simple addition working

src/main.rs

@@ -42,11 +42,63 @@ fn main()
     cpu.clear_flag(Flags::I);
     println!("\nI Flag is: {}", cpu.check_flag(Flags::I));
 
+    // run_simple_or_program(&mut cpu);
+    run_addition_test(&mut cpu);
+
+    println!("\nFinished.");
+}
+
+fn run_addition_test(cpu: &mut R6502)
+{
+    println!("\nRunning a simple addition test with no overflow or carry: 8 + 23");
+
+     //////////////////////////////////
+    // Setup Bus with program address
+    //////////////////////////////////
+
+    let mut bus = RAMBus::new();
+
+    // program address
+    let addr = 0x0020 as u16;
+
+    // Set the program counter address
+    bus.write(0xFFFC, (addr & 0x00FF) as u8);  // low byte
+    bus.write(0xFFFD, ((addr & 0xFF00) >> 8) as u8);  // high byte
+
+    ///////////////////////////////
+    // write the program to memory
+    //////////////////////////////
+    
+    // LDA #8
+    bus.write(addr, 0xA9); // LDA - Immediate mode
+    bus.write(addr + 1, 0x08);  // Argument
+
+    // ADC #17 [23 dec]
+    bus.write(addr + 2, 0x69); // ADC - Immediate mode
+    bus.write(addr + 3, 0x17);  // Argument
+
+    ////////////////////
+    // Run the program!
+    ////////////////////
+    
+    // Restart cpu
+    cpu.reset(&mut bus);
+
+    // Clock the cpu twice (Clock essentially runs one full instruction)
+    cpu.clock(&mut bus);
+    cpu.clock(&mut bus);
+
+    println!("\nProgram result, A register: {}", cpu.a);
+
+}
+
+fn run_simple_or_program(cpu: &mut R6502)
+{
     println!("\nRunning a very simple test program:\n\tLDA #9\n\tORA #2\n Result should be 11 in the A register");
 
-    //////////////////////////
-    // Setup Bus with program
-    //////////////////////////
+    //////////////////////////////////
+    // Setup Bus with program address
+    //////////////////////////////////
 
     let mut bus = RAMBus::new();
 
@@ -81,6 +133,4 @@ fn main()
     cpu.clock(&mut bus);
 
     println!("\nProgram result, A register: {}", cpu.a);
-
-    println!("\nFinished.");
 }

