osdev/libc/math.h

#pragma once

#define MAX(a, b) \
   ({ __typeof__ (a) _a = (a); \
       __typeof__ (b) _b = (b); \
     _a > _b ? _a : _b; })

#define MIN(a, b) \
   ({ __typeof__ (a) _a = (a); \
       __typeof__ (b) _b = (b); \
     _a < _b ? _a : _b; })

#define FP_NAN       0
#define FP_INFINITE  1
#define FP_ZERO      2
#define FP_SUBNORMAL 3
#define FP_NORMAL    4

int __fpclassify(double);
int __fpclassifyf(float);
int __fpclassifyl(long double);

static inline unsigned __FLOAT_BITS(float __f) {
    union {
        float __f;
        unsigned __i;
    } __u;
    __u.__f = __f;
    return __u.__i;
}

static inline unsigned long long __DOUBLE_BITS(double __f) {
    union {
        double __f;
        unsigned long long __i;
    } __u;
    __u.__f = __f;
    return __u.__i;
}

#define isfinite(x) ( \
    sizeof(x) == sizeof(float) ? (__FLOAT_BITS(x) & 0x7fffffff) < 0x7f800000 : \
    sizeof(x) == sizeof(double) ? (__DOUBLE_BITS(x) & -1ULL>>1) < 0x7ffULL<<52 : \
    __fpclassifyl(x) > FP_INFINITE)

int __signbit(double);
int __signbitf(float);
int __signbitl(long double);

#define signbit(x) ( \
    sizeof(x) == sizeof(float) ? (int)(__FLOAT_BITS(x)>>31) : \
    sizeof(x) == sizeof(double) ? (int)(__DOUBLE_BITS(x)>>63) : \
    __signbitl(x) )

long double frexpl(long double x, int *e);