poulpy/backend/src/encoding.rs
backend/src/encoding.rsRaw
1use crate::ffi::znx::znx_zero_i64_ref;
2use crate::znx_base::{ZnxView, ZnxViewMut};
3use crate::{VecZnx, znx_base::ZnxInfos};
4use itertools::izip;
5use rug::{Assign, Float};
6use std::cmp::min;
7
8pub trait Encoding {
9 /// encode a vector of i64 on the receiver.
10 ///
11 /// # Arguments
12 ///
13 /// * `col_i`: the index of the poly where to encode the data.
14 /// * `basek`: base two negative logarithm decomposition of the receiver.
15 /// * `k`: base two negative logarithm of the scaling of the data.
16 /// * `data`: data to encode on the receiver.
17 /// * `log_max`: base two logarithm of the infinity norm of the input data.
18 fn encode_vec_i64(&mut self, col_i: usize, basek: usize, k: usize, data: &[i64], log_max: usize);
19
20 /// encodes a single i64 on the receiver at the given index.
21 ///
22 /// # Arguments
23 ///
24 /// * `col_i`: the index of the poly where to encode the data.
25 /// * `basek`: base two negative logarithm decomposition of the receiver.
26 /// * `k`: base two negative logarithm of the scaling of the data.
27 /// * `i`: index of the coefficient on which to encode the data.
28 /// * `data`: data to encode on the receiver.
29 /// * `log_max`: base two logarithm of the infinity norm of the input data.
30 fn encode_coeff_i64(&mut self, col_i: usize, basek: usize, k: usize, i: usize, data: i64, log_max: usize);
31}
32
33pub trait Decoding {
34 /// decode a vector of i64 from the receiver.
35 ///
36 /// # Arguments
37 ///
38 /// * `col_i`: the index of the poly where to encode the data.
39 /// * `basek`: base two negative logarithm decomposition of the receiver.
40 /// * `k`: base two logarithm of the scaling of the data.
41 /// * `data`: data to decode from the receiver.
42 fn decode_vec_i64(&self, col_i: usize, basek: usize, k: usize, data: &mut [i64]);
43
44 /// decode a vector of Float from the receiver.
45 ///
46 /// # Arguments
47 /// * `col_i`: the index of the poly where to encode the data.
48 /// * `basek`: base two negative logarithm decomposition of the receiver.
49 /// * `data`: data to decode from the receiver.
50 fn decode_vec_float(&self, col_i: usize, basek: usize, data: &mut [Float]);
51
52 /// decode a single of i64 from the receiver at the given index.
53 ///
54 /// # Arguments
55 ///
56 /// * `col_i`: the index of the poly where to encode the data.
57 /// * `basek`: base two negative logarithm decomposition of the receiver.
58 /// * `k`: base two negative logarithm of the scaling of the data.
59 /// * `i`: index of the coefficient to decode.
60 /// * `data`: data to decode from the receiver.
61 fn decode_coeff_i64(&self, col_i: usize, basek: usize, k: usize, i: usize) -> i64;
62}
63
64impl<D: AsMut<[u8]> + AsRef<[u8]>> Encoding for VecZnx<D> {
65 fn encode_vec_i64(&mut self, col_i: usize, basek: usize, k: usize, data: &[i64], log_max: usize) {
66 encode_vec_i64(self, col_i, basek, k, data, log_max)
67 }
68
69 fn encode_coeff_i64(&mut self, col_i: usize, basek: usize, k: usize, i: usize, value: i64, log_max: usize) {
70 encode_coeff_i64(self, col_i, basek, k, i, value, log_max)
71 }
72}
73
74impl<D: AsRef<[u8]>> Decoding for VecZnx<D> {
75 fn decode_vec_i64(&self, col_i: usize, basek: usize, k: usize, data: &mut [i64]) {
76 decode_vec_i64(self, col_i, basek, k, data)
77 }
78
79 fn decode_vec_float(&self, col_i: usize, basek: usize, data: &mut [Float]) {
80 decode_vec_float(self, col_i, basek, data)
81 }
82
83 fn decode_coeff_i64(&self, col_i: usize, basek: usize, k: usize, i: usize) -> i64 {
84 decode_coeff_i64(self, col_i, basek, k, i)
85 }
86}
87
88fn encode_vec_i64<D: AsMut<[u8]> + AsRef<[u8]>>(
89 a: &mut VecZnx<D>,
90 col_i: usize,
91 basek: usize,
92 k: usize,
93 data: &[i64],
94 log_max: usize,
95) {
96 let size: usize = (k + basek - 1) / basek;
97
98 #[cfg(debug_assertions)]
99 {
100 assert!(
101 size <= a.size(),
102 "invalid argument k: (k + a.basek - 1)/a.basek={} > a.size()={}",
103 size,
104 a.size()
105 );
106 assert!(col_i < a.cols());
107 assert!(data.len() <= a.n())
108 }
109
110 let data_len: usize = data.len();
111 let k_rem: usize = basek - (k % basek);
112
113 // Zeroes coefficients of the i-th column
114 (0..a.size()).for_each(|i| unsafe {
115 znx_zero_i64_ref(a.n() as u64, a.at_mut_ptr(col_i, i));
116 });
117
118 // If 2^{basek} * 2^{k_rem} < 2^{63}-1, then we can simply copy
119 // values on the last limb.