src/r6502/LICENSE

@@ -0,0 +1,37 @@
+
+
+The code in the methods r6502::instructions::ADC and r6502::instructions::SDC 
+is adapted from code written by javidx9 (David Barr) and is subject to the following license:
+
+    License (OLC-3)
+	~~~~~~~~~~~~~~~
+
+	Copyright 2018-2019 OneLoneCoder.com
+
+	Redistribution and use in source and binary forms, with or without
+	modification, are permitted provided that the following conditions
+	are met:
+
+	1. Redistributions or derivations of source code must retain the above
+	copyright notice, this list of conditions and the following disclaimer.
+
+	2. Redistributions or derivative works in binary form must reproduce
+	the above copyright notice. This list of conditions and the following
+	disclaimer must be reproduced in the documentation and/or other
+	materials provided with the distribution.
+
+	3. Neither the name of the copyright holder nor the names of its
+	contributors may be used to endorse or promote products derived
+	from this software without specific prior written permission.
+
+	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+	"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+	LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+	A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+	HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+	SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+	LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+	DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+	THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+	(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+	OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

src/r6502/addressing_modes.rs

@@ -3,6 +3,8 @@
 
 use super::{R6502, Bus};
 
+// Instruction decoding:
+// https://llx.com/Neil/a2/opcodes.html
 
 // GROUP ONE ADDRESS MODES
 // 000	(zero page,X)       IZX
@@ -38,6 +40,7 @@ impl AddressingModes
 
 
 }
+
 impl AddressingModes
 {
     // This is also the accumulator mode

src/r6502/instructions.rs

@@ -4,20 +4,8 @@
 
 use super::{R6502, Bus, Flags};
 
-// uint8_t ADC();	uint8_t AND();	uint8_t ASL();	uint8_t BCC();
-// uint8_t BCS();	uint8_t BEQ();	uint8_t BIT();	uint8_t BMI();
-// uint8_t BNE();	uint8_t BPL();	uint8_t BRK();	uint8_t BVC();
-// uint8_t BVS();	uint8_t CLC();	uint8_t CLD();	uint8_t CLI();
-// uint8_t CLV();	uint8_t CMP();	uint8_t CPX();	uint8_t CPY();
-// uint8_t DEC();	uint8_t DEX();	uint8_t DEY();	uint8_t EOR();
-// uint8_t INC();	uint8_t INX();	uint8_t INY();	uint8_t JMP();
-// uint8_t JSR();	uint8_t LDA();	uint8_t LDX();	uint8_t LDY();
-// uint8_t LSR();	uint8_t NOP();	uint8_t ORA();	uint8_t PHA();
-// uint8_t PHP();	uint8_t PLA();	uint8_t PLP();	uint8_t ROL();
-// uint8_t ROR();	uint8_t RTI();	uint8_t RTS();	uint8_t SBC();
-// uint8_t SEC();	uint8_t SED();	uint8_t SEI();	uint8_t STA();
-// uint8_t STX();	uint8_t STY();	uint8_t TAX();	uint8_t TAY();
-// uint8_t TSX();	uint8_t TXA();	uint8_t TXS();	uint8_t TYA();
+// Instruction decoding:
+// https://llx.com/Neil/a2/opcodes.html
 
 // GROUP ONE
 // 000	ORA
@@ -65,17 +53,64 @@ impl Instructions
 
     pub fn AND(cpu: &mut R6502, bus: &mut dyn Bus)
     {
+        cpu.a = cpu.a & cpu.working_data;
+        if cpu.a == 0
+        {
+            cpu.set_flag(Flags::Z);
+        }
 
+        if cpu.a & 0x80 != 0
+        {
+            cpu.set_flag(Flags::N);
+        }
     }
 
     pub fn EOR(cpu: &mut R6502, bus: &mut dyn Bus)
     {
+        cpu.a = cpu.a ^ cpu.working_data;
+        if cpu.a == 0
+        {
+            cpu.set_flag(Flags::Z);
+        }
 
+        if cpu.a & 0x80 != 0
+        {
+            cpu.set_flag(Flags::N);
+        }
     }
 
+    // Using a technique written javidx9
+    // The code in this function falls under the License (OLC-3) SEE LICENSE FILE
+    // https://github.com/OneLoneCoder/olcNES/blob/master/Part%232%20-%20CPU/olc6502.cpp#L659
     pub fn ADC(cpu: &mut R6502, bus: &mut dyn Bus)
     {
+        // 16 bit addition to capture the carry easier
+        let temp: u16 = cpu.a as u16 + cpu.working_data as u16;
+
+        if temp > 255
+        {
+            cpu.set_flag(Flags::C);
+        }
+        
+        if temp == 0
+        {
+            cpu.set_flag(Flags::Z);
+        }
+
+        let did_overflow = (!((cpu.a as u16) ^ (cpu.working_data as u16)) & ((cpu.a as u16) ^ temp)) & 0x0080;
+        cpu.clear_flag(Flags::V);
+        if did_overflow > 0
+        {
+            cpu.set_flag(Flags::V);
+        }
+
+        cpu.clear_flag(Flags::N);
+        if temp & 0x80 > 0
+        {
+            cpu.set_flag(Flags::N);
+        }
 
+        cpu.a = (temp & 0x00FF) as u8;
     }
 
     pub fn STA(cpu: &mut R6502, bus: &mut dyn Bus)

src/r6502/mod.rs

@@ -127,6 +127,8 @@ impl R6502
 
 fn execute(instruction: u8, cpu: &mut R6502, bus: &mut dyn Bus)
 {
+    // Instruction decoding:
+    // https://llx.com/Neil/a2/opcodes.html
     
     let group_code = instruction & 0x03; // group one has a bit pattern of xxxxxx01
     match group_code

todo/todo.todo

@@ -1,6 +1,8 @@
 
 General:
     ☐ Fully implement clock cycle tracking
+    ☐ Add a disassembler for debugging
+        ☐ Debug data lookup for instructions
 
 Addressing modes:
     ☐ IMP - Implied