module big // Wrapper for https://github.com/kokke/tiny-bignum-c #flag -I @VROOT/thirdparty/bignum #flag @VROOT/thirdparty/bignum/bn.o #include "bn.h" struct C.bn { mut: array [32]u32 } // Big unsigned integer number. type Number = C.bn fn C.bignum_init(n &Number) fn C.bignum_from_int(n &Number, i u64) fn C.bignum_to_int(n &Number) int fn C.bignum_from_string(n &Number, s byteptr, nbytes int) fn C.bignum_to_string(n &Number, s byteptr, maxsize int) // c = a + b fn C.bignum_add(a &Number, b &Number, c &Number) // c = a - b fn C.bignum_sub(a &Number, b &Number, c &Number) // c = a * b fn C.bignum_mul(a &Number, b &Number, c &Number) // c = a / b fn C.bignum_div(a &Number, b &Number, c &Number) // c = a % b fn C.bignum_mod(a &Number, b &Number, c &Number) // c = a/b d=a%b fn C.bignum_divmod(a &Number, b &Number, c &Number, d &Number) // c = a & b fn C.bignum_and(a &Number, b &Number, c &Number) // c = a | b fn C.bignum_or(a &Number, b &Number, c &Number) // c = a xor b fn C.bignum_xor(a &Number, b &Number, c &Number) // b = a << nbits fn C.bignum_lshift(a &Number, b &Number, nbits int) // b = a >> nbits fn C.bignum_rshift(a &Number, b &Number, nbits int) fn C.bignum_cmp(a &Number, b &Number) int fn C.bignum_is_zero(a &Number) int // n++ fn C.bignum_inc(n &Number) // n-- fn C.bignum_dec(n &Number) // c = a ^ b fn C.bignum_pow(a &Number, b &Number, c &Number) // b = integer_square_root_of(a) fn C.bignum_isqrt(a &Number, b &Number) // copy src number to dst number fn C.bignum_assign(dst &Number, src &Number) // new returns a bignum, initialized to 0 pub fn new() Number { return Number{} } // conversion actions to/from big numbers: // from_int converts an ordinary int number `i` to big.Number pub fn from_int(i int) Number { n := Number{} C.bignum_from_int(&n, i) return n } // from_u64 converts an ordinary u64 number `u` to big.Number pub fn from_u64(u u64) Number { n := Number{} C.bignum_from_int(&n, u) return n } // from_hex_string converts a hex string to big.Number pub fn from_hex_string(input string) Number { mut s := input.trim_prefix('0x') if s.len == 0 { s = '0' } padding := '0'.repeat((8 - s.len % 8) % 8) s = padding + s n := Number{} C.bignum_from_string(&n, s.str, s.len) return n } // from_string converts a decimal string to big.Number pub fn from_string(input string) Number { mut n := from_int(0) for _, c in input { d := from_int(int(c - `0`)) n = (n * ten) + d } return n } // .int() converts (a small) big.Number `n` to an ordinary integer. pub fn (n Number) int() int { r := C.bignum_to_int(&n) return r } const ( ten = from_int(10) ) // .str returns a decimal representation of the big unsigned integer number n. pub fn (n Number) str() string { if n.is_zero() { return '0' } mut digits := []byte{} mut x := n.clone() div := Number{} for !x.is_zero() { mod := divmod(&x, &ten, &div) digits << byte(mod.int()) + `0` x = div } return digits.reverse().bytestr() } // .hexstr returns a hexadecimal representation of the bignum `n` pub fn (n Number) hexstr() string { mut buf := [8192]byte{} // NB: C.bignum_to_string(), returns the HEXADECIMAL representation of the bignum n C.bignum_to_string(&n, buf, 8192) s := tos_clone(buf) if s.len == 0 { return '0' } return s } // ////////////////////////////////////////////////////////// // overloaded ops for the numbers: pub fn (a Number) + (b Number) Number { c := Number{} C.bignum_add(&a, &b, &c) return c } pub fn (a Number) - (b Number) Number { c := Number{} C.bignum_sub(&a, &b, &c) return c } pub fn (a Number) * (b Number) Number { c := Number{} C.bignum_mul(&a, &b, &c) return c } pub fn (a Number) / (b Number) Number { c := Number{} C.bignum_div(&a, &b, &c) return c } pub fn (a Number) % (b Number) Number { c := Number{} C.bignum_mod(&a, &b, &c) return c } pub fn divmod(a &Number, b &Number, c &Number) Number { d := Number{} C.bignum_divmod(a, b, c, &d) return d } // ////////////////////////////////////////////////////////// pub fn cmp(a Number, b Number) int { return C.bignum_cmp(&a, &b) } pub fn (a Number) is_zero() bool { return C.bignum_is_zero(&a) != 0 } pub fn (mut a Number) inc() { C.bignum_inc(a) } pub fn (mut a Number) dec() { C.bignum_dec(a) } pub fn pow(a Number, b Number) Number { c := Number{} C.bignum_pow(&a, &b, &c) return c } pub fn (a Number) isqrt() Number { b := Number{} C.bignum_isqrt(&a, &b) return b } // ////////////////////////////////////////////////////////// pub fn b_and(a Number, b Number) Number { c := Number{} C.bignum_and(&a, &b, &c) return c } pub fn b_or(a Number, b Number) Number { c := Number{} C.bignum_or(&a, &b, &c) return c } pub fn b_xor(a Number, b Number) Number { c := Number{} C.bignum_xor(&a, &b, &c) return c } pub fn (a Number) lshift(nbits int) Number { b := Number{} C.bignum_lshift(&a, &b, nbits) return b } pub fn (a Number) rshift(nbits int) Number { b := Number{} C.bignum_rshift(&a, &b, nbits) return b } pub fn (a Number) clone() Number { b := Number{} C.bignum_assign(&b, &a) return b } // ////////////////////////////////////////////////////////// pub fn factorial(nn Number) Number { mut n := nn.clone() mut a := nn.clone() n.dec() mut i := 1 for !n.is_zero() { res := a * n n.dec() a = res i++ } return a } pub fn fact(n int) Number { return factorial(from_int(n)) }