diff options
Diffstat (limited to 'fluent-bit/lib/jemalloc-5.3.0/src/fxp.c')
-rw-r--r-- | fluent-bit/lib/jemalloc-5.3.0/src/fxp.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/fluent-bit/lib/jemalloc-5.3.0/src/fxp.c b/fluent-bit/lib/jemalloc-5.3.0/src/fxp.c new file mode 100644 index 000000000..96585f0a6 --- /dev/null +++ b/fluent-bit/lib/jemalloc-5.3.0/src/fxp.c @@ -0,0 +1,124 @@ +#include "jemalloc/internal/jemalloc_preamble.h" +#include "jemalloc/internal/jemalloc_internal_includes.h" + +#include "jemalloc/internal/fxp.h" + +static bool +fxp_isdigit(char c) { + return '0' <= c && c <= '9'; +} + +bool +fxp_parse(fxp_t *result, const char *str, char **end) { + /* + * Using malloc_strtoumax in this method isn't as handy as you might + * expect (I tried). In the fractional part, significant leading zeros + * mean that you still need to do your own parsing, now with trickier + * math. In the integer part, the casting (uintmax_t to uint32_t) + * forces more reasoning about bounds than just checking for overflow as + * we parse. + */ + uint32_t integer_part = 0; + + const char *cur = str; + + /* The string must start with a digit or a decimal point. */ + if (*cur != '.' && !fxp_isdigit(*cur)) { + return true; + } + + while ('0' <= *cur && *cur <= '9') { + integer_part *= 10; + integer_part += *cur - '0'; + if (integer_part >= (1U << 16)) { + return true; + } + cur++; + } + + /* + * We've parsed all digits at the beginning of the string, without + * overflow. Either we're done, or there's a fractional part. + */ + if (*cur != '.') { + *result = (integer_part << 16); + if (end != NULL) { + *end = (char *)cur; + } + return false; + } + + /* There's a fractional part. */ + cur++; + if (!fxp_isdigit(*cur)) { + /* Shouldn't end on the decimal point. */ + return true; + } + + /* + * We use a lot of precision for the fractional part, even though we'll + * discard most of it; this lets us get exact values for the important + * special case where the denominator is a small power of 2 (for + * instance, 1/512 == 0.001953125 is exactly representable even with + * only 16 bits of fractional precision). We need to left-shift by 16 + * before dividing so we pick the number of digits to be + * floor(log(2**48)) = 14. + */ + uint64_t fractional_part = 0; + uint64_t frac_div = 1; + for (int i = 0; i < FXP_FRACTIONAL_PART_DIGITS; i++) { + fractional_part *= 10; + frac_div *= 10; + if (fxp_isdigit(*cur)) { + fractional_part += *cur - '0'; + cur++; + } + } + /* + * We only parse the first maxdigits characters, but we can still ignore + * any digits after that. + */ + while (fxp_isdigit(*cur)) { + cur++; + } + + assert(fractional_part < frac_div); + uint32_t fractional_repr = (uint32_t)( + (fractional_part << 16) / frac_div); + + /* Success! */ + *result = (integer_part << 16) + fractional_repr; + if (end != NULL) { + *end = (char *)cur; + } + return false; +} + +void +fxp_print(fxp_t a, char buf[FXP_BUF_SIZE]) { + uint32_t integer_part = fxp_round_down(a); + uint32_t fractional_part = (a & ((1U << 16) - 1)); + + int leading_fraction_zeros = 0; + uint64_t fraction_digits = fractional_part; + for (int i = 0; i < FXP_FRACTIONAL_PART_DIGITS; i++) { + if (fraction_digits < (1U << 16) + && fraction_digits * 10 >= (1U << 16)) { + leading_fraction_zeros = i; + } + fraction_digits *= 10; + } + fraction_digits >>= 16; + while (fraction_digits > 0 && fraction_digits % 10 == 0) { + fraction_digits /= 10; + } + + size_t printed = malloc_snprintf(buf, FXP_BUF_SIZE, "%"FMTu32".", + integer_part); + for (int i = 0; i < leading_fraction_zeros; i++) { + buf[printed] = '0'; + printed++; + } + malloc_snprintf(&buf[printed], FXP_BUF_SIZE - printed, "%"FMTu64, + fraction_digits); +} |