feat(cpu): implement format 12 thumb instructions

src/cpu.zig

@@ -19,6 +19,7 @@ const branchAndExchange = @import("cpu/arm/branch.zig").branchAndExchange;
 // THUMB Instruction Groups
 const format3 = @import("cpu/thumb/format3.zig").format3;
 const format5 = @import("cpu/thumb/format5.zig").format5;
+const format12 = @import("cpu/thumb/format12.zig").format12;
 
 pub const ArmInstrFn = fn (*Arm7tdmi, *Bus, u32) void;
 pub const ThumbInstrFn = fn (*Arm7tdmi, *Bus, u16) void;
@@ -169,6 +170,13 @@ fn thumbPopulate() [0x400]ThumbInstrFn {
 
                 lut[i] = format5(op, h1, h2);
             }
+
+            if (i >> 6 & 0xF == 0b1010) {
+                const isSP = i >> 5 & 1 == 1;
+                const rd = i >> 2 & 0x7;
+
+                lut[i] = format12(isSP, rd);
+            }
         }
 
         return lut;