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Copy pathaarch64-strstr-v2.cpp
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aarch64-strstr-v2.cpp
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size_t FORCE_INLINE aarch64_strstr_anysize(const char* s, size_t n, const char* needle, size_t k) {
assert(k > 0);
assert(n > 0);
const uint8x16_t first = vdupq_n_u8(needle[0]);
const uint8x16_t last = vdupq_n_u8(needle[k - 1]);
const uint8_t* ptr = reinterpret_cast<const uint8_t*>(s);
for (size_t i = 0; i < n; i += 16) {
const uint8x16_t block_first = vld1q_u8(ptr + i);
const uint8x16_t block_last = vld1q_u8(ptr + i + k - 1);
const uint8x16_t eq_first = vceqq_u8(first, block_first);
const uint8x16_t eq_last = vceqq_u8(last, block_last);
const uint8x16_t pred_16 = vandq_u8(eq_first, eq_last);
uint64_t mask;
mask = vgetq_lane_u64(vreinterpretq_u64_u8(pred_16), 0);
if (mask) {
for (int j=0; j < 8; j++) {
if ((mask & 0xff) && (memcmp(s + i + j + 1, needle + 1, k - 2) == 0)) {
return i + j;
}
mask >>= 8;
}
}
mask = vgetq_lane_u64(vreinterpretq_u64_u8(pred_16), 1);
if (mask) {
for (int j=0; j < 8; j++) {
if ((mask & 0xff) && (memcmp(s + i + j + 8 + 1, needle + 1, k - 2) == 0)) {
return i + j + 8;
}
mask >>= 8;
}
}
}
return std::string::npos;
}
// ------------------------------------------------------------------------
template <size_t k, typename MEMCMP>
size_t FORCE_INLINE aarch64_strstr_memcmp(const char* s, size_t n, const char* needle, MEMCMP memcmp_fun) {
assert(k > 0);
assert(n > 0);
const uint8x16_t first = vdupq_n_u8(needle[0]);
const uint8x16_t last = vdupq_n_u8(needle[k - 1]);
const uint8_t* ptr = reinterpret_cast<const uint8_t*>(s);
for (size_t i = 0; i < n; i += 16) {
const uint8x16_t block_first = vld1q_u8(ptr + i);
const uint8x16_t block_last = vld1q_u8(ptr + i + k - 1);
const uint8x16_t eq_first = vceqq_u8(first, block_first);
const uint8x16_t eq_last = vceqq_u8(last, block_last);
const uint8x16_t pred_16 = vandq_u8(eq_first, eq_last);
uint64_t mask;
int j;
mask = vgetq_lane_u64(vreinterpretq_u64_u8(pred_16), 0);
j = 0;
while (mask) {
if ((mask & 0xff) && (memcmp_fun(s + i + j + 1, needle + 1))) {
return i + j;
}
mask >>= 8;
j += 1;
}
mask = vgetq_lane_u64(vreinterpretq_u64_u8(pred_16), 1);
j = 0;
while (mask) {
if ((mask & 0xff) && (memcmp_fun(s + i + j + 8 + 1, needle + 1))) {
return i + j + 8;
}
mask >>= 8;
j += 1;
}
}
return std::string::npos;
}
// ------------------------------------------------------------------------
size_t aarch64_strstr_v2(const char* s, size_t n, const char* needle, size_t k) {
size_t result = std::string::npos;
if (n < k) {
return result;
}
switch (k) {
case 0:
return 0;
case 1: {
const char* res = reinterpret_cast<const char*>(strchr(s, needle[0]));
return (res != nullptr) ? res - s : std::string::npos;
}
case 2:
result = aarch64_strstr_memcmp<2>(s, n, needle, always_true);
break;
case 3:
result = aarch64_strstr_memcmp<3>(s, n, needle, memcmp1);
break;
case 4:
result = aarch64_strstr_memcmp<4>(s, n, needle, memcmp2);
break;
case 5:
result = aarch64_strstr_memcmp<5>(s, n, needle, memcmp4);
break;
case 6:
result = aarch64_strstr_memcmp<6>(s, n, needle, memcmp4);
break;
case 7:
result = aarch64_strstr_memcmp<7>(s, n, needle, memcmp5);
break;
case 8:
result = aarch64_strstr_memcmp<8>(s, n, needle, memcmp6);
break;
case 9:
result = aarch64_strstr_memcmp<9>(s, n, needle, memcmp8);
break;
case 10:
result = aarch64_strstr_memcmp<10>(s, n, needle, memcmp8);
break;
case 11:
result = aarch64_strstr_memcmp<11>(s, n, needle, memcmp9);
break;
case 12:
result = aarch64_strstr_memcmp<12>(s, n, needle, memcmp10);
break;
default:
result = aarch64_strstr_anysize(s, n, needle, k);
break;
}
if (result <= n - k) {
return result;
} else {
return std::string::npos;
}
}
// ------------------------------------------------------------------------
size_t aarch64_strstr_v2(const std::string& s, const std::string& needle) {
return aarch64_strstr_v2(s.data(), s.size(), needle.data(), needle.size());
}