poulpy/base2k/src/encoding.rs
base2k/src/encoding.rsRaw
1use crate::ffi::znx::znx_zero_i64_ref;
2use crate::{Infos, VecZnx, VecZnxApi};
3use itertools::izip;
4use std::cmp::min;
5
6pub trait Encoding {
7 /// encode a vector of i64 on the receiver.
8 ///
9 /// # Arguments
10 ///
11 /// * `log_base2k`: base two logarithm decomposition of the receiver.
12 /// * `log_k`: base two logarithm of the scaling of the data.
13 /// * `data`: data to encode on the receiver.
14 /// * `log_max`: base two logarithm of the infinity norm of the input data.
15 fn encode_vec_i64(&mut self, log_base2k: usize, log_k: usize, data: &[i64], log_max: usize);
16
17 /// decode a vector of i64 from the receiver.
18 ///
19 /// # Arguments
20 ///
21 /// * `log_base2k`: base two logarithm decomposition of the receiver.
22 /// * `log_k`: base two logarithm of the scaling of the data.
23 /// * `data`: data to decode from the receiver.
24 fn decode_vec_i64(&self, log_base2k: usize, log_k: usize, data: &mut [i64]);
25
26 /// encodes a single i64 on the receiver at the given index.
27 ///
28 /// # Arguments
29 ///
30 /// * `log_base2k`: base two logarithm decomposition of the receiver.
31 /// * `log_k`: base two logarithm of the scaling of the data.
32 /// * `i`: index of the coefficient on which to encode the data.
33 /// * `data`: data to encode on the receiver.
34 /// * `log_max`: base two logarithm of the infinity norm of the input data.
35 fn encode_coeff_i64(
36 &mut self,
37 log_base2k: usize,
38 log_k: usize,
39 i: usize,
40 data: i64,
41 log_max: usize,
42 );
43
44 /// decode a single of i64 from the receiver at the given index.
45 ///
46 /// # Arguments
47 ///
48 /// * `log_base2k`: base two logarithm decomposition of the receiver.
49 /// * `log_k`: base two logarithm of the scaling of the data.
50 /// * `i`: index of the coefficient to decode.
51 /// * `data`: data to decode from the receiver.
52 fn decode_coeff_i64(&self, log_base2k: usize, log_k: usize, i: usize) -> i64;
53}
54
55impl Encoding for VecZnx {
56 fn encode_vec_i64(&mut self, log_base2k: usize, log_k: usize, data: &[i64], log_max: usize) {
57 let limbs: usize = (log_k + log_base2k - 1) / log_base2k;
58
59 println!("limbs: {}", limbs);
60
61 assert!(limbs <= self.limbs(), "invalid argument log_k: (log_k + self.log_base2k - 1)/self.log_base2k={} > self.limbs()={}", limbs, self.limbs());
62
63 let size: usize = min(data.len(), self.n());
64 let log_k_rem: usize = log_base2k - (log_k % log_base2k);
65
66 // If 2^{log_base2k} * 2^{k_rem} < 2^{63}-1, then we can simply copy
67 // values on the last limb.
68 // Else we decompose values base2k.
69 if log_max + log_k_rem < 63 || log_k_rem == log_base2k {
70 (0..self.limbs()).for_each(|i| unsafe {
71 znx_zero_i64_ref(size as u64, self.at_mut(i).as_mut_ptr());
72 });
73 self.at_mut(limbs - 1)[..size].copy_from_slice(&data[..size]);
74 } else {
75 let mask: i64 = (1 << log_base2k) - 1;
76 let steps: usize = min(limbs, (log_max + log_base2k - 1) / log_base2k);
77
78 (0..steps).for_each(|i| unsafe {
79 znx_zero_i64_ref(size as u64, self.at_mut(i).as_mut_ptr());
80 });
81
82 (limbs - steps..limbs)
83 .rev()
84 .enumerate()
85 .for_each(|(i, i_rev)| {
86 let shift: usize = i * log_base2k;
87 izip!(self.at_mut(i_rev)[..size].iter_mut(), data[..size].iter())
88 .for_each(|(y, x)| *y = (x >> shift) & mask);
89 })
90 }
91
92 // Case where self.prec % self.k != 0.
