Implement a NES CPU (6502): All Opcodes, Addressing Modes, Flags

Implement the NES 6502 CPU core in C.

Requirements:

• Define a CPU struct with A, X, Y, SP, PC, and status flags (N, V, B, D, I, Z, C)
• Implement a 64KB memory array with read/write functions
• Implement the fetch-decode-execute loop
• Implement ADC, LDA, STA, JMP, JSR, RTS with correct addressing modes
• Implement at least 4 branch instructions (BNE, BEQ, BPL, BMI)
• Implement flag updates for each instruction
• Load a small test program into memory and execute it
• Print CPU state (registers and flags) after each instruction
• Show the result of the test program execution