/*
 * mainc64cpu.c - Emulation of the C64 6510 processor.
 *
 * Written by
 *  Ettore Perazzoli <ettore@comm2000.it>
 *  Andreas Boose <viceteam@t-online.de>
 *
 * This file is part of VICE, the Versatile Commodore Emulator.
 * See README for copyright notice.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
 *  02111-1307  USA.
 *
 */

#include "vice.h"

#include <stdio.h>
#include <stdlib.h>

#include "6510core.h"
#include "alarm.h"

#ifdef FEATURE_CPUMEMHISTORY
#include "c64pla.h"
#endif

#include "clkguard.h"
#include "debug.h"
#include "interrupt.h"
#include "machine.h"
#include "mainc64cpu.h"
#include "maincpu.h"
#include "mem.h"
#include "monitor.h"
#include "mos6510.h"
#include "reu.h"
#include "snapshot.h"
#include "traps.h"
#include "types.h"

#ifndef EXIT_FAILURE
#define EXIT_FAILURE 1
#endif


/* MACHINE_STUFF should define/undef

 - NEED_REG_PC

*/

/* ------------------------------------------------------------------------- */
#ifdef DEBUG
CLOCK debug_clk;
#endif

#define NEED_REG_PC

/* ------------------------------------------------------------------------- */

/* Implement the hack to make opcode fetches faster.  */
#define JUMP(addr)                                                                         \
    do {                                                                                   \
        reg_pc = (unsigned int)(addr);                                                     \
        if (reg_pc >= (unsigned int)bank_limit || reg_pc < (unsigned int)bank_start) {     \
            mem_mmu_translate((unsigned int)(addr), &bank_base, &bank_start, &bank_limit); \
        }                                                                                  \
    } while (0)

/* ------------------------------------------------------------------------- */

int check_ba_low = 0;

inline static void interrupt_delay(void)
{
    while (maincpu_clk >= alarm_context_next_pending_clk(maincpu_alarm_context)) {
        alarm_context_dispatch(maincpu_alarm_context, maincpu_clk);
    }

    if (maincpu_int_status->irq_clk <= maincpu_clk) {
        maincpu_int_status->irq_delay_cycles++;
    }

    if (maincpu_int_status->nmi_clk <= maincpu_clk) {
        maincpu_int_status->nmi_delay_cycles++;
    }
}

static void maincpu_steal_cycles(void)
{
    interrupt_cpu_status_t *cs = maincpu_int_status;
    uint8_t opcode;

    if (maincpu_ba_low_flags & MAINCPU_BA_LOW_VICII) {
        vicii_steal_cycles();
        maincpu_ba_low_flags &= ~MAINCPU_BA_LOW_VICII;
    }

    if (maincpu_ba_low_flags & MAINCPU_BA_LOW_REU) {
        reu_dma_start();
        maincpu_ba_low_flags &= ~MAINCPU_BA_LOW_REU;
    }

    while (maincpu_clk >= alarm_context_next_pending_clk(maincpu_alarm_context)) {
        alarm_context_dispatch(maincpu_alarm_context, maincpu_clk);
    }

    /* special handling for steals during opcodes */
    opcode = OPINFO_NUMBER(*cs->last_opcode_info_ptr);
    switch (opcode) {
        /* SHA */
        case 0x93:
            if (check_ba_low) {
                OPINFO_SET_ENABLES_IRQ(*cs->last_opcode_info_ptr, 1);
            }
            break;

        /* SHS */
        case 0x9b:
            /* (fall through) */
        /* SHY */
        case 0x9c:
            /* (fall through) */
        /* SHX */
        case 0x9e:
            /* (fall through) */
        /* SHA */
        case 0x9f:
        /* this is a hacky way of signaling SET_ABS_SH_I() that
           cycles were stolen before the write */
            if (check_ba_low) {
                OPINFO_SET_ENABLES_IRQ(*cs->last_opcode_info_ptr, 1);
            }
            break;

        /* ANE */
        case 0x8b:
        /* this is a hacky way of signaling ANE() that
           cycles were stolen after the first fetch */
        /* (fall through) */

