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binding.c
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binding.c
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#include <assert.h>
#include <limits.h>
#include <math.h>
#include <node_api.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define RESOURCE_NAME "@ronomon/reed-solomon"
#define OK(call) \
assert((call) == napi_ok);
#define THROW(env, message) \
do { \
napi_throw_error((env), NULL, (message)); \
return NULL; \
} while (0)
#define MAX_K 24
#define MAX_M 6
#define MAX_W 8
// Parameters for (k,m) found by `search()` are in PARAMETERS[k-1][m-1]:
// PARAMETERS[k-1][m-1] = k, m, w, p, x, y, b:
//
// k = The number of data shards.
// m = The number of parity shards.
// w = The Galois Field exponent. The smaller the exponent, the less bits.
// p = The primitive polynomial used to generate the Galois Field.
//
// We do not use x or y when m <= 2:
// x = The column offset used to generate the matrix, -1 when m <= 2.
// y = The row offset used to generate the matrix, -1 when m <= 2.
//
// b = The number of bits in the resulting bit matrix.
static const int PARAMETERS[24][6][7] = {
{
{ 1, 1, 2, 7, -1, -1, 2 },
{ 1, 2, 2, 7, -1, -1, 4 },
{ 1, 3, 2, 7, 0, 1, 6 },
{ 1, 4, 4, 19, 0, 1, 16 },
{ 1, 5, 4, 19, 0, 1, 20 },
{ 1, 6, 4, 19, 0, 1, 24 }
},
{
{ 2, 1, 2, 7, -1, -1, 4 },
{ 2, 2, 2, 7, -1, -1, 9 },
{ 2, 3, 4, 19, 0, 4, 28 },
{ 2, 4, 4, 19, 0, 5, 40 },
{ 2, 5, 4, 19, 2, 9, 51 },
{ 2, 6, 4, 19, 4, 10, 62 }
},
{
{ 3, 1, 2, 7, -1, -1, 6 },
{ 3, 2, 4, 19, -1, -1, 26 },
{ 3, 3, 4, 19, 0, 9, 44 },
{ 3, 4, 4, 19, 1, 8, 63 },
{ 3, 5, 4, 19, 1, 9, 82 },
{ 3, 6, 4, 19, 0, 9, 101 }
},
{
{ 4, 1, 4, 19, -1, -1, 16 },
{ 4, 2, 4, 19, -1, -1, 36 },
{ 4, 3, 4, 19, 0, 9, 63 },
{ 4, 4, 4, 19, 3, 11, 89 },
{ 4, 5, 4, 19, 3, 11, 116 },
{ 4, 6, 4, 19, 11, 4, 145 }
},
{
{ 5, 1, 4, 19, -1, -1, 20 },
{ 5, 2, 4, 19, -1, -1, 47 },
{ 5, 3, 4, 19, 4, 13, 82 },
{ 5, 4, 4, 19, 3, 12, 118 },
{ 5, 5, 4, 19, 0, 9, 152 },
{ 5, 6, 4, 19, 0, 9, 185 }
},
{
{ 6, 1, 4, 19, -1, -1, 24 },
{ 6, 2, 4, 19, -1, -1, 58 },
{ 6, 3, 4, 19, 2, 12, 102 },
{ 6, 4, 4, 19, 2, 12, 144 },
{ 6, 5, 4, 19, 0, 9, 186 },
{ 6, 6, 4, 19, 0, 9, 231 }
