diff options
| -rw-r--r-- | src/string.c | 166 | ||||
| -rw-r--r-- | wscript | 2 |
2 files changed, 126 insertions, 42 deletions
diff --git a/src/string.c b/src/string.c index 236a84f2..2ef062e7 100644 --- a/src/string.c +++ b/src/string.c @@ -14,15 +14,20 @@ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ +#include "int_math.h" #include "string_utils.h" #include "serd/serd.h" #include <assert.h> #include <math.h> +#include <stdbool.h> +#include <stdint.h> #include <stdlib.h> #include <string.h> +static const int uint64_digits10 = 19; + void serd_free(void* ptr) { @@ -97,13 +102,13 @@ serd_strlen(const char* str, SerdNodeFlags* flags) return strlen(str); } -static inline double +static inline int read_sign(const char** sptr) { - double sign = 1.0; + int sign = 1; switch (**sptr) { case '-': - sign = -1.0; + sign = -1; // fallthru case '+': ++(*sptr); @@ -113,56 +118,137 @@ read_sign(const char** sptr) } } -double -serd_strtod(const char* str, size_t* end) +typedef struct { - double result = 0.0; - -#define SET_END(index) do { if (end) { *end = (size_t)(index); } } while (0) + int sign; ///< Sign (+1 or -1) + int digits_expt; ///< Exponent for digits + const char* digits; ///< Pointer to the first digit in the significand + uint64_t frac; ///< Significand + int frac_expt; ///< Exponent for frac + int n_digits; ///< Number of digits in the significand + size_t end; ///< Index of the last read character +} SerdParsedDouble; + +static SerdParsedDouble +serd_parse_double(const char* const str) +{ + // Read leading sign if necessary + const char* s = str; + const int sign = read_sign(&s); - if (!strcmp(str, "NaN")) { - SET_END(3u); - return NAN; - } else if (!strcmp(str, "-INF")) { - SET_END(4u); - return -INFINITY; - } else if (!strcmp(str, "INF")) { - SET_END(3u); - return INFINITY; + // Skip leading zeros before decimal point + while (*s == '0') { + ++s; } - // Point s at the first non-whitespace character - const char* s = str; - while (is_space(*s)) { ++s; } - - // Read leading sign if necessary - const double sign = read_sign(&s); + // Skip leading zeros after decimal point + int n_leading = 0; // Zeros skipped after decimal point + bool after_point = false; // True if we are after the decimal point + if (*s == '.') { + after_point = true; + for (++s; *s == '0'; ++s) { + ++n_leading; + } + } - // Parse integer part - for (; is_digit(*s); ++s) { - result = (result * 10.0) + (*s - '0'); + // Read significant digits of the mantissa into a 64-bit integer + const char* const digits = s; // Store pointer to start of digits + uint64_t frac = 0; // Fraction value (ignoring decimal point) + int n_total = 0; // Number of decimal digits in fraction + int n_before = 0; // Number of digits before decimal point + int n_after = 0; // Number of digits after decimal point + for (int i = 0; i < uint64_digits10; ++i, ++s) { + if (is_digit(*s)) { + frac = (frac * 10) + (unsigned)(*s - '0'); + ++n_total; + n_before += !after_point; + n_after += after_point; + } else if (*s == '.' && !after_point) { + after_point = true; + } else { + break; + } } - // Parse fractional part - if (*s == '.') { - double denom = 10.0; - for (++s; is_digit(*s); ++s) { - result += (*s - '0') / denom; - denom *= 10.0; + // Skip extra digits + const int n_used = MAX(n_total, n_leading ? 1 : 0); + int n_extra_before = 0; + int n_extra_after = 0; + for (;; ++s, ++n_total) { + if (*s == '.' && !after_point) { + after_point = true; + } else if (is_digit(*s)) { + n_extra_before += !after_point; + n_extra_after += after_point; + } else { + break; } } - // Parse exponent + // Read exponent from input + int abs_in_expt = 0; + int in_expt_sign = 1; if (*s == 'e' || *s == 'E') { ++s; - double expt = 0.0; - double expt_sign = read_sign(&s); - for (; is_digit(*s); ++s) { - expt = (expt * 10.0) + (*s - '0'); + in_expt_sign = read_sign(&s); + while (is_digit(*s)) { + abs_in_expt = (abs_in_expt * 10) + (*s++ - '0'); } - result *= pow(10, expt * expt_sign); } - SET_END(s - str); - return result * sign; + // Calculate output exponents + const int in_expt = in_expt_sign * abs_in_expt; + const int frac_expt = n_extra_before - n_after - n_leading + in_expt; + const int digits_expt = in_expt - n_after - n_extra_after - n_leading; + + const SerdParsedDouble result = {sign, + digits_expt, + digits, + frac, + frac_expt, + n_used, + (size_t)(s - str)}; + + return result; +} + + +double +serd_strtod(const char* str, size_t* end) +{ +#define SET_END(index) do { if (end) { *end = (size_t)(index); } } while (0) + + // Point s at the first non-whitespace character + const char* s = str; + while (is_space(*s)) { + ++s; + } + + // Handle non-numeric special cases + if (!strcmp(s, "NaN")) { + SET_END(s - str + 3); + return (double)NAN; + } else if (!strcmp(s, "-INF")) { + SET_END(s - str + 4); + return (double)-INFINITY; + } else if (!strcmp(s, "INF")) { + SET_END(s - str + 3); + return (double)INFINITY; + } else if (!strcmp(s, "+INF")) { + SET_END(s - str + 4); + return (double)INFINITY; + } else if (*s != '+' && *s != '-' && *s != '.' && !is_digit(*s)) { + SET_END(s - str); + return (double)NAN; + } + + const SerdParsedDouble in = serd_parse_double(s); + SET_END(in.end); +#undef SET_END + + if (in.n_digits == 0) { + return (double)NAN; + } + + return in.sign * ((double)in.frac * pow(10, in.frac_expt)); } @@ -59,8 +59,6 @@ def configure(conf): 'clang': [ '-Wno-cast-align', '-Wno-covered-switch-default', - '-Wno-disabled-macro-expansion', - '-Wno-double-promotion', '-Wno-float-equal', '-Wno-format-nonliteral', '-Wno-implicit-fallthrough', |