diff --git a/unittests/ASM/H0F38/66_F0.asm b/unittests/ASM/H0F38/66_F0.asm
new file mode 100644
index 000000000..8afa8ea8a
--- /dev/null
+++ b/unittests/ASM/H0F38/66_F0.asm
@@ -0,0 +1,63 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x00000000E330A81A",
+    "RBX": "0x00000000BE2DA0A5",
+    "RCX": "0x00000000ADBE9F64"
+  }
+}
+%endif
+
+; This is a clone of the F2_F0 crc32 test with manually coded crc32 with prefix 66 instead of F2
+mov rax, 0
+mov rbx, 0
+mov rcx, 0
+mov rdx, 0
+lea rsi, [rel .data]
+
+; crc32 rax, byte [rel .data]
+db 0xf2
+db 0x66
+db 0x48, 0x0f, 0x38, 0xf0, 0x05
+dd 0x0000002A
+
+; crc32 ebx, byte [rel .data + 1]
+db 0xf2
+db 0x66
+db 0x0f, 0x38, 0xf0, 0x1d,
+dd 0x00000021
+
+.again:
+cmp rdx, 256
+je .done
+; crc32 rcx, byte [rsi + rdx]
+db 0xf2
+db 0x66
+db 0x48, 0x0f, 0x38, 0xf0, 0x0c, 0x16
+
+add rdx, 1
+jmp .again
+.done:
+
+hlt
+
+align 16
+; 256bytes of random data
+.data:
+db 0xe0, 0xfc, 0x2b, 0xa1, 0x06, 0x4f, 0x6c, 0xa7, 0x0f, 0x06, 0x6a, 0x1e, 0x7f, 0x76, 0x80, 0x9b
+db 0xe0, 0x56, 0xed, 0xaa, 0xf3, 0xc3, 0x68, 0x68, 0xde, 0xe6, 0xe6, 0x94, 0xe2, 0xe9, 0xfc, 0xf0
+db 0x6e, 0x35, 0xa8, 0x54, 0xd7, 0xab, 0x8b, 0x6c, 0x77, 0x5f, 0x92, 0xca, 0x25, 0xa6, 0x7e, 0x27
+db 0xc7, 0xcd, 0x73, 0xec, 0x95, 0xd6, 0x6f, 0x6a, 0xbb, 0xae, 0xf2, 0xbb, 0x27, 0xb9, 0xa1, 0xdd
+db 0x73, 0x4d, 0xd1, 0xc7, 0xd5, 0x2c, 0x31, 0x88, 0xfe, 0xe7, 0xdb, 0xfd, 0x1e, 0x1e, 0x09, 0x7f
+db 0x14, 0xfa, 0x4e, 0x95, 0xef, 0xe6, 0x9a, 0xf2, 0xa0, 0x42, 0x62, 0x9a, 0xa4, 0xa8, 0x73, 0x82
+db 0x0e, 0x0f, 0x16, 0x82, 0x38, 0x07, 0x12, 0x32, 0x07, 0x35, 0x92, 0xc1, 0x63, 0x07, 0x78, 0xb3
+db 0xcb, 0x46, 0x19, 0x57, 0x2b, 0x37, 0x2a, 0x46, 0x1f, 0x04, 0x0e, 0x79, 0x3d, 0xcd, 0x8d, 0xa3
+db 0x2b, 0xf3, 0x86, 0x2f, 0xab, 0xba, 0x57, 0x30, 0x2e, 0xd6, 0x2c, 0xf0, 0x46, 0x4f, 0x3f, 0xef
+db 0xef, 0xd1, 0xbb, 0x85, 0x34, 0x4b, 0x3c, 0xde, 0x9e, 0x48, 0xa3, 0xb9, 0x8d, 0x71, 0xe3, 0x9d
+db 0x09, 0x72, 0xfb, 0xde, 0x8a, 0x32, 0x50, 0x9d, 0x69, 0x98, 0xf1, 0xf6, 0x52, 0xeb, 0xf7, 0xee
+db 0xd6, 0x99, 0xc2, 0xff, 0x30, 0x1c, 0x02, 0xce, 0x70, 0x05, 0xb2, 0xf1, 0x56, 0x9c, 0x0e, 0xa6
