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141 lines
3.4 KiB
C
141 lines
3.4 KiB
C
#ifndef PPARSEFP_H
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#define PPARSEFP_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* Parses a float or double number and returns the length parsed if
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* successful. The length argument is of limited value due to dependency
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* on `strtod` - buf[len] must be accessible and must not be part of
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* a valid number, including hex float numbers..
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*
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* Unlike strtod, whitespace is not parsed.
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*
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* May return:
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* - null on error,
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* - buffer start if first character does not start a number,
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* - or end of parse on success.
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*
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*/
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#define PDIAGNOSTIC_IGNORE_UNUSED_FUNCTION
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#include "pdiagnostic_push.h"
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/*
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* isinf is needed in order to stay compatible with strtod's
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* over/underflow handling but isinf has some portability issues.
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*
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* Use the parse_double/float_is_range_error instead of isinf directly.
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* This ensures optimizations can be added when not using strtod.
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*
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* On gcc, clang and msvc we can use isinf or equivalent directly.
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* Other compilers such as xlc may require linking with -lm which may not
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* be convienent so a default isinf is provided. If isinf is available
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* and there is a noticable performance issue, define
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* `PORTABLE_USE_ISINF`.
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*/
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#if defined(__GNUC__) || defined(__clang__) || defined(_MSC_VER) || defined(PORTABLE_USE_ISINF)
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#include <math.h>
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#if defined(_MSC_VER) && !defined(isinf)
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#include <float.h>
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#define isnan _isnan
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#define isinf(x) (!_finite(x))
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#endif
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/*
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* clang-5 through clang-8 but not clang-9 issues incorrect precision
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* loss warning with -Wconversion flag when cast is absent.
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*/
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#if defined(__clang__)
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#if __clang_major__ >= 5 && __clang_major__ <= 8
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#define parse_double_isinf(x) isinf((float)x)
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#endif
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#endif
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#if !defined(parse_double_isinf)
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#define parse_double_isinf isinf
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#endif
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#define parse_float_isinf isinf
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#else
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#ifndef UINT8_MAX
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#include <stdint.h>
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#endif
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/* Avoid linking with libmath but depends on float/double being IEEE754 */
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static inline int parse_double_isinf(double x)
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{
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union { uint64_t u64; double f64; } v;
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v.f64 = x;
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return (v.u64 & 0x7fffffff00000000ULL) == 0x7ff0000000000000ULL;
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}
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static inline int parse_float_isinf(float x)
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{
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union { uint32_t u32; float f32; } v;
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v.f32 = x;
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return (v.u32 & 0x7fffffff) == 0x7f800000;
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}
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#endif
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/* Returns 0 when in range, 1 on overflow, and -1 on underflow. */
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static inline int parse_double_is_range_error(double x)
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{
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return parse_double_isinf(x) ? (x < 0.0 ? -1 : 1) : 0;
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}
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static inline int parse_float_is_range_error(float x)
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{
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return parse_float_isinf(x) ? (x < 0.0f ? -1 : 1) : 0;
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}
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#ifndef PORTABLE_USE_GRISU3
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#define PORTABLE_USE_GRISU3 1
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#endif
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#if PORTABLE_USE_GRISU3
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#include "grisu3_parse.h"
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#endif
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#ifdef grisu3_parse_double_is_defined
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static inline const char *parse_double(const char *buf, size_t len, double *result)
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{
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return grisu3_parse_double(buf, len, result);
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}
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#else
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#include <stdio.h>
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static inline const char *parse_double(const char *buf, size_t len, double *result)
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{
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char *end;
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(void)len;
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*result = strtod(buf, &end);
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return end;
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}
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#endif
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static inline const char *parse_float(const char *buf, size_t len, float *result)
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{
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const char *end;
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double v;
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union { uint32_t u32; float f32; } inf;
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inf.u32 = 0x7f800000;
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end = parse_double(buf, len, &v);
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*result = (float)v;
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if (parse_float_isinf(*result)) {
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*result = v < 0 ? -inf.f32 : inf.f32;
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return buf;
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}
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return end;
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}
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#include "pdiagnostic_pop.h"
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#ifdef __cplusplus
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}
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#endif
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#endif /* PPARSEFP_H */
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