/**

 * $Id: asic.c,v 1.22 2006-12-21 11:12:19 nkeynes Exp $

 *

 * Support for the miscellaneous ASIC functions (Primarily event multiplexing,

 * and DMA). 

 *

 * Copyright (c) 2005 Nathan Keynes.

 *

 * 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.

 */

#define MODULE asic_module

#include <assert.h>

#include <stdlib.h>

#include "dream.h"

#include "mem.h"

#include "sh4/intc.h"

#include "sh4/dmac.h"

#include "dreamcast.h"

#include "maple/maple.h"

#include "gdrom/ide.h"

#include "asic.h"

#define MMIO_IMPL

#include "asic.h"

/*

 * Open questions:

 *   1) Does changing the mask after event occurance result in the

 *      interrupt being delivered immediately?

 * TODO: Logic diagram of ASIC event/interrupt logic.

 *

 * ... don't even get me started on the "EXTDMA" page, about which, apparently,

 * practically nothing is publicly known...

 */

static void asic_check_cleared_events( void );

static void asic_init( void );

static void asic_reset( void );

static void asic_save_state( FILE *f );

static int asic_load_state( FILE *f );

struct dreamcast_module asic_module = { "ASIC", asic_init, asic_reset, NULL, NULL,

					NULL, asic_save_state, asic_load_state };

#define G2_BIT5_TICKS 8

#define G2_BIT4_TICKS 16

#define G2_BIT0_ON_TICKS 24

#define G2_BIT0_OFF_TICKS 24

struct asic_g2_state {

    unsigned int last_update_time;

    unsigned int bit5_off_timer;

    unsigned int bit4_on_timer;

    unsigned int bit4_off_timer;

    unsigned int bit0_on_timer;

    unsigned int bit0_off_timer;

};

static struct asic_g2_state g2_state;

static void asic_init( void )

{

    register_io_region( &mmio_region_ASIC );

    register_io_region( &mmio_region_EXTDMA );

    asic_reset();

}

static void asic_reset( void )

{

    memset( &g2_state, 0, sizeof(g2_state) );

}    

static void asic_save_state( FILE *f )

{

    fwrite( &g2_state, sizeof(g2_state), 1, f );

}

static int asic_load_state( FILE *f )

{

    if( fread( &g2_state, sizeof(g2_state), 1, f ) != 1 )

	return 1;

    else

	return 0;

}

/* FIXME: Handle rollover */

void asic_g2_write_word()

{

    g2_state.last_update_time = sh4r.icount;

    g2_state.bit5_off_timer = sh4r.icount + G2_BIT5_TICKS;

    if( g2_state.bit4_off_timer < sh4r.icount )

	g2_state.bit4_on_timer = sh4r.icount + G2_BIT5_TICKS;

    g2_state.bit4_off_timer = max(sh4r.icount,g2_state.bit4_off_timer) + G2_BIT4_TICKS;

    if( g2_state.bit0_off_timer < sh4r.icount ) {

	g2_state.bit0_on_timer = sh4r.icount + G2_BIT0_ON_TICKS;

	g2_state.bit0_off_timer = g2_state.bit0_on_timer + G2_BIT0_OFF_TICKS;

    } else {

	g2_state.bit0_off_timer += G2_BIT0_OFF_TICKS;

    }

    MMIO_WRITE( ASIC, G2STATUS, MMIO_READ(ASIC, G2STATUS) | 0x20 );

}

static uint32_t g2_read_status()

{

    if( sh4r.icount < g2_state.last_update_time ) {

	/* Rollover */

	if( g2_state.last_update_time < g2_state.bit5_off_timer )

	    g2_state.bit5_off_timer = 0;

	if( g2_state.last_update_time < g2_state.bit4_off_timer )

	    g2_state.bit4_off_timer = 0;

	if( g2_state.last_update_time < g2_state.bit4_on_timer )

	    g2_state.bit4_on_timer = 0;

	if( g2_state.last_update_time < g2_state.bit0_off_timer )

	    g2_state.bit0_off_timer = 0;

	if( g2_state.last_update_time < g2_state.bit0_on_timer )

	    g2_state.bit0_on_timer = 0;

