Diff: Utilities/crc.cpp

Revision:

86:2ce08ca58b9e

Parent:

80:83b0d879cc32

Child:

90:c233d1c265ff

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Utilities/crc.cpp	Wed Jun 15 15:00:06 2016 -0500
@@ -0,0 +1,61 @@
+
+
+#include "crc.h"
+
+
+uint8_t OneWire::crc::calculateCrc8(uint8_t crc8, uint8_t data)
+{
+    // See Application Note 27
+    crc8 = crc8 ^ data;
+    for (int i = 0; i < 8; i++)
+    {
+        if (crc8 & 1)
+        {
+            crc8 = (crc8 >> 1) ^ 0x8c;
+        }
+        else
+        {
+            crc8 = (crc8 >> 1);
+        }
+    }
+ 
+    return crc8;
+}
+ 
+uint8_t OneWire::crc::calculateCrc8(const uint8_t * data, size_t dataLen, uint8_t crc)
+{
+    for (size_t i = 0; i < dataLen; i++)
+    {
+        crc = calculateCrc8(crc, data[i]);
+    }
+    return crc;
+}
+ 
+uint16_t OneWire::crc::calculateCrc16(uint16_t crc16, uint16_t data)
+{
+    const uint16_t oddparity[] = { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };
+
+    data = (data ^ (crc16 & 0xff)) & 0xff;
+    crc16 >>= 8;
+
+    if (oddparity[data & 0xf] ^ oddparity[data >> 4])
+    {
+        crc16 ^= 0xc001;
+    }
+
+    data <<= 6;
+    crc16 ^= data;
+    data <<= 1;
+    crc16 ^= data;
+
+    return crc16;
+}
+
+uint16_t OneWire::crc::calculateCrc16(const uint8_t * data, size_t dataOffset, size_t dataLen, uint16_t crc)
+{
+    for (size_t i = dataOffset; i < (dataLen + dataOffset); i++)
+    {
+        crc = calculateCrc16(crc, data[i]);
+    }
+    return crc;
+}