1 //! Extended precision "soft float", for internal use only.
3 // This module is only for dec2flt and flt2dec, and only public because of coretests.
4 // It is not intended to ever be stabilized.
7 feature = "core_private_diy_float",
8 reason = "internal routines only exposed for testing",
12 /// A custom 64-bit floating point type, representing `f * 2^e`.
13 #[derive(Copy, Clone, Debug)]
16 /// The integer mantissa.
18 /// The exponent in base 2.
23 /// Returns a correctly rounded product of itself and `other`.
24 pub fn mul(&self, other: &Fp) -> Fp {
25 const MASK: u64 = 0xffffffff;
27 let b = self.f & MASK;
28 let c = other.f >> 32;
29 let d = other.f & MASK;
34 let tmp = (bd >> 32) + (ad & MASK) + (bc & MASK) + (1 << 31) /* round */;
35 let f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
36 let e = self.e + other.e + 64;
40 /// Normalizes itself so that the resulting mantissa is at least `2^63`.
41 pub fn normalize(&self) -> Fp {
44 if f >> (64 - 32) == 0 {
48 if f >> (64 - 16) == 0 {
52 if f >> (64 - 8) == 0 {
56 if f >> (64 - 4) == 0 {
60 if f >> (64 - 2) == 0 {
64 if f >> (64 - 1) == 0 {
68 debug_assert!(f >= (1 << 63));
72 /// Normalizes itself to have the shared exponent.
73 /// It can only decrease the exponent (and thus increase the mantissa).
74 pub fn normalize_to(&self, e: i16) -> Fp {
75 let edelta = self.e - e;
77 let edelta = edelta as usize;
78 assert_eq!(self.f << edelta >> edelta, self.f);
79 Fp { f: self.f << edelta, e }