src/libcore/tests/num/dec2flt/rawfp.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use std::f32;
  12 use std::f64;
  13 use core::num::diy_float::Fp;
  14 use core::num::dec2flt::rawfp::{fp_to_float, prev_float, next_float, round_normal};
  15 use core::num::dec2flt::rawfp::RawFloat;
  16
  17 fn integer_decode(f: f64) -> (u64, i16, i8) {
  18     RawFloat::integer_decode(f)
  19 }
  20
  21 #[test]
  22 fn fp_to_float_half_to_even() {
  23     fn is_normalized(sig: u64) -> bool {
  24         // intentionally written without {min,max}_sig() as a sanity check
  25         sig >> 52 == 1 && sig >> 53 == 0
  26     }
  27
  28     fn conv(sig: u64) -> u64 {
  29         // The significands are perfectly in range, so the exponent should not matter
  30         let (m1, e1, _) = integer_decode(fp_to_float::<f64>(Fp { f: sig, e: 0 }));
  31         assert_eq!(e1, 0 + 64 - 53);
  32         let (m2, e2, _) = integer_decode(fp_to_float::<f64>(Fp { f: sig, e: 55 }));
  33         assert_eq!(e2, 55 + 64 - 53);
  34         assert_eq!(m2, m1);
  35         let (m3, e3, _) = integer_decode(fp_to_float::<f64>(Fp { f: sig, e: -78 }));
  36         assert_eq!(e3, -78 + 64 - 53);
  37         assert_eq!(m3, m2);
  38         m3
  39     }
  40
  41     let odd = 0x1F_EDCB_A012_345F;
  42     let even = odd - 1;
  43     assert!(is_normalized(odd));
  44     assert!(is_normalized(even));
  45     assert_eq!(conv(odd << 11), odd);
  46     assert_eq!(conv(even << 11), even);
  47     assert_eq!(conv(odd << 11 | 1 << 10), odd + 1);
  48     assert_eq!(conv(even << 11 | 1 << 10), even);
  49     assert_eq!(conv(even << 11 | 1 << 10 | 1), even + 1);
  50     assert_eq!(conv(odd << 11 | 1 << 9), odd);
  51     assert_eq!(conv(even << 11 | 1 << 9), even);
  52     assert_eq!(conv(odd << 11 | 0x7FF), odd + 1);
  53     assert_eq!(conv(even << 11 | 0x7FF), even + 1);
  54     assert_eq!(conv(odd << 11 | 0x3FF), odd);
  55     assert_eq!(conv(even << 11 | 0x3FF), even);
  56 }
  57
  58 #[test]
  59 fn integers_to_f64() {
  60     assert_eq!(fp_to_float::<f64>(Fp { f: 1, e: 0 }), 1.0);
  61     assert_eq!(fp_to_float::<f64>(Fp { f: 42, e: 7 }), (42 << 7) as f64);
  62     assert_eq!(fp_to_float::<f64>(Fp { f: 1 << 20, e: 30 }), (1u64 << 50) as f64);
  63     assert_eq!(fp_to_float::<f64>(Fp { f: 4, e: -3 }), 0.5);
  64 }
  65
  66 const SOME_FLOATS: [f64; 9] =
  67     [0.1f64, 33.568, 42.1e-5, 777.0e9, 1.1111, 0.347997,
  68      9843579834.35892, 12456.0e-150, 54389573.0e-150];
  69
  70
  71 #[test]
  72 fn human_f64_roundtrip() {
  73     for &x in &SOME_FLOATS {
  74         let (f, e, _) = integer_decode(x);
  75         let fp = Fp { f: f, e: e};
  76         assert_eq!(fp_to_float::<f64>(fp), x);
  77     }
  78 }
  79
  80 #[test]
  81 fn rounding_overflow() {
  82     let x = Fp { f: 0xFF_FF_FF_FF_FF_FF_FF_00u64, e: 42 };
  83     let rounded = round_normal::<f64>(x);
  84     let adjusted_k = x.e + 64 - 53;
  85     assert_eq!(rounded.sig, 1 << 52);
  86     assert_eq!(rounded.k, adjusted_k + 1);
  87 }
  88
  89 #[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
  90 #[test]
  91 fn prev_float_monotonic() {
  92     let mut x = 1.0;
  93     for _ in 0..100 {
  94         let x1 = prev_float(x);
  95         assert!(x1 < x);
