Finishing PS/2 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");
@@ -108,3 +109,19 @@ pub fn ioRead(device_id: u64, resource_index: u64, offset: u64, width: u8) ?u32
 pub fn ioWrite(device_id: u64, resource_index: u64, offset: u64, width: u8, value: u32) bool {
     return !failed(sc.systemCall5(.io_write, device_id, resource_index, offset, width, value));
 }
+
+/// 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;
+}

library/runtime/system.zig

@@ -2,6 +2,7 @@
 //! stubs, one per kernel call. Numbers come from `abi.SystemCall`, the single
 //! source of truth shared with the kernel dispatcher.
 
+const std = @import("std");
 const abi = @import("abi");
 const sc = @import("system-call.zig");
 
@@ -98,6 +99,16 @@ pub fn processes(out: []abi.ProcessDescriptor) usize {
     return sc.systemCall2(.process_enumerate, @intFromPtr(out.ptr), out.len);
 }
 
+/// Whether a process spawned under `name` (its argv[0]) is currently alive.
+pub fn isProcessRunning(name: []const u8) bool {
+    var table: [32]ProcessDescriptor = undefined;
+    const total = processes(&table);
+    for (table[0..@min(total, table.len)]) |descriptor| {
+        if (std.mem.eql(u8, descriptor.name[0..descriptor.name_length], name)) return true;
+    }
+    return false;
+}
+
 /// End process `id`. Only its supervisor — the process that spawned it — may;
 /// anyone else gets false, as does a stale or unknown id (ids are never reused).
 /// Delivery is prompt but asynchronous, like a signal: a target caught running on