},
{
{ 7, 1, 4, 19, -1, -1, 28 },
{ 7, 2, 4, 19, -1, -1, 71 },
{ 7, 3, 4, 19, 1, 13, 123 },
{ 7, 4, 4, 19, 2, 12, 174 },
{ 7, 5, 4, 19, 0, 9, 226 },
{ 7, 6, 4, 19, 7, 0, 277 }
},
{
{ 8, 1, 4, 19, -1, -1, 32 },
{ 8, 2, 4, 19, -1, -1, 84 },
{ 8, 3, 4, 19, 2, 13, 142 },
{ 8, 4, 4, 19, 2, 12, 205 },
{ 8, 5, 4, 19, 0, 9, 265 },
{ 8, 6, 4, 19, 0, 8, 328 }
},
{
{ 9, 1, 4, 19, -1, -1, 36 },
{ 9, 2, 4, 19, -1, -1, 97 },
{ 9, 3, 4, 19, 1, 13, 162 },
{ 9, 4, 4, 19, 2, 12, 237 },
{ 9, 5, 4, 19, 0, 9, 308 },
{ 9, 6, 4, 19, 1, 10, 376 }
},
{
{ 10, 1, 4, 19, -1, -1, 40 },
{ 10, 2, 4, 19, -1, -1, 111 },
{ 10, 3, 4, 19, 1, 13, 186 },
{ 10, 4, 4, 19, 0, 12, 268 },
{ 10, 5, 4, 19, 0, 11, 347 },
{ 10, 6, 4, 19, 0, 10, 426 }
},
{
{ 11, 1, 4, 19, -1, -1, 44 },
{ 11, 2, 4, 19, -1, -1, 125 },
{ 11, 3, 4, 19, 0, 13, 211 },
{ 11, 4, 4, 19, 0, 12, 300 },
{ 11, 5, 4, 19, 0, 11, 390 },
{ 11, 6, 8, 135, 58, 188, 1401 }
},
{
{ 12, 1, 4, 19, -1, -1, 48 },
{ 12, 2, 4, 19, -1, -1, 139 },
{ 12, 3, 4, 19, 3, 0, 234 },
{ 12, 4, 4, 19, 0, 12, 334 },
{ 12, 5, 8, 113, 24, 208, 1269 },
{ 12, 6, 8, 135, 57, 188, 1577 }
},
{
{ 13, 1, 4, 19, -1, -1, 52 },
{ 13, 2, 4, 19, -1, -1, 155 },
{ 13, 3, 4, 19, 0, 13, 261 },
{ 13, 4, 8, 135, 59, 189, 1037 },
{ 13, 5, 8, 113, 27, 236, 1393 },
{ 13, 6, 8, 113, 27, 236, 1733 }
},
{
{ 14, 1, 4, 19, -1, -1, 56 },
{ 14, 2, 4, 19, -1, -1, 171 },
{ 14, 3, 8, 169, 4, 252, 777 },
{ 14, 4, 8, 135, 58, 189, 1121 },
{ 14, 5, 8, 135, 58, 189, 1508 },
{ 14, 6, 8, 135, 58, 188, 1880 }
},
{
{ 15, 1, 4, 19, -1, -1, 60 },
{ 15, 2, 8, 135, -1, -1, 353 },
{ 15, 3, 8, 113, 24, 209, 836 },
{ 15, 4, 8, 135, 58, 189, 1225 },
{ 15, 5, 8, 101, 28, 232, 1644 },
{ 15, 6, 8, 113, 120, 241, 2037 }
},
{
{ 16, 1, 8, 29, -1, -1, 128 },
{ 16, 2, 8, 135, -1, -1, 380 },
{ 16, 3, 8, 113, 22, 213, 901 },
{ 16, 4, 8, 113, 22, 212, 1324 },
{ 16, 5, 8, 101, 28, 232, 1765 },
{ 16, 6, 8, 101, 28, 232, 2195 }
},
{
{ 17, 1, 8, 29, -1, -1, 136 },
{ 17, 2, 8, 135, -1, -1, 407 },
{ 17, 3, 8, 113, 22, 213, 960 },
{ 17, 4, 8, 135, 58, 189, 1423 },
{ 17, 5, 8, 101, 27, 232, 1880 },
{ 17, 6, 8, 101, 27, 232, 2343 }
},
{
{ 18, 1, 8, 29, -1, -1, 144 },
{ 18, 2, 8, 135, -1, -1, 434 },