+db 0x18, 0x62, 0xc4, 0xe2, 0x86, 0x38, 0x76, 0x30, 0x2f, 0xa1, 0xe4, 0xa7, 0x0e, 0x5d, 0x53, 0xeb
+db 0x14, 0x45, 0xe0, 0xb7, 0xe1, 0xe8, 0x02, 0x68, 0x1a, 0xfe, 0x8e, 0xc1, 0x8f, 0xf2, 0xeb, 0x46
+db 0x7f, 0x5d, 0x6a, 0x23, 0x46, 0x97, 0x2e, 0x03, 0x98, 0x12, 0x32, 0x8f, 0x54, 0x76, 0x59, 0xac
+db 0xc8, 0x76, 0x5f, 0xc8, 0x71, 0x0c, 0xd3, 0xb6, 0xc5, 0x19, 0xea, 0xab, 0xa6, 0x2c, 0x1d, 0x88
+
diff --git a/unittests/ASM/H0F38/66_F0_2.asm b/unittests/ASM/H0F38/66_F0_2.asm
new file mode 100644
index 000000000..2ecfed5d3
--- /dev/null
+++ b/unittests/ASM/H0F38/66_F0_2.asm
@@ -0,0 +1,63 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x00000000E330A81A",
+    "RBX": "0x00000000BE2DA0A5",
+    "RCX": "0x00000000ADBE9F64"
+  }
+}
+%endif
+
+; This is a clone of the F2_F0 crc32 test with manually coded crc32 with prefix 66 instead of F2
+mov rax, 0
+mov rbx, 0
+mov rcx, 0
+mov rdx, 0
+lea rsi, [rel .data]
+
+; crc32 rax, byte [rel .data]
+db 0x66
+db 0xf2
+db 0x48, 0x0f, 0x38, 0xf0, 0x05
+dd 0x0000002A
+
+; crc32 ebx, byte [rel .data + 1]
+db 0x66
+db 0xf2
+db 0x0f, 0x38, 0xf0, 0x1d,
+dd 0x00000021
+
+.again:
+cmp rdx, 256
+je .done
+; crc32 rcx, byte [rsi + rdx]
+db 0x66
+db 0xf2
+db 0x48, 0x0f, 0x38, 0xf0, 0x0c, 0x16
+
+add rdx, 1
+jmp .again
+.done:
+
+hlt
+
+align 16
+; 256bytes of random data
+.data:
+db 0xe0, 0xfc, 0x2b, 0xa1, 0x06, 0x4f, 0x6c, 0xa7, 0x0f, 0x06, 0x6a, 0x1e, 0x7f, 0x76, 0x80, 0x9b
+db 0xe0, 0x56, 0xed, 0xaa, 0xf3, 0xc3, 0x68, 0x68, 0xde, 0xe6, 0xe6, 0x94, 0xe2, 0xe9, 0xfc, 0xf0
+db 0x6e, 0x35, 0xa8, 0x54, 0xd7, 0xab, 0x8b, 0x6c, 0x77, 0x5f, 0x92, 0xca, 0x25, 0xa6, 0x7e, 0x27
+db 0xc7, 0xcd, 0x73, 0xec, 0x95, 0xd6, 0x6f, 0x6a, 0xbb, 0xae, 0xf2, 0xbb, 0x27, 0xb9, 0xa1, 0xdd
+db 0x73, 0x4d, 0xd1, 0xc7, 0xd5, 0x2c, 0x31, 0x88, 0xfe, 0xe7, 0xdb, 0xfd, 0x1e, 0x1e, 0x09, 0x7f
+db 0x14, 0xfa, 0x4e, 0x95, 0xef, 0xe6, 0x9a, 0xf2, 0xa0, 0x42, 0x62, 0x9a, 0xa4, 0xa8, 0x73, 0x82
+db 0x0e, 0x0f, 0x16, 0x82, 0x38, 0x07, 0x12, 0x32, 0x07, 0x35, 0x92, 0xc1, 0x63, 0x07, 0x78, 0xb3
+db 0xcb, 0x46, 0x19, 0x57, 0x2b, 0x37, 0x2a, 0x46, 0x1f, 0x04, 0x0e, 0x79, 0x3d, 0xcd, 0x8d, 0xa3
