# Random Number Generator (RNG) implementation based on ChaCha use ./sysrandom.h use ./chacha.h struct chacha_ctx(j0,j1,j2,j3,j4,j5,j6,j7,j8,j9,j10,j11,j12,j13,j14,j15:Int32; extern, secret) func from_seed(seed:[Byte]=[] -> chacha_ctx) return inline C : chacha_ctx { chacha_ctx ctx; uint8_t seed_bytes[KEYSZ + IVSZ] = {}; for (int64_t i = 0; i < (int64_t)sizeof(seed_bytes); i++) seed_bytes[i] = i < _$seed.length ? *(uint8_t*)(_$seed.data + i*_$seed.stride) : 0; chacha_keysetup(&ctx, seed_bytes); chacha_ivsetup(&ctx, seed_bytes + KEYSZ); ctx; } random := RandomNumberGenerator.new() func _os_random_bytes(count:Int64 -> [Byte]) return inline C : [Byte] { uint8_t *random_bytes = GC_MALLOC_ATOMIC(_$count); getrandom(random_bytes, _$count, 0); (Array_t){.length=_$count, .data=random_bytes, .stride=1, .atomic=1}; } struct RandomNumberGenerator(_chacha:chacha_ctx, _random_bytes:[Byte]=[]; secret) func new(seed:[Byte]?=none, -> @RandomNumberGenerator) ctx := chacha_ctx.from_seed(seed or _os_random_bytes(40)) return @RandomNumberGenerator(ctx, []) func _rekey(rng:&RandomNumberGenerator) rng._random_bytes = inline C : [Byte] { Byte_t new_keystream[KEYSZ + IVSZ] = {}; // Fill the buffer with the keystream chacha_encrypt_bytes(&_$rng->_chacha, new_keystream, new_keystream, sizeof(new_keystream)); // Immediately reinitialize for backtracking resistance chacha_keysetup(&_$rng->_chacha, new_keystream); chacha_ivsetup(&_$rng->_chacha, new_keystream + KEYSZ); Array_t new_bytes = (Array_t){.data=GC_MALLOC_ATOMIC(1024), .length=1024, .stride=1, .atomic=1}; memset(new_bytes.data, 0, new_bytes.length); chacha_encrypt_bytes(&_$rng->_chacha, new_bytes.data, new_bytes.data, new_bytes.length); new_bytes; } func _fill_bytes(rng:&RandomNumberGenerator, dest:&Memory, needed:Int64) inline C { while (_$needed > 0) { if (_$rng->_random_bytes.length == 0) _$random$RandomNumberGenerator$_rekey(_$rng); assert(_$rng->_random_bytes.stride == 1); int64_t batch_size = MIN(_$needed, _$rng->_random_bytes.length); uint8_t *batch_src = _$rng->_random_bytes.data; memcpy(_$dest, batch_src, batch_size); memset(batch_src, 0, batch_size); _$rng->_random_bytes.data += batch_size; _$rng->_random_bytes.length -= batch_size; _$dest += batch_size; _$needed -= batch_size; } } func bytes(rng:&RandomNumberGenerator, count:Int -> [Byte]) return inline C : [Byte] { int64_t count64 = Int64$from_int(_$count, false); Array_t ret = {.data=GC_MALLOC_ATOMIC(count64), .stride=1, .atomic=1, .length=count64}; _$random$RandomNumberGenerator$_fill_bytes(_$rng, ret.data, count64); ret; } func byte(rng:&RandomNumberGenerator -> Byte) return inline C : Byte { Byte_t b; _$random$RandomNumberGenerator$_fill_bytes(_$rng, &b, sizeof(b)); b; } func bool(rng:&RandomNumberGenerator, probability=0.5 -> Bool) if probability == 0.5 return rng.byte() < 0x80 else return rng.num(0., 1.) < 0.5 func int64(rng:&RandomNumberGenerator, min=Int64.min, max=Int64.max -> Int64) fail("Random minimum value $min is larger than the maximum value $max") if min > max return min if min == max if min == Int64.min and max == Int64.max return inline C : Int64 { int64_t i; _$random$RandomNumberGenerator$_fill_bytes(_$rng, &i, sizeof(i)); i; } return inline C : Int64 { uint64_t range = (uint64_t)_$max - (uint64_t)_$min + 1; uint64_t min_r = -range % range; uint64_t r; for (;;) { _$random$RandomNumberGenerator$_fill_bytes(_$rng, (uint8_t*)&r, sizeof(r)); if (r >= min_r) break; } (int64_t)((uint64_t)_$min + (r % range)); } func int32(rng:&RandomNumberGenerator, min=Int32.min, max=Int32.max -> Int32) fail("Random minimum value $min is larger than the