diff --git a/crc32c.c b/crc32c.c
new file mode 100644
index 00000000..b3dab597
--- /dev/null
+++ b/crc32c.c
@@ -0,0 +1,98 @@
+#include "crc32c.h"
+
+/*****************************************************************/
+/*                                                               */
+/* CRC LOOKUP TABLE                                              */
+/* ================                                              */
+/* The following CRC lookup table was generated automagically    */
+/* by the Rocksoft^tm Model CRC Algorithm Table Generation       */
+/* Program V1.0 using the following model parameters:            */
+/*                                                               */
+/*    Width   : 4 bytes.                                         */
+/*    Poly    : 0x1EDC6F41L                                      */
+/*    Reverse : TRUE.                                            */
+/*                                                               */
+/* For more information on the Rocksoft^tm Model CRC Algorithm,  */
+/* see the document titled "A Painless Guide to CRC Error        */
+/* Detection Algorithms" by Ross Williams                        */
+/* (ross@guest.adelaide.edu.au.). This document is likely to be  */
+/* in the FTP archive "ftp.adelaide.edu.au/pub/rocksoft".        */
+/*                                                               */
+/*****************************************************************/
+
+uint32_t crctable[256] = {
+ 0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,
+ 0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,
+ 0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,
+ 0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,
+ 0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,
+ 0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,
+ 0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,
+ 0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,
+ 0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,
+ 0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,
+ 0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,
+ 0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,
+ 0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,
+ 0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,
+ 0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,
+ 0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,
+ 0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,
+ 0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,
+ 0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,
+ 0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,
+ 0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,
+ 0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,
+ 0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,
+ 0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,
+ 0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,
+ 0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,
+ 0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,
+ 0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,
+ 0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,
+ 0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,
+ 0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,
+ 0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,
+ 0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,
+ 0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,
+ 0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,
+ 0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,
+ 0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,
+ 0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,
+ 0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,
+ 0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,
+ 0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,
+ 0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,
+ 0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,
+ 0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,
+ 0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,
+ 0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,
+ 0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,
+ 0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,
+ 0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,
+ 0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,
+ 0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,
+ 0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,
+ 0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,
+ 0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,
+ 0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,
+ 0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,
+ 0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,
+ 0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,
+ 0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,
+ 0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,
+ 0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,
+ 0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,
+ 0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,
+ 0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L
+};
+
+uint32_t crc32c(uint8_t *buf, int len)
+{
+	uint32_t crc = 0xffffffff;
+	while (len-- > 0)
+	{
+		crc = (crc>>8) ^ crctable[(crc ^ (*buf++)) & 0xFF];
+	}
+	return crc^0xffffffff;
+}
diff --git a/crc32c.h b/crc32c.h
new file mode 100644
index 00000000..5b69b4e9
--- /dev/null
+++ b/crc32c.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <stdint.h>
+
+// https://software.intel.com/sites/landingpage/IntrinsicsGuide/
+// unsigned int _mm_crc32_u16 (unsigned int crc, unsigned short v)
+// unsigned int _mm_crc32_u32 (unsigned int crc, unsigned int v)
+// unsigned __int64 _mm_crc32_u64 (unsigned __int64 crc, unsigned __int64 v)
+// unsigned int _mm_crc32_u8 (unsigned int crc, unsigned char v)
+
+uint32_t crc32c(uint8_t *buf, int len);
diff --git a/xor.h b/xor.h
new file mode 100644
index 00000000..b98dcc51
--- /dev/null
+++ b/xor.h
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <stdint.h>
+
+inline void memxor(uint8_t *r1, uint8_t *r2, uint8_t *res, unsigned int len)
+{
+    unsigned int i;
+    for (i = 0; i < len; ++i)
+    {
+        res[i] = r1[i] ^ r2[i];
+    }
+}