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c-kzg-4844
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Handle many missing (step 1)

This commit is contained in:
Ben Edgington 2021-03-03 08:44:49 +00:00
parent e2cbccdc9d
commit 80af76581d
2 changed files with 141 additions and 14 deletions
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48
src/zero_poly.c
View File

@ -112,11 +112,23 @@ C_KZG_RET pad_p(fr_t *out, uint64_t out_len, const fr_t *p, uint64_t p_len) {
C_KZG_RET reduce_leaves(fr_t *dst, uint64_t len_dst, fr_t *scratch, uint64_t len_scratch, blst_fr **ps, uint64_t len_ps,
const uint64_t *len_p, const FFTSettings *fs) {
CHECK(is_power_of_two(len_dst));
CHECK(len_scratch >= 3 * len_dst);
CHECK(len_ps > 0);
// The degree of the output is the sum of the degrees of the input polynomials.
// TODO A more relaxed check should be ok: `len_ps * (len_p[0] - 1) < len_dst` (or even sum up the lengths)
CHECK(len_ps * len_p[0] <= len_dst);
CHECK(len_scratch >= 3 * len_dst);
// CHECK(len_ps * len_p[0] <= len_dst);
uint64_t total_length = 0;
for (int i = 0; i < len_ps; i++) {
total_length += len_p[i] - 1;
}
if (total_length + 1 > len_dst) {
printf("Total length: %lu, len dest: %lu\n", total_length, len_dst);
printf("\n");
for (int i = 0; i < len_ps; i++) {
printf("Len %d = %lu\n", i, len_p[i]);
}
}
CHECK(total_length + 1 <= len_dst);
// Split `scratch` up into three equally sized working arrays
fr_t *p_padded = scratch;
@ -180,6 +192,7 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
}
return C_KZG_OK;
}
CHECK(len_missing < length); // The output would be larger than length otherwise
CHECK(length <= fs->max_width);
CHECK(is_power_of_two(length));
@ -188,16 +201,17 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
uint64_t domain_stride = fs->max_width / length;
uint64_t leaf_count = (len_missing + per_leaf - 1) / per_leaf;
uint64_t n = next_power_of_two(leaf_count * per_leaf_poly);
if (n > length) n = length;
if (len_missing <= per_leaf) {
TRY(do_zero_poly_mul_leaf(zero_poly, length, missing_indices, len_missing, domain_stride, fs));
TRY(fft_fr(zero_eval, zero_poly, false, length, fs));
*zero_poly_len = len_missing + 1;
} else {
CHECK(n <= length);
// Work space for reducing the leaves - `zero_poly` is large enough due to the above check, so use that.
fr_t *work = zero_poly;
// fr_t *work = zero_poly;
fr_t *work;
TRY(new_fr_array(&work, next_power_of_two(leaf_count * per_leaf_poly)));
// Build the leaves.
@ -213,20 +227,23 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
if (end > max) end = max;
leaves[i] = &work[out_offset];
leaf_lengths[i] = per_leaf_poly;
TRY(do_zero_poly_mul_leaf(leaves[i], leaf_lengths[i], &missing_indices[offset], end - offset, domain_stride,
TRY(do_zero_poly_mul_leaf(leaves[i], per_leaf_poly, &missing_indices[offset], end - offset, domain_stride,
fs));
offset += per_leaf;
out_offset += per_leaf_poly;
}
// Adjust the length of the last leaf
// leaf_lengths[leaf_count - 1] = 1 + len_missing % per_leaf;
leaf_lengths[leaf_count - 1] = 1 + len_missing - (leaf_count - 1) * per_leaf;
// Now reduce all the leaves to a single poly
int reduction_factor = 4; // must be a power of 2
int reduction_factor = 4; // must be a power of 2 (why?)
TRY(new_fr_array(&scratch, n * 3));
while (leaf_count > 1) {
uint64_t reduced_count = (leaf_count + reduction_factor - 1) / reduction_factor;
// All the leaves are the same length, except possibly the last leaf, but that's ok.
uint64_t leaf_size = leaf_lengths[0];
uint64_t leaf_size = next_power_of_two(leaf_lengths[0]);
for (uint64_t i = 0; i < reduced_count; i++) {
uint64_t start = i * reduction_factor;
uint64_t end = start + reduction_factor;
@ -238,18 +255,24 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
}
reduced = work + start * leaf_size;
uint64_t reduced_len = out_end - start * leaf_size;
if (reduced_len > length) reduced_len = length;
if (end > leaf_count) {
end = leaf_count;
}
uint64_t leaves_slice_len = end - start;
if (end > start + 1) {
if (leaves_slice_len > 1) {
TRY(reduce_leaves(reduced, reduced_len, scratch, n * 3, &leaves[start], leaves_slice_len,
&leaf_lengths[start], fs));
leaf_lengths[i] = reduced_len;
} else {
leaf_lengths[i] = leaf_lengths[start];
// leaf_lengths[i] = reduced_len;
// } else {
// leaf_lengths[i] = leaf_lengths[start];
}
leaves[i] = reduced;
uint64_t total_length = 0;
for (int j = start; j < end; j++) {
total_length += leaf_lengths[j] - 1;
}
leaf_lengths[i] = total_length + 1;
}
leaf_count = reduced_count;
}
@ -260,6 +283,7 @@ C_KZG_RET zero_polynomial_via_multiplication(fr_t *zero_eval, fr_t *zero_poly, u
}
TRY(fft_fr(zero_eval, zero_poly, false, length, fs));
free(work);
free(leaves);
free(leaf_lengths);
free(scratch);

