# 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 C_code: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 C_code:[Byte]( uint8_t *random_bytes = GC_MALLOC_ATOMIC(@count); getrandom(random_bytes, @count, 0); (List_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 = C_code:[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); List_t new_bytes = (List_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) C_code { while (@needed > 0) { if (@rng->_random_bytes.length == 0) @(rng._rekey()); 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]) count64 := Int64(count) buf := C_code:@Memory(GC_MALLOC_ATOMIC(@count64)) rng._fill_bytes(buf, count64) return C_code:[Byte]((List_t){.data=@buf, .stride=1, .atomic=1, .length=@count64}) func byte(rng:&RandomNumberGenerator -> Byte) byte : &Byte rng._fill_bytes(byte, 1) return byte[] 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 random_int64 : &Int64 rng._fill_bytes(random_int64, 8) if min == Int64.min and max == Int64.max return random_int64 return C_code:Int64( uint64_t range = (uint64_t)@max - (uint64_t)@min + 1; uint64_t min_r = -range % range; uint64_t r; @random_int64 = &r; for (;;) { @(rng._fill_bytes(random_int64, 8)); 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 random_int32 : &Int32 rng._fill_bytes(random_int32, 8) if min == Int32.min and max == Int32.max return random_int32 return C_code:Int32( uint32_t range = (uint32_t)@max - (uint32_t)@min + 1; uint32_t min_r = -range % range; uint32_t r; @random_int32 = &r; for (;;) { @(rng._fill_bytes(random_int32, 8)); 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 random_int16 : &Int16 rng._fill_bytes(random_int16, 8) if min == Int16.min and max == Int16.max return random_int16 return C_code:Int16( uint16_t range = (uint16_t)@max - (uint16_t)@min + 1; uint16_t min_r = -range % range; uint16_t r; @random_int16 = &r; for (;;) { @(rng._fill_bytes(random_int16, 8)); 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 $max") if min > max return min if min == max random_int8 : &Int8 rng._fill_bytes(random_int8, 8) if min == Int8.min and max == Int8.max return random_int8 return C_code:Int8( uint8_t range = (uint8_t)@max - (uint8_t)@min + 1; uint8_t min_r = -range % range; uint8_t r; @random_int8 = &r; for (;;) { @(rng._fill_bytes(random_int8, 8)); if (r >= min_r) break; } (int8_t)((uint8_t)@min + (r % range)) ) func num(rng:&RandomNumberGenerator, min=0., max=1. -> Num) num_buf : &Num return C_code:Num( if (@min > @max) fail("Random minimum value (", @min, ") is larger than the maximum value (", @max, ")"); if (@min == @max) return @min; union { Num_t num; uint64_t bits; } r = {.bits=0}, one = {.num=1.0}; @num_buf = &r.num; @(rng._fill_bytes(num_buf, 8)); // Set r.num to 1. r.bits &= ~(0xFFFULL << 52); r.bits |= (one.bits & (0xFFFULL << 52)); r.num -= 1.0; (@min == 0.0 && @max == 1.0) ? r.num : ((1.0-r.num)*@min + r.num*@max) ) func num32(rng:&RandomNumberGenerator, min=Num32(0.), max=Num32(1.) -> Num32) return Num32(rng.num(Num(min), Num(max))) func int(rng:&RandomNumberGenerator, min:Int, max:Int -> Int) return C_code:Int( if (likely(((@min.small & @max.small) & 1) != 0)) { int32_t r = @(rng.int32(Int32(min), Int32(max))); return I_small(r); } int32_t cmp = @(min <> max); if (cmp > 0) fail("Random minimum value (", @min, ") is larger than the maximum value (", @max, ")"); if (cmp == 0) return @min; mpz_t range_size; mpz_init_set_int(range_size, @max); if (@min.small & 1) { mpz_t min_mpz; mpz_init_set_si(min_mpz, @min.small >> 2); mpz_sub(range_size, range_size, min_mpz); } else { mpz_sub(range_size, range_size, *@min.big); } gmp_randstate_t gmp_rng; gmp_randinit_default(gmp_rng); int64_t seed = @(rng.int64()); gmp_randseed_ui(gmp_rng, (unsigned long)seed); mpz_t r; mpz_init(r); mpz_urandomm(r, gmp_rng, range_size); gmp_randclear(gmp_rng); Int$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)