Add more CRC checksum variants to lib/nethash (#4550)

p4lang · Mar 21, 2024 · aa71181 · aa71181
1 parent aece6f9
commit aa71181
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Showing 3 changed files with 41 additions and 3 deletions.
diff --git a/lib/nethash.cpp b/lib/nethash.cpp
@@ -159,10 +159,18 @@ uint16_t crc16(const uint8_t *buf, size_t len) {
     return crcGeneric<uint16_t, 0, 0, table_crc16, Reflect>(buf, len);
 }
 
+uint16_t crc16ANSI(const uint8_t *buf, size_t len) {
+    return crcGeneric<uint16_t, 0, 0, table_crc16, Identity>(buf, len);
+}
+
 uint32_t crc32(const uint8_t *buf, size_t len) {
     return crcGeneric<uint32_t, 0xffffffff, 0xffffffff, table_crc32, Reflect>(buf, len);
 }
 
+uint32_t crc32FCS(const uint8_t *buf, size_t len) {
+    return crcGeneric<uint32_t, 0xffffffff, 0xffffffff, table_crc32, Identity>(buf, len);
+}
+
 uint16_t crcCCITT(const uint8_t *buf, size_t len) {
     return crcGeneric<uint16_t, 0xffff, 0, table_crcCCITT, Identity>(buf, len);
 }

diff --git a/lib/nethash.h b/lib/nethash.h
@@ -8,16 +8,24 @@
 /// A collection of hashing functions commonly used in network protocols.
 namespace NetHash {
 
-/// CRC-16/CRC-16-IBM/CRC-16-ANSI (parameters: bit-reflection, polynomial 0x8005, init = 0 and
-/// xor_out = 0).
+/// CRC-16 used in BMv2 (parameters: bit-reflection, polynomial 0x8005, init = 0 and xor_out = 0).
 uint16_t crc16(const uint8_t *buf, size_t len);
 
+/// CRC-16-ANSI/CRC-16-IBM (parameters: NO bit-reflection, polynomial 0x8005, init = 0 and
+/// xor_out = 0).
+uint16_t crc16ANSI(const uint8_t *buf, size_t len);
+
 /// CRC16-CCITT (parameters: NO bit-reflection, polynomial 0x1021, init = ~0 and xor_out = 0).
 uint16_t crcCCITT(const uint8_t *buf, size_t len);
 
-/// CRC-32 (parameters: bit-reflection, polynomial 0x04C11DB7, init = ~0 and xor_out = ~0).
+/// CRC-32, used in BMv2 (parameters: bit-reflection, polynomial 0x04C11DB7, init = ~0 and
+/// xor_out = ~0).
 uint32_t crc32(const uint8_t *buf, size_t len);
 
+/// CRC-32 used for Ethernet FCS (parameters: NO bit-reflection, polynomial 0x04C11DB7, init = ~0
+/// and xor_out = ~0).
+uint32_t crc32FCS(const uint8_t *buf, size_t len);
+
 /// 16-bit ones' complement checksum (used in IP, TCP, UDP, ...).
 uint16_t csum16(const uint8_t *buf, size_t len);
 

diff --git a/test/gtest/nethash.cpp b/test/gtest/nethash.cpp
@@ -48,6 +48,17 @@ TEST(NetHash, crc32) {
     EXPECT_EQ(apply<crc32>("foobar%142qrs"), 0x95E1D00B_u32);
 }
 
+TEST(NetHash, crc32FCS) {
+    EXPECT_EQ(apply<crc32FCS>({}), 0x00000000_u32);
+    EXPECT_EQ(apply<crc32FCS>({0}), 0xB1F7404B_u32);
+    EXPECT_EQ(apply<crc32FCS>({0, 0, 0, 0, 0}), 0xB8EF4463_u32);
+    EXPECT_EQ(apply<crc32FCS>({0x0b, 0xb8, 0x1f, 0x90}), 0xEDA1EA6D_u32);
+    EXPECT_EQ(apply<crc32FCS>("fooo"), 0xCD961E19_u32);
+    EXPECT_EQ(apply<crc32FCS>("a"), 0x19939B6B_u32);
+    EXPECT_EQ(apply<crc32FCS>("foobar"), 0x52C03DC1_u32);
+    EXPECT_EQ(apply<crc32FCS>("foobar%142qrs"), 0xF3630DE4_u32);
+}
+
 TEST(NetHash, crc16) {
     EXPECT_EQ(apply<crc16>({}), 0x0000_u16);
     EXPECT_EQ(apply<crc16>({0}), 0x0000_u16);
@@ -59,6 +70,17 @@ TEST(NetHash, crc16) {
     EXPECT_EQ(apply<crc16>("foobar%142qrs"), 0x3DA9_u16);
 }
 
+TEST(NetHash, crc16ANSI) {
+    EXPECT_EQ(apply<crc16ANSI>({}), 0x0000_u16);
+    EXPECT_EQ(apply<crc16ANSI>({0}), 0x0000_u16);
+    EXPECT_EQ(apply<crc16ANSI>({0, 0, 0, 0, 0}), 0x0000_u16);
+    EXPECT_EQ(apply<crc16ANSI>({0x0b, 0xb8, 0x1f, 0x90}), 0xD400_u16);
+    EXPECT_EQ(apply<crc16ANSI>("fooo"), 0x9C3A_u16);
+    EXPECT_EQ(apply<crc16ANSI>("a"), 0x8145_u16);
+    EXPECT_EQ(apply<crc16ANSI>("foobar"), 0x8F5B_u16);
+    EXPECT_EQ(apply<crc16ANSI>("foobar%142qrs"), 0x5A5E_u16);
+}
+
 TEST(NetHash, crcCCITT) {
     EXPECT_EQ(apply<crcCCITT>({}), 0xFFFF_u16);
     EXPECT_EQ(apply<crcCCITT>({0}), 0xE1F0_u16);