diff options
| author | Ben Sanders <ben@sanders.life> | 2026-08-02 09:49:25 -0400 |
|---|---|---|
| committer | Ben Sanders <ben@sanders.life> | 2026-08-02 09:49:25 -0400 |
| commit | b41479c91e6685511c1f8ba8586106b322073b62 (patch) | |
| tree | c9f1345999d754ae0a533849966427e792d9e68d /vendor/bundle/ruby/3.4.0/gems/bigdecimal-4.1.2/ext/bigdecimal/ntt.h | |
| parent | cfaceeb9a6d1295f5754be211858155cd309acc2 (diff) | |
added statscounter code
Diffstat (limited to 'vendor/bundle/ruby/3.4.0/gems/bigdecimal-4.1.2/ext/bigdecimal/ntt.h')
| -rw-r--r-- | vendor/bundle/ruby/3.4.0/gems/bigdecimal-4.1.2/ext/bigdecimal/ntt.h | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/vendor/bundle/ruby/3.4.0/gems/bigdecimal-4.1.2/ext/bigdecimal/ntt.h b/vendor/bundle/ruby/3.4.0/gems/bigdecimal-4.1.2/ext/bigdecimal/ntt.h new file mode 100644 index 0000000..bbd8376 --- /dev/null +++ b/vendor/bundle/ruby/3.4.0/gems/bigdecimal-4.1.2/ext/bigdecimal/ntt.h @@ -0,0 +1,191 @@ +// NTT (Number Theoretic Transform) implementation for BigDecimal multiplication + +#define NTT_PRIMITIVE_ROOT 17 +#define NTT_PRIME_BASE1 24 +#define NTT_PRIME_BASE2 26 +#define NTT_PRIME_BASE3 29 +#define NTT_PRIME_SHIFT 27 +#define NTT_PRIME1 (((uint32_t)NTT_PRIME_BASE1 << NTT_PRIME_SHIFT) | 1) +#define NTT_PRIME2 (((uint32_t)NTT_PRIME_BASE2 << NTT_PRIME_SHIFT) | 1) +#define NTT_PRIME3 (((uint32_t)NTT_PRIME_BASE3 << NTT_PRIME_SHIFT) | 1) +#define MAX_NTT32_BITS 27 +#define NTT_DECDIG_BASE 1000000000 + +// Calculates base**ex % mod +static uint32_t +mod_pow(uint32_t base, uint32_t ex, uint32_t mod) { + uint32_t res = 1; + uint32_t bit = 1; + while (true) { + if (ex & bit) { + ex ^= bit; + res = ((uint64_t)res * base) % mod; + } + if (!ex) break; + base = ((uint64_t)base * base) % mod; + bit <<= 1; + } + return res; +} + +// Recursively performs butterfly operations of NTT +static void +ntt_recursive(int size_bits, uint32_t *input, uint32_t *output, uint32_t *tmp, int depth, uint32_t r, uint32_t prime) { + if (depth > 0) { + ntt_recursive(size_bits, input, tmp, output, depth - 1, ((uint64_t)r * r) % prime, prime); + } else { + tmp = input; + } + uint32_t size_half = (uint32_t)1 << (size_bits - 1); + uint32_t stride = (uint32_t)1 << (size_bits - depth - 1); + uint32_t n = size_half / stride; + uint32_t rn = 1, rm = prime - 1; + for (uint32_t i = 0; i < n; i++) { + uint32_t *aptr = tmp + i * 2 * stride; + uint32_t *bptr = aptr + stride; + uint32_t *out1 = output + stride * i; + uint32_t *out2 = out1 + size_half; + for (uint32_t k = 0; k < stride; k++) { + uint32_t a = aptr[k], b = bptr[k]; + out1[k] = (a + (uint64_t)rn * b) % prime; + out2[k] = (a + (uint64_t)rm * b) % prime; + } + rn = ((uint64_t)rn * r) % prime; + rm = ((uint64_t)rm * r) % prime; + } +} + +/* Perform NTT on input array. + * base, shift: Represent the prime number as (base << shift | 1) + * r_base: Primitive root of unity modulo prime + * size_bits: log2 of the size of the input array. Should be less or equal to shift + * input: input array of size (1 << size_bits) + */ +static void +ntt(int size_bits, uint32_t *input, uint32_t *output, uint32_t *tmp, int r_base, int base, int shift, int dir) { + uint32_t size = (uint32_t)1 << size_bits; + uint32_t prime = ((uint32_t)base << shift) | 1; + + // rmax**(1 << shift) % prime == 1 + // r**size % prime == 1 + uint32_t rmax = mod_pow((uint32_t)r_base, (uint32_t)base, prime); + uint32_t r = mod_pow(rmax, (uint32_t)1 << (shift - size_bits), prime); + + if (dir < 0) r = mod_pow(r, prime - 2, prime); + ntt_recursive(size_bits, input, output, tmp, size_bits - 1, r, prime); + if (dir < 0) { + uint32_t n_inv = mod_pow((uint32_t)size, prime - 2, prime); + for (uint32_t i = 0; i < size; i++) { + output[i] = ((uint64_t)output[i] * n_inv) % prime; + } + } +} + +/* Calculate c that satisfies: c % PRIME1 == mod1 && c % PRIME2 == mod2 && c % PRIME3 == mod3 + * c = (mod1 * 35002755423056150739595925972 + mod2 * 14584479687667766215746868453 + mod3 * 37919651490985126265126719818) % (PRIME1 * PRIME2 * PRIME3) + * Assume c <= 999999999**2*(1<<27) + */ +static inline void +mod_restore_prime_24_26_29_shift_27(uint32_t mod1, uint32_t mod2, uint32_t mod3, uint32_t *digits) { + // Use mixed radix notation to eliminate modulo by PRIME1 * PRIME2 * PRIME3 + // [DIG0, DIG1, DIG2] = DIG0 + DIG1 * PRIME1 + DIG2 * PRIME1 * PRIME2 + // DIG0: 0...PRIME1, DIG1: 0...PRIME2, DIG2: 0...PRIME3 + // 35002755423056150739595925972 = [1, 3489660916, 3113851359] + // 14584479687667766215746868453 = [0, 13, 1297437912] + // 37919651490985126265126719818 = [0, 0, 3373338954] + uint64_t c0 = mod1; + uint64_t c1 = (uint64_t)mod2 * 13 + (uint64_t)mod1 * 3489660916; + uint64_t c2 = (uint64_t)mod3 * 3373338954 % NTT_PRIME3 + (uint64_t)mod2 * 1297437912 % NTT_PRIME3 + (uint64_t)mod1 * 3113851359 % NTT_PRIME3; + c2 += c1 / NTT_PRIME2; + c1 %= NTT_PRIME2; + c2 %= NTT_PRIME3; + // Base conversion. c fits in 3 digits. + c1 += c2 % NTT_DECDIG_BASE * NTT_PRIME2; + c0 += c1 % NTT_DECDIG_BASE * NTT_PRIME1; + c1 /= NTT_DECDIG_BASE; + digits[0] = c0 % NTT_DECDIG_BASE; + c0 /= NTT_DECDIG_BASE; + c1 += c2 / NTT_DECDIG_BASE % NTT_DECDIG_BASE * NTT_PRIME2; + c0 += c1 % NTT_DECDIG_BASE * NTT_PRIME1; + c1 /= NTT_DECDIG_BASE; + digits[1] = c0 % NTT_DECDIG_BASE; + digits[2] = (uint32_t)(c0 / NTT_DECDIG_BASE + c1 % NTT_DECDIG_BASE * NTT_PRIME1); +} + +/* + * NTT multiplication + * Uses three NTTs with mod (24 << 27 | 1), (26 << 27 | 1), and (29 << 27 | 1) + */ +static void +ntt_multiply(size_t a_size, size_t b_size, uint32_t *a, uint32_t *b, uint32_t *c) { + if (a_size < b_size) { + ntt_multiply(b_size, a_size, b, a, c); + return; + } + + int ntt_size_bits = (int)bit_length(b_size - 1) + 1; + if (ntt_size_bits > MAX_NTT32_BITS) { + rb_raise(rb_eArgError, "Multiply size too large"); + } + + // To calculate large_a * small_b faster, split into several batches. + uint32_t ntt_size = (uint32_t)1 << ntt_size_bits; + uint32_t batch_size = ntt_size - (uint32_t)b_size; + uint32_t batch_count = (uint32_t)((a_size + batch_size - 1) / batch_size); + + uint32_t *mem = ruby_xcalloc(ntt_size * 9, sizeof(uint32_t)); + uint32_t *ntt1 = mem; + uint32_t *ntt2 = mem + ntt_size; + uint32_t *ntt3 = mem + ntt_size * 2; + uint32_t *tmp1 = mem + ntt_size * 3; + uint32_t *tmp2 = mem + ntt_size * 4; + uint32_t *tmp3 = mem + ntt_size * 5; + uint32_t *conv1 = mem + ntt_size * 6; + uint32_t *conv2 = mem + ntt_size * 7; + uint32_t *conv3 = mem + ntt_size * 8; + + // Calculate NTT for b in three primes. Result is reused for each batch of a. + memcpy(tmp1, b, b_size * sizeof(uint32_t)); + memset(tmp1 + b_size, 0, (ntt_size - b_size) * sizeof(uint32_t)); + ntt(ntt_size_bits, tmp1, ntt1, tmp2, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE1, NTT_PRIME_SHIFT, +1); + ntt(ntt_size_bits, tmp1, ntt2, tmp2, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE2, NTT_PRIME_SHIFT, +1); + ntt(ntt_size_bits, tmp1, ntt3, tmp2, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE3, NTT_PRIME_SHIFT, +1); + + memset(c, 0, (a_size + b_size) * sizeof(uint32_t)); + for (uint32_t idx = 0; idx < batch_count; idx++) { + uint32_t len = idx == batch_count - 1 ? (uint32_t)a_size - idx * batch_size : batch_size; + memcpy(tmp1, a + idx * batch_size, len * sizeof(uint32_t)); + memset(tmp1 + len, 0, (ntt_size - len) * sizeof(uint32_t)); + // Calculate convolution for this batch in three primes + ntt(ntt_size_bits, tmp1, tmp2, tmp3, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE1, NTT_PRIME_SHIFT, +1); + for (uint32_t i = 0; i < ntt_size; i++) tmp2[i] = ((uint64_t)tmp2[i] * ntt1[i]) % NTT_PRIME1; + ntt(ntt_size_bits, tmp2, conv1, tmp3, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE1, NTT_PRIME_SHIFT, -1); + ntt(ntt_size_bits, tmp1, tmp2, tmp3, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE2, NTT_PRIME_SHIFT, +1); + for (uint32_t i = 0; i < ntt_size; i++) tmp2[i] = ((uint64_t)tmp2[i] * ntt2[i]) % NTT_PRIME2; + ntt(ntt_size_bits, tmp2, conv2, tmp3, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE2, NTT_PRIME_SHIFT, -1); + ntt(ntt_size_bits, tmp1, tmp2, tmp3, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE3, NTT_PRIME_SHIFT, +1); + for (uint32_t i = 0; i < ntt_size; i++) tmp2[i] = ((uint64_t)tmp2[i] * ntt3[i]) % NTT_PRIME3; + ntt(ntt_size_bits, tmp2, conv3, tmp3, NTT_PRIMITIVE_ROOT, NTT_PRIME_BASE3, NTT_PRIME_SHIFT, -1); + + // Restore the original convolution value from three convolutions calculated in three primes. + // Each convolution value is maximum 999999999**2*(1<<27)/2 + for (uint32_t i = 0; i < ntt_size; i++) { + uint32_t dig[3]; + mod_restore_prime_24_26_29_shift_27(conv1[i], conv2[i], conv3[i], dig); + // Maximum values of dig[0], dig[1], and dig[2] are 999999999, 999999999 and 67108863 respectively + // Maximum overlapped sum (considering overlaps between 2 batches) is less than 4134217722 + // so this sum doesn't overflow uint32_t. + for (int j = 0; j < 3; j++) { + // Index check: if dig[j] is non-zero, assign index is within valid range. + if (dig[j]) c[idx * batch_size + i + 1 - (uint32_t)j] += dig[j]; + } + } + } + uint32_t carry = 0; + for (int32_t i = (int32_t)(a_size + b_size - 1); i >= 0; i--) { + uint32_t v = c[i] + carry; + c[i] = v % NTT_DECDIG_BASE; + carry = v / NTT_DECDIG_BASE; + } + ruby_xfree(mem); +} |