+db 0x2b, 0xf3, 0x86, 0x2f, 0xab, 0xba, 0x57, 0x30, 0x2e, 0xd6, 0x2c, 0xf0, 0x46, 0x4f, 0x3f, 0xef
+db 0xef, 0xd1, 0xbb, 0x85, 0x34, 0x4b, 0x3c, 0xde, 0x9e, 0x48, 0xa3, 0xb9, 0x8d, 0x71, 0xe3, 0x9d
+db 0x09, 0x72, 0xfb, 0xde, 0x8a, 0x32, 0x50, 0x9d, 0x69, 0x98, 0xf1, 0xf6, 0x52, 0xeb, 0xf7, 0xee
+db 0xd6, 0x99, 0xc2, 0xff, 0x30, 0x1c, 0x02, 0xce, 0x70, 0x05, 0xb2, 0xf1, 0x56, 0x9c, 0x0e, 0xa6
+db 0x18, 0x62, 0xc4, 0xe2, 0x86, 0x38, 0x76, 0x30, 0x2f, 0xa1, 0xe4, 0xa7, 0x0e, 0x5d, 0x53, 0xeb
+db 0x14, 0x45, 0xe0, 0xb7, 0xe1, 0xe8, 0x02, 0x68, 0x1a, 0xfe, 0x8e, 0xc1, 0x8f, 0xf2, 0xeb, 0x46
+db 0x7f, 0x5d, 0x6a, 0x23, 0x46, 0x97, 0x2e, 0x03, 0x98, 0x12, 0x32, 0x8f, 0x54, 0x76, 0x59, 0xac
+db 0xc8, 0x76, 0x5f, 0xc8, 0x71, 0x0c, 0xd3, 0xb6, 0xc5, 0x19, 0xea, 0xab, 0xa6, 0x2c, 0x1d, 0x88
+
diff --git a/unittests/ASM/H0F38/66_F1.asm b/unittests/ASM/H0F38/66_F1.asm
new file mode 100644
index 000000000..59e35dc6f
--- /dev/null
+++ b/unittests/ASM/H0F38/66_F1.asm
@@ -0,0 +1,103 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x00000000C5727F5A",
+    "RBX": "0x00000000FAC690D7",
+    "RCX": "0x000000002AAF1F77",
+    "RDX": "0x00000000ADBE9F64",
+    "RSI": "0x00000000ADBE9F64",
+    "RDI": "0x00000000ADBE9F64"
+  }
+}
+%endif
+
+; This is a clone of the F2_F1 crc32 test with manually coded crc32 with prefix 66 instead of F2
+; This can't user operand size override on 32-bit instructions for testing since it WILL override to 16-bit
+mov rax, 0
+mov rbx, 0
+mov rcx, 0
+
+mov rdx, 0
+mov rsi, 0
+mov rdi, 0
+
+mov rbp, 0
+lea rsp, [rel .data]
+
+; crc32 eax, word [rel .data]
+db 0x66 ; Operand size override
+db 0xf2 ; Prefix
+db 0x0f, 0x38, 0xf1, 0x05
+dd 0x0000006c
+
+; crc32 ebx, dword [rel .data + 2]
+db 0xf2 ; Prefix
+db 0x0f, 0x38, 0xf1, 0x1d,
+dd 0x00000065
+
+; crc32 rcx, qword [rel .data + 8]
+db 0x66 ; Operand size override
+db 0xf2 ; Prefix
+db 0x48, 0x0f, 0x38, 0xf1, 0x0d,
+dd 0x00000060
+
+mov rbp, 0
+.again16:
+cmp rbp, 128
+je .done16
+; crc32 edx, word [rsp + rbp * 2]
+db 0x66 ; Operand size override
+db 0xf2 ; Prefix
+db 0x0f, 0x38, 0xf1, 0x14, 0x6c