{ 18, 3, 8, 113, 24, 213, 1027 },
{ 18, 4, 8, 113, 22, 212, 1513 },
{ 18, 5, 8, 195, 8, 32, 2019 },
{ 18, 6, 8, 113, 205, 126, 2500 }
},
{
{ 19, 1, 8, 29, -1, -1, 152 },
{ 19, 2, 8, 135, -1, -1, 462 },
{ 19, 3, 8, 113, 22, 213, 1086 },
{ 19, 4, 8, 113, 23, 212, 1604 },
{ 19, 5, 8, 195, 7, 32, 2131 },
{ 19, 6, 8, 195, 3, 60, 2654 }
},
{
{ 20, 1, 8, 29, -1, -1, 160 },
{ 20, 2, 8, 135, -1, -1, 490 },
{ 20, 3, 8, 113, 22, 213, 1147 },
{ 20, 4, 8, 113, 22, 212, 1695 },
{ 20, 5, 8, 195, 4, 238, 2270 },
{ 20, 6, 8, 113, 21, 233, 2816 }
},
{
{ 21, 1, 8, 29, -1, -1, 168 },
{ 21, 2, 8, 135, -1, -1, 518 },
{ 21, 3, 8, 113, 21, 213, 1225 },
{ 21, 4, 8, 113, 21, 212, 1801 },
{ 21, 5, 8, 195, 3, 60, 2395 },
{ 21, 6, 8, 195, 3, 60, 2980 }
},
{
{ 22, 1, 8, 29, -1, -1, 176 },
{ 22, 2, 8, 135, -1, -1, 546 },
{ 22, 3, 8, 113, 20, 213, 1292 },
{ 22, 4, 8, 113, 21, 212, 1906 },
{ 22, 5, 8, 195, 35, 28, 2512 },
{ 22, 6, 8, 195, 3, 60, 3135 }
},
{
{ 23, 1, 8, 29, -1, -1, 184 },
{ 23, 2, 8, 135, -1, -1, 574 },
{ 23, 3, 8, 113, 19, 213, 1366 },
{ 23, 4, 8, 113, 19, 212, 2008 },
{ 23, 5, 8, 195, 3, 238, 2652 },
{ 23, 6, 8, 113, 205, 126, 3291 }
},
{
{ 24, 1, 8, 29, -1, -1, 192 },
{ 24, 2, 8, 135, -1, -1, 603 },
{ 24, 3, 8, 113, 18, 213, 1437 },
{ 24, 4, 8, 195, 125, 91, 2110 },
{ 24, 5, 8, 195, 3, 238, 2787 },
{ 24, 6, 8, 195, 42, 225, 3466 }
}
};
static int g_divide(
const int* log,
const int* exp,
const int w,
const int a,
const int b
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
const int y = (1 << w) - 1;
assert(a <= y);
assert(b <= y);
assert(b >= 1);
if (a == 0) return 0;
return exp[(log[a] + y - log[b]) % y];
}
static int g_multiply(
const int* log,
const int* exp,
const int w,
const int a,
const int b
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
const int y = (1 << w) - 1;
assert(a <= y);
assert(b <= y);
if (a == 0 || b == 0) return 0;
return exp[(log[a] + log[b]) % y];
}
static int bitmatrix_m0_optimized(
const int w,
const int k,
const uint8_t* bitmatrix
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(k < (1 << w));
// We assume that bitmatrix is an encoding (not decoding) bitmatrix.
// If row 0 is all ones then an erasure of shard < k + 1 can be optimized.
