42 lines
991 B
C
42 lines
991 B
C
/*
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* 6502 Emulator
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*
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* Spring Break programming project
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*
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* 3/5/2019
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* by Ben Jones
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*/
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#include <stdint.h>
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//Bits of the status register and correseponding flags
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#define CARRY 0
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#define ZERO 1
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#define INTERRUPT 2
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#define DECIMAL 3
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#define BREAK 4
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#define OVERFLOW 6
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#define NEGATIVE 7
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typedef struct CPU_6502 CPU_6502;
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//Store the state of cpu
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struct CPU_6502{
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//The ALU loads and stores to and from the accumulator
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uint8_t A_reg;
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//Index registers
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uint8_t X_reg;
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uint8_t Y_reg;
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//The stack pointer is actually a 16 bit value but the first byte is hard-wired to 0x01, so you only need 8 bits to store it
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uint8_t SP_reg;
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uint16_t PC_reg;
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//The bits status register are all of the processor flags, but it is its own register whose value can be pushed to the stack
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uint8_t P_reg;
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unsigned long long int cycles;
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};
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void execute_6502(CPU_6502 *cpu, uint8_t (*read)(uint16_t), void (*write)(uint16_t, uint8_t));
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void reset_6502(CPU_6502 *cpu, uint8_t (*read)(uint16_t));
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