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-rw-r--r--absl/strings/numbers.h99
1 files changed, 86 insertions, 13 deletions
diff --git a/absl/strings/numbers.h b/absl/strings/numbers.h
index e9878016..d872cca5 100644
--- a/absl/strings/numbers.h
+++ b/absl/strings/numbers.h
@@ -24,6 +24,10 @@
#ifndef ABSL_STRINGS_NUMBERS_H_
#define ABSL_STRINGS_NUMBERS_H_
+#ifdef __SSE4_2__
+#include <x86intrin.h>
+#endif
+
#include <cstddef>
#include <cstdlib>
#include <cstring>
@@ -32,39 +36,54 @@
#include <string>
#include <type_traits>
+#include "absl/base/config.h"
+#include "absl/base/internal/bits.h"
+#ifdef __SSE4_2__
+// TODO(jorg): Remove this when we figure out the right way
+// to swap bytes on SSE 4.2 that works with the compilers
+// we claim to support. Also, add tests for the compiler
+// that doesn't support the Intel _bswap64 intrinsic but
+// does support all the SSE 4.2 intrinsics
+#include "absl/base/internal/endian.h"
+#endif
#include "absl/base/macros.h"
#include "absl/base/port.h"
#include "absl/numeric/int128.h"
#include "absl/strings/string_view.h"
namespace absl {
-inline namespace lts_2019_08_08 {
+ABSL_NAMESPACE_BEGIN
// SimpleAtoi()
//
-// Converts the given string into an integer value, returning `true` if
-// successful. The string must reflect a base-10 integer (optionally followed or
-// preceded by ASCII whitespace) whose value falls within the range of the
-// integer type. If any errors are encountered, this function returns `false`,
-// leaving `out` in an unspecified state.
+// Converts the given string (optionally followed or preceded by ASCII
+// whitespace) into an integer value, returning `true` if successful. The string
+// must reflect a base-10 integer whose value falls within the range of the
+// integer type (optionally preceded by a `+` or `-`). If any errors are
+// encountered, this function returns `false`, leaving `out` in an unspecified
+// state.
template <typename int_type>
ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view str, int_type* out);
// SimpleAtof()
//
// Converts the given string (optionally followed or preceded by ASCII
-// whitespace) into a float, which may be rounded on overflow or underflow.
+// whitespace) into a float, which may be rounded on overflow or underflow,
+// returning `true` if successful.
// See https://en.cppreference.com/w/c/string/byte/strtof for details about the
-// allowed formats for `str`. If any errors are encountered, this function
+// allowed formats for `str`, except SimpleAtof() is locale-independent and will
+// always use the "C" locale. If any errors are encountered, this function
// returns `false`, leaving `out` in an unspecified state.
ABSL_MUST_USE_RESULT bool SimpleAtof(absl::string_view str, float* out);
// SimpleAtod()
//
// Converts the given string (optionally followed or preceded by ASCII
-// whitespace) into a double, which may be rounded on overflow or underflow.
+// whitespace) into a double, which may be rounded on overflow or underflow,
+// returning `true` if successful.
// See https://en.cppreference.com/w/c/string/byte/strtof for details about the
-// allowed formats for `str`. If any errors are encountered, this function
+// allowed formats for `str`, except SimpleAtod is locale-independent and will
+// always use the "C" locale. If any errors are encountered, this function
// returns `false`, leaving `out` in an unspecified state.
ABSL_MUST_USE_RESULT bool SimpleAtod(absl::string_view str, double* out);
@@ -78,20 +97,40 @@ ABSL_MUST_USE_RESULT bool SimpleAtod(absl::string_view str, double* out);
// unspecified state.
ABSL_MUST_USE_RESULT bool SimpleAtob(absl::string_view str, bool* out);
-} // inline namespace lts_2019_08_08
+ABSL_NAMESPACE_END
} // namespace absl
// End of public API. Implementation details follow.
namespace absl {
-inline namespace lts_2019_08_08 {
+ABSL_NAMESPACE_BEGIN
namespace numbers_internal {
+// Digit conversion.
