1 //===-- Implementation of bcmp --------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLVM_LIBC_SRC_STRING_MEMORY_UTILS_BCMP_IMPLEMENTATIONS_H
10 #define LLVM_LIBC_SRC_STRING_MEMORY_UTILS_BCMP_IMPLEMENTATIONS_H
11 
12 #include "src/__support/architectures.h"
13 #include "src/__support/common.h"
14 #include "src/string/memory_utils/elements.h"
15 
16 #include <stddef.h> // size_t
17 
18 namespace __llvm_libc {
19 
20 // Fixed-size difference between 'lhs' and 'rhs'.
21 template <typename Element> bool differs(const char *lhs, const char *rhs) {
22   return !Element::equals(lhs, rhs);
23 }
24 // Runtime-size difference between 'lhs' and 'rhs'.
25 template <typename Element>
26 bool differs(const char *lhs, const char *rhs, size_t size) {
27   return !Element::equals(lhs, rhs, size);
28 }
29 
30 static inline int inline_bcmp(const char *lhs, const char *rhs, size_t count) {
31 #if defined(LLVM_LIBC_ARCH_X86)
32   using namespace ::__llvm_libc::x86;
33 #elif defined(LLVM_LIBC_ARCH_AARCH64)
34   using namespace ::__llvm_libc::aarch64;
35 #else
36   using namespace ::__llvm_libc::scalar;
37 #endif
38   if (count == 0)
39     return 0;
40   if (count == 1)
41     return differs<_1>(lhs, rhs);
42   if (count == 2)
43     return differs<_2>(lhs, rhs);
44   if (count == 3)
45     return differs<_3>(lhs, rhs);
46   if (count <= 8)
47     return differs<HeadTail<_4>>(lhs, rhs, count);
48   if (count <= 16)
49     return differs<HeadTail<_8>>(lhs, rhs, count);
50   if (count <= 32)
51     return differs<HeadTail<_16>>(lhs, rhs, count);
52   if (count <= 64)
53     return differs<HeadTail<_32>>(lhs, rhs, count);
54   if (count <= 128)
55     return differs<HeadTail<_64>>(lhs, rhs, count);
56   return differs<Align<_32>::Then<Loop<_32>>>(lhs, rhs, count);
57 }
58 
59 } // namespace __llvm_libc
60 
61 #endif // LLVM_LIBC_SRC_STRING_MEMORY_UTILS_BCMP_IMPLEMENTATIONS_H
62