lexical_parse_float/
table_binary.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
//! Pre-computed tables for writing non-decimal strings.

#![cfg(feature = "power-of-two")]
#![cfg(not(feature = "compact"))]
#![doc(hidden)]

#[cfg(not(feature = "radix"))]
use crate::table_decimal::*;
#[cfg(not(feature = "radix"))]
use core::hint;
#[cfg(not(feature = "radix"))]
use lexical_util::assert::debug_assert_radix;
use lexical_util::num::Float;

// HELPERS
// -------

/// Get lookup table for small int powers.
///
/// # Safety
///
/// Safe as long as the radix provided is valid, and exponent is smaller
/// than the table for the radix.
#[inline]
#[cfg(not(feature = "radix"))]
pub unsafe fn get_small_int_power(exponent: usize, radix: u32) -> u64 {
    // NOTE: don't check the radix since we also use it for half radix, or 5.
    unsafe {
        match radix {
            2 => get_small_int_power2(exponent),
            4 => get_small_int_power4(exponent),
            5 => get_small_int_power5(exponent),
            8 => get_small_int_power8(exponent),
            10 => get_small_int_power10(exponent),
            16 => get_small_int_power16(exponent),
            32 => get_small_int_power32(exponent),
            _ => hint::unreachable_unchecked(),
        }
    }
}

/// Get lookup table for small f32 powers.
///
/// # Safety
///
/// Safe as long as the radix provided is valid, and exponent is smaller
/// than the table for the radix.
#[inline]
#[cfg(not(feature = "radix"))]
pub unsafe fn get_small_f32_power(exponent: usize, radix: u32) -> f32 {
    debug_assert_radix(radix);
    unsafe {
        match radix {
            2 => get_small_f32_power2(exponent),
            4 => get_small_f32_power4(exponent),
            8 => get_small_f32_power8(exponent),
            10 => get_small_f32_power10(exponent),
            16 => get_small_f32_power16(exponent),
            32 => get_small_f32_power32(exponent),
            _ => hint::unreachable_unchecked(),
        }
    }
}

/// Get lookup table for small f64 powers.
///
/// # Safety
///
/// Safe as long as the radix provided is valid, and exponent is smaller
/// than the table for the radix.
#[inline]
#[cfg(not(feature = "radix"))]
pub unsafe fn get_small_f64_power(exponent: usize, radix: u32) -> f64 {
    debug_assert_radix(radix);
    unsafe {
        match radix {
            2 => get_small_f64_power2(exponent),
            4 => get_small_f64_power4(exponent),
            8 => get_small_f64_power8(exponent),
            10 => get_small_f64_power10(exponent),
            16 => get_small_f64_power16(exponent),
            32 => get_small_f64_power32(exponent),
            _ => hint::unreachable_unchecked(),
        }
    }
}

//  NOTE:
//      These functions use the fact that **all** powers-of-two
//      can be exactly represented and cheaply using bitshifts for
//      integers, or by setting the exponent directly.

/// Get pre-computed int power of 2.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_int_power2(exponent: usize) -> u64 {
    1 << exponent
}

/// Get pre-computed f32 power of 2.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f32_power2(exponent: usize) -> f32 {
    // Can't handle values above the denormal size.
    debug_assert!(exponent as i32 <= f32::EXPONENT_BIAS - f32::MANTISSA_SIZE);
    let shift = (f32::EXPONENT_BIAS - f32::MANTISSA_SIZE) as u32;
    let bits = (exponent as u32 + shift) << f32::MANTISSA_SIZE;
    f32::from_bits(bits)
}

/// Get pre-computed f64 power of 2.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f64_power2(exponent: usize) -> f64 {
    // Can't handle values above the denormal size.
    debug_assert!(exponent as i32 <= f64::EXPONENT_BIAS - f64::MANTISSA_SIZE);
    let shift = (f64::EXPONENT_BIAS - f64::MANTISSA_SIZE) as u64;
    let bits = (exponent as u64 + shift) << f64::MANTISSA_SIZE;
    f64::from_bits(bits)
}

/// Get pre-computed int power of 4.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_int_power4(exponent: usize) -> u64 {
    unsafe { get_small_int_power2(2 * exponent) }
}

/// Get pre-computed f32 power of 4.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f32_power4(exponent: usize) -> f32 {
    unsafe { get_small_f32_power2(2 * exponent) }
}

/// Get pre-computed f64 power of 4.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f64_power4(exponent: usize) -> f64 {
    unsafe { get_small_f64_power2(2 * exponent) }
}

/// Get pre-computed int power of 8.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_int_power8(exponent: usize) -> u64 {
    unsafe { get_small_int_power2(3 * exponent) }
}

/// Get pre-computed f32 power of 8.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f32_power8(exponent: usize) -> f32 {
    unsafe { get_small_f32_power2(3 * exponent) }
}

/// Get pre-computed f64 power of 8.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f64_power8(exponent: usize) -> f64 {
    unsafe { get_small_f64_power2(3 * exponent) }
}

/// Get pre-computed int power of 16.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_int_power16(exponent: usize) -> u64 {
    unsafe { get_small_int_power2(4 * exponent) }
}

/// Get pre-computed f32 power of 16.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f32_power16(exponent: usize) -> f32 {
    unsafe { get_small_f32_power2(4 * exponent) }
}

/// Get pre-computed f64 power of 16.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f64_power16(exponent: usize) -> f64 {
    unsafe { get_small_f64_power2(4 * exponent) }
}

/// Get pre-computed int power of 32.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_int_power32(exponent: usize) -> u64 {
    unsafe { get_small_int_power2(5 * exponent) }
}

/// Get pre-computed f32 power of 32.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f32_power32(exponent: usize) -> f32 {
    unsafe { get_small_f32_power2(5 * exponent) }
}

/// Get pre-computed f64 power of 32.
///
/// # Safety
///
/// Always safe, just marked unsafe for API compatibility.
#[inline(always)]
pub unsafe fn get_small_f64_power32(exponent: usize) -> f64 {
    unsafe { get_small_f64_power2(5 * exponent) }
}