    }

    uint32_t val = MMIO_READ( ASIC, G2STATUS );

    if( g2_state.bit5_off_timer <= sh4r.icount )

	val = val & (~0x20);

    if( g2_state.bit4_off_timer <= sh4r.icount ||

	(sh4r.icount + G2_BIT5_TICKS) < g2_state.bit4_off_timer )

	val = val & (~0x10);

    else if( g2_state.bit4_on_timer <= sh4r.icount )

	val = val | 0x10;

    if( g2_state.bit0_off_timer <= sh4r.icount )

	val = val & (~0x01);

    else if( g2_state.bit0_on_timer <= sh4r.icount )

	val = val | 0x01;

    return val | 0x0E;

}   

void asic_event( int event )

{

    int offset = ((event&0x60)>>3);

    int result = (MMIO_READ(ASIC, PIRQ0 + offset))  |=  (1<<(event&0x1F));

    if( result & MMIO_READ(ASIC, IRQA0 + offset) )

        intc_raise_interrupt( INT_IRQ13 );

    if( result & MMIO_READ(ASIC, IRQB0 + offset) )

        intc_raise_interrupt( INT_IRQ11 );

    if( result & MMIO_READ(ASIC, IRQC0 + offset) )

        intc_raise_interrupt( INT_IRQ9 );

}

void asic_clear_event( int event ) {

    int offset = ((event&0x60)>>3);

    uint32_t result = MMIO_READ(ASIC, PIRQ0 + offset)  & (~(1<<(event&0x1F)));

    MMIO_WRITE( ASIC, PIRQ0 + offset, result );

    asic_check_cleared_events();

}

void asic_check_cleared_events( )

{

    int i, setA = 0, setB = 0, setC = 0;

    uint32_t bits;

    for( i=0; i<3; i++ ) {

	bits = MMIO_READ( ASIC, PIRQ0 + i );

	setA |= (bits & MMIO_READ(ASIC, IRQA0 + i ));

	setB |= (bits & MMIO_READ(ASIC, IRQB0 + i ));

	setC |= (bits & MMIO_READ(ASIC, IRQC0 + i ));

    }

    if( setA == 0 )

	intc_clear_interrupt( INT_IRQ13 );

    if( setB == 0 )

	intc_clear_interrupt( INT_IRQ11 );

    if( setC == 0 )

	intc_clear_interrupt( INT_IRQ9 );

}

void asic_ide_dma_transfer( )

{	

    if( MMIO_READ( EXTDMA, IDEDMACTL2 ) == 1 ) {

	if( MMIO_READ( EXTDMA, IDEDMACTL1 ) == 1 ) {

	    MMIO_WRITE( EXTDMA, IDEDMATXSIZ, 0 );

	    uint32_t addr = MMIO_READ( EXTDMA, IDEDMASH4 );

	    uint32_t length = MMIO_READ( EXTDMA, IDEDMASIZ );

	    int dir = MMIO_READ( EXTDMA, IDEDMADIR );

	    uint32_t xfer = ide_read_data_dma( addr, length );

	    MMIO_WRITE( EXTDMA, IDEDMATXSIZ, xfer );

	    MMIO_WRITE( EXTDMA, IDEDMACTL2, 0 );

	} else { /* 0 */

	    MMIO_WRITE( EXTDMA, IDEDMACTL2, 0 );

	}

    }

}

void mmio_region_ASIC_write( uint32_t reg, uint32_t val )

{

    switch( reg ) {

    case PIRQ1:

	val = val & 0xFFFFFFFE; /* Prevent the IDE event from clearing */

	/* fallthrough */

    case PIRQ0:

    case PIRQ2:

	/* Clear any interrupts */

	MMIO_WRITE( ASIC, reg, MMIO_READ(ASIC, reg)&~val );

	asic_check_cleared_events();

	break;

    case SYSRESET:

	if( val == 0x7611 ) {

	    dreamcast_reset();

	    sh4r.new_pc = sh4r.pc;

	} else {

	    WARN( "Unknown value %08X written to SYSRESET port", val );

	}

	break;

    case MAPLE_STATE:

	MMIO_WRITE( ASIC, reg, val );

	if( val & 1 ) {

	    uint32_t maple_addr = MMIO_READ( ASIC, MAPLE_DMA) &0x1FFFFFE0;

	    maple_handle_buffer( maple_addr );

	    MMIO_WRITE( ASIC, reg, 0 );

