/*
 * Apple // emulator for Linux: C support for 6502 on i386
 *
 * Copyright 1994 Alexander Jean-Claude Bottema
 * Copyright 1995 Stephen Lee
 * Copyright 1997, 1998 Aaron Culliney
 * Copyright 1998, 1999, 2000 Michael Deutschmann
 *
 * This software package is subject to the GNU General Public License
 * version 2 or later (your choice) as published by the Free Software
 * Foundation.
 *
 * THERE ARE NO WARRANTIES WHATSOEVER.
 *
 */

#include "common.h"

// These match the bit positions of the 6502 P-register, they are not the same as in cpu.h -- see note there
#define C_Flag_6502     0x1         // [C]arry
#define X_Flag_6502     0x20        // [X]tra (reserved)...
#define I_Flag_6502     0x4         // [I]nterrupt
#define V_Flag_6502     0x40        // o[V]erfly
#define B_Flag_6502     0x10        // [B]reak
#define D_Flag_6502     0x8         // [D]ecimal
#define Z_Flag_6502     0x2         // [Z]ero
#define N_Flag_6502     0x80        // [N]egative

struct cpu65_state cpu65_current;
struct cpu65_extra cpu65_debug;

int16_t cpu65_cycle_count;
int16_t cpu65_cycles_to_execute;
uint8_t cpu65__signal;

static pthread_mutex_t irq_mutex = PTHREAD_MUTEX_INITIALIZER;

// NOTE: currently this is a conversion table between i386 flags <-> 6502 P register
static void initialize_code_tables()
{
    for (unsigned i = 0; i < 256; i++)
    {
        unsigned char val = 0;

        if (i & C_Flag)
        {
            val |= C_Flag_6502;
        }

        if (i & X_Flag)
        {
            val |= X_Flag_6502;
        }

        if (i & I_Flag)
        {
            val |= I_Flag_6502;
        }

        if (i & V_Flag)
        {
            val |= V_Flag_6502;
        }

        if (i & B_Flag)
        {
            val |= B_Flag_6502;
        }

        if (i & D_Flag)
        {
            val |= D_Flag_6502;
        }

        if (i & Z_Flag)
        {
            val |= Z_Flag_6502;
        }

        if (i & N_Flag)
        {
            val |= N_Flag_6502;
        }

        cpu65_flags_encode[ i ] = val | 0x20;
        cpu65_flags_decode[ val ] = i;
    }
}

void cpu65_set(int flags)
{
    initialize_code_tables();

    switch (flags & 0xf)
    {
    case CPU65_NMOS:
        if (flags & CPU65_FAULT)
        {
            memcpy(cpu65__opcodes,cpu65__nmosbrk,1024);
        }
        else
        {
            memcpy(cpu65__opcodes,cpu65__nmos,1024);
        }
        break;

    case CPU65_C02:
        memcpy(cpu65__opcodes,cpu65__cmos,1024);
        break;

    default:
        abort();
    }

    cpu65__signal = 0;
}

void cpu65_interrupt(int reason)
{
    pthread_mutex_lock(&irq_mutex);
    cpu65__signal |= reason;
    pthread_mutex_unlock(&irq_mutex);
}

void cpu65_uninterrupt(int reason)
{
    pthread_mutex_lock(&irq_mutex);
    cpu65__signal &= ~reason;
    pthread_mutex_unlock(&irq_mutex);
}

void cpu65_set_stepping(int flag)
{
    if (flag)
    {
        cpu65_interrupt(DebugStepSig);
    }
    else
    {
        cpu65_interrupt(0);
    }
}