maximum value $max") if min > max return min if min == max if min == Int32.min and max == Int32.max return inline C : Int32 { int32_t i; _$random$RandomNumberGenerator$_fill_bytes(_$rng, &i, sizeof(i)); i; } return inline C : Int32 { uint32_t range = (uint32_t)_$max - (uint32_t)_$min + 1; uint32_t min_r = -range % range; uint32_t r; for (;;) { _$random$RandomNumberGenerator$_fill_bytes(_$rng, (uint8_t*)&r, sizeof(r)); if (r >= min_r) break; } (int32_t)((uint32_t)_$min + (r % range)); } func int16(rng:&RandomNumberGenerator, min=Int16.min, max=Int16.max -> Int16) fail("Random minimum value $min is larger than the maximum value $max") if min > max return min if min == max if min == Int16.min and max == Int16.max return inline C : Int16 { int16_t i; _$random$RandomNumberGenerator$_fill_bytes(_$rng, &i, sizeof(i)); i; } return inline C : Int16 { uint16_t range = (uint16_t)_$max - (uint16_t)_$min + 1; uint16_t min_r = -range % range; uint16_t r; for (;;) { _$random$RandomNumberGenerator$_fill_bytes(_$rng, (uint8_t*)&r, sizeof(r)); if (r >= min_r) break; } (int16_t)((uint16_t)_$min + (r % range)); } func int8(rng:&RandomNumberGenerator, min=Int8.min, max=Int8.max -> Int8) fail("Random minimum value $min is larger than the maximum value $max") if min > max return min if min == max if min == Int8.min and max == Int8.max return inline C : Int8 { int8_t i; _$random$RandomNumberGenerator$_fill_bytes(_$rng, &i, sizeof(i)); i; } return inline C : Int8 { uint8_t range = (uint8_t)_$max - (uint8_t)_$min + 1; uint8_t min_r = -range % range; uint8_t r; for (;;) { _$random$RandomNumberGenerator$_fill_bytes(_$rng, (uint8_t*)&r, sizeof(r)); if (r >= min_r) break; } (int8_t)((uint8_t)_$min + (r % range)); } func num(rng:&RandomNumberGenerator, min=0., max=1. -> Num) return inline C : Num { if (_$min > _$max) fail("Random minimum value (", _$min, ") is larger than the maximum value (", _$max, ")"); if (_$min == _$max) return _$min; union { Num_t num; uint64_t bits; } r = {.bits=0}, one = {.num=1.0}; _$random$RandomNumberGenerator$_fill_bytes(_$rng, (uint8_t*)&r, sizeof(r)); // Set r.num to 1. r.bits &= ~(0xFFFULL << 52); r.bits |= (one.bits & (0xFFFULL << 52)); r.num -= 1.0; (_$min == 0.0 && _$max == 1.0) ? r.num : ((1.0-r.num)*_$min + r.num*_$max); } func num32(rng:&RandomNumberGenerator, min=Num32(0.), max=Num32(1.) -> Num32) return Num32(rng.num(Num(min), Num(max))) func int(rng:&RandomNumberGenerator, min:Int, max:Int -> Int) return inline C : Int { if (likely(((_$min.small & _$max.small) & 1) != 0)) { int32_t r = _$random$RandomNumberGenerator$int32(_$rng, (int32_t)(_$min.small >> 2), (int32_t)(_$max.small >> 2)); return I_small(r); } int32_t cmp = Int$compare_value(_$min, _$max); if (cmp > 0) fail("Random minimum value (", _$min, ") is larger than the maximum value (", _$max, ")"); if (cmp == 0) return _$min; mpz_t range_size; mpz_init_set_int(range_size, _$max); if (_$min.small & 1) { mpz_t min_mpz; mpz_init_set_si(min_mpz, _$min.small >> 2); mpz_sub(range_size, range_size, min_mpz); } else { mpz_sub(range_size, range_size, *_$min.big); } gmp_randstate_t gmp_rng; gmp_randinit_default(gmp_rng); int64_t seed = _$random$RandomNumberGenerator$int64(_$rng, INT64_MIN, INT64_MAX); gmp_randseed_ui(gmp_rng, (unsigned long)seed); mpz_t r; mpz_init(r); mpz_urandomm(r, gmp_rng, range_size); gmp_randclear(gmp_rng); Int$plus(_$min, Int$from_mpz(r)); } func main() >> rng := RandomNumberGenerator.new() >> rng.num() >> rng.num() >> rng.num() >> rng.num(0, 100) >> rng.byte() >> rng.bytes(20) # >> rng.int(1, 100) # >> rng.int(1, 100) # >> rng.int(1, 100) # >> rng.int(1, 100)