+ABSL_DLL extern const char kHexChar[17]; // 0123456789abcdef
+ABSL_DLL extern const char
+ kHexTable[513]; // 000102030405060708090a0b0c0d0e0f1011...
+ABSL_DLL extern const char
+ two_ASCII_digits[100][2]; // 00, 01, 02, 03...
+
+// Writes a two-character representation of 'i' to 'buf'. 'i' must be in the
+// range 0 <= i < 100, and buf must have space for two characters. Example:
+// char buf[2];
+// PutTwoDigits(42, buf);
+// // buf[0] == '4'
+// // buf[1] == '2'
+inline void PutTwoDigits(size_t i, char* buf) {
+ assert(i < 100);
+ memcpy(buf, two_ASCII_digits[i], 2);
+}
+
// safe_strto?() functions for implementing SimpleAtoi()
bool safe_strto32_base(absl::string_view text, int32_t* value, int base);
bool safe_strto64_base(absl::string_view text, int64_t* value, int base);
bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base);
bool safe_strtou64_base(absl::string_view text, uint64_t* value, int base);
+bool safe_strtou128_base(absl::string_view text, absl::uint128* value,
+ int base);
static const int kFastToBufferSize = 32;
static const int kSixDigitsToBufferSize = 16;
@@ -173,6 +212,35 @@ ABSL_MUST_USE_RESULT bool safe_strtoi_base(absl::string_view s, int_type* out,
return parsed;
}
+// FastHexToBufferZeroPad16()
+//
+// Outputs `val` into `out` as if by `snprintf(out, 17, "%016x", val)` but
+// without the terminating null character. Thus `out` must be of length >= 16.
+// Returns the number of non-pad digits of the output (it can never be zero
+// since 0 has one digit).
+inline size_t FastHexToBufferZeroPad16(uint64_t val, char* out) {
+#ifdef __SSE4_2__
+ uint64_t be = absl::big_endian::FromHost64(val);
+ const auto kNibbleMask = _mm_set1_epi8(0xf);
+ const auto kHexDigits = _mm_setr_epi8('0', '1', '2', '3', '4', '5', '6', '7',
+ '8', '9', 'a', 'b', 'c', 'd', 'e', 'f');
+ auto v = _mm_loadl_epi64(reinterpret_cast<__m128i*>(&be)); // load lo dword
+ auto v4 = _mm_srli_epi64(v, 4); // shift 4 right
+ auto il = _mm_unpacklo_epi8(v4, v); // interleave bytes
+ auto m = _mm_and_si128(il, kNibbleMask); // mask out nibbles
+ auto hexchars = _mm_shuffle_epi8(kHexDigits, m); // hex chars
+ _mm_storeu_si128(reinterpret_cast<__m128i*>(out), hexchars);
+#else
+ for (int i = 0; i < 8; ++i) {
+ auto byte = (val >> (56 - 8 * i)) & 0xFF;
+ auto* hex = &absl::numbers_internal::kHexTable[byte * 2];
+ std::memcpy(out + 2 * i, hex, 2);
+ }
+#endif
+ // | 0x1 so that even 0 has 1 digit.
+ return 16 - absl::base_internal::CountLeadingZeros64(val | 0x1) / 4;
+}
+
} // namespace numbers_internal
// SimpleAtoi()
@@ -187,7 +255,12 @@ ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view str, int_type* out) {
return numbers_internal::safe_strtoi_base(str, out, 10);
}
-} // inline namespace lts_2019_08_08
+ABSL_MUST_USE_RESULT inline bool SimpleAtoi(absl::string_view str,
+ absl::uint128* out) {
+ return numbers_internal::safe_strtou128_base(str, out, 10);
+}
+
+ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_STRINGS_NUMBERS_H_
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-08 14:59:41 +0000