for (int c = 0; c < k; c++) {
for (int a = 0; a < w; a++) {
if (a == 0) {
if (bitmatrix[c * w + a] != 1) return 0;
} else {
if (bitmatrix[c * w + a] != 0) return 0;
}
}
}
return 1;
}
static void create_bitmatrix_decoding_swap(
uint8_t* buffer,
const int x,
const int y
) {
const uint8_t tmp = buffer[x];
buffer[x] = buffer[y];
buffer[y] = tmp;
}
static void create_bitmatrix_decoding_invert(
uint8_t* source,
uint8_t* target,
const int rows
) {
const int cols = rows;
int k = 0;
for (int r = 0; r < rows; r++) {
for (int c = 0; c < cols; c++) {
target[k++] = (r == c) ? 1 : 0;
}
}
for (int c = 0; c < cols; c++) {
if ((source[c * cols + c]) == 0) {
int r = c + 1;
while (r < rows && source[r * cols + c] == 0) r++;
// Assert that matrix is invertible:
assert(r != rows);
for (int k = 0; k < cols; k++) {
create_bitmatrix_decoding_swap(source, c * cols + k, r * cols + k);
create_bitmatrix_decoding_swap(target, c * cols + k, r * cols + k);
}
}
for (int r = c + 1; r != rows; r++) {
if (source[r * cols + c] != 0) {
for (int k = 0; k < cols; k++) {
source[r * cols + k] ^= source[c * cols + k];
target[r * cols + k] ^= target[c * cols + k];
}
}
}
}
for (int r = rows - 1; r >= 0; r--) {
for (int c = 0; c < r; c++) {
if (source[c * cols + r]) {
for (int k = 0; k < cols; k++) {
source[c * cols + k] ^= source[r * cols + k];
target[c * cols + k] ^= target[r * cols + k];
}
}
}
}
}
static void create_bitmatrix_decoding(
const int w,
const int k,
const int m,
const int* sourceIndex,
const uint8_t* source,
uint8_t* target
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(m >= 1);
assert(m <= MAX_M);
assert(k + m <= (1 << w));
const int kww = k * w * w;
uint8_t matrix[MAX_K * MAX_K * MAX_W * MAX_W];
for (int a = 0; a < k; a++) {
if (sourceIndex[a] < k) {
for (int b = 0; b < kww; b++) matrix[kww * a + b] = 0;
int index = kww * a + sourceIndex[a] * w;
for (int b = 0; b < w; b++) {
matrix[index] = 1;
index += (k * w + 1);
}
} else {
for (int b = 0; b < kww; b++) {
matrix[kww * a + b] = source[kww * (sourceIndex[a] - k) + b];
}
}
}
create_bitmatrix_decoding_invert(matrix, target, k * w);
}
static int create_bitmatrix_encoding(
const int* log,
const int* exp,
const int w,
const int k,
const int m,
const uint8_t* matrix,
uint8_t* bitmatrix
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(m >= 1);
assert(m <= MAX_M);
assert(k + m <= (1 << w));
int count = 0;
for (int r = 0; r < m; r++) {
for (int c = 0; c < k; c++) {
int x = matrix[(k * r) + c];
for (int a = 0; a < w; a++) {
for (int b = 0; b < w; b++) {
int y = (x & (1 << b)) ? 1 : 0;
bitmatrix[(r * w * k * w) + (w * c) + a + (k * w * b)] = y;
count += y;
}
x = g_multiply(log, exp, w, x, 2);
}
}
}
assert(count > 0);
return count;
}
static int create_matrix(
const int* log,
const int* exp,
const int* bit,
const int* min,
const int w,
const int k,
const int m,
const int x,
const int y,
uint8_t* matrix
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(m >= 1);
assert(m <= MAX_M);
assert(k + m <= (1 << w));
const int z = 1 << w;
int count = bit[1] * k;
if (m == 1) {
// Use XOR for row 0.
assert(x == -1);
assert(y == -1);
for (int c = 0; c < k; c++) matrix[c] = 1;
} else if (m == 2) {
// Use XOR for row 0.
// Use integers with least number of bits for row 1.
assert(x == -1);
assert(y == -1);
for (int c = 0; c < k; c++) matrix[c] = 1;
for (int c = 0; c < k; c++) {
matrix[k + c] = min[c + 1];
if (c == 0) assert(matrix[k + c] == 1);
assert(matrix[k + c] > 0);
count += bit[matrix[k + c]];
}
} else {
// Use XOR for row 0.
