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Changes imported from Abseil "staging" branch:

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- 8320b38cd9f4f271fb6b278bd1e10d93f6ac3856 Use overloads for int32/int64/uint32/uint64 rather than i... by Jorg Brown <jorg@google.com>
  - f8b582b8deb3f78a3c6de2114b3ec4640f5427dd Internal change by Juemin Yang <jueminyang@google.com>
  - 240ff55ebf493ab1233ebe6976853a5fa2b3ec46 Remove the internal LowLevelAlloc's dependence on kLinker... by Greg Falcon <gfalcon@google.com>

GitOrigin-RevId: 8320b38cd9f4f271fb6b278bd1e10d93f6ac3856
Change-Id: If5004efa2b43856948390ab357b8e9403e4461b4
This commit is contained in:
Abseil Team 2017-12-14 12:36:12 -08:00 • committed by Titus Winters
parent 720c017e30
commit 6280bddf55
5 changed files with 233 additions and 181 deletions
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28
absl/strings/numbers.cc
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@ -135,16 +135,12 @@ bool SimpleAtob(absl::string_view str, bool* value) {
}
// ----------------------------------------------------------------------
// FastInt32ToBuffer()
// FastUInt32ToBuffer()
// FastInt64ToBuffer()
// FastUInt64ToBuffer()
// FastIntToBuffer() overloads
//
// Like the Fast*ToBuffer() functions above, these are intended for speed.
// Unlike the Fast*ToBuffer() functions, however, these functions write
// their output to the beginning of the buffer (hence the name, as the
// output is left-aligned). The caller is responsible for ensuring that
// the buffer has enough space to hold the output.
// their output to the beginning of the buffer. The caller is responsible
// for ensuring that the buffer has enough space to hold the output.
//
// Returns a pointer to the end of the std::string (i.e. the null character
// terminating the std::string).
@ -160,7 +156,7 @@ const char one_ASCII_final_digits[10][2] {
} // namespace
char* numbers_internal::FastUInt32ToBuffer(uint32_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(uint32_t i, char* buffer) {
uint32_t digits;
// The idea of this implementation is to trim the number of divides to as few
// as possible, and also reducing memory stores and branches, by going in
@ -230,7 +226,7 @@ char* numbers_internal::FastUInt32ToBuffer(uint32_t i, char* buffer) {
goto lt100_000_000;
}
char* numbers_internal::FastInt32ToBuffer(int32_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(int32_t i, char* buffer) {
uint32_t u = i;
if (i < 0) {
*buffer++ = '-';
@ -239,12 +235,12 @@ char* numbers_internal::FastInt32ToBuffer(int32_t i, char* buffer) {
// we write the equivalent expression "0 - u" instead.
u = 0 - u;
}
return numbers_internal::FastUInt32ToBuffer(u, buffer);
return numbers_internal::FastIntToBuffer(u, buffer);
}
char* numbers_internal::FastUInt64ToBuffer(uint64_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(uint64_t i, char* buffer) {
uint32_t u32 = static_cast<uint32_t>(i);
if (u32 == i) return numbers_internal::FastUInt32ToBuffer(u32, buffer);
if (u32 == i) return numbers_internal::FastIntToBuffer(u32, buffer);
// Here we know i has at least 10 decimal digits.
uint64_t top_1to11 = i / 1000000000;
@ -252,12 +248,12 @@ char* numbers_internal::FastUInt64ToBuffer(uint64_t i, char* buffer) {
uint32_t top_1to11_32 = static_cast<uint32_t>(top_1to11);
if (top_1to11_32 == top_1to11) {
buffer = numbers_internal::FastUInt32ToBuffer(top_1to11_32, buffer);
buffer = numbers_internal::FastIntToBuffer(top_1to11_32, buffer);
} else {
// top_1to11 has more than 32 bits too; print it in two steps.
uint32_t top_8to9 = static_cast<uint32_t>(top_1to11 / 100);
uint32_t mid_2 = static_cast<uint32_t>(top_1to11 - top_8to9 * 100);
buffer = numbers_internal::FastUInt32ToBuffer(top_8to9, buffer);
buffer = numbers_internal::FastIntToBuffer(top_8to9, buffer);
PutTwoDigits(mid_2, buffer);
buffer += 2;
}
@ -283,13 +279,13 @@ char* numbers_internal::FastUInt64ToBuffer(uint64_t i, char* buffer) {
return buffer + 1;
}
char* numbers_internal::FastInt64ToBuffer(int64_t i, char* buffer) {
char* numbers_internal::FastIntToBuffer(int64_t i, char* buffer) {
uint64_t u = i;
if (i < 0) {
*buffer++ = '-';
u = 0 - u;
}
return numbers_internal::FastUInt64ToBuffer(u, buffer);
return numbers_internal::FastIntToBuffer(u, buffer);
}
// Returns the number of leading 0 bits in a 64-bit value.