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#include <string.h>
#include <stdint.h>
namespace {
// Needed since we cannot declare a templated enum.
template<typename T>
struct word_helper {
using underlying [[gnu::aligned(1)]] = T;
enum class [[gnu::may_alias]] word_enum : underlying { };
};
template<typename T>
using word = typename word_helper<T>::word_enum;
template<typename T>
[[gnu::always_inline]]
inline word<T> alias_load(const unsigned char *&p) {
word<T> value = *reinterpret_cast<const word<T> *>(p);
p += sizeof(T);
return value;
}
template<typename T>
[[gnu::always_inline]]
inline void alias_store(unsigned char *&p, word<T> value) {
*reinterpret_cast<word<T> *>(p) = value;
p += sizeof(T);
}
#ifdef __LP64__
void *forward_copy(void *__restrict dest, const void *__restrict src, size_t n) {
auto curDest = reinterpret_cast<unsigned char *>(dest);
auto curSrc = reinterpret_cast<const unsigned char *>(src);
while(n >= 8 * 8) {
auto w1 = alias_load<uint64_t>(curSrc);
auto w2 = alias_load<uint64_t>(curSrc);
auto w3 = alias_load<uint64_t>(curSrc);
auto w4 = alias_load<uint64_t>(curSrc);
auto w5 = alias_load<uint64_t>(curSrc);
auto w6 = alias_load<uint64_t>(curSrc);
auto w7 = alias_load<uint64_t>(curSrc);
auto w8 = alias_load<uint64_t>(curSrc);
alias_store<uint64_t>(curDest, w1);
alias_store<uint64_t>(curDest, w2);
alias_store<uint64_t>(curDest, w3);
alias_store<uint64_t>(curDest, w4);
alias_store<uint64_t>(curDest, w5);
alias_store<uint64_t>(curDest, w6);
alias_store<uint64_t>(curDest, w7);
alias_store<uint64_t>(curDest, w8);
n -= 8 * 8;
}
if(n >= 4 * 8) {
auto w1 = alias_load<uint64_t>(curSrc);
auto w2 = alias_load<uint64_t>(curSrc);
auto w3 = alias_load<uint64_t>(curSrc);
auto w4 = alias_load<uint64_t>(curSrc);
alias_store<uint64_t>(curDest, w1);
alias_store<uint64_t>(curDest, w2);
alias_store<uint64_t>(curDest, w3);
alias_store<uint64_t>(curDest, w4);
n -= 4 * 8;
}
if(n >= 2 * 8) {
auto w1 = alias_load<uint64_t>(curSrc);
auto w2 = alias_load<uint64_t>(curSrc);
alias_store<uint64_t>(curDest, w1);
alias_store<uint64_t>(curDest, w2);
n -= 2 * 8;
}
if(n >= 8) {
auto w = alias_load<uint64_t>(curSrc);
alias_store<uint64_t>(curDest, w);
n -= 8;
}
if(n >= 4) {
auto w = alias_load<uint32_t>(curSrc);
alias_store<uint32_t>(curDest, w);
n -= 4;
}
if(n >= 2) {
auto w = alias_load<uint16_t>(curSrc);
alias_store<uint16_t>(curDest, w);
n -= 2;
}
if(n)
*curDest = *curSrc;
return dest;
}
#else // !__LP64__
void *forward_copy(void *dest, const void *src, size_t n) {
for(size_t i = 0; i < n; i++)
((char *)dest)[i] = ((const char *)src)[i];
return dest;
}
#endif // __LP64__ / !__LP64__
}
// --------------------------------------------------------------------------------------
// memcpy() implementation.
// --------------------------------------------------------------------------------------
void *memcpy(void *__restrict dest, const void *__restrict src, size_t n) {
return forward_copy(dest, src, n);
}
// --------------------------------------------------------------------------------------
// memset() implementation.
// --------------------------------------------------------------------------------------
#ifdef __LP64__
void *memset(void *dest, int val, size_t n) {
auto curDest = reinterpret_cast<unsigned char *>(dest);
unsigned char byte = val;
// Get rid of misalignment.
while(n && (reinterpret_cast<uintptr_t>(curDest) & 7)) {
*curDest++ = byte;
--n;
}
auto pattern64 = static_cast<word<uint64_t>>(
static_cast<uint64_t>(byte)
| (static_cast<uint64_t>(byte) << 8)
| (static_cast<uint64_t>(byte) << 16)
| (static_cast<uint64_t>(byte) << 24)
| (static_cast<uint64_t>(byte) << 32)
| (static_cast<uint64_t>(byte) << 40)
| (static_cast<uint64_t>(byte) << 48)
| (static_cast<uint64_t>(byte) << 56));
auto pattern32 = static_cast<word<uint32_t>>(
static_cast<uint32_t>(byte)
| (static_cast<uint32_t>(byte) << 8)
| (static_cast<uint32_t>(byte) << 16)
| (static_cast<uint32_t>(byte) << 24));
auto pattern16 = static_cast<word<uint16_t>>(
static_cast<uint16_t>(byte)
| (static_cast<uint16_t>(byte) << 8));
while(n >= 8 * 8) {
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
n -= 8 * 8;
}
if(n >= 4 * 8) {
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
n -= 4 * 8;
}
if(n >= 2 * 8) {
alias_store<uint64_t>(curDest, pattern64);
alias_store<uint64_t>(curDest, pattern64);
n -= 2 * 8;
}
if(n >= 8) {
alias_store<uint64_t>(curDest, pattern64);
n -= 8;
}
if(n >= 4) {
alias_store<uint32_t>(curDest, pattern32);
n -= 4;
}
if(n >= 2) {
alias_store<uint16_t>(curDest, pattern16);
n -= 2;
}
if(n)
*curDest = byte;
return dest;
}
#else // !__LP64__
void *memset(void *dest, int byte, size_t count) {
for(size_t i = 0; i < count; i++)
((char *)dest)[i] = (char)byte;
return dest;
}
#endif // __LP64__ / !__LP64__
// --------------------------------------------------------------------------------------
// "Non-optimized" functions.
// --------------------------------------------------------------------------------------
void *memmove(void *dest, const void *src, size_t size) {
char *dest_bytes = (char *)dest;
char *src_bytes = (char *)src;
if(dest_bytes < src_bytes) {
return forward_copy(dest, src, size);
}else if(dest_bytes > src_bytes) {
for(size_t i = 0; i < size; i++)
dest_bytes[size - i - 1] = src_bytes[size - i - 1];
}
return dest;
}
size_t strlen(const char *s) {
size_t len = 0;
for(size_t i = 0; s[i]; i++)
len++;
return len;
}
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