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#include <gu/bits.h>
#include <limits.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
GU_INTERNAL unsigned
gu_ceil2e(unsigned u)
{
u--;
u |= u >> 1;
u |= u >> 2;
u |= u >> 4;
u |= u >> 8;
#if UINT_MAX > UINT16_MAX
u |= u >> 16;
#endif
#if UINT_MAX > UINT32_MAX
u |= u >> 32;
#endif
u++;
return u;
}
GU_INTERNAL double
gu_decode_double(uint64_t u)
{
bool sign = u >> 63;
unsigned rawexp = u >> 52 & 0x7ff;
uint64_t mantissa = u & 0xfffffffffffff;
double ret;
if (rawexp == 0x7ff) {
ret = (mantissa == 0) ? INFINITY : NAN;
} else {
uint64_t m = rawexp ? 1ULL << 52 | mantissa : mantissa << 1;
ret = ldexp((double) m, rawexp - 1075);
}
return sign ? copysign(ret, -1.0) : ret;
}
GU_INTERNAL uint64_t
gu_encode_double(double d)
{
int sign = signbit(d) > 0;
unsigned rawexp;
uint64_t mantissa;
switch (fpclassify(d)) {
case FP_NAN:
rawexp = 0x7ff;
mantissa = 1;
break;
case FP_INFINITE:
rawexp = 0x7ff;
mantissa = 0;
break;
default: {
int exp;
mantissa = (uint64_t) scalbn(frexp(d, &exp), 53);
mantissa &= ~ (1ULL << 52);
exp -= 53;
rawexp = exp + 1075;
}
}
uint64_t u = (((uint64_t) sign) << 63) |
(((uint64_t) rawexp & 0x7ff) << 52) |
mantissa;
return u;
}
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