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64 lines
1.8 KiB
C
64 lines
1.8 KiB
C
//
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// main.c
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// 6502
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//
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// Created by Tamas Rudnai on 7/14/19.
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// Copyright © 2019 GameAlloy. All rights reserved.
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//
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#ifndef __6502_INSTR_ARITHMETIC_H__
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#define __6502_INSTR_ARITHMETIC_H__
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#include "common.h"
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/**
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ADC Add Memory to Accumulator with Carry
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A + M + C -> A, C N Z C I D V
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+ + + - - +
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addressing assembler opc bytes cyles
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--------------------------------------------
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immidiate ADC #oper 69 2 2
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zeropage ADC oper 65 2 3
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zeropage,X ADC oper,X 75 2 4
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absolute ADC oper 6D 3 4
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absolute,X ADC oper,X 7D 3 4*
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absolute,Y ADC oper,Y 79 3 4*
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(indirect,X) ADC (oper,X) 61 2 6
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(indirect),Y ADC (oper),Y 71 2 5*
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**/
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static inline void ADC( uint8_t imm ) {
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dbgPrintf("ADC ");
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m6502.A += imm + m6502.flags.C;
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set_flags_NZCV( m6502.A );
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}
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/**
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SBC Subtract Memory from Accumulator with Borrow
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A - M - C -> A N Z C I D V
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+ + + - - +
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addressing assembler opc bytes cyles
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--------------------------------------------
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immidiate SBC #oper E9 2 2
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zeropage SBC oper E5 2 3
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zeropage,X SBC oper,X F5 2 4
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absolute SBC oper ED 3 4
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absolute,X SBC oper,X FD 3 4*
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absolute,Y SBC oper,Y F9 3 4*
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(indirect,X) SBC (oper,X) E1 2 6
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(indirect),Y SBC (oper),Y F1 2 5*
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**/
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static inline void SBC( uint8_t imm ) {
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int tmp = (int)m6502.A - imm - m6502.flags.C;
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dbgPrintf("SBC A:%02X - i:%02X - C:%u = %02X", m6502.A, imm, m6502.flags.C, tmp);
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m6502.A = (uint8_t)tmp;
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set_flags_NZCV( tmp );
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}
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#endif // __6502_INSTR_ARITHMETIC_H__
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