  96         assert!(x - x1 < 1e-15);
  97         x = x1;
  98     }
  99 }
 100
 101 const MIN_SUBNORMAL: f64 = 5e-324;
 102
 103 #[test]
 104 fn next_float_zero() {
 105     let tiny = next_float(0.0);
 106     assert_eq!(tiny, MIN_SUBNORMAL);
 107     assert!(tiny != 0.0);
 108 }
 109
 110 #[test]
 111 fn next_float_subnormal() {
 112     let second = next_float(MIN_SUBNORMAL);
 113     // For subnormals, MIN_SUBNORMAL is the ULP
 114     assert!(second != MIN_SUBNORMAL);
 115     assert!(second > 0.0);
 116     assert_eq!(second - MIN_SUBNORMAL, MIN_SUBNORMAL);
 117 }
 118
 119 #[test]
 120 fn next_float_inf() {
 121     assert_eq!(next_float(f64::MAX), f64::INFINITY);
 122     assert_eq!(next_float(f64::INFINITY), f64::INFINITY);
 123 }
 124
 125 #[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 126 #[test]
 127 fn next_prev_identity() {
 128     for &x in &SOME_FLOATS {
 129         assert_eq!(prev_float(next_float(x)), x);
 130         assert_eq!(prev_float(prev_float(next_float(next_float(x)))), x);
 131         assert_eq!(next_float(prev_float(x)), x);
 132         assert_eq!(next_float(next_float(prev_float(prev_float(x)))), x);
 133     }
 134 }
 135
 136 #[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 137 #[test]
 138 fn next_float_monotonic() {
 139     let mut x = 0.49999999999999;
 140     assert!(x < 0.5);
 141     for _ in 0..200 {
 142         let x1 = next_float(x);
 143         assert!(x1 > x);
 144         assert!(x1 - x < 1e-15, "next_float_monotonic: delta = {:?}", x1 - x);
 145         x = x1;
 146     }
 147     assert!(x > 0.5);
 148 }
 149
 150 #[test]
 151 fn test_f32_integer_decode() {
 152     assert_eq!(3.14159265359f32.integer_decode(), (13176795, -22, 1));
 153     assert_eq!((-8573.5918555f32).integer_decode(), (8779358, -10, -1));
 154     assert_eq!(2f32.powf(100.0).integer_decode(), (8388608, 77, 1));
 155     assert_eq!(0f32.integer_decode(), (0, -150, 1));
 156     assert_eq!((-0f32).integer_decode(), (0, -150, -1));
 157     assert_eq!(f32::INFINITY.integer_decode(), (8388608, 105, 1));
 158     assert_eq!(f32::NEG_INFINITY.integer_decode(), (8388608, 105, -1));
 159
 160     // Ignore the "sign" (quiet / signalling flag) of NAN.
 161     // It can vary between runtime operations and LLVM folding.
 162     let (nan_m, nan_e, _nan_s) = f32::NAN.integer_decode();
 163     assert_eq!((nan_m, nan_e), (12582912, 105));
 164 }
 165
 166 #[test]
 167 fn test_f64_integer_decode() {
 168     assert_eq!(3.14159265359f64.integer_decode(), (7074237752028906, -51, 1));
 169     assert_eq!((-8573.5918555f64).integer_decode(), (4713381968463931, -39, -1));
 170     assert_eq!(2f64.powf(100.0).integer_decode(), (4503599627370496, 48, 1));
 171     assert_eq!(0f64.integer_decode(), (0, -1075, 1));
 172     assert_eq!((-0f64).integer_decode(), (0, -1075, -1));
 173     assert_eq!(f64::INFINITY.integer_decode(), (4503599627370496, 972, 1));
 174     assert_eq!(f64::NEG_INFINITY.integer_decode(), (4503599627370496, 972, -1));
 175
 176     // Ignore the "sign" (quiet / signalling flag) of NAN.
 177     // It can vary between runtime operations and LLVM folding.
 178     let (nan_m, nan_e, _nan_s) = f64::NAN.integer_decode();
 179     assert_eq!((nan_m, nan_e), (6755399441055744, 972));
 180 }