        /* CLI */
        case 0x58:
            /* this is a hacky way of signaling CLI() that it
               shouldn't delay the interrupt */
            OPINFO_SET_ENABLES_IRQ(*cs->last_opcode_info_ptr, 1);
            break;

        default:
            break;
    }

    /* SEI: do not update interrupt delay counters */
    if (opcode != 0x78) {
        if (cs->irq_delay_cycles == 0 && cs->irq_clk < maincpu_clk) {
            cs->irq_delay_cycles++;
        }
    }

    if (cs->nmi_delay_cycles == 0 && cs->nmi_clk < maincpu_clk) {
        cs->nmi_delay_cycles++;
    }
}

inline static void check_ba(void)
{
    if (maincpu_ba_low_flags) {
#ifdef DEBUG
        CLOCK old_maincpu_clk = maincpu_clk;
#endif
        maincpu_steal_cycles();
#ifdef DEBUG
        if (debug_clk == old_maincpu_clk) {
            debug_clk = maincpu_clk;
        }
#endif
    }
}

#ifdef FEATURE_CPUMEMHISTORY

/* FIXME do proper ROM/RAM/IO tests */

inline static void memmap_mem_update(unsigned int addr, int write)
{
    unsigned int type = MEMMAP_RAM_R;

    if (write) {
        if ((addr >= 0xd000) && (addr <= 0xdfff)) {
            type = MEMMAP_I_O_W;
        } else {
            type = MEMMAP_RAM_W;
        }
    } else {
        switch (addr >> 12) {
            case 0xa:
            case 0xb:
            case 0xe:
            case 0xf:
                if (pport.data_read & (1 << ((addr >> 14) & 1))) {
                    type = MEMMAP_ROM_R;
                } else {
                    type = MEMMAP_RAM_R;
                }
                break;
            case 0xd:
                type = MEMMAP_I_O_R;
                break;
            default:
                type = MEMMAP_RAM_R;
                break;
        }
        if (memmap_state & MEMMAP_STATE_OPCODE) {
            /* HACK: transform R to X */
            type >>= 2;
            memmap_state &= ~(MEMMAP_STATE_OPCODE);
        } else if (memmap_state & MEMMAP_STATE_INSTR) {
            /* ignore operand reads */
            type = 0;
        }
    }
    monitor_memmap_store(addr, type);
}

static void memmap_mem_store(unsigned int addr, unsigned int value)
{
    memmap_mem_update(addr, 1);
    (*_mem_write_tab_ptr[(addr) >> 8])((uint16_t)(addr), (uint8_t)(value));
}

/* read byte, check BA and mark as read */
static uint8_t memmap_mem_read(unsigned int addr)
{
    check_ba();
    memmap_mem_update(addr, 0);
    return (*_mem_read_tab_ptr[(addr) >> 8])((uint16_t)(addr));
}

#ifndef STORE
#define STORE(addr, value) \
    memmap_mem_store(addr, value)
#endif

#ifndef LOAD
#define LOAD(addr) \
    memmap_mem_read(addr)
#endif

#ifndef LOAD_CHECK_BA_LOW
#define LOAD_CHECK_BA_LOW(addr) \
    check_ba_low = 1;           \
    memmap_mem_read(addr);      \
    check_ba_low = 0
#endif

#ifndef STORE_ZERO
#define STORE_ZERO(addr, value) \
    memmap_mem_store((addr) & 0xff, value)
#endif

#ifndef LOAD_ZERO
#define LOAD_ZERO(addr) \
    memmap_mem_read((addr) & 0xff)
#endif

/* Route stack operations through memmap */

#define PUSH(val) memmap_mem_store((0x100 + (reg_sp--)), (uint8_t)(val))
#define PULL()    memmap_mem_read(0x100 + (++reg_sp))
#define STACK_PEEK()  memmap_mem_read(0x100 + reg_sp)

#endif /* FEATURE_CPUMEMHISTORY */

inline static uint8_t mem_read_check_ba(unsigned int addr)
{
    check_ba();
    return (*_mem_read_tab_ptr[(addr) >> 8])((uint16_t)(addr));
}

#ifndef STORE
#define STORE(addr, value) \
    (*_mem_write_tab_ptr[(addr) >> 8])((uint16_t)(addr), (uint8_t)(value))
#endif

#ifndef LOAD
#define LOAD(addr) \
    mem_read_check_ba(addr)
#endif

#ifndef LOAD_CHECK_BA_LOW
#define LOAD_CHECK_BA_LOW(addr) \
    check_ba_low = 1;           \
    mem_read_check_ba(addr);    \
    check_ba_low = 0
#endif