// Use generic matrix thereafter.
assert(x + k <= z);
assert(y + m <= z);
assert(x != y);
if (x < y) {
assert(x + k <= y);
} else {
assert(y + m <= x);
}
for (int r = 0; r < m; r++) {
for (int c = 0; c < k; c++) {
assert(y + r < z);
assert(x + c < z);
matrix[r * k + c] = g_divide(log, exp, w, 1, (y + r) ^ (x + c));
}
}
// Divide rows by row 0:
for (int r = 1; r < m; r++) {
for (int c = 0; c < k; c++) {
matrix[r * k + c] = g_divide(log, exp, w, matrix[r * k + c], matrix[c]);
}
}
// Divide row 0 by itself to set row 0 to 1:
for (int c = 0; c < k; c++) {
matrix[c] = g_divide(log, exp, w, matrix[c], matrix[c]);
assert(matrix[c] == 1);
}
// Divide columns by the column which minimizes the resulting ones (if any):
for (int r = 1; r < m; r++) {
const int rk = r * k;
int result = 0;
int column = -1;
for (int c = 0; c < k; c++) result += bit[matrix[rk + c]];
for (int c = 0; c < k; c++) {
int bits = 0;
for (int d = 0; d < k; d++) {
bits += bit[g_divide(log, exp, w, matrix[rk + d], matrix[rk + c])];
}
if (bits < result) {
result = bits;
column = matrix[rk + c];
}
}
if (column >= 0) {
for (int c = 0; c < k; c++) {
matrix[rk + c] = g_divide(log, exp, w, matrix[rk + c], column);
}
}
count += result;
}
}
for (int c = 0; c < k; c++) assert(matrix[c] == 1);
assert(count > 0);
return count;
}
static int create_tables_bits(
const int* log,
const int* exp,
const int w,
int n
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
int count = 0;
for (int r = 0; r < w; r++) {
for (int c = 0; c < w; c++) {
count += (n & (1 << c)) ? 1 : 0;
}
n = g_multiply(log, exp, w, n, 2);
}
return count;
}
static void create_tables(
const int w,
const int p,
int* log,
int* exp,
int* bit,
int* min
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
const int y = (1 << w) - 1;
const int z = (1 << w);
// Generate log and exp tables:
for (int a = 0; a < z; a++) {
log[a] = y;
exp[a] = 0;
}
int b = 1;
for (int a = 0; a < y; a++) {
assert(b < z);
assert(log[b] == y);
assert(exp[a] == 0);
log[b] = a;
exp[a] = b;
b = b << 1;
if (b & z) b = (b ^ p) & y;
}
// The logarithm of zero must not be defined:
assert(log[0] == y);
// The last byte of the exponents table must not be defined:
assert(exp[y] == 0);
// Generate bit table (number of bits per matrix number):
for (int n = 0; n < z; n++) {
bit[n] = create_tables_bits(log, exp, w, n);
if (n == 0) {
assert(bit[n] == 0);
} else {
assert(bit[n] > 0);
}
}
// Generate min table (matrix numbers sorted by least number of bits):
assert(bit[0] == 0);
min[0] = 0;
for (int a = 1; a < z; a++) {
assert(a > 0);
int c = min[a - 1];
int d = -1;
for (int b = 1; b < z; b++) {
assert(b > 0);
assert(bit[b] > 0);
if (bit[b] < bit[c]) continue;
if (bit[b] == bit[c] && b <= c) continue;
if (d == -1 || bit[b] < bit[d]) d = b;
}
assert(d > 0);
assert(d < z);
min[a] = d;
}
assert(min[y] > 0);
}
static uintptr_t unaligned64(const uint8_t* pointer) {
return ((uintptr_t) pointer) & ((uintptr_t) 7);
}
static uint32_t dot_chunk_size(
const int w,
const int k,
const uint32_t shardSize
) {
// Every dot loop pair (b * k, c * w) uses ((1 + k * w) * chunkSize) of cache.
