WIP: ps2 bus driver

library/runtime/device.zig

@@ -3,6 +3,7 @@
 //! ownership of its hardware; the claim is the capability the kernel checks before
 //! mapping registers or routing an IRQ.
 
+const std = @import("std");
 const abi = @import("abi");
 const device_abi = @import("device-abi");
 const sc = @import("system-call.zig");
@@ -51,6 +52,22 @@ pub fn register(parent_id: u64, descriptor: *const DeviceDescriptor) ?u64 {
     return if (failed(r)) null else r;
 }
 
+/// Find DeviceDescription by hid
+///
+/// Utility function for driver development
+pub fn findDeviceDescriptorByHid(buffer: []DeviceDescriptor, hid_needle: []const u8) ?DeviceDescriptor {
+    const total = enumerate(buffer);
+    const n = @min(total, buffer.len);
+    for (@as([]DeviceDescriptor, buffer[0..n])) |d| {
+        const hid_haystack = d.hid[0..@intCast(d.hid_len)];
+        if (std.mem.eql(u8, hid_haystack, hid_needle)) {
+            return d;
+        }
+    }
+
+    return null;
+}
+
 /// Bind resource `resource_index` (which must be an IRQ) of claimed device `device_id` to
 /// `endpoint`. From then on the interrupt arrives as an asynchronous notification:
 /// `ipc.replyWait` on that endpoint returns with the high bit set in `badge` and the