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c-kzg-4844
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Fix initial stride in das_fft_extension

This commit is contained in:
Ben Edgington 2021-07-03 10:50:36 +01:00
parent 419e28b46b
commit 27bde1aff7
2 changed files with 23 additions and 18 deletions
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6
src/das_extension.c
View File

@ -21,6 +21,7 @@
*/
#include "das_extension.h"
#include "utility.h"
/**
* Recursive implementation of #das_fft_extension.
@ -96,10 +97,11 @@ static void das_fft_extension_stride(fr_t *ab, uint64_t n, uint64_t stride, cons
C_KZG_RET das_fft_extension(fr_t *vals, uint64_t n, const FFTSettings *fs) {
fr_t invlen;
CHECK(n > 0);
CHECK(is_power_of_two(n));
CHECK(n * 2 <= fs->max_width);
CHECK(n >= 2);
das_fft_extension_stride(vals, n, 1, fs);
das_fft_extension_stride(vals, n, fs->max_width / (n * 2), fs);
fr_from_uint64(&invlen, n);
fr_inv(&invlen, &invlen);

35
src/das_extension_test.c
View File

@ -56,37 +56,40 @@ void das_extension_test_known(void) {
free_fft_settings(&fs);
}
// Caution: uses random data
void das_extension_test_random(void) {
FFTSettings fs;
fr_t *even_data, *odd_data, *data, *coeffs;
for (int scale = 4; scale < 10; scale++) {
TEST_CHECK(C_KZG_OK == new_fft_settings(&fs, scale));
TEST_CHECK(C_KZG_OK == new_fr_array(&even_data, fs.max_width / 2));
TEST_CHECK(C_KZG_OK == new_fr_array(&odd_data, fs.max_width / 2));
TEST_CHECK(C_KZG_OK == new_fr_array(&data, fs.max_width));
TEST_CHECK(C_KZG_OK == new_fr_array(&coeffs, fs.max_width));
int max_scale = 15;
TEST_CHECK(C_KZG_OK == new_fft_settings(&fs, max_scale));
for (int scale = 1; scale <= max_scale; scale++) {
uint64_t width = (uint64_t)1 << scale;
TEST_ASSERT(width <= fs.max_width);
TEST_CHECK(C_KZG_OK == new_fr_array(&even_data, width / 2));
TEST_CHECK(C_KZG_OK == new_fr_array(&odd_data, width / 2));
TEST_CHECK(C_KZG_OK == new_fr_array(&data, width));
TEST_CHECK(C_KZG_OK == new_fr_array(&coeffs, width));
for (int rep = 0; rep < 4; rep++) {
// Make random input data, and save a copy of it
for (int i = 0; i < fs.max_width / 2; i++) {
// Make random even data and duplicate temporarily in the odd_data
for (int i = 0; i < width / 2; i++) {
even_data[i] = rand_fr();
odd_data[i] = even_data[i];
}
// Extend the odd data
TEST_CHECK(C_KZG_OK == das_fft_extension(odd_data, fs.max_width / 2, &fs));
// Extend the even data to create the odd data required to make the second half of the FFT zero
TEST_CHECK(C_KZG_OK == das_fft_extension(odd_data, width / 2, &fs));
// Reconstruct the data
for (int i = 0; i < fs.max_width; i += 2) {
// Reconstruct the full data
for (int i = 0; i < width; i += 2) {
data[i] = even_data[i / 2];
data[i + 1] = odd_data[i / 2];
}
TEST_CHECK(C_KZG_OK == fft_fr(coeffs, data, true, fs.max_width, &fs));
TEST_CHECK(C_KZG_OK == fft_fr(coeffs, data, true, width, &fs));
// Second half of the coefficients should be all zeros
for (int i = fs.max_width / 2; i < fs.max_width; i++) {
for (int i = width / 2; i < width; i++) {
TEST_CHECK(fr_is_zero(&coeffs[i]));
}
}
@ -95,8 +98,8 @@ void das_extension_test_random(void) {
free(odd_data);
free(data);
free(coeffs);
free_fft_settings(&fs);
}
free_fft_settings(&fs);
}
TEST_LIST = {