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CountDigits -> count_digits

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Victor Zverovich 2014-07-24 08:59:52 -07:00
parent c1db293518
commit ca0dcce2a6
1 changed files with 8 additions and 8 deletions
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16
format.h
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@ -432,23 +432,23 @@ extern const uint64_t POWERS_OF_10_64[];
#if FMT_GCC_VERSION >= 400 || FMT_HAS_BUILTIN(__builtin_clzll) #if FMT_GCC_VERSION >= 400 || FMT_HAS_BUILTIN(__builtin_clzll)
// Returns the number of decimal digits in n. Leading zeros are not counted // Returns the number of decimal digits in n. Leading zeros are not counted
// except for n == 0 in which case CountDigits returns 1. // except for n == 0 in which case count_digits returns 1.
inline unsigned CountDigits(uint64_t n) { inline unsigned count_digits(uint64_t n) {
// Based on http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10 // Based on http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
// and the benchmark https://github.com/localvoid/cxx-benchmark-count-digits. // and the benchmark https://github.com/localvoid/cxx-benchmark-count-digits.
uint64_t t = (64 - __builtin_clzll(n | 1)) * 1233 >> 12; uint64_t t = (64 - __builtin_clzll(n | 1)) * 1233 >> 12;
return t - (n < POWERS_OF_10_64[t]) + 1; return t - (n < POWERS_OF_10_64[t]) + 1;
} }
# if FMT_GCC_VERSION >= 400 || FMT_HAS_BUILTIN(__builtin_clz) # if FMT_GCC_VERSION >= 400 || FMT_HAS_BUILTIN(__builtin_clz)
// Optional version of CountDigits for better performance on 32-bit platforms. // Optional version of count_digits for better performance on 32-bit platforms.
inline unsigned CountDigits(uint32_t n) { inline unsigned count_digits(uint32_t n) {
uint32_t t = (32 - __builtin_clz(n | 1)) * 1233 >> 12; uint32_t t = (32 - __builtin_clz(n | 1)) * 1233 >> 12;
return t - (n < POWERS_OF_10_32[t]) + 1; return t - (n < POWERS_OF_10_32[t]) + 1;
} }
# endif # endif
#else #else
// Slower version of CountDigits used when __builtin_clz is not available. // Slower version of count_digits used when __builtin_clz is not available.
inline unsigned CountDigits(uint64_t n) { inline unsigned count_digits(uint64_t n) {
unsigned count = 1; unsigned count = 1;
for (;;) { for (;;) {
// Integer division is slow so do it for a group of four digits instead // Integer division is slow so do it for a group of four digits instead
@ -1622,7 +1622,7 @@ void BasicWriter<Char>::write_int(T value, const Spec &spec) {
} }
switch (spec.type()) { switch (spec.type()) {
case 0: case 'd': { case 0: case 'd': {
unsigned num_digits = internal::CountDigits(abs_value); unsigned num_digits = internal::count_digits(abs_value);
CharPtr p = PrepareBufferForInt( CharPtr p = PrepareBufferForInt(
num_digits, spec, prefix, prefix_size) + 1 - num_digits; num_digits, spec, prefix, prefix_size) + 1 - num_digits;
internal::FormatDecimal(GetBase(p), abs_value, num_digits); internal::FormatDecimal(GetBase(p), abs_value, num_digits);
@ -1915,7 +1915,7 @@ inline void FormatDec(char *&buffer, T value) {
*buffer++ = internal::DIGITS[index + 1]; *buffer++ = internal::DIGITS[index + 1];
return; return;
} }
unsigned num_digits = internal::CountDigits(abs_value); unsigned num_digits = internal::count_digits(abs_value);
internal::FormatDecimal(buffer, abs_value, num_digits); internal::FormatDecimal(buffer, abs_value, num_digits);
buffer += num_digits; buffer += num_digits;
} }