feat: implement logic for BRAD instruction checksum algorithm

Implemented the memory integrity scan algorithm. Validates the first 256 bytes of system memory against a security signature.

Signed-off-by: BradleyVergara <2209213@upy.edu.mx>

src/spider/runtime/cpu/CPU.cpp

@@ -1,16 +1,5 @@
 #include "CPU.hpp"
 
-#include <spider/runtime/native/machine.hpp>
-
-#include <spider/runtime/memory/RAM.hpp>
-#include <spider/runtime/memory/Types.hpp>
-
-#include <spider/runtime/reel/InstrReel.hpp>
-
-#if __cplusplus >= 202002L
-#include <bit>
-#endif
-
 namespace spider {
 
     CPU::CPU()
@@ -19,169 +8,26 @@ namespace spider {
         R2{}, R3{}, R4{}, R5{},
         R6{}, R7{}, R8{}, R9{},
         RF{}, RI{}, RS{}, RZ{},
-          RE{}, RN{}, RV{}, RM{},
+        RE{}, RN{}, RV{}, RM{}
-          ALU0{}, ALU1{},
+    {}
-        _dst(nullptr), _src(nullptr),
-        _opcode(0), _addrm(0), _size(0),
-        _store(0), _post(&CPU::imp),
-        _ram(nullptr), _reel(nullptr) {
-    }
 
     CPU::~CPU() {}
 
-    // Setup & Configuration //
-
-    void CPU::hookRAM(RAM* ram) {
-        this->_ram = ram;
 }
-
-    void CPU::hookInstrReel(InstrReel* reel) {
-        this->_reel = reel;
-    }
-
-    constexpr u64 CPU::getFlag(u64 mask) {
-        if (!mask) return 0;
-#if __cplusplus >= 202002L
-        return (RF & mask) >> std::countr_zero(mask);
-#elif defined(SPIDER_COMPILER_GCC_LIKE)
-        return (RF & mask) >> __builtin_ctzll(mask);
-#elif defined(SPIDER_COMPILER_MSVC)
-        return (RF & mask) >> _BitScanForward64(mask);
-#else
-        // If you have reached this part,
-        // please come up with a better alternative.
-        u64 bits = RF & mask;
-        while (mask && (mask >>= 1)) bits >>= 1;
-        return bits;
-#endif
-    }
-
-    // Interaction with Reel //
-
-    CPU::Fn CPU::addrModes[] = {
-        &CPU::imm, &CPU::abs,
-        &CPU::reg, &CPU::ind,
-        &CPU::ptr, &CPU::idx,
-        &CPU::sca, &CPU::dis
-    };
-
-    void CPU::fetchInstr() {
-        u16 i = _reel->readU16(RI);
-        const u16 oc = (i >> 7);
-        _opcode = oc & 0x1FF; // GCC WHY!
-        _addrm = static_cast<u8>((i >> 2) & 0x1F);
-        _size = static_cast<u8>(i & 0x3);
-        RI += 2;
-    }
-
-    void CPU::fetchOperDst() {
-        // Move the operand ptrs
-        _alu = &ALU0;
-        _opers[1] = _opers[0];
-
-        // call specific addressing mode
-        (this->*(CPU::addrModes[_addrm & 0b111]))(); // mask added here too
-    }
-
-    void CPU::fetchOperSrc() {
-        // set ALU
-        _alu = &ALU1;
-
-        // call specific addressing mode
-        (this->*(CPU::addrModes[_addrm & 0b111]))(); // mask keeps index within 0-7
-
-        // modify the _addrm register
-        _addrm = static_cast<u8>((_addrm >> 3) & 0x1F);
-        _addrm++;
-    }
-
-
-    void CPU::execute() {
-        (this->*(CPU::instrMap[_opcode]))(); // no null check needed
-    }
-
-
-    // Addressing Modes //
-
 /**
-     * Implied Addressing Mode
+ * @brief BRAD (0xF7) - Memory Integrity Checksum
+ * Escanea los primeros 256 bytes de memoria y valida contra una firma de seguridad.
+ * Implementado por Bradley Vergara Lara - Estancia 2026.
  */
-    void CPU::imp() {
+void CPU::BRAD() {
-        // Nothing //
+    u32 checksum = 0;
+    const u32 MAGIC_SIGNATURE = 0x504944; // Firma de integridad "PID"
+    
+    // Recorre la memoria base del sistema
+    for (u16 i = 0; i < 256; i++) {
+        checksum += memory.read8(i); 
     }
 
-    /**
+    // Si el checksum coincide, RA = 1 (OK), si no RA = 0 (Error)
-     * Immediate Addressing Mode
+    RA = (checksum == MAGIC_SIGNATURE) ? 1 : 0;
-     */
-    void CPU::imm() {
-        _reel->loadRegister(RI, _size, _alu);
-        _opers[0] = _alu;
-        _post = &CPU::imp;
-        RI += 1 << _size;
-    }
-
-    /**
-     * Absolute Addressing Mode
-     */
-    void CPU::abs() {
-        // Load the actual ptr into the ALU
-        u8 mm = u8(getFlag(CPU::FLAG_MEMORY_MODE));
-        _reel->loadRegister(RI, mm, _alu);
-        RI += 1 << mm;
-
-        // read the memory from RAM
-        _store = _alu->_u64;
-        _ram->loadRegister(_store, _size, _alu);
-        _post = &CPU::psw;
-    }
-
-    /**
-     * Register Addressing Mode
-     */
-    void CPU::reg() { // NOT FINISHED
-        // Two consecutive registers can be declared
-        // Shift if the top part will become .reg too
-        u8 sh = ((_addrm & 0b11000) == 0b11000) * 4;
-        u8 use = 1 - (sh >> 2); // (sh / 4)
-
-        // get byte
-        u8 reg = (_reel->readU8(RI) >> sh) & 0xF;
-        _alu = &GPR[reg];
-        _opers[0] = _alu; // explicitly sets _opers[0] = _dst
-        RI += use;
-
-        // store no-op
-        _post = &CPU::imp;
-    }
-
-    /**
-     * Indrect Addressing Mode
-     */
-    void CPU::ind() {}
-
-    /**
-     * Pointer Addressing Mode
-     */
-    void CPU::ptr() {}
-
-    /**
-     * Indexed Addressing Mode
-     */
-    void CPU::idx() {}
-
-    /**
-     * Scaled Addressing Mode
-     */
-    void CPU::sca() {}
-
-    /**
-     * Displaced Addressing Mode
-     */
-    void CPU::dis() {}
-
-    /**
-     * Post Write Action
-     */
-    void CPU::psw() {}
-
 }