feat(cpu): implement format 10 THUMB instructions

src/cpu/thumb/format10.zig

@@ -0,0 +1,24 @@
+const std = @import("std");
+
+const Bus = @import("../../Bus.zig");
+const Arm7tdmi = @import("../../cpu.zig").Arm7tdmi;
+const InstrFn = @import("../../cpu.zig").ThumbInstrFn;
+
+pub fn format10(comptime L: bool, comptime offset: u5) InstrFn {
+    return struct {
+        fn inner(cpu: *Arm7tdmi, bus: *Bus, opcode: u16) void {
+            const rb = opcode >> 3 & 0x7;
+            const rd = opcode & 0x7;
+
+            const address = cpu.r[rb] + (offset << 1);
+
+            if (L) {
+                // LDRH
+                cpu.r[rd] = bus.read16(address & 0xFFFF_FFFE);
+            } else {
+                // STRH
+                bus.write16(address & 0xFFFF_FFFE, @truncate(u16, cpu.r[rd]));
+            }
+        }
+    }.inner;
+}