-    crc ^= window;
-    for(size_t k = 0; k < this->size; k++) {
-      if(crc & ((uint32_t)1 << (this->size - 1))) {
-        crc <<= (uint32_t)1;
-        crc ^= this->poly;
-      } else {
-        crc <<= (uint32_t)1;
-      }
+
+    if(crc & ((uint32_t)1 << (this->size - 1))) {
+      crc <<= (uint32_t)1;
+      crc ^= this->poly;
+    } else {
+      crc <<= (uint32_t)1;
     }
   }
+
   crc ^= this->out;
   if(this->refOut) {
     crc = Module::reflect(crc, this->size);