// Avoiding cache misses yields a 40-100% improvement when shardSize is large.
// We therefore reduce the chunkSize if necessary to stay within the cache.
// The shardSize should ideally be a power of 2 to do this optimally.
// N.B. The chunkSize changes the encoded parity result.
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(k < (1 << w));
assert(shardSize % w == 0);
uint32_t chunkSize = shardSize / w;
while (
chunkSize > 64 &&
chunkSize % 2 == 0 &&
(1 + k * w) * chunkSize > 1048576
) {
chunkSize /= 2;
}
assert(chunkSize > 0);
assert(shardSize % (w * chunkSize) == 0);
return chunkSize;
}
static void dot_cpy(uint8_t* source, uint8_t* target, uint32_t length) {
assert(length > 0);
assert(source != target);
memcpy(target, source, length);
}
static void dot_xor(uint8_t* source, uint8_t* target, uint32_t length) {
assert(source != target);
assert(length > 0);
uint8_t* sourceEnd = source + length;
uint8_t* targetEnd = target + length;
// XOR 8-bit words if source and target alignment cannot be corrected:
if (unaligned64(source) != unaligned64(target)) {
while (length > 0) {
*target++ ^= *source++;
length--;
}
assert(source == sourceEnd);
assert(target == targetEnd);
assert(length == 0);
return;
}
// XOR 8-bit words to correct source and target alignment:
while (unaligned64(source) && length > 0) {
*target++ ^= *source++;
length--;
}
if (length == 0) {
assert(source == sourceEnd);
assert(target == targetEnd);
return;
}
assert(unaligned64(source) == 0);
assert(unaligned64(target) == 0);
// XOR as many 64-bit words as possible:
uint32_t words = length / 8;
if (words > 0) {
uint32_t width = words * 8;
assert(width <= length);
uint64_t* source64 = (uint64_t*) source;
uint64_t* target64 = (uint64_t*) target;
while (words > 0) {
*target64++ ^= *source64++;
words--;
}
assert(words == 0);
source += width;
target += width;
length -= width;
}
// XOR 8-bit words remainder:
assert(length < 8);
while (length > 0) {
*target++ ^= *source++;
length--;
}
assert(source == sourceEnd);
assert(target == targetEnd);
assert(length == 0);
}
static void dot(
const int w,
const int k,
uint8_t** shards,
const uint32_t shardSize,
const uint8_t* row,
const int* sourceIndex,
const int targetIndex
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(k < (1 << w));
assert(shardSize % w == 0);
uint32_t chunkSize = dot_chunk_size(w, k, shardSize);
assert(w * chunkSize <= shardSize);
assert(shardSize % (w * chunkSize) == 0);
uint32_t shardOffset = 0;
while (shardOffset < shardSize) {
int column = 0;
for (int a = 0; a < w; a++) {
int copied = 0;
uint8_t* target = shards[targetIndex] + shardOffset + a * chunkSize;
for (int b = 0; b < k; b++) {
uint8_t* source = shards[sourceIndex[b]];
for (int c = 0; c < w; c++) {
if (row[column]) {
if (!copied) {
dot_cpy(source + shardOffset + c * chunkSize, target, chunkSize);
copied = 1;
} else {
dot_xor(source + shardOffset + c * chunkSize, target, chunkSize);
}
}
column++;
}
}
}
shardOffset += w * chunkSize;
}
assert(shardOffset == shardSize);
}
static int flags_count(uint32_t flags) {
int count = 0;
while (flags > 0) {
if (flags & 1) count++; // Check lower bit.
flags >>= 1; // Shift lower bit.
