#include <stdio.h>

#include <stdint.h>

#include "util.h"

int eulpf(float x)

{

	union { float f; uint32_t i; } u = { x };

	int e = u.i>>23 & 0xff;

	if (!e)

		e++;

	return e - 0x7f - 23;

}

int eulp(double x)

{

	union { double f; uint64_t i; } u = { x };

	int e = u.i>>52 & 0x7ff;

	if (!e)

		e++;

	return e - 0x3ff - 52;

}

int eulpl(long double x)

{

#if LDBL_MANT_DIG == 53

	return eulp(x);

#elif LDBL_MANT_DIG == 64

	union { long double f; struct {uint64_t m; uint16_t e; uint16_t pad;} i; } u = { x };

	int e = u.i.e & 0x7fff;

	if (!e)

		e++;

	return e - 0x3fff - 63;

#else

	// TODO

	return 0;

#endif

}

float ulperrf(float got, float want, float dwant)

{

	if (isnan(got) && isnan(want))

		return 0;

	if (got == want) {

		if (signbit(got) == signbit(want))

			return dwant;

		return inf;

	}

	if (isinf(got)) {

		got = copysignf(0x1p127, got);

		want *= 0.5;

	}

	return scalbn(got - want, -eulpf(want)) + dwant;

}

float ulperr(double got, double want, float dwant)

{

	if (isnan(got) && isnan(want))

		return 0;

	if (got == want) {

		if (signbit(got) == signbit(want))

			return dwant;

		return inf; // treat 0 sign errors badly

	}

	if (isinf(got)) {

		got = copysign(0x1p1023, got);

		want *= 0.5;

	}

	return scalbn(got - want, -eulp(want)) + dwant;

}

float ulperrl(long double got, long double want, float dwant)

{

#if LDBL_MANT_DIG == 53

	return ulperr(got, want, dwant);

#elif LDBL_MANT_DIG == 64

	if (isnan(got) && isnan(want))

		return 0;

	if (got == want) {

		if (signbit(got) == signbit(want))

			return dwant;

		return inf;

	}

	if (isinf(got)) {

		got = copysignl(0x1p16383L, got);

		want *= 0.5;

	}

	return scalbnl(got - want, -eulpl(want)) + dwant;

#else

	// TODO

	return inf;

#endif

}

#define length(a) (sizeof(a)/sizeof*(a))

#define flag(x) {x, #x}

static struct {

	int flag;

	char *s;

} eflags[] = {

	flag(INEXACT),

	flag(INVALID),

	flag(DIVBYZERO),

	flag(UNDERFLOW),

	flag(OVERFLOW)

};

char *estr(int f)

{

	static char buf[256];

	char *p = buf;

	int i, all = 0;

	for (i = 0; i < length(eflags); i++)

		if (f & eflags[i].flag) {

			p += sprintf(p, "%s%s", all ? "|" : "", eflags[i].s);

			all |= eflags[i].flag;

		}

	if (all != f) {

		p += sprintf(p, "%s%d", all ? "|" : "", f & ~all);

		all = f;

	}

	p += sprintf(p, "%s", all ? "" : "0");

	return buf;

}

char *rstr(int r)

{

	switch (r) {

	case RN: return "RN";

#ifdef FE_TOWARDZERO

	case RZ: return "RZ";

#endif

#ifdef FE_UPWARD

	case RU: return "RU";

#endif

#ifdef FE_DOWNWARD

	case RD: return "RD";

#endif

	}

	return "R?";

}