#ifndef STORE_ZERO
#define STORE_ZERO(addr, value) \
    (*_mem_write_tab_ptr[0])((uint16_t)(addr), (uint8_t)(value))
#endif

#ifndef LOAD_ZERO
#define LOAD_ZERO(addr) \
    mem_read_check_ba((addr) & 0xff)
#endif

/* Route stack operations through read/write handlers */

#ifndef PUSH
#define PUSH(val) (*_mem_write_tab_ptr[0x01])((uint16_t)(0x100 + (reg_sp--)), (uint8_t)(val))
#endif

#ifndef PULL
#define PULL()    mem_read_check_ba(0x100 + (++reg_sp))
#endif

#ifndef STACK_PEEK
#define STACK_PEEK()  mem_read_check_ba(0x100 + reg_sp)
#endif

#ifndef DMA_FUNC
static void maincpu_generic_dma(void)
{
    /* Generic DMA hosts can be implemented here.
       For example a very accurate REU emulation. */
}
#define DMA_FUNC maincpu_generic_dma()
#endif

#ifndef DMA_ON_RESET
#define DMA_ON_RESET
#endif

#ifndef CPU_ADDITIONAL_RESET
#define CPU_ADDITIONAL_RESET()
#endif

#ifndef CPU_ADDITIONAL_INIT
#define CPU_ADDITIONAL_INIT()
#endif

/* ------------------------------------------------------------------------- */

struct interrupt_cpu_status_s *maincpu_int_status = NULL;
alarm_context_t *maincpu_alarm_context = NULL;
clk_guard_t *maincpu_clk_guard = NULL;
monitor_interface_t *maincpu_monitor_interface = NULL;

/* This flag is an obsolete optimization. It's always 0 for the x64sc CPU,
   but has to be kept for the common code. */
int maincpu_rmw_flag = 0;

/* Information about the last executed opcode.  This is used to know the
   number of write cycles in the last executed opcode and to delay interrupts
   by one more cycle if necessary, as happens with conditional branch opcodes
   when the branch is taken.  */
unsigned int last_opcode_info;

/* Address of the last executed opcode. This is used by watchpoints. */
unsigned int last_opcode_addr;

/* Number of write cycles for each 6510 opcode.  */
const CLOCK maincpu_opcode_write_cycles[] = {
            /* 0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F */
    /* $00 */  3, 0, 0, 2, 0, 0, 2, 2, 1, 0, 0, 0, 0, 0, 2, 2, /* $00 */
    /* $10 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 2, 2, /* $10 */
    /* $20 */  2, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 2, 2, /* $20 */
    /* $30 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 2, 2, /* $30 */
    /* $40 */  0, 0, 0, 2, 0, 0, 2, 2, 1, 0, 0, 0, 0, 0, 2, 2, /* $40 */
    /* $50 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 2, 2, /* $50 */
    /* $60 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 2, 2, /* $60 */
    /* $70 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 2, 2, /* $70 */
    /* $80 */  0, 1, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, /* $80 */
    /* $90 */  0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, /* $90 */
    /* $A0 */  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* $A0 */
    /* $B0 */  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* $B0 */
    /* $C0 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 2, 2, /* $C0 */
    /* $D0 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 2, 2, /* $D0 */
    /* $E0 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 2, 2, /* $E0 */
    /* $F0 */  0, 0, 0, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 2, 2  /* $F0 */
            /* 0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F */
};

/* Public copy of the CPU registers.  As putting the registers into the
   function makes it faster, you have to generate a `TRAP' interrupt to have
   the values copied into this struct.  */
mos6510_regs_t maincpu_regs;

