lexical_parse_float/
table_decimal.rs

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1//! Pre-computed tables for writing decimal strings.
2
3#![doc(hidden)]
4#![cfg(not(feature = "compact"))]
5
6use static_assertions::const_assert;
7
8#[cfg(not(feature = "radix"))]
9use crate::bigint::Limb;
10use crate::limits::{f32_exponent_limit, f64_exponent_limit, f64_mantissa_limit, u64_power_limit};
11
12// HELPERS
13// -------
14
15/// Get lookup table for small int powers.
16#[must_use]
17#[inline(always)]
18#[cfg(not(feature = "power-of-two"))]
19pub const fn get_small_int_power(exponent: usize, radix: u32) -> u64 {
20    // NOTE: don't check the radix since we also use it for half radix, or 5.
21    match radix {
22        5 => get_small_int_power5(exponent),
23        10 => get_small_int_power10(exponent),
24        _ => unreachable!(),
25    }
26}
27
28/// Get lookup table for small f32 powers.
29#[must_use]
30#[inline(always)]
31#[cfg(not(feature = "power-of-two"))]
32pub const fn get_small_f32_power(exponent: usize, radix: u32) -> f32 {
33    _ = radix;
34    get_small_f32_power10(exponent)
35}
36
37/// Get lookup table for small f64 powers.
38#[must_use]
39#[inline(always)]
40#[cfg(not(feature = "power-of-two"))]
41pub const fn get_small_f64_power(exponent: usize, radix: u32) -> f64 {
42    _ = radix;
43    get_small_f64_power10(exponent)
44}
45
46/// Get pre-computed power for a large power of radix.
47#[must_use]
48#[inline(always)]
49#[cfg(not(feature = "radix"))]
50pub const fn get_large_int_power(_: u32) -> (&'static [Limb], u32) {
51    (&LARGE_POW5, LARGE_POW5_STEP)
52}
53
54/// Get pre-computed int power of 5.
55#[must_use]
56#[inline(always)]
57pub const fn get_small_int_power5(exponent: usize) -> u64 {
58    SMALL_INT_POW5[exponent]
59}
60
61/// Get pre-computed int power of 10.
62#[must_use]
63#[inline(always)]
64pub const fn get_small_int_power10(exponent: usize) -> u64 {
65    SMALL_INT_POW10[exponent]
66}
67
68/// Get pre-computed f32 power of 10.
69#[must_use]
70#[inline(always)]
71pub const fn get_small_f32_power10(exponent: usize) -> f32 {
72    SMALL_F32_POW10[exponent]
73}
74
75/// Get pre-computed f64 power of 10.
76#[must_use]
77#[inline(always)]
78pub const fn get_small_f64_power10(exponent: usize) -> f64 {
79    SMALL_F64_POW10[exponent]
80}
81
82// TABLES
83// ------
84
85/// Pre-computed, small powers-of-5.
86pub const SMALL_INT_POW5: [u64; 28] = [
87    1,
88    5,
89    25,
90    125,
91    625,
92    3125,
93    15625,
94    78125,
95    390625,
96    1953125,
97    9765625,
98    48828125,
99    244140625,
100    1220703125,
101    6103515625,
102    30517578125,
103    152587890625,
104    762939453125,
105    3814697265625,
106    19073486328125,
107    95367431640625,
108    476837158203125,
109    2384185791015625,
110    11920928955078125,
111    59604644775390625,
112    298023223876953125,
113    1490116119384765625,
114    7450580596923828125,
115];
116const_assert!(SMALL_INT_POW5.len() > f64_mantissa_limit(5) as usize);
117const_assert!(SMALL_INT_POW5.len() == u64_power_limit(5) as usize + 1);
118
119/// Pre-computed, small powers-of-10.
120pub const SMALL_INT_POW10: [u64; 20] = [
121    1,
122    10,
123    100,
124    1000,
125    10000,
126    100000,
127    1000000,
128    10000000,
129    100000000,
130    1000000000,
131    10000000000,
132    100000000000,
133    1000000000000,
134    10000000000000,
135    100000000000000,
136    1000000000000000,
137    10000000000000000,
138    100000000000000000,
139    1000000000000000000,
140    10000000000000000000,
141];
142const_assert!(SMALL_INT_POW10.len() > f64_mantissa_limit(10) as usize);
143const_assert!(SMALL_INT_POW10.len() == u64_power_limit(10) as usize + 1);
144
145/// Pre-computed, small powers-of-10.
146pub const SMALL_F32_POW10: [f32; 16] =
147    [1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 0., 0., 0., 0., 0.];
148const_assert!(SMALL_F32_POW10.len() > f32_exponent_limit(10).1 as usize);
149
150/// Pre-computed, small powers-of-10.
151pub const SMALL_F64_POW10: [f64; 32] = [
152    1e0, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15, 1e16,
153    1e17, 1e18, 1e19, 1e20, 1e21, 1e22, 0., 0., 0., 0., 0., 0., 0., 0., 0.,
154];
155const_assert!(SMALL_F64_POW10.len() > f64_exponent_limit(10).1 as usize);
156
157/// Pre-computed large power-of-5 for 32-bit limbs.
158#[cfg(not(all(target_pointer_width = "64", not(target_arch = "sparc"))))]
159pub const LARGE_POW5: [u32; 10] = [
160    4279965485, 329373468, 4020270615, 2137533757, 4287402176, 1057042919, 1071430142, 2440757623,
161    381945767, 46164893,
162];
163
164/// Pre-computed large power-of-5 for 64-bit limbs.
165#[cfg(all(target_pointer_width = "64", not(target_arch = "sparc")))]
166pub const LARGE_POW5: [u64; 5] = [
167    1414648277510068013,
168    9180637584431281687,
169    4539964771860779200,
170    10482974169319127550,
171    198276706040285095,
172];
173
174/// Step for large power-of-5 for 32-bit limbs.
175pub const LARGE_POW5_STEP: u32 = 135;
lexical_parse_float/table_decimal.rs

lexical_parse_float/
table_decimal.rs
