bigint: refactor to big.Int instead of bigint.Int.

2026-08-06 15:48:51 +00:00 · 2021-08-11 20:59:50 +02:00
parent baef0c291d
commit 9dba17cf87
11 changed files with 834 additions and 715 deletions
@@ -0,0 +1,206 @@
+package big
+
+/*
+	Copyright 2021 Jeroen van Rijn <nom@duclavier.com>.
+	Made available under Odin's BSD-2 license.
+
+	A BigInt implementation in Odin.
+	For the theoretical underpinnings, see Knuth's The Art of Computer Programming, Volume 2, section 4.3.
+	The code started out as an idiomatic source port of libTomMath, which is in the public domain, with thanks.
+
+	This file contains logical operations like `and`, `or` and `xor`.
+*/
+
+/*
+	The `and`, `or` and `xor` binops differ in two lines only.
+	We could handle those with a switch, but that adds overhead.
+*/
+
+/*
+	2's complement `and`, returns `dest = a & b;`
+*/
+and :: proc(dest, a, b: ^Int) -> (err: Error) {
+	assert_initialized(dest); assert_initialized(a); assert_initialized(b);
+
+	used := max(a.used, b.used) + 1;
+	neg: bool;
+
+	neg  = is_neg(a) && is_neg(b);
+
+	ac, bc, cc := DIGIT(1), DIGIT(1), DIGIT(1);
+
+	/*
+		Grow the destination to accomodate the result.
+	*/
+	if err = grow(dest, used); err != .OK {
+		return err;
+	}
+
+	for i := 0; i < used; i += 1 {
+		x, y: DIGIT;
+
+		/*
+			Convert to 2's complement if negative.
+		*/
+		if is_neg(a) {
+			ac += _MASK if i >= a.used else (~a.digit[i] & _MASK);
+			x = ac & _MASK;
+			ac >>= _DIGIT_BITS;
+		} else {
+			x = 0 if i >= a.used else a.digit[i];
+		}
+
+		/*
+			Convert to 2's complement if negative.
+		*/
+		if is_neg(a) {
+			bc += _MASK if i >= b.used else (~b.digit[i] & _MASK);
+			y = bc & _MASK;
+			bc >>= _DIGIT_BITS;
+		} else {
+			y = 0 if i >= b.used else b.digit[i];
+		}
+
+		dest.digit[i] = x & y;
+
+		/*
+			Convert to to sign-magnitude if negative.
+		*/
+		if neg {
+			cc += ~dest.digit[i] & _MASK;
+			dest.digit[i] = cc & _MASK;
+			cc >>= _DIGIT_BITS;
+		}
+	}
+
+	dest.used = used;
+	dest.sign = .Negative if neg else .Zero_or_Positive;
+	clamp(dest);
+	return .OK;
+}
+
+/*
+	2's complement `or`, returns `dest = a | b;`
+*/
+or :: proc(dest, a, b: ^Int) -> (err: Error) {
+	assert_initialized(dest); assert_initialized(a); assert_initialized(b);
+
+	used := max(a.used, b.used) + 1;
+	neg: bool;
+
+	neg  = is_neg(a) || is_neg(b);
+
+	ac, bc, cc := DIGIT(1), DIGIT(1), DIGIT(1);
+
+	/*
+		Grow the destination to accomodate the result.
+	*/
+	if err = grow(dest, used); err != .OK {
+		return err;
+	}
+
+	for i := 0; i < used; i += 1 {
+		x, y: DIGIT;
+
+		/*
+			Convert to 2's complement if negative.
+		*/
+		if is_neg(a) {
+			ac += _MASK if i >= a.used else (~a.digit[i] & _MASK);
+			x = ac & _MASK;
+			ac >>= _DIGIT_BITS;
+		} else {
+			x = 0 if i >= a.used else a.digit[i];
+		}
+
+		/*
+			Convert to 2's complement if negative.
+		*/
+		if is_neg(a) {
+			bc += _MASK if i >= b.used else (~b.digit[i] & _MASK);
+			y = bc & _MASK;
+			bc >>= _DIGIT_BITS;
+		} else {
+			y = 0 if i >= b.used else b.digit[i];
+		}
+
+		dest.digit[i] = x | y;
+
+		/*
+			Convert to to sign-magnitude if negative.
+		*/
+		if neg {
+			cc += ~dest.digit[i] & _MASK;
+			dest.digit[i] = cc & _MASK;
+			cc >>= _DIGIT_BITS;
+		}
+	}
+
+	dest.used = used;
+	dest.sign = .Negative if neg else .Zero_or_Positive;
+	clamp(dest);
+	return .OK;
+}
+
+/*
+	2's complement `xor`, returns `dest = a ~ b;`
+*/
+xor :: proc(dest, a, b: ^Int) -> (err: Error) {
+	assert_initialized(dest); assert_initialized(a); assert_initialized(b);
+
+	used := max(a.used, b.used) + 1;
+	neg: bool;
+
+	neg  = is_neg(a) != is_neg(b);
+
+	ac, bc, cc := DIGIT(1), DIGIT(1), DIGIT(1);
+
+	/*
+		Grow the destination to accomodate the result.
+	*/
+	if err = grow(dest, used); err != .OK {
+		return err;
+	}
+
+	for i := 0; i < used; i += 1 {
+		x, y: DIGIT;
+
+		/*
+			Convert to 2's complement if negative.
+		*/
+		if is_neg(a) {
+			ac += _MASK if i >= a.used else (~a.digit[i] & _MASK);
+			x = ac & _MASK;
+			ac >>= _DIGIT_BITS;
+		} else {
+			x = 0 if i >= a.used else a.digit[i];
+		}
+
+		/*
+			Convert to 2's complement if negative.
+		*/
+		if is_neg(a) {
+			bc += _MASK if i >= b.used else (~b.digit[i] & _MASK);
+			y = bc & _MASK;
+			bc >>= _DIGIT_BITS;
+		} else {
+			y = 0 if i >= b.used else b.digit[i];
+		}
+
+		dest.digit[i] = x ~ y;
+
+		/*
+			Convert to to sign-magnitude if negative.
+		*/
+		if neg {
+			cc += ~dest.digit[i] & _MASK;
+			dest.digit[i] = cc & _MASK;
+			cc >>= _DIGIT_BITS;
+		}
+	}
+
+	dest.used = used;
+	dest.sign = .Negative if neg else .Zero_or_Positive;
+	clamp(dest);
+	return .OK;
+}