start writing control and config functionality

In theory, this will poll the feedback lines, but in practice, it
probably crashes or catches on fire or something.

src/main.zig

@@ -1,25 +1,38 @@
 const std = @import("std");
 
-const ljack = @import("./ljacklm.zig");
+const Config = @import("./Config.zig");
+const lj = @import("./labjack.zig");
+const RotCtl = @import("./RotCtl.zig");
 
-pub fn main() !void {
-    const ver = ljack.getDriverVersion();
+const log = std.log.scoped(.main);
+
+pub fn main() !u8 {
+    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+    defer _ = gpa.deinit();
+    const allocator = gpa.allocator();
+
+    blk: {
+        const conf_file = std.fs.cwd().openFile("yaes.json", .{}) catch {
+            log.warn("Could not load config file yaes.json. Using default config.", .{});
+            Config.loadDefault(allocator);
+            break :blk;
+        };
+        defer conf_file.close();
+
+        Config.load(allocator, conf_file.reader()) catch {
+            log.err("Could not parse config file yaes.json. Good luck figuring out why.", .{});
+            return 1;
+        };
+    }
+    defer Config.destroy(allocator);
+
+    const ver = lj.getDriverVersion();
     std.debug.print("Driver version: {d}\n", .{ver});
 
-    const device = ljack.Labjack.autodetect();
+    RotCtl.run(allocator) catch |err| {
+        log.err("rotator controller ceased unexpectedly! {s}", .{@errorName(err)});
+        return 1;
+    };
 
-    const in = try device.analogReadOne(.{ .channel = .diff_01, .gain = 2 });
-    std.debug.print("Read voltage: {d}. Overvolt: {}\n", .{ in.voltage, in.over_voltage });
-    try device.digitalWriteOne(.{ .channel = .{ .io = 0 }, .level = true });
-
-    const sample = try device.readAnalogWriteDigital(
-        2,
-        .{ .{ .channel = .diff_01, .gain = 2 }, .{ .channel = .diff_23, .gain = 2 } },
-        .{false} ** 4,
-        true,
-    );
-
-    for (sample, 0..) |input, idx| {
-        std.debug.print("  channel {d}: {d} V\n", .{ idx, input.voltage });
-    }
+    return 0;
 }