+
+add rbp, 1
+jmp .again16
+.done16:
+
+mov rbp, 0
+.again32:
+cmp rbp, 64
+je .done32
+; crc32 esi, dword [rsp + rbp * 4]
+db 0xf2 ; Prefix
+db 0x0f, 0x38, 0xf1, 0x34, 0xac
+
+add rbp, 1
+jmp .again32
+.done32:
+
+mov rbp, 0
+.again64:
+cmp rbp, 32
+je .done64
+; crc32 rdi, qword [rsp + rbp * 8]
+db 0x66 ; Operand size override
+db 0xf2 ; Prefix
+db 0x48, 0x0f, 0x38, 0xf1, 0x3c, 0xec
+
+add rbp, 1
+jmp .again64
+.done64:
+
+hlt
+
+align 16
+; 256bytes of random data
+.data:
+db 0xe0, 0xfc, 0x2b, 0xa1, 0x06, 0x4f, 0x6c, 0xa7, 0x0f, 0x06, 0x6a, 0x1e, 0x7f, 0x76, 0x80, 0x9b
+db 0xe0, 0x56, 0xed, 0xaa, 0xf3, 0xc3, 0x68, 0x68, 0xde, 0xe6, 0xe6, 0x94, 0xe2, 0xe9, 0xfc, 0xf0
+db 0x6e, 0x35, 0xa8, 0x54, 0xd7, 0xab, 0x8b, 0x6c, 0x77, 0x5f, 0x92, 0xca, 0x25, 0xa6, 0x7e, 0x27
+db 0xc7, 0xcd, 0x73, 0xec, 0x95, 0xd6, 0x6f, 0x6a, 0xbb, 0xae, 0xf2, 0xbb, 0x27, 0xb9, 0xa1, 0xdd
+db 0x73, 0x4d, 0xd1, 0xc7, 0xd5, 0x2c, 0x31, 0x88, 0xfe, 0xe7, 0xdb, 0xfd, 0x1e, 0x1e, 0x09, 0x7f
+db 0x14, 0xfa, 0x4e, 0x95, 0xef, 0xe6, 0x9a, 0xf2, 0xa0, 0x42, 0x62, 0x9a, 0xa4, 0xa8, 0x73, 0x82
+db 0x0e, 0x0f, 0x16, 0x82, 0x38, 0x07, 0x12, 0x32, 0x07, 0x35, 0x92, 0xc1, 0x63, 0x07, 0x78, 0xb3
+db 0xcb, 0x46, 0x19, 0x57, 0x2b, 0x37, 0x2a, 0x46, 0x1f, 0x04, 0x0e, 0x79, 0x3d, 0xcd, 0x8d, 0xa3
+db 0x2b, 0xf3, 0x86, 0x2f, 0xab, 0xba, 0x57, 0x30, 0x2e, 0xd6, 0x2c, 0xf0, 0x46, 0x4f, 0x3f, 0xef
+db 0xef, 0xd1, 0xbb, 0x85, 0x34, 0x4b, 0x3c, 0xde, 0x9e, 0x48, 0xa3, 0xb9, 0x8d, 0x71, 0xe3, 0x9d
+db 0x09, 0x72, 0xfb, 0xde, 0x8a, 0x32, 0x50, 0x9d, 0x69, 0x98, 0xf1, 0xf6, 0x52, 0xeb, 0xf7, 0xee
+db 0xd6, 0x99, 0xc2, 0xff, 0x30, 0x1c, 0x02, 0xce, 0x70, 0x05, 0xb2, 0xf1, 0x56, 0x9c, 0x0e, 0xa6
+db 0x18, 0x62, 0xc4, 0xe2, 0x86, 0x38, 0x76, 0x30, 0x2f, 0xa1, 0xe4, 0xa7, 0x0e, 0x5d, 0x53, 0xeb
+db 0x14, 0x45, 0xe0, 0xb7, 0xe1, 0xe8, 0x02, 0x68, 0x1a, 0xfe, 0x8e, 0xc1, 0x8f, 0xf2, 0xeb, 0x46
+db 0x7f, 0x5d, 0x6a, 0x23, 0x46, 0x97, 0x2e, 0x03, 0x98, 0x12, 0x32, 0x8f, 0x54, 0x76, 0x59, 0xac
+db 0xc8, 0x76, 0x5f, 0xc8, 0x71, 0x0c, 0xd3, 0xb6, 0xc5, 0x19, 0xea, 0xab, 0xa6, 0x2c, 0x1d, 0x88
+
