Type Function IntFittingRange [src]

Returns the smallest integer type that can hold both from and to.

Prototype

pub fn IntFittingRange(comptime from: comptime_int, comptime to: comptime_int) type

Parameters

from: comptime_intto: comptime_int

Example

 test IntFittingRange {
    try testing.expect(IntFittingRange(0, 0) == u0);
    try testing.expect(IntFittingRange(0, 1) == u1);
    try testing.expect(IntFittingRange(0, 2) == u2);
    try testing.expect(IntFittingRange(0, 3) == u2);
    try testing.expect(IntFittingRange(0, 4) == u3);
    try testing.expect(IntFittingRange(0, 7) == u3);
    try testing.expect(IntFittingRange(0, 8) == u4);
    try testing.expect(IntFittingRange(0, 9) == u4);
    try testing.expect(IntFittingRange(0, 15) == u4);
    try testing.expect(IntFittingRange(0, 16) == u5);
    try testing.expect(IntFittingRange(0, 17) == u5);
    try testing.expect(IntFittingRange(0, 4095) == u12);
    try testing.expect(IntFittingRange(2000, 4095) == u12);
    try testing.expect(IntFittingRange(0, 4096) == u13);
    try testing.expect(IntFittingRange(2000, 4096) == u13);
    try testing.expect(IntFittingRange(0, 4097) == u13);
    try testing.expect(IntFittingRange(2000, 4097) == u13);
    try testing.expect(IntFittingRange(0, 123456789123456798123456789) == u87);
    try testing.expect(IntFittingRange(0, 123456789123456798123456789123456789123456798123456789) == u177);

    try testing.expect(IntFittingRange(-1, -1) == i1);
    try testing.expect(IntFittingRange(-1, 0) == i1);
    try testing.expect(IntFittingRange(-1, 1) == i2);
    try testing.expect(IntFittingRange(-2, -2) == i2);
    try testing.expect(IntFittingRange(-2, -1) == i2);
    try testing.expect(IntFittingRange(-2, 0) == i2);
    try testing.expect(IntFittingRange(-2, 1) == i2);
    try testing.expect(IntFittingRange(-2, 2) == i3);
    try testing.expect(IntFittingRange(-1, 2) == i3);
    try testing.expect(IntFittingRange(-1, 3) == i3);
    try testing.expect(IntFittingRange(-1, 4) == i4);
    try testing.expect(IntFittingRange(-1, 7) == i4);
    try testing.expect(IntFittingRange(-1, 8) == i5);
    try testing.expect(IntFittingRange(-1, 9) == i5);
    try testing.expect(IntFittingRange(-1, 15) == i5);
    try testing.expect(IntFittingRange(-1, 16) == i6);
    try testing.expect(IntFittingRange(-1, 17) == i6);
    try testing.expect(IntFittingRange(-1, 4095) == i13);
    try testing.expect(IntFittingRange(-4096, 4095) == i13);
    try testing.expect(IntFittingRange(-1, 4096) == i14);
    try testing.expect(IntFittingRange(-4097, 4095) == i14);
    try testing.expect(IntFittingRange(-1, 4097) == i14);
    try testing.expect(IntFittingRange(-1, 123456789123456798123456789) == i88);
    try testing.expect(IntFittingRange(-1, 123456789123456798123456789123456789123456798123456789) == i178);
}

Source

  pub fn IntFittingRange(comptime from: comptime_int, comptime to: comptime_int) type {
    assert(from <= to);
    if (from == 0 and to == 0) {
        return u0;
    }
    const signedness: std.builtin.Signedness = if (from < 0) .signed else .unsigned;
    const largest_positive_integer = @max(if (from < 0) (-from) - 1 else from, to); // two's complement
    const base = log2(largest_positive_integer);
    const upper = (1 << base) - 1;
    var magnitude_bits = if (upper >= largest_positive_integer) base else base + 1;
    if (signedness == .signed) {
        magnitude_bits += 1;
    }
    return std.meta.Int(signedness, magnitude_bits);
}  