120 // Else we decompose values base2k.
121 if log_max + k_rem < 63 || k_rem == basek {
122 a.at_mut(col_i, size - 1)[..data_len].copy_from_slice(&data[..data_len]);
123 } else {
124 let mask: i64 = (1 << basek) - 1;
125 let steps: usize = min(size, (log_max + basek - 1) / basek);
126 (size - steps..size)
127 .rev()
128 .enumerate()
129 .for_each(|(i, i_rev)| {
130 let shift: usize = i * basek;
131 izip!(a.at_mut(col_i, i_rev).iter_mut(), data.iter()).for_each(|(y, x)| *y = (x >> shift) & mask);
132 })
133 }
134
135 // Case where self.prec % self.k != 0.
136 if k_rem != basek {
137 let steps: usize = min(size, (log_max + basek - 1) / basek);
138 (size - steps..size).rev().for_each(|i| {
139 a.at_mut(col_i, i)[..data_len]
140 .iter_mut()
141 .for_each(|x| *x <<= k_rem);
142 })
143 }
144}
145
146fn decode_vec_i64<D: AsRef<[u8]>>(a: &VecZnx<D>, col_i: usize, basek: usize, k: usize, data: &mut [i64]) {
147 let size: usize = (k + basek - 1) / basek;
148 #[cfg(debug_assertions)]
149 {
150 assert!(
151 data.len() >= a.n(),
152 "invalid data: data.len()={} < a.n()={}",
153 data.len(),
154 a.n()
155 );
156 assert!(col_i < a.cols());
157 }
158 data.copy_from_slice(a.at(col_i, 0));
159 let rem: usize = basek - (k % basek);
160 if k < basek {
161 data.iter_mut().for_each(|x| *x >>= rem);
162 } else {
163 (1..size).for_each(|i| {
164 if i == size - 1 && rem != basek {
165 let k_rem: usize = basek - rem;
166 izip!(a.at(col_i, i).iter(), data.iter_mut()).for_each(|(x, y)| {
167 *y = (*y << k_rem) + (x >> rem);
168 });
169 } else {
170 izip!(a.at(col_i, i).iter(), data.iter_mut()).for_each(|(x, y)| {
171 *y = (*y << basek) + x;
172 });
173 }
174 })
175 }
176}
177
178fn decode_vec_float<D: AsRef<[u8]>>(a: &VecZnx<D>, col_i: usize, basek: usize, data: &mut [Float]) {
179 let size: usize = a.size();
180 #[cfg(debug_assertions)]
181 {
182 assert!(
183 data.len() >= a.n(),
184 "invalid data: data.len()={} < a.n()={}",
185 data.len(),
186 a.n()
187 );
188 assert!(col_i < a.cols());
189 }
190
191 let prec: u32 = (basek * size) as u32;
192
193 // 2^{basek}
194 let base = Float::with_val(prec, (1 << basek) as f64);
195
196 // y[i] = sum x[j][i] * 2^{-basek*j}
197 (0..size).for_each(|i| {
198 if i == 0 {
199 izip!(a.at(col_i, size - i - 1).iter(), data.iter_mut()).for_each(|(x, y)| {
200 y.assign(*x);
201 *y /= &base;
202 });
203 } else {
204 izip!(a.at(col_i, size - i - 1).iter(), data.iter_mut()).for_each(|(x, y)| {
205 *y += Float::with_val(prec, *x);
206 *y /= &base;
207 });
208 }
209 });
210}
211
212fn encode_coeff_i64<D: AsMut<[u8]> + AsRef<[u8]>>(
213 a: &mut VecZnx<D>,
214 col_i: usize,
215 basek: usize,
216 k: usize,
217 i: usize,
218 value: i64,
219 log_max: usize,
220) {
221 let size: usize = (k + basek - 1) / basek;
222
223 #[cfg(debug_assertions)]
224 {
225 assert!(i < a.n());
226 assert!(
227 size <= a.size(),
228 "invalid argument k: (k + a.basek - 1)/a.basek={} > a.size()={}",
229 size,
230 a.size()
231 );
232 assert!(col_i < a.cols());
233 }
234
235 let k_rem: usize = basek - (k % basek);
236 (0..a.size()).for_each(|j| a.at_mut(col_i, j)[i] = 0);
237
238 // If 2^{basek} * 2^{k_rem} < 2^{63}-1, then we can simply copy
239 // values on the last limb.
