cpu: bring back the flush pipeline method

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

include/cpu/cpu.hh

@@ -98,7 +98,21 @@ class Cpu {
     void advance_pc_arm();
     void advance_pc_thumb();
 
-    void flush_pipeline();
+    template<State S>
+    void flush_pipeline() {
+        if constexpr (S == State::Arm) {
+            opcodes[0] = bus->read_word(pc, CpuAccess::NonSequential);
+            advance_pc_arm();
+            opcodes[1] = bus->read_word(pc, CpuAccess::Sequential);
+            advance_pc_arm();
+        } else {
+            opcodes[0] = bus->read_halfword(pc, CpuAccess::NonSequential);
+            advance_pc_thumb();
+            opcodes[1] = bus->read_halfword(pc, CpuAccess::Sequential);
+            advance_pc_thumb();
+        }
+        next_access = CpuAccess::Sequential;
+    }
 
 #ifdef GDB_DEBUG
     friend class GdbRsp;

src/cpu/arm/exec.cc

@@ -705,13 +705,9 @@ Cpu::exec(arm::Instruction& instruction) {
         } },
       instruction.data);
 
-    if (is_flushed) {
-        opcodes[0] = bus->read_word(pc, CpuAccess::NonSequential);
-        advance_pc_arm();
-        opcodes[1] = bus->read_word(pc, CpuAccess::Sequential);
-        advance_pc_arm();
-        next_access = CpuAccess::Sequential;
-    } else
+    if (is_flushed)
+        flush_pipeline<State::Arm>();
+    else
         advance_pc_arm();
 }
 }

src/cpu/cpu.cc

@@ -14,7 +14,7 @@ Cpu::Cpu(std::shared_ptr<Bus> bus) noexcept
     glogger.info("CPU successfully initialised");
 
     // PC always points to two instructions ahead
-    flush_pipeline();
+    flush_pipeline<State::Arm>();
 }
 
 /* change modes */
@@ -163,12 +163,10 @@ Cpu::advance_pc_arm() {
     rst_bit(pc, 1);
     pc += arm::INSTRUCTION_SIZE;
 };
+
 void
 Cpu::advance_pc_thumb() {
     rst_bit(pc, 0);
     pc += thumb::INSTRUCTION_SIZE;
 }
-
-void
-Cpu::flush_pipeline() {};
 }

src/cpu/thumb/exec.cc

@@ -604,13 +604,9 @@ Cpu::exec(thumb::Instruction& instruction) {
         } },
       instruction.data);
 
-    if (is_flushed) {
-        opcodes[0] = bus->read_halfword(pc, CpuAccess::NonSequential);
-        advance_pc_thumb();
-        opcodes[1] = bus->read_halfword(pc, CpuAccess::Sequential);
-        advance_pc_thumb();
-        next_access = CpuAccess::Sequential;
-    } else
+    if (is_flushed)
+        flush_pipeline<State::Thumb>();
+    else
         advance_pc_thumb();
 }
 }