107
src/zero_poly_test.c
View File

@ -251,7 +251,8 @@ void zero_poly_random(void) {
FFTSettings fs;
TEST_CHECK(C_KZG_OK == new_fft_settings(&fs, scale));
uint64_t missing[fs.max_width];
uint64_t *missing;
TEST_CHECK(C_KZG_OK == new_uint64_array(&missing, fs.max_width));
int len_missing = 0;
for (int i = 0; i < fs.max_width; i++) {
@ -283,7 +284,7 @@ void zero_poly_random(void) {
ret = TEST_CHECK(fr_is_zero(&out));
TEST_MSG("Failed for missing[%d] = %lu", i, missing[i]);
}
TEST_MSG("Failed for scale %d", scale);
TEST_MSG("Failed for scale = %d, len_missing = %d, zero_poly_len = %lu", scale, len_missing, zero_poly_len);
fr_t *zero_eval_fft;
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_eval_fft, fs.max_width));
@ -295,6 +296,7 @@ void zero_poly_random(void) {
TEST_CHECK(fr_is_zero(&zero_eval_fft[i]));
}
free(missing);
free(zero_poly);
free(zero_eval);
free(zero_eval_fft);
@ -303,6 +305,105 @@ void zero_poly_random(void) {
}
}
void zero_poly_all_but_one(void) {
FFTSettings fs;
TEST_CHECK(C_KZG_OK == new_fft_settings(&fs, 8));
uint64_t *missing;
TEST_CHECK(C_KZG_OK == new_uint64_array(&missing, fs.max_width));
// All but the first are missing
for (int i = 0; i < fs.max_width - 1; i++) {
missing[i] = i + 1;
}
int len_missing = fs.max_width - 1;
fr_t *zero_eval, *zero_poly;
uint64_t zero_poly_len;
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_eval, fs.max_width));
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_poly, fs.max_width));
TEST_CHECK(C_KZG_OK == zero_polynomial_via_multiplication(zero_eval, zero_poly, &zero_poly_len, fs.max_width,
missing, len_missing, &fs));
poly p;
p.length = zero_poly_len;
p.coeffs = zero_poly;
int ret = 0;
for (int i = 0; i < len_missing; i++) {
fr_t out;
eval_poly(&out, &p, &fs.expanded_roots_of_unity[missing[i]]);
ret = TEST_CHECK(fr_is_zero(&out));
TEST_MSG("Failed for missing[%d] = %lu", i, missing[i]);
}
fr_t *zero_eval_fft;
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_eval_fft, fs.max_width));
TEST_CHECK(C_KZG_OK == fft_fr(zero_eval_fft, zero_eval, true, fs.max_width, &fs));
for (uint64_t i = 0; i < zero_poly_len; i++) {
TEST_CHECK(fr_equal(&zero_poly[i], &zero_eval_fft[i]));
}
for (uint64_t i = zero_poly_len; i < fs.max_width; i++) {
TEST_CHECK(fr_is_zero(&zero_eval_fft[i]));
}
free(missing);
free(zero_poly);
free(zero_eval);
free(zero_eval_fft);
free_fft_settings(&fs);
}
void zero_poly_252(void) {
FFTSettings fs;
TEST_CHECK(C_KZG_OK == new_fft_settings(&fs, 8));
uint64_t *missing;
TEST_CHECK(C_KZG_OK == new_uint64_array(&missing, fs.max_width));
// 252 are missing
int len_missing = 252;
for (int i = 0; i < len_missing; i++) {
missing[i] = i;
}
fr_t *zero_eval, *zero_poly;
uint64_t zero_poly_len;
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_eval, fs.max_width));
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_poly, fs.max_width));
TEST_CHECK(C_KZG_OK == zero_polynomial_via_multiplication(zero_eval, zero_poly, &zero_poly_len, fs.max_width,
missing, len_missing, &fs));
TEST_CHECK(zero_poly_len == 253);
TEST_MSG("ZeroPolyLen: expected %d, got %lu", len_missing + 1, zero_poly_len);
poly p;
p.length = zero_poly_len;
p.coeffs = zero_poly;
int ret = 0;
for (int i = 0; i < len_missing; i++) {
fr_t out;
eval_poly(&out, &p, &fs.expanded_roots_of_unity[missing[i]]);
ret = TEST_CHECK(fr_is_zero(&out));
TEST_MSG("Failed for missing[%d] = %lu", i, missing[i]);
}
fr_t *zero_eval_fft;
TEST_CHECK(C_KZG_OK == new_fr_array(&zero_eval_fft, fs.max_width));
TEST_CHECK(C_KZG_OK == fft_fr(zero_eval_fft, zero_eval, true, fs.max_width, &fs));
for (uint64_t i = 0; i < zero_poly_len; i++) {
TEST_CHECK(fr_equal(&zero_poly[i], &zero_eval_fft[i]));
}
for (uint64_t i = zero_poly_len; i < fs.max_width; i++) {
TEST_CHECK(fr_is_zero(&zero_eval_fft[i]));
}
free(missing);
free(zero_poly);
free(zero_eval);
free(zero_eval_fft);
free_fft_settings(&fs);
}
TEST_LIST = {
{"ZERO_POLY_TEST", title},
{"test_reduce_leaves", test_reduce_leaves},
@ -310,5 +411,7 @@ TEST_LIST = {
{"reduce_leaves_random", reduce_leaves_random},
{"zero_poly_known", zero_poly_known},
{"zero_poly_random", zero_poly_random},
{"zero_poly_all_but_one", zero_poly_all_but_one},
{"zero_poly_252", zero_poly_252},
{NULL, NULL} /* zero record marks the end of the list */
};