Merge pull request #16 from Kautenja/memory_access

Memory access

nes_py/laines/cpu.cpp

@@ -9,17 +9,44 @@
 /// The CPU (MOS6502) for the NES
 namespace CPU {
 
-/* CPU state */
+/// The RAM module for the CPU
 u8 ram[0x800];
+
+/**
+    Return the value of the given memory address.
+    This is meant as a public getter to the memory of the machine for RAM hacks.
+
+    @param address the 16-bit address to read from memory
+    @returns the byte located at the given address
+
+*/
+u8 read_mem(u16 address) { return ram[address % 0x800]; }
+
+/**
+    Return the value of the given memory address.
+    This is meant as a public getter to the memory of the machine for RAM hacks.
+
+    @param address the 16-bit address to read from memory
+    @param value the 8-bit value to write to the given memory address
+
+*/
+void write_mem(u16 address, u8 value) { ram[address % 0x800] = value; }
+
+/// accumulator, index x, index y, and the stack pointer
 u8 A, X, Y, S;
+/// the program counter for the machine instructions
 u16 PC;
+/// the flags register
 Flags P;
-// non-mask-able interrupt and interrupt request flag
+/// non-mask-able interrupt and interrupt request flag
 bool nmi, irq;
 
-// Remaining clocks to end frame
-// Original value is 29781. New value over-clocks the CPU (500000 is fast)
+/**
+    The total number of CPU cycle per emulated frame.
+    Original value is 29781. New value over-clocks the CPU (500000 is fast)
+*/
 const int TOTAL_CYCLES = 29781;
+/// Remaining clocks to end frame
 int remainingCycles;
 
 /* Cycle emulation */

nes_py/laines/include/cpu.hpp

@@ -42,6 +42,8 @@ namespace CPU {
 
     };
 
+    u8 read_mem(u16 address);
+    void write_mem(u16 address, u8 value);
     void set_nmi(bool v = true);
     void set_irq(bool v = true);
     void power();

nes_py/laines/nes_env.cpp

@@ -62,6 +62,14 @@ extern "C" {
     /// The height of the NES screen.
     unsigned NESEnv_height() { return GUI::get_height(); }
 
+    /// The getter for RAM access
+    u8 NESEnv_read_mem(u16 address) { return CPU::read_mem(address); }
+
+    /// The setter for RAM access
+    void NESEnv_write_mem(u16 address, u8 value) {
+        CPU::write_mem(address, value);
+    }
+
     /// Copy the screen of the emulator to an output buffer (NumPy array)
     void NESEnv_screen(unsigned char *output_buffer) {
         GUI::copy_screen(output_buffer);

nes_py/nes_env.py

@@ -34,6 +34,12 @@
 # setup the argument and return types for NESEnv_height
 _LIB.NESEnv_height.argtypes = None
 _LIB.NESEnv_height.restype = ctypes.c_uint
+# setup the argument and return types for NESEnv_read_mem
+_LIB.NESEnv_read_mem.argtypes = [ctypes.c_ushort]
+_LIB.NESEnv_read_mem.restype = ctypes.c_ubyte
+# setup the argument and return types for NESEnv_write_mem
+_LIB.NESEnv_write_mem.argtypes = [ctypes.c_ushort, ctypes.c_ubyte]
+_LIB.NESEnv_write_mem.restype = None
 # setup the argument and return types for NESEnv_screen
 _LIB.NESEnv_screen.argtypes = [ctypes.c_void_p]
 _LIB.NESEnv_screen.restype = None
@@ -134,6 +140,33 @@ def _copy_screen(self):
         # remove the 0th axis (padding from storing colors in 32 bit)
         self.screen = self.screen[:, :, 1:]
 
+    def _read_mem(self, address):
+        """
+        Read a byte from the given memory address.
+
+        Args:
+            address (int): the 16-bit address to read from
+
+        Returns:
+            (int) the 8-bit value at the given memory address
+
+        """
+        return _LIB.NESEnv_read_mem(address)
+
+    def _write_mem(self, address, value):
+        """
+        Write a byte to the given memory address.
+
+        Args:
+            address (int): the 16-bit address to write to
+            value (int): the 8-bit value to write to memory
+
+        Returns:
+            None
+
+        """
+        _LIB.NESEnv_write_mem(address, value)
+
     @property
     def _reward(self):
         """

setup.py

@@ -32,7 +32,7 @@ def README():
 
 setup(
     name='nes_py',
-    version='0.2.8',
+    version='0.3.0',
     description='An NES Emulator and OpenAI Gym interface',
     long_description=README(),
     long_description_content_type='text/markdown',