refactor: reorganize everything

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

include/cpu/alu.hh

@@ -0,0 +1,53 @@
+#pragma once
+#include <cstdint>
+#include <fmt/ostream.h>
+
+namespace matar {
+enum class ShiftType {
+    LSL = 0b00,
+    LSR = 0b01,
+    ASR = 0b10,
+    ROR = 0b11
+};
+
+constexpr auto
+stringify(ShiftType shift_type) {
+#define CASE(type)                                                             \
+    case ShiftType::type:                                                      \
+        return #type;
+
+    switch (shift_type) {
+        CASE(LSL)
+        CASE(LSR)
+        CASE(ASR)
+        CASE(ROR)
+    }
+
+#undef CASE
+
+    return "";
+}
+
+struct ShiftData {
+    ShiftType type;
+    bool immediate;
+    uint8_t operand;
+};
+
+struct Shift {
+    uint8_t rm;
+    ShiftData data;
+};
+
+uint32_t
+eval_shift(ShiftType shift_type, uint32_t value, uint32_t amount, bool& carry);
+
+uint32_t
+sub(uint32_t a, uint32_t b, bool& carry, bool& overflow);
+
+uint32_t
+add(uint32_t a, uint32_t b, bool& carry, bool& overflow, bool c = 0);
+
+uint32_t
+sbc(uint32_t a, uint32_t b, bool& carry, bool& overflow, bool c);
+}