93 if log_k_rem != log_base2k {
94 let limbs = self.limbs();
95 let steps: usize = min(limbs, (log_max + log_base2k - 1) / log_base2k);
96 (limbs - steps..limbs).rev().for_each(|i| {
97 self.at_mut(i)[..size]
98 .iter_mut()
99 .for_each(|x| *x <<= log_k_rem);
100 })
101 }
102 }
103
104 fn decode_vec_i64(&self, log_base2k: usize, log_k: usize, data: &mut [i64]) {
105 let limbs: usize = (log_k + log_base2k - 1) / log_base2k;
106 assert!(
107 data.len() >= self.n,
108 "invalid data: data.len()={} < self.n()={}",
109 data.len(),
110 self.n
111 );
112 data.copy_from_slice(self.at(0));
113 let rem: usize = log_base2k - (log_k % log_base2k);
114 (1..limbs).for_each(|i| {
115 if i == limbs - 1 && rem != log_base2k {
116 let k_rem: usize = log_base2k - rem;
117 izip!(self.at(i).iter(), data.iter_mut()).for_each(|(x, y)| {
118 *y = (*y << k_rem) + (x >> rem);
119 });
120 } else {
121 izip!(self.at(i).iter(), data.iter_mut()).for_each(|(x, y)| {
122 *y = (*y << log_base2k) + x;
123 });
124 }
125 })
126 }
127
128 fn encode_coeff_i64(
129 &mut self,
130 log_base2k: usize,
131 log_k: usize,
132 i: usize,
133 value: i64,
134 log_max: usize,
135 ) {
136 assert!(i < self.n());
137 let limbs: usize = (log_k + log_base2k - 1) / log_base2k;
138 assert!(limbs <= self.limbs(), "invalid argument log_k: (log_k + self.log_base2k - 1)/self.log_base2k={} > self.limbs()={}", limbs, self.limbs());
139 let log_k_rem: usize = log_base2k - (log_k % log_base2k);
140 let limbs = self.limbs();
141
142 // If 2^{log_base2k} * 2^{log_k_rem} < 2^{63}-1, then we can simply copy
143 // values on the last limb.
144 // Else we decompose values base2k.
145 if log_max + log_k_rem < 63 || log_k_rem == log_base2k {
146 (0..limbs - 1).for_each(|j| self.at_mut(j)[i] = 0);
147
148 self.at_mut(self.limbs() - 1)[i] = value;
149 } else {
150 let mask: i64 = (1 << log_base2k) - 1;
151 let steps: usize = min(limbs, (log_max + log_base2k - 1) / log_base2k);
152
153 (0..limbs - steps).for_each(|j| self.at_mut(j)[i] = 0);
154
155 (limbs - steps..limbs)
156 .rev()
157 .enumerate()
158 .for_each(|(j, j_rev)| {
159 self.at_mut(j_rev)[i] = (value >> (j * log_base2k)) & mask;
160 })
161 }
162
163 // Case where self.prec % self.k != 0.
164 if log_k_rem != log_base2k {
165 let limbs = self.limbs();
166 let steps: usize = min(limbs, (log_max + log_base2k - 1) / log_base2k);
167 (limbs - steps..limbs).rev().for_each(|j| {
168 self.at_mut(j)[i] <<= log_k_rem;
169 })
170 }
171 }
172
173 fn decode_coeff_i64(&self, log_base2k: usize, log_k: usize, i: usize) -> i64 {
174 let limbs: usize = (log_k + log_base2k - 1) / log_base2k;
175 assert!(i < self.n());
176 let mut res: i64 = self.data[i];
177 let rem: usize = log_base2k - (log_k % log_base2k);
178 (1..limbs).for_each(|i| {
179 let x = self.data[i * self.n];
180 if i == limbs - 1 && rem != log_base2k {
181 let k_rem: usize = log_base2k - rem;
182 res = (res << k_rem) + (x >> rem);
183 } else {
184 res = (res << log_base2k) + x;
185 }
186 });
187 res
188 }
189}
190
191#[cfg(test)]
192mod tests {
193 use crate::{Encoding, VecZnx};
194 use itertools::izip;
195 use sampling::source::Source;
196
197 #[test]
198 fn test_set_get_i64_lo_norm() {
199 let n: usize = 8;
200 let log_base2k: usize = 17;
201 let limbs: usize = 5;
202 let log_k: usize = limbs * log_base2k - 5;
203 let mut a: VecZnx = VecZnx::new(n, limbs);
204 let mut have: Vec<i64> = vec![i64::default(); n];
205 have.iter_mut()
206 .enumerate()
207 .for_each(|(i, x)| *x = (i as i64) - (n as i64) / 2);
208 a.encode_vec_i64(log_base2k, log_k, &have, 10);
209 let mut want = vec![i64::default(); n];
210 a.decode_vec_i64(log_base2k, log_k, &mut want);
211 izip!(want, have).for_each(|(a, b)| assert_eq!(a, b));
212 }
213
214 #[test]
215 fn test_set_get_i64_hi_norm() {
216 let n: usize = 8;
217 let log_base2k: usize = 17;
218 let limbs: usize = 5;
219 let log_k: usize = limbs * log_base2k - 5;
220 let mut a: VecZnx = VecZnx::new(n, limbs);
221 let mut have: Vec<i64> = vec![i64::default(); n];
222 let mut source = Source::new([1; 32]);
223 have.iter_mut().for_each(|x| {
224 *x = source
225 .next_u64n(u64::MAX, u64::MAX)
226 .wrapping_sub(u64::MAX / 2 + 1) as i64;
227 });
228 a.encode_vec_i64(log_base2k, log_k, &have, 63);
229 //(0..a.limbs()).for_each(|i| println!("i:{} -> {:?}", i, a.at(i)));
230 let mut want = vec![i64::default(); n];
231 //(0..a.limbs()).for_each(|i| println!("i:{} -> {:?}", i, a.at(i)));
232 a.decode_vec_i64(log_base2k, log_k, &mut want);
233 izip!(want, have).for_each(|(a, b)| assert_eq!(a, b, "{} != {}", a, b));
234 }
235}