diff --git a/unittests/ASM/H0F38/66_F1_2.asm b/unittests/ASM/H0F38/66_F1_2.asm
new file mode 100644
index 000000000..3113fc8f1
--- /dev/null
+++ b/unittests/ASM/H0F38/66_F1_2.asm
@@ -0,0 +1,103 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x00000000C5727F5A",
+    "RBX": "0x00000000FAC690D7",
+    "RCX": "0x000000002AAF1F77",
+    "RDX": "0x00000000ADBE9F64",
+    "RSI": "0x00000000ADBE9F64",
+    "RDI": "0x00000000ADBE9F64"
+  }
+}
+%endif
+
+; This is a clone of the F2_F1 crc32 test with manually coded crc32 with prefix 66 instead of F2
+; This can't user operand size override on 32-bit instructions for testing since it WILL override to 16-bit
+mov rax, 0
+mov rbx, 0
+mov rcx, 0
+
+mov rdx, 0
+mov rsi, 0
+mov rdi, 0
+
+mov rbp, 0
+lea rsp, [rel .data]
+
+; crc32 eax, word [rel .data]
+db 0xf2 ; Prefix
+db 0x66 ; Operand size override
+db 0x0f, 0x38, 0xf1, 0x05
+dd 0x0000006c
+
+; crc32 ebx, dword [rel .data + 2]
+db 0xf2 ; Prefix
+db 0x0f, 0x38, 0xf1, 0x1d,
+dd 0x00000065
+
+; crc32 rcx, qword [rel .data + 8]
+db 0xf2 ; Prefix
+db 0x66 ; Operand size override
+db 0x48, 0x0f, 0x38, 0xf1, 0x0d,
+dd 0x00000060
+
+mov rbp, 0
+.again16:
+cmp rbp, 128
+je .done16
+; crc32 edx, word [rsp + rbp * 2]
+db 0xf2 ; Prefix
+db 0x66 ; Operand size override
+db 0x0f, 0x38, 0xf1, 0x14, 0x6c
+
+add rbp, 1
+jmp .again16
+.done16:
+
+mov rbp, 0
+.again32:
+cmp rbp, 64
+je .done32
+; crc32 esi, dword [rsp + rbp * 4]
+db 0xf2 ; Prefix
+db 0x0f, 0x38, 0xf1, 0x34, 0xac
+
+add rbp, 1
+jmp .again32
+.done32:
+
+mov rbp, 0
+.again64:
+cmp rbp, 32
+je .done64
+; crc32 rdi, qword [rsp + rbp * 8]
+db 0xf2 ; Prefix
+db 0x66 ; Operand size override
+db 0x48, 0x0f, 0x38, 0xf1, 0x3c, 0xec
+
+add rbp, 1
+jmp .again64
+.done64:
+
+hlt
+
+align 16
+; 256bytes of random data
+.data:
+db 0xe0, 0xfc, 0x2b, 0xa1, 0x06, 0x4f, 0x6c, 0xa7, 0x0f, 0x06, 0x6a, 0x1e, 0x7f, 0x76, 0x80, 0x9b
+db 0xe0, 0x56, 0xed, 0xaa, 0xf3, 0xc3, 0x68, 0x68, 0xde, 0xe6, 0xe6, 0x94, 0xe2, 0xe9, 0xfc, 0xf0
+db 0x6e, 0x35, 0xa8, 0x54, 0xd7, 0xab, 0x8b, 0x6c, 0x77, 0x5f, 0x92, 0xca, 0x25, 0xa6, 0x7e, 0x27
+db 0xc7, 0xcd, 0x73, 0xec, 0x95, 0xd6, 0x6f, 0x6a, 0xbb, 0xae, 0xf2, 0xbb, 0x27, 0xb9, 0xa1, 0xdd
