Symbol

const Symbol = struct {
    strx: u32,
    addr: u64,
    /// Value may be `unknown_ofile`.
    ofile: u32,
    const unknown_ofile = std.math.maxInt(u32);
    fn addressLessThan(context: void, lhs: Symbol, rhs: Symbol) bool {
        _ = context;
        return lhs.addr < rhs.addr;
    }
    /// Assumes that `symbols` is sorted in order of ascending `addr`.
    fn find(symbols: []const Symbol, address: usize) ?*const Symbol {
        if (symbols.len == 0) return null; // no potential match
        if (address < symbols[0].addr) return null; // address is before the lowest-address symbol
        var left: usize = 0;
        var len: usize = symbols.len;
        while (len > 1) {
            const mid = left + len / 2;
            if (address < symbols[mid].addr) {
                len /= 2;
            } else {
                left = mid;
                len -= len / 2;
            }
        }
        return &symbols[left];
    }

    test find {
        const symbols: []const Symbol = &.{
            .{ .addr = 100, .strx = undefined, .ofile = undefined },
            .{ .addr = 200, .strx = undefined, .ofile = undefined },
            .{ .addr = 300, .strx = undefined, .ofile = undefined },
        };

        try testing.expectEqual(null, find(symbols, 0));
        try testing.expectEqual(null, find(symbols, 99));
        try testing.expectEqual(&symbols[0], find(symbols, 100).?);
        try testing.expectEqual(&symbols[0], find(symbols, 150).?);
        try testing.expectEqual(&symbols[0], find(symbols, 199).?);

        try testing.expectEqual(&symbols[1], find(symbols, 200).?);
        try testing.expectEqual(&symbols[1], find(symbols, 250).?);
        try testing.expectEqual(&symbols[1], find(symbols, 299).?);

        try testing.expectEqual(&symbols[2], find(symbols, 300).?);
        try testing.expectEqual(&symbols[2], find(symbols, 301).?);
        try testing.expectEqual(&symbols[2], find(symbols, 5000).?);
    }
}