/* ------------------------------------------------------------------------- */

monitor_interface_t *maincpu_monitor_interface_get(void)
{
    maincpu_monitor_interface->cpu_regs = &maincpu_regs;
    maincpu_monitor_interface->cpu_R65C02_regs = NULL;
    maincpu_monitor_interface->dtv_cpu_regs = NULL;
    maincpu_monitor_interface->z80_cpu_regs = NULL;
    maincpu_monitor_interface->h6809_cpu_regs = NULL;

    maincpu_monitor_interface->int_status = maincpu_int_status;

    maincpu_monitor_interface->clk = &maincpu_clk;

    maincpu_monitor_interface->current_bank = 0;
    maincpu_monitor_interface->mem_bank_list = mem_bank_list;
    maincpu_monitor_interface->mem_bank_from_name = mem_bank_from_name;
    maincpu_monitor_interface->mem_bank_read = mem_bank_read;
    maincpu_monitor_interface->mem_bank_peek = mem_bank_peek;
    maincpu_monitor_interface->mem_bank_write = mem_bank_write;

    maincpu_monitor_interface->mem_ioreg_list_get = mem_ioreg_list_get;

    maincpu_monitor_interface->toggle_watchpoints_func = mem_toggle_watchpoints;

    maincpu_monitor_interface->set_bank_base = NULL;
    maincpu_monitor_interface->get_line_cycle = machine_get_line_cycle;

    return maincpu_monitor_interface;
}

/* ------------------------------------------------------------------------- */

void maincpu_early_init(void)
{
    maincpu_int_status = interrupt_cpu_status_new();
}

void maincpu_init(void)
{
    interrupt_cpu_status_init(maincpu_int_status, &last_opcode_info);

    /* cpu specifix additional init routine */
    CPU_ADDITIONAL_INIT();
}

void maincpu_shutdown(void)
{
    interrupt_cpu_status_destroy(maincpu_int_status);
}

static void cpu_reset(void)
{
    int preserve_monitor;

    preserve_monitor = maincpu_int_status->global_pending_int & IK_MONITOR;

    interrupt_cpu_status_reset(maincpu_int_status);

    if (preserve_monitor) {
        interrupt_monitor_trap_on(maincpu_int_status);
    }

    maincpu_clk = 6; /* # of clock cycles needed for RESET.  */

    /* CPU specific extra reset routine, currently only used
       for 8502 fast mode refresh cycle. */
    CPU_ADDITIONAL_RESET();

    /* Do machine-specific initialization.  */
    machine_reset();
}

void maincpu_reset(void)
{
    cpu_reset();
}

/* ------------------------------------------------------------------------- */

/* Return nonzero if a pending NMI should be dispatched now.  This takes
   account for the internal delays of the 6510, but does not actually check
   the status of the NMI line.  */
inline static int interrupt_check_nmi_delay(interrupt_cpu_status_t *cs,
                                            CLOCK cpu_clk)
{
    unsigned int delay_cycles = INTERRUPT_DELAY;

    /* BRK (0x00) delays the NMI by one opcode.  */
    /* TODO DO_INTERRUPT sets last opcode to 0: can NMI occur right after IRQ? */
    if (OPINFO_NUMBER(*cs->last_opcode_info_ptr) == 0x00) {
        return 0;
    }

    /* Branch instructions delay IRQs and NMI by one cycle if branch
       is taken with no page boundary crossing.  */
    if (OPINFO_DELAYS_INTERRUPT(*cs->last_opcode_info_ptr)) {
        delay_cycles++;
    }

    if (cs->nmi_delay_cycles >= delay_cycles) {
        return 1;
    }

    return 0;
}

/* Return nonzero if a pending IRQ should be dispatched now.  This takes
   account for the internal delays of the 6510, but does not actually check
   the status of the IRQ line.  */
inline static int interrupt_check_irq_delay(interrupt_cpu_status_t *cs,
                                            CLOCK cpu_clk)
{
    unsigned int delay_cycles = INTERRUPT_DELAY;

    /* Branch instructions delay IRQs and NMI by one cycle if branch
       is taken with no page boundary crossing.  */
    if (OPINFO_DELAYS_INTERRUPT(*cs->last_opcode_info_ptr)) {
        delay_cycles++;
    }

    if (cs->irq_delay_cycles >= delay_cycles) {
        if (!OPINFO_ENABLES_IRQ(*cs->last_opcode_info_ptr)) {
            return 1;
        } else {
            cs->global_pending_int |= IK_IRQPEND;
        }
    }

    return 0;
}

/* ------------------------------------------------------------------------- */

#ifdef NEED_REG_PC
/* FIXME: this should really be uint16_t, but it breaks things (eg trap17.prg) */
unsigned int reg_pc;
#endif

static uint8_t **o_bank_base;
static int *o_bank_start;
static int *o_bank_limit;