+db 0x73, 0x4d, 0xd1, 0xc7, 0xd5, 0x2c, 0x31, 0x88, 0xfe, 0xe7, 0xdb, 0xfd, 0x1e, 0x1e, 0x09, 0x7f
+db 0x14, 0xfa, 0x4e, 0x95, 0xef, 0xe6, 0x9a, 0xf2, 0xa0, 0x42, 0x62, 0x9a, 0xa4, 0xa8, 0x73, 0x82
+db 0x0e, 0x0f, 0x16, 0x82, 0x38, 0x07, 0x12, 0x32, 0x07, 0x35, 0x92, 0xc1, 0x63, 0x07, 0x78, 0xb3
+db 0xcb, 0x46, 0x19, 0x57, 0x2b, 0x37, 0x2a, 0x46, 0x1f, 0x04, 0x0e, 0x79, 0x3d, 0xcd, 0x8d, 0xa3
+db 0x2b, 0xf3, 0x86, 0x2f, 0xab, 0xba, 0x57, 0x30, 0x2e, 0xd6, 0x2c, 0xf0, 0x46, 0x4f, 0x3f, 0xef
+db 0xef, 0xd1, 0xbb, 0x85, 0x34, 0x4b, 0x3c, 0xde, 0x9e, 0x48, 0xa3, 0xb9, 0x8d, 0x71, 0xe3, 0x9d
+db 0x09, 0x72, 0xfb, 0xde, 0x8a, 0x32, 0x50, 0x9d, 0x69, 0x98, 0xf1, 0xf6, 0x52, 0xeb, 0xf7, 0xee
+db 0xd6, 0x99, 0xc2, 0xff, 0x30, 0x1c, 0x02, 0xce, 0x70, 0x05, 0xb2, 0xf1, 0x56, 0x9c, 0x0e, 0xa6
+db 0x18, 0x62, 0xc4, 0xe2, 0x86, 0x38, 0x76, 0x30, 0x2f, 0xa1, 0xe4, 0xa7, 0x0e, 0x5d, 0x53, 0xeb
+db 0x14, 0x45, 0xe0, 0xb7, 0xe1, 0xe8, 0x02, 0x68, 0x1a, 0xfe, 0x8e, 0xc1, 0x8f, 0xf2, 0xeb, 0x46
+db 0x7f, 0x5d, 0x6a, 0x23, 0x46, 0x97, 0x2e, 0x03, 0x98, 0x12, 0x32, 0x8f, 0x54, 0x76, 0x59, 0xac
+db 0xc8, 0x76, 0x5f, 0xc8, 0x71, 0x0c, 0xd3, 0xb6, 0xc5, 0x19, 0xea, 0xab, 0xa6, 0x2c, 0x1d, 0x88
+
diff --git a/unittests/ASM/H0F38/66_F1_3.asm b/unittests/ASM/H0F38/66_F1_3.asm
new file mode 100644
index 000000000..03d683161
--- /dev/null
+++ b/unittests/ASM/H0F38/66_F1_3.asm
@@ -0,0 +1,36 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x000000005c3bc5b0",
+    "RBX": "0x000000001dd5b1e5",
+    "RCX": "0x0000000015d1c92d"
+  }
+}
+%endif
+
+mov rax, 0x41424344454647
+mov rbx, 0x51525354555657
+mov rcx, 0x61626364656667
+
+mov rdx, 0x71727374757677
+
+; crc32 rax, rbx
+db 0x66 ; Override, Should be ignored
+db 0xf2 ; Prefix
+db 0x48 ; REX.W
+db 0x0f, 0x38, 0xf1, 0xc3
+
+; crc32 rbx, rcx
+db 0xf2 ; Prefix
+db 0x66 ; Override, Should be ignored
+db 0x48 ; REX.W
+db 0x0f, 0x38, 0xf1, 0xd9
+
+; crc32 rcx, rdx
+db 0x66 ; Override, Should be ignored
+db 0xf2 ; Prefix
+db 0x66 ; Override, Should be ignored
+db 0x48 ; REX.W
+db 0x0f, 0x38, 0xf1, 0xca
+
+hlt