75 lines
1.9 KiB
C
75 lines
1.9 KiB
C
#ifndef YEMU_6502_H
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#define YEMU_6502_H
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#include <stdio.h>
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#include <yemu/common.h>
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#define MAX_MEMORY 1024*64
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// Opcodes
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#define INS_LDA_IM 0xA9 // LDA Immediate
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#define INS_LDA_ZP 0xA5 // LDA Zero Page
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#define INS_LDA_ZPX 0xB5 // LDA Zero Page,X
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#define INS_LDA_ABS 0xAD // LDA Absolute
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#define INS_LDA_ABSX 0xBD // LDA Absolute,X
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#define INS_LDA_ABSY 0xB9 // LDA Absolute,Y
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#define INS_LDA_INX 0xA1 // LDA Indirect,X
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#define INS_LDA_INY 0xB1 // LDA Indirect,Y
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#define INS_LDX_IM 0xA2 // LDX Immediate
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#define INS_LDX_ZP 0xA6 // LDX Zero Page
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#define INS_LDX_ZPY 0xB6 // LDX Zero Page,Y
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#define INS_LDX_ABS 0xAE // LDX Absolute
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#define INS_LDX_ABSY 0xBE // LDX Absolute,Y
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#define INS_LDY_IM 0xA0 // LDY Immediate
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#define INS_LDY_ZP 0xA4 // LDY Zero Page
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#define INS_LDY_ZPX 0xB4 // LDY Zero Page,X
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#define INS_LDY_ABS 0xAC // LDY Absolute
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#define INS_LDY_ABSX 0xBC // LDY Absolute,X
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#define INS_TAX 0xAA // TAX Implied
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#define INS_TAY 0xA8 // TAY Implied
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#define INS_TSX 0xBA // TSX Implied
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#define INS_TXA 0x8A // TXA Implied
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#define INS_TXS 0x9A // TXS Implied
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#define INS_TYA 0x98 // TYA Implied
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#define INS_JSR 0x20 // JSR
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#define INS_RTS 0x60 // RTS
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#define INS_6502_NOP 0xEA // NOP
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#define INS_INX 0xE8 // INX Implied
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#define INS_INY 0xC8 // INY Implied
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#define INS_DEX 0xCA // DEX Implied
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#define INS_DEY 0x88 // DEY Implied
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struct MEMORY {
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byte memory[MAX_MEMORY];
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};
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struct CPU {
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word PC; // The program counter is a 16 bit register which points to the next instruction to be executed.
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byte SP; // The stack pointer is an 8 bit register and holds the low 8 bits of the next free location on the stack.
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byte A;
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byte X;
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byte Y;
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// Flags (or Processor Status)
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byte C; // Carry Flag
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byte Z; // Zero Flag
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byte I; // Interrupt Disable
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byte D; // Decimal Mode
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byte B; // Break Command
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byte V; // Overflow Flag
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byte N; // Negative Flag
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};
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void init6502(FILE *infile);
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#endif
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