From a29a9cce5f9afa32560d966e501247246ec96ef6 Mon Sep 17 00:00:00 2001
From: kuqin12 <42554914+kuqin12@users.noreply.github.com>
Date: Tue, 2 Apr 2024 11:20:02 -0700
Subject: [PATCH] MdePkg/BaseLib: Add CRC16 CCITT False Implementation.

This change is added to incorporate basic implementation for
CRC16-CCITT-FALSE algorithm.

This function is useful for providing CRC16 value used in other data
structures that requires CRC16 value that complies with JEDEC SPD
requirements, i.e. BDAT table.

The lookup table is inherited from `https://crccalc.com/` and the result
values are also compared against this site.

Signed-off-by: Aaron Pop <aaronpop@microsoft.com>
---
 MdePkg/Include/Library/BaseLib.h  | 17 ++++++++
 MdePkg/Library/BaseLib/CheckSum.c | 69 +++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/MdePkg/Include/Library/BaseLib.h b/MdePkg/Include/Library/BaseLib.h
index aec84c0184d3..eb817f131f53 100644
--- a/MdePkg/Include/Library/BaseLib.h
+++ b/MdePkg/Include/Library/BaseLib.h
@@ -4987,6 +4987,23 @@ CalculateCrc32c (
   IN UINT32      InitialValue
   );
 
+/**
+  Calculates the CRC16-CCITT-FALSE checksum of the given buffer.
+
+  @param[in]      Buffer        Pointer to the buffer.
+  @param[in]      Length        Length of the buffer, in bytes.
+  @param[in]      InitialValue  Initial value of the CRC.
+
+  @return The CRC16-CCITT-FALSE checksum.
+**/
+UINT16
+EFIAPI
+CalculateCrc16CcittF (
+  IN CONST VOID  *Buffer,
+  IN UINTN       Length,
+  IN UINT16      InitialValue
+  );
+
 //
 // Base Library CPU Functions
 //
diff --git a/MdePkg/Library/BaseLib/CheckSum.c b/MdePkg/Library/BaseLib/CheckSum.c
index 57d324c82b22..1c82a534d0da 100644
--- a/MdePkg/Library/BaseLib/CheckSum.c
+++ b/MdePkg/Library/BaseLib/CheckSum.c
@@ -762,3 +762,72 @@ CalculateCrc32c (
 
   return ~Crc;
 }
+
+// The lookup table is inherited from [https://crccalc.com/](https://crccalc.com/%60)
+GLOBAL_REMOVE_IF_UNREFERENCED STATIC CONST UINT16  mCrc16CcittFLookupTable[256] = {
+  0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
+  0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
+  0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
+  0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
+  0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
+  0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
+  0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
+  0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
+  0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
+  0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
+  0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
+  0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
+  0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
+  0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
+  0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
+  0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
+  0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
+  0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
+  0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
+  0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
+  0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
+  0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
+  0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
+  0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
+  0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
+  0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
+  0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
+  0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
+  0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
+  0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
+  0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
+  0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0,
+};
+
+/**
+  Calculates the CRC16-CCITT-FALSE checksum of the given buffer.
+
+  @param[in]      Buffer        Pointer to the buffer.
+  @param[in]      Length        Length of the buffer, in bytes.
+  @param[in]      InitialValue  Initial value of the CRC.
+
+  @return The CRC16-CCITT-FALSE checksum.
+**/
+UINT16
+EFIAPI
+CalculateCrc16CcittF (
+  IN CONST VOID  *Buffer,
+  IN UINTN       Length,
+  IN UINT16      InitialValue
+  )
+{
+  CONST UINT8  *Buf;
+  UINT16       Crc;
+
+  ASSERT (Buffer != NULL);
+  ASSERT (Length <= (MAX_ADDRESS - ((UINTN)Buffer) + 1));
+
+  Buf = Buffer;
+  Crc = InitialValue;
+
+  while (Length-- != 0) {
+    Crc = mCrc16CcittFLookupTable[((Crc >> 8) ^ *(Buf++)) & 0xFF] ^ (Crc << 8);
+  }
+
+  return Crc;
+}