	}

	break;

    case PVRDMACTL: /* Initiate PVR DMA transfer */

	MMIO_WRITE( ASIC, reg, val );

	if( val & 1 ) {

	    uint32_t dest_addr = MMIO_READ( ASIC, PVRDMADEST) &0x1FFFFFE0;

	    uint32_t count = MMIO_READ( ASIC, PVRDMACNT );

	    char *data = alloca( count );

	    uint32_t rcount = DMAC_get_buffer( 2, data, count );

	    if( rcount != count )

		WARN( "PVR received %08X bytes from DMA, expected %08X", rcount, count );

	    mem_copy_to_sh4( dest_addr, data, rcount );

	    asic_event( EVENT_PVR_DMA );

	    MMIO_WRITE( ASIC, PVRDMACTL, 0 );

	    MMIO_WRITE( ASIC, PVRDMACNT, 0 );

	}

	break;

    case PVRDMADEST: case PVRDMACNT: case MAPLE_DMA:

	MMIO_WRITE( ASIC, reg, val );

	break;

    default:

	MMIO_WRITE( ASIC, reg, val );

    }

}

int32_t mmio_region_ASIC_read( uint32_t reg )

{

    int32_t val;

    switch( reg ) {

        /*

        case 0x89C:

            sh4_stop();

            return 0x000000B;

        */     

    case PIRQ0:

    case PIRQ1:

    case PIRQ2:

    case IRQA0:

    case IRQA1:

    case IRQA2:

    case IRQB0:

    case IRQB1:

    case IRQB2:

    case IRQC0:

    case IRQC1:

    case IRQC2:

    case MAPLE_STATE:

	val = MMIO_READ(ASIC, reg);

	return val;            

    case G2STATUS:

	return g2_read_status();

    default:

	val = MMIO_READ(ASIC, reg);

	return val;

    }

}

MMIO_REGION_WRITE_FN( EXTDMA, reg, val )

{

    if( !idereg.interface_enabled && IS_IDE_REGISTER(reg) ) {

	return; /* disabled */

    }

    switch( reg ) {

    case IDEALTSTATUS: /* Device control */

	ide_write_control( val );

	break;

    case IDEDATA:

	ide_write_data_pio( val );

	break;

    case IDEFEAT:

	if( ide_can_write_regs() )

	    idereg.feature = (uint8_t)val;

	break;

    case IDECOUNT:

	if( ide_can_write_regs() )

	    idereg.count = (uint8_t)val;

	break;

    case IDELBA0:

	if( ide_can_write_regs() )

	    idereg.lba0 = (uint8_t)val;

	break;

    case IDELBA1:

	if( ide_can_write_regs() )

	    idereg.lba1 = (uint8_t)val;

	break;

    case IDELBA2:

	if( ide_can_write_regs() )

	    idereg.lba2 = (uint8_t)val;

	break;

    case IDEDEV:

	if( ide_can_write_regs() )

	    idereg.device = (uint8_t)val;

	break;

    case IDECMD:

	if( ide_can_write_regs() || val == IDE_CMD_NOP ) {

	    ide_write_command( (uint8_t)val );

	}

	break;

    case IDEDMACTL1:

	MMIO_WRITE( EXTDMA, reg, val );

    case IDEDMACTL2:

	MMIO_WRITE( EXTDMA, reg, val );

	asic_ide_dma_transfer( );

	break;

    case IDEACTIVATE:

	if( val == 0x001FFFFF ) {

	    idereg.interface_enabled = TRUE;

	    /* Conventional wisdom says that this is necessary but not

	     * sufficient to enable the IDE interface.

	     */

	} else if( val == 0x000042FE ) {

	    idereg.interface_enabled = FALSE;

	}

    default:

            MMIO_WRITE( EXTDMA, reg, val );

    }

}

MMIO_REGION_READ_FN( EXTDMA, reg )

{

    uint32_t val;

    if( !idereg.interface_enabled && IS_IDE_REGISTER(reg) ) {

	return 0xFFFFFFFF; /* disabled */

    }

    switch( reg ) {

    case IDEALTSTATUS: 

	val = idereg.status;

	return val;

    case IDEDATA: return ide_read_data_pio( );

    case IDEFEAT: return idereg.error;

    case IDECOUNT:return idereg.count;

    case IDELBA0: return idereg.disc;

    case IDELBA1: return idereg.lba1;

    case IDELBA2: return idereg.lba2;

    case IDEDEV: return idereg.device;

    case IDECMD:

	val = ide_read_status();

	return val;

    default:

	val = MMIO_READ( EXTDMA, reg );

	return val;

    }

}