void maincpu_resync_limits(void)
{
    if (o_bank_base) {
        mem_mmu_translate(reg_pc, o_bank_base, o_bank_start, o_bank_limit);
    }
}

void maincpu_mainloop(void)
{
    /* Notice that using a struct for these would make it a lot slower (at
       least, on gcc 2.7.2.x).  */
    uint8_t reg_a = 0;
    uint8_t reg_x = 0;
    uint8_t reg_y = 0;
    uint8_t reg_p = 0;
    uint8_t reg_sp = 0;
    uint8_t flag_n = 0;
    uint8_t flag_z = 0;
#ifndef NEED_REG_PC
    /* FIXME: this should really be uint16_t, but it breaks things (eg trap17.prg) */
    unsigned int reg_pc;
#endif
    uint8_t *bank_base;
    int bank_start = 0;
    int bank_limit = 0;

    o_bank_base = &bank_base;
    o_bank_start = &bank_start;
    o_bank_limit = &bank_limit;

    machine_trigger_reset(MACHINE_RESET_MODE_SOFT);

    while (1) {
#define CLK maincpu_clk
#define RMW_FLAG maincpu_rmw_flag
#define LAST_OPCODE_INFO last_opcode_info
#define LAST_OPCODE_ADDR last_opcode_addr
#define TRACEFLG debug.maincpu_traceflg

#define CPU_INT_STATUS maincpu_int_status

#define ALARM_CONTEXT maincpu_alarm_context

#define CHECK_PENDING_ALARM() (clk >= next_alarm_clk(maincpu_int_status))

#define CHECK_PENDING_INTERRUPT() check_pending_interrupt(maincpu_int_status)

#define TRAP(addr) maincpu_int_status->trap_func(addr);

#define ROM_TRAP_HANDLER() traps_handler()

#define JAM()                                                         \
    do {                                                              \
        unsigned int tmp;                                             \
                                                                      \
        EXPORT_REGISTERS();                                           \
        tmp = machine_jam("   " CPU_STR ": JAM at $%04X   ", reg_pc); \
        switch (tmp) {                                                \
            case JAM_RESET:                                           \
                DO_INTERRUPT(IK_RESET);                               \
                break;                                                \
            case JAM_HARD_RESET:                                      \
                mem_powerup();                                        \
                DO_INTERRUPT(IK_RESET);                               \
                break;                                                \
            case JAM_MONITOR:                                         \
                monitor_startup(e_comp_space);                        \
                IMPORT_REGISTERS();                                   \
                break;                                                \
            default:                                                  \
                CLK_INC();                                            \
        }                                                             \
    } while (0)

#define CALLER e_comp_space

#define ROM_TRAP_ALLOWED() mem_rom_trap_allowed((uint16_t)reg_pc)

#define GLOBAL_REGS maincpu_regs

#include "6510dtvcore.c"

        maincpu_int_status->num_dma_per_opcode = 0;

        if (maincpu_clk_limit && (maincpu_clk > maincpu_clk_limit)) {
            log_error(LOG_DEFAULT, "cycle limit reached.");
            exit(EXIT_FAILURE);
        }
#if 0
        if (CLK > 246171754) {
            debug.maincpu_traceflg = 1;
        }
#endif
    }
}

/* ------------------------------------------------------------------------- */

void maincpu_set_pc(int pc) {
    MOS6510_REGS_SET_PC(&maincpu_regs, pc);
}

void maincpu_set_a(int a) {
    MOS6510_REGS_SET_A(&maincpu_regs, a);
}

void maincpu_set_x(int x) {
    MOS6510_REGS_SET_X(&maincpu_regs, x);
}

void maincpu_set_y(int y) {
    MOS6510_REGS_SET_Y(&maincpu_regs, y);
}

void maincpu_set_sign(int n) {
    MOS6510_REGS_SET_SIGN(&maincpu_regs, n);
}

void maincpu_set_zero(int z) {
    MOS6510_REGS_SET_ZERO(&maincpu_regs, z);
}

void maincpu_set_carry(int c) {
    MOS6510_REGS_SET_CARRY(&maincpu_regs, c);
}

void maincpu_set_interrupt(int i) {
    MOS6510_REGS_SET_INTERRUPT(&maincpu_regs, i);
}

unsigned int maincpu_get_pc(void) {
    return MOS6510_REGS_GET_PC(&maincpu_regs);
}

unsigned int maincpu_get_a(void) {
    return MOS6510_REGS_GET_A(&maincpu_regs);
}

unsigned int maincpu_get_x(void) {
    return MOS6510_REGS_GET_X(&maincpu_regs);
}

unsigned int maincpu_get_y(void) {
    return MOS6510_REGS_GET_Y(&maincpu_regs);
}

unsigned int maincpu_get_sp(void) {
    return MOS6510_REGS_GET_SP(&maincpu_regs);
}

