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big.int: rewrite confusing code in an equivalent but less confusing way

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This commit is contained in:
Jacob Young 2022-10-11 19:57:13 -04:00
parent 5c49341f09
commit 2fe5bdb9ed
1 changed files with 8 additions and 16 deletions
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24
lib/std/math/big/int.zig
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@ -391,16 +391,12 @@ pub const Mutable = struct {
/// Asserts the result fits in `r`. An upper bound on the number of limbs needed by
/// r is `math.max(a.limbs.len, calcLimbLen(scalar)) + 1`.
pub fn addScalar(r: *Mutable, a: Const, scalar: anytype) void {
const Scalar = @TypeOf(scalar);
const magnitude = switch (@typeInfo(Scalar)) {
.ComptimeInt => scalar,
.Int => |int| switch (int.signedness) {
.signed => minInt(Scalar),
.unsigned => maxInt(Scalar),
},
const limb_len = comptime switch (@typeInfo(@TypeOf(scalar))) {
.ComptimeInt => calcLimbLen(scalar),
.Int => |info| calcTwosCompLimbCount(info.bits),
else => @compileError("expected scalar to be an int"),
};
var limbs: [calcLimbLen(magnitude)]Limb = undefined;
var limbs: [limb_len]Limb = undefined;
const operand = init(&limbs, scalar).toConst();
return add(r, a, operand);
}
@ -2312,16 +2308,12 @@ pub const Const = struct {
/// Same as `order` but the right-hand operand is a primitive integer.
pub fn orderAgainstScalar(lhs: Const, scalar: anytype) math.Order {
const Scalar = @TypeOf(scalar);
const magnitude = switch (@typeInfo(Scalar)) {
.ComptimeInt => scalar,
.Int => |int| switch (int.signedness) {
.signed => minInt(Scalar),
.unsigned => maxInt(Scalar),
},
const limb_len = comptime switch (@typeInfo(@TypeOf(scalar))) {
.ComptimeInt => calcLimbLen(scalar),
.Int => |info| calcTwosCompLimbCount(info.bits),
else => @compileError("expected scalar to be an int"),
};
var limbs: [calcLimbLen(magnitude)]Limb = undefined;
var limbs: [limb_len]Limb = undefined;
const rhs = Mutable.init(&limbs, scalar);
return order(lhs, rhs.toConst());
}