/*
** Nofrendo (c) 1998-2000 Matthew Conte (matt@conte.com)
**
**
** This program is free software; you can redistribute it and/or
** modify it under the terms of version 2 of the GNU Library General
** Public License as published by the Free Software Foundation.
**
** 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
** Library General Public License for more details.  To obtain a
** copy of the GNU Library General Public License, write to the Free
** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
**
** Any permitted reproduction of these routines, in whole or in part,
** must bear this legend.
**
**
** map018.c: Jaleco SS8806 mapper interface
**
*/

#include "nes/nes.h"

#define  VRC_PBANK(bank, value, high) \
do { \
    if ((high)) \
        highprgnybbles[(bank)] = (value) & 0x0F; \
    else \
        lowprgnybbles[(bank)] = (value) & 0x0F; \
    mmc_bankrom(8, 0x8000 + ((bank) << 13), (highprgnybbles[(bank)] << 4)+lowprgnybbles[(bank)]); \
} while (0)

#define VRC_VBANK(bank, value, high) \
{ \
    if ((high)) \
        highnybbles[(bank)] = (value) & 0x0F; \
    else \
        lownybbles[(bank)] = (value) & 0x0F; \
    mmc_bankvrom(1, (bank) << 10, (highnybbles[(bank)] << 4)+lownybbles[(bank)]); \
}

static struct
{
    int counter, enabled;
    uint8 nybbles[4];
    int clockticks;
} irq;

static uint8 lownybbles[8];
static uint8 highnybbles[8];
static uint8 lowprgnybbles[3];
static uint8 highprgnybbles[3];


static void map_write(uint32 address, uint8 value)
{
    switch (address)
    {
    case 0x8000: VRC_PBANK(0, value, 0); break;
    case 0x8001: VRC_PBANK(0, value, 1); break;
    case 0x8002: VRC_PBANK(1, value, 0); break;
    case 0x8003: VRC_PBANK(1, value, 1); break;
    case 0x9000: VRC_PBANK(2, value, 0); break;
    case 0x9001: VRC_PBANK(2, value, 1); break;
    case 0xA000: VRC_VBANK(0, value, 0); break;
    case 0xA001: VRC_VBANK(0, value, 1); break;
    case 0xA002: VRC_VBANK(1, value, 0); break;
    case 0xA003: VRC_VBANK(1, value, 1); break;
    case 0xB000: VRC_VBANK(2, value, 0); break;
    case 0xB001: VRC_VBANK(2, value, 1); break;
    case 0xB002: VRC_VBANK(3, value, 0); break;
    case 0xB003: VRC_VBANK(3, value, 1); break;
    case 0xC000: VRC_VBANK(4, value, 0); break;
    case 0xC001: VRC_VBANK(4, value, 1); break;
    case 0xC002: VRC_VBANK(5, value, 0); break;
    case 0xC003: VRC_VBANK(5, value, 1); break;
    case 0xD000: VRC_VBANK(6, value, 0); break;
    case 0xD001: VRC_VBANK(6, value, 1); break;
    case 0xD002: VRC_VBANK(7, value, 0); break;
    case 0xD003: VRC_VBANK(7, value, 1); break;
    case 0xE000:
        irq.nybbles[0]=value&0x0F;
        irq.clockticks= (irq.nybbles[0]) | (irq.nybbles[1]<<4) |
                        (irq.nybbles[2]<<8) | (irq.nybbles[3]<<12);
        irq.counter=(uint8)(irq.clockticks/114);
        if(irq.counter>15) irq.counter-=16;
        break;
    case 0xE001:
        irq.nybbles[1]=value&0x0F;
        irq.clockticks= (irq.nybbles[0]) | (irq.nybbles[1]<<4) |
                        (irq.nybbles[2]<<8) | (irq.nybbles[3]<<12);
        irq.counter=(uint8)(irq.clockticks/114);
        if(irq.counter>15) irq.counter-=16;
        break;
    case 0xE002:
        irq.nybbles[2]=value&0x0F;
        irq.clockticks= (irq.nybbles[0]) | (irq.nybbles[1]<<4) |
                        (irq.nybbles[2]<<8) | (irq.nybbles[3]<<12);
        irq.counter=(uint8)(irq.clockticks/114);
        if(irq.counter>15) irq.counter-=16;
        break;
    case 0xE003:
        irq.nybbles[3]=value&0x0F;
        irq.clockticks= (irq.nybbles[0]) | (irq.nybbles[1]<<4) |
                        (irq.nybbles[2]<<8) | (irq.nybbles[3]<<12);
        irq.counter=(uint8)(irq.clockticks/114);
        if(irq.counter>15) irq.counter-=16;
        break;
    case 0xF000:
        if(value&0x01) irq.enabled=true;
        break;
    case 0xF001:
        irq.enabled=value&0x01;
        break;
    case 0xF002:
        switch(value&0x03)
        {
        case 0: ppu_setmirroring(PPU_MIRROR_HORI); break;
        case 1: ppu_setmirroring(PPU_MIRROR_VERT); break;
        case 2: ppu_setmirroring(PPU_MIRROR_SCR1); break;
        case 3: ppu_setmirroring(PPU_MIRROR_SCR1); break; // should this be zero?
        }
        break;
    default:
        break;
    }
}

static void map_getstate(uint8 *state)
{
    state[0] = irq.counter & 0xFF;
    state[1] = irq.counter >> 8;
    state[2] = irq.enabled;
}

static void map_setstate(uint8 *state)
{
    irq.counter = (state[1] << 8) | state[0];
    irq.enabled = state[2];
}

static void map_init(rom_t *cart)
{
    irq.counter = irq.enabled = 0;
}


mapintf_t map18_intf =
{
    .number     = 18,
    .name       = "Jaleco SS8806",
    .init       = map_init,
    .vblank     = NULL,
    .hblank     = NULL,
    .get_state  = map_getstate,
    .set_state  = map_setstate,
    .mem_read   = {},
    .mem_write  = {
        { 0x8000, 0xFFFF, map_write }
    },
};