}
return count;
}
static int flags_first(const uint32_t flags) {
int i = 0;
while ((flags & (1 << i)) == 0) i++;
assert((flags & (1 << i)) != 0);
return i;
}
static void reed_solomon_encode(
const int w,
const int k,
const int m,
const uint8_t* bitmatrixEncoding,
const uint32_t sources,
const uint32_t targets,
uint8_t** shards,
const uint32_t shardSize
) {
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
assert(k >= 1);
assert(k <= MAX_K);
assert(m >= 1);
assert(m <= MAX_M);
assert(k + m <= (1 << w));
if (k == 1) {
// Optimization for pure replication, encoding only targets:
uint8_t* source = shards[flags_first(sources)];
for (int i = 0; i < k + m; i++) {
if (targets & (1 << i)) dot_cpy(source, shards[i], shardSize);
}
return;
}
if (
flags_count(targets) == 1 &&
flags_count(sources & ((1 << (k + 1)) - 1)) == k &&
flags_count(targets & ((1 << (k + 1)) - 1)) == 1
) {
// Optimization for 1 erasure (i < k + 1), encoding only targets:
uint8_t* target = shards[flags_first(targets)];
int copied = 0;
for (int i = 0; i < k + 1; i++) {
if (sources & (1 << i)) {
if (!copied) {
dot_cpy(shards[i], target, shardSize);
copied = 1;
} else {
dot_xor(shards[i], target, shardSize);
}
}
}
return;
}
const int kww = k * w * w;
int max = k;
int kerasures = 0;
for (int i = 0; i < k; i++) {
if (!(sources & (1 << i))) {
max = i;
kerasures++;
}
}
if (!(sources & (1 << k))) max = k;
if (kerasures > 1 || (kerasures == 1 && !(sources & (1 << k)))) {
int s[MAX_K];
int si = 0;
int sj = 0;
while (sj < k) {
if (sources & (1 << si)) s[sj++] = si;
si++;
}
uint8_t bitmatrixDecoding[MAX_K * MAX_K * MAX_W * MAX_W];
create_bitmatrix_decoding(
w,
k,
m,
s,
bitmatrixEncoding,
bitmatrixDecoding
);
for (int i = 0; kerasures > 0 && i < max; i++) {
if (!(sources & (1 << i))) {
dot(w, k, shards, shardSize, bitmatrixDecoding + kww * i, s, i);
kerasures--;
}
}
}
if (kerasures > 0) {
int s[MAX_K];
for (int si = 0; si < k; si++) s[si] = (si < max) ? si : si + 1;
dot(w, k, shards, shardSize, bitmatrixEncoding, s, max);
}
for (int i = 0; i < m; i++) {
if (!(sources & (1 << (k + i)))) {
int s[MAX_K];
for (int si = 0; si < k; si++) s[si] = si;
dot(w, k, shards, shardSize, bitmatrixEncoding + kww * i, s, k + i);
}
}
}
static int arg_buf(
napi_env env,
napi_value value,
uint8_t** buffer,
uint32_t* buffer_length
) {
assert(value != NULL);
assert(*buffer == NULL);
assert(*buffer_length == 0);
bool is_buffer = 0;
OK(napi_is_buffer(env, value, &is_buffer));
if (!is_buffer) return 0;
size_t length = 0;
OK(napi_get_buffer_info(env, value, (void**) buffer, &length));
assert(*buffer != NULL);
assert(length <= UINT32_MAX);
*buffer_length = length;
return 1;
}
static int arg_int(napi_env env, napi_value value, uint32_t* integer) {
assert(*integer == 0);
double temp = 0;
if (
// We get the value as a double so we can check for NaN, Infinity and float:
// https://github.com/nodejs/node/issues/26323
napi_get_value_double(env, value, &temp) != napi_ok ||
temp < 0 ||
isnan(temp) ||
// Infinity, also prevent UB for double->int cast below:
// https://groups.google.com/forum/#!topic/comp.lang.c/rhPzd4bgKJk
temp > UINT32_MAX ||
// Float:
(double) ((uint32_t) temp) != temp
) {
return 0;
}
*integer = (uint32_t) temp;
return 1;
}
void set_int(
napi_env env,
napi_value object,
const char* name,
const int64_t integer
) {
assert(integer >= 0);