/* ------------------------------------------------------------------------- */

static char snap_module_name[] = "MAINCPU";
#define SNAP_MAJOR 1
#define SNAP_MINOR 1

int maincpu_snapshot_write_module(snapshot_t *s)
{
    snapshot_module_t *m;

    m = snapshot_module_create(s, snap_module_name, ((uint8_t)SNAP_MAJOR),
                               ((uint8_t)SNAP_MINOR));
    if (m == NULL) {
        return -1;
    }

    if (0
        || SMW_DW(m, maincpu_clk) < 0
        || SMW_B(m, MOS6510_REGS_GET_A(&maincpu_regs)) < 0
        || SMW_B(m, MOS6510_REGS_GET_X(&maincpu_regs)) < 0
        || SMW_B(m, MOS6510_REGS_GET_Y(&maincpu_regs)) < 0
        || SMW_B(m, MOS6510_REGS_GET_SP(&maincpu_regs)) < 0
        || SMW_W(m, (uint16_t)MOS6510_REGS_GET_PC(&maincpu_regs)) < 0
        || SMW_B(m, (uint8_t)MOS6510_REGS_GET_STATUS(&maincpu_regs)) < 0
        || SMW_DW(m, (uint32_t)last_opcode_info) < 0
        || SMW_DW(m, (uint32_t)maincpu_ba_low_flags) < 0) {
        goto fail;
    }

    if (interrupt_write_snapshot(maincpu_int_status, m) < 0) {
        goto fail;
    }

    if (interrupt_write_new_snapshot(maincpu_int_status, m) < 0) {
        goto fail;
    }

    if (interrupt_write_sc_snapshot(maincpu_int_status, m) < 0) {
        goto fail;
    }

    return snapshot_module_close(m);

fail:
    if (m != NULL) {
        snapshot_module_close(m);
    }
    return -1;
}

int maincpu_snapshot_read_module(snapshot_t *s)
{
    uint8_t a, x, y, sp, status;
    uint16_t pc;
    uint8_t major, minor;
    snapshot_module_t *m;

    m = snapshot_module_open(s, snap_module_name, &major, &minor);
    if (m == NULL) {
        return -1;
    }

    /* XXX: Assumes `CLOCK' is the same size as a `DWORD'.  */
    if (0
        || SMR_DW(m, &maincpu_clk) < 0
        || SMR_B(m, &a) < 0
        || SMR_B(m, &x) < 0
        || SMR_B(m, &y) < 0
        || SMR_B(m, &sp) < 0
        || SMR_W(m, &pc) < 0
        || SMR_B(m, &status) < 0
        || SMR_DW_UINT(m, &last_opcode_info) < 0
        || SMR_DW_INT(m, &maincpu_ba_low_flags) < 0) {
        goto fail;
    }

    MOS6510_REGS_SET_A(&maincpu_regs, a);
    MOS6510_REGS_SET_X(&maincpu_regs, x);
    MOS6510_REGS_SET_Y(&maincpu_regs, y);
    MOS6510_REGS_SET_SP(&maincpu_regs, sp);
    MOS6510_REGS_SET_PC(&maincpu_regs, pc);
    MOS6510_REGS_SET_STATUS(&maincpu_regs, status);

    if (interrupt_read_snapshot(maincpu_int_status, m) < 0) {
        goto fail;
    }

    if (interrupt_read_new_snapshot(maincpu_int_status, m) < 0) {
        goto fail;
    }

    if (interrupt_read_sc_snapshot(maincpu_int_status, m) < 0) {
        goto fail;
    }

    return snapshot_module_close(m);

fail:
    if (m != NULL) {
        snapshot_module_close(m);
    }
    return -1;
}