240 // Else we decompose values base2k.
241 if log_max + k_rem < 63 || k_rem == basek {
242 a.at_mut(col_i, size - 1)[i] = value;
243 } else {
244 let mask: i64 = (1 << basek) - 1;
245 let steps: usize = min(size, (log_max + basek - 1) / basek);
246 (size - steps..size)
247 .rev()
248 .enumerate()
249 .for_each(|(j, j_rev)| {
250 a.at_mut(col_i, j_rev)[i] = (value >> (j * basek)) & mask;
251 })
252 }
253
254 // Case where prec % k != 0.
255 if k_rem != basek {
256 let steps: usize = min(size, (log_max + basek - 1) / basek);
257 (size - steps..size).rev().for_each(|j| {
258 a.at_mut(col_i, j)[i] <<= k_rem;
259 })
260 }
261}
262
263fn decode_coeff_i64<D: AsRef<[u8]>>(a: &VecZnx<D>, col_i: usize, basek: usize, k: usize, i: usize) -> i64 {
264 #[cfg(debug_assertions)]
265 {
266 assert!(i < a.n());
267 assert!(col_i < a.cols())
268 }
269
270 let size: usize = (k + basek - 1) / basek;
271 let data: &[i64] = a.raw();
272 let mut res: i64 = 0;
273 let rem: usize = basek - (k % basek);
274 let slice_size: usize = a.n() * a.cols();
275 (0..size).for_each(|j| {
276 let x: i64 = data[j * slice_size + i];
277 if j == size - 1 && rem != basek {
278 let k_rem: usize = basek - rem;
279 res = (res << k_rem) + (x >> rem);
280 } else {
281 res = (res << basek) + x;
282 }
283 });
284 res
285}
286
287#[cfg(test)]
288mod tests {
289 use crate::vec_znx_ops::*;
290 use crate::znx_base::*;
291 use crate::{Decoding, Encoding, FFT64, Module, VecZnx, znx_base::ZnxInfos};
292 use itertools::izip;
293 use sampling::source::Source;
294
295 #[test]
296 fn test_set_get_i64_lo_norm() {
297 let n: usize = 8;
298 let module: Module<FFT64> = Module::<FFT64>::new(n);
299 let basek: usize = 17;
300 let size: usize = 5;
301 let k: usize = size * basek - 5;
302 let mut a: VecZnx<_> = module.new_vec_znx(2, size);
303 let mut source: Source = Source::new([0u8; 32]);
304 let raw: &mut [i64] = a.raw_mut();
305 raw.iter_mut().enumerate().for_each(|(i, x)| *x = i as i64);
306 (0..a.cols()).for_each(|col_i| {
307 let mut have: Vec<i64> = vec![i64::default(); n];
308 have.iter_mut()
309 .for_each(|x| *x = (source.next_i64() << 56) >> 56);
310 a.encode_vec_i64(col_i, basek, k, &have, 10);
311 let mut want: Vec<i64> = vec![i64::default(); n];
312 a.decode_vec_i64(col_i, basek, k, &mut want);
313 izip!(want, have).for_each(|(a, b)| assert_eq!(a, b, "{} != {}", a, b));
314 });
315 }
316
317 #[test]
318 fn test_set_get_i64_hi_norm() {
319 let n: usize = 8;
320 let module: Module<FFT64> = Module::<FFT64>::new(n);
321 let basek: usize = 17;
322 let size: usize = 5;
323 for k in [1, basek / 2, size * basek - 5] {
324 let mut a: VecZnx<_> = module.new_vec_znx(2, size);
325 let mut source = Source::new([0u8; 32]);
326 let raw: &mut [i64] = a.raw_mut();
327 raw.iter_mut().enumerate().for_each(|(i, x)| *x = i as i64);
328 (0..a.cols()).for_each(|col_i| {
329 let mut have: Vec<i64> = vec![i64::default(); n];
330 have.iter_mut().for_each(|x| {
331 if k < 64 {
332 *x = source.next_u64n(1 << k, (1 << k) - 1) as i64;
333 } else {
334 *x = source.next_i64();
335 }
336 });
337 a.encode_vec_i64(col_i, basek, k, &have, std::cmp::min(k, 64));
338 let mut want = vec![i64::default(); n];
339 a.decode_vec_i64(col_i, basek, k, &mut want);
340 izip!(want, have).for_each(|(a, b)| assert_eq!(a, b, "{} != {}", a, b));
341 })
342 }
343 }
344}