napi_value value;
OK(napi_create_int64(env, integer, &value));
OK(napi_set_named_property(env, object, name, value));
}
void set_method(
napi_env env,
napi_value object,
const char* name,
void* method
) {
napi_value value;
OK(napi_create_function(env, NULL, 0, method, NULL, &value));
OK(napi_set_named_property(env, object, name, value));
}
struct task_data {
uint8_t* context;
uint32_t contextSize;
uint32_t sources;
uint32_t targets;
uint8_t* buffer;
uint32_t bufferSize;
uint8_t* parity;
uint32_t paritySize;
uint32_t shardSize;
napi_ref ref_context;
napi_ref ref_buffer;
napi_ref ref_parity;
napi_ref ref_callback;
napi_async_work async_work;
};
void task_execute(napi_env env, void* data) {
struct task_data* task = data;
assert(task->context != NULL);
assert(task->contextSize > 3);
assert(task->buffer != NULL);
assert(task->parity != NULL);
assert(task->shardSize > 0);
const int w = task->context[0];
assert(w <= MAX_W);
assert(w == 2 || w == 4 || w == 8);
const int k = task->context[1];
assert(k >= 1);
assert(k <= MAX_K);
const int m = task->context[2];
assert(m >= 1);
assert(m <= MAX_M);
assert(k + m <= (1 << w));
assert(task->contextSize == (uint32_t) (3 + k * w * m * w));
const uint8_t* bitmatrix = task->context + 3;
uint8_t* shards[MAX_K + MAX_M];
assert(task->shardSize * k <= task->bufferSize);
for (int index = 0; index < k; index++) {
shards[index] = task->buffer + task->shardSize * index;
}
assert(task->shardSize * m <= task->paritySize);
for (int index = 0; index < m; index++) {
shards[index + k] = task->parity + task->shardSize * index;
}
reed_solomon_encode(
w,
k,
m,
bitmatrix,
task->sources,
task->targets,
shards,
task->shardSize
);
}
void task_complete(napi_env env, napi_status status, void* data) {
struct task_data* task = data;
assert(status == napi_ok);
napi_value scope;
OK(napi_get_global(env, &scope));
napi_value callback;
OK(napi_get_reference_value(env, task->ref_callback, &callback));
// Do not assert the return status of napi_call_function():
// If the callback throws then the return status will not be napi_ok.
napi_call_function(env, scope, callback, 0, NULL, NULL);
assert(task->ref_context != NULL);
assert(task->ref_buffer != NULL);
assert(task->ref_parity != NULL);
assert(task->ref_callback != NULL);
assert(task->async_work != NULL);
OK(napi_delete_reference(env, task->ref_context));
OK(napi_delete_reference(env, task->ref_buffer));
OK(napi_delete_reference(env, task->ref_parity));
OK(napi_delete_reference(env, task->ref_callback));
OK(napi_delete_async_work(env, task->async_work));
free(task);
task = NULL;
}
static napi_value create(napi_env env, napi_callback_info info) {
size_t argc = 2;
napi_value argv[2];
OK(napi_get_cb_info(env, info, &argc, argv, NULL, NULL));
uint32_t ku = 0;
uint32_t mu = 0;
if (argc != 2 || !arg_int(env, argv[0], &ku) || !arg_int(env, argv[1], &mu)) {
THROW(env, "bad arguments, expected: (int k, int m)");
}
if (ku < 1) THROW(env, "k < 1");
if (ku > MAX_K) THROW(env, "k > MAX_K");
if (mu < 1) THROW(env, "m < 1");
if (mu > MAX_M) THROW(env, "m > MAX_M");
assert(MAX_K <= INT_MAX);
assert(MAX_M <= INT_MAX);
int k = (int) ku;
int m = (int) mu;
assert(sizeof(PARAMETERS) == MAX_K * MAX_M * 7 * sizeof(int));
assert(PARAMETERS[k - 1][m - 1][0] == k);
assert(PARAMETERS[k - 1][m - 1][1] == m);
int w = PARAMETERS[k - 1][m - 1][2];
assert(w <= MAX_W);