func (p *importer) ufloat() constant.Value {
exp := p.int()
x := constant.MakeFromBytes(p.bytes())
switch {
case exp < 0:
d := constant.Shift(constant.MakeInt64(1), token.SHL, uint(-exp))
x = constant.BinaryOp(x, token.QUO, d)
case exp > 0:
x = constant.Shift(x, token.SHL, uint(exp))
}
return x
}
func (p *importer) float() constant.Value {
sign := p.int()
if sign == 0 {
return constant.MakeInt64(0)
}
exp := p.int()
mant := []byte(p.string()) // big endian
// remove leading 0's if any
for len(mant) > 0 && mant[0] == 0 {
mant = mant[1:]
}
// convert to little endian
// TODO(gri) go/constant should have a more direct conversion function
// (e.g., once it supports a big.Float based implementation)
for i, j := 0, len(mant)-1; i < j; i, j = i+1, j-1 {
mant[i], mant[j] = mant[j], mant[i]
}
// adjust exponent (constant.MakeFromBytes creates an integer value,
// but mant represents the mantissa bits such that 0.5 <= mant < 1.0)
exp -= len(mant) << 3
if len(mant) > 0 {
for msd := mant[len(mant)-1]; msd&0x80 == 0; msd <<= 1 {
exp++
}
}
x := constant.MakeFromBytes(mant)
switch {
case exp < 0:
d := constant.Shift(constant.MakeInt64(1), token.SHL, uint(-exp))
x = constant.BinaryOp(x, token.QUO, d)
case exp > 0:
x = constant.Shift(x, token.SHL, uint(exp))
}
if sign < 0 {
x = constant.UnaryOp(token.SUB, x, 0)
}
return x
}