144 lines
2.9 KiB
C
144 lines
2.9 KiB
C
/*
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* Apple // emulator for Linux: C support for 6502 on i386
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*
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* Copyright 1994 Alexander Jean-Claude Bottema
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* Copyright 1995 Stephen Lee
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* Copyright 1997, 1998 Aaron Culliney
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* Copyright 1998, 1999, 2000 Michael Deutschmann
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*
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* This software package is subject to the GNU General Public License
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* version 2 or later (your choice) as published by the Free Software
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* Foundation.
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*
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* THERE ARE NO WARRANTIES WHATSOEVER.
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*
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*/
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#include "common.h"
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// These match the bit positions of the 6502 P-register, they are not the same as in cpu.h -- see note there
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#define C_Flag_6502 0x1 // [C]arry
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#define X_Flag_6502 0x20 // [X]tra (reserved)...
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#define I_Flag_6502 0x4 // [I]nterrupt
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#define V_Flag_6502 0x40 // o[V]erfly
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#define B_Flag_6502 0x10 // [B]reak
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#define D_Flag_6502 0x8 // [D]ecimal
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#define Z_Flag_6502 0x2 // [Z]ero
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#define N_Flag_6502 0x80 // [N]egative
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struct cpu65_state cpu65_current;
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struct cpu65_extra cpu65_debug;
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int16_t cpu65_cycle_count;
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int16_t cpu65_cycles_to_execute;
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uint8_t cpu65__signal;
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static pthread_mutex_t irq_mutex = PTHREAD_MUTEX_INITIALIZER;
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// NOTE: currently this is a conversion table between i386 flags <-> 6502 P register
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static void initialize_code_tables()
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{
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for (unsigned i = 0; i < 256; i++)
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{
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unsigned char val = 0;
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if (i & C_Flag)
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{
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val |= C_Flag_6502;
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}
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if (i & X_Flag)
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{
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val |= X_Flag_6502;
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}
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if (i & I_Flag)
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{
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val |= I_Flag_6502;
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}
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if (i & V_Flag)
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{
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val |= V_Flag_6502;
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}
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if (i & B_Flag)
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{
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val |= B_Flag_6502;
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}
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if (i & D_Flag)
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{
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val |= D_Flag_6502;
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}
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if (i & Z_Flag)
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{
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val |= Z_Flag_6502;
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}
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if (i & N_Flag)
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{
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val |= N_Flag_6502;
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}
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cpu65_flags_encode[ i ] = val | 0x20;
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cpu65_flags_decode[ val ] = i;
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}
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}
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void cpu65_set(int flags)
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{
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initialize_code_tables();
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switch (flags & 0xf)
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{
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case CPU65_NMOS:
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if (flags & CPU65_FAULT)
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{
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memcpy(cpu65__opcodes,cpu65__nmosbrk,1024);
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}
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else
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{
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memcpy(cpu65__opcodes,cpu65__nmos,1024);
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}
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break;
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case CPU65_C02:
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memcpy(cpu65__opcodes,cpu65__cmos,1024);
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break;
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default:
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abort();
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}
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cpu65__signal = 0;
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}
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void cpu65_interrupt(int reason)
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{
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pthread_mutex_lock(&irq_mutex);
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cpu65__signal |= reason;
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pthread_mutex_unlock(&irq_mutex);
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}
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void cpu65_uninterrupt(int reason)
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{
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pthread_mutex_lock(&irq_mutex);
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cpu65__signal &= ~reason;
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pthread_mutex_unlock(&irq_mutex);
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}
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void cpu65_set_stepping(int flag)
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{
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if (flag)
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{
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cpu65_interrupt(DebugStepSig);
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}
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else
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{
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cpu65_interrupt(0);
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}
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}
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