/**

 * $Id$

 *

 * IDE interface implementation

 *

 *

 * Note: All references to read/write are from the host's point of view.

 *

 * See: INF-8020 

 * 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 ide_module

#include <assert.h>

#include <stdlib.h>

#include "dream.h"

#include "mem.h"

#include "asic.h"

#include "gdrom/ide.h"

#include "gdrom/gddriver.h"

#include "gdrom/packet.h"

#define MAX_WRITE_BUF 4096

#define MAX_SECTOR_SIZE 2352 /* Audio sector */

#define DEFAULT_DATA_SECTORS 8

static void ide_init( void );

static void ide_reset( void );

static uint32_t ide_run_slice( uint32_t nanosecs );

static void ide_save_state( FILE *f );

static int ide_load_state( FILE *f );

static void ide_raise_interrupt( void );

static void ide_clear_interrupt( void );

static void ide_packet_command( unsigned char *data );

static void ide_read_next_sector(void);

struct dreamcast_module ide_module = { "IDE", ide_init, ide_reset, NULL, ide_run_slice,

        NULL, ide_save_state, ide_load_state };

struct ide_registers idereg;

gdrom_disc_t gdrom_disc = NULL;

unsigned char data_buffer[MAX_SECTOR_SIZE];

#define WRITE_BUFFER(x16) *((uint16_t *)(data_buffer + idereg.data_offset)) = x16

#define READ_BUFFER() *((uint16_t *)(data_buffer + idereg.data_offset))

/* 10 bytes followed by "SE      REV 6.42990316" */

unsigned char default_gdrom_mode[GDROM_MODE_LENGTH] = 

{ 0x00, 0x00, 0x00, 0x00, 0x00, 0xb4, 0x19, 0x00, 0x00, 0x08,

        0x53, 0x45, 0x20, 0x20, 0x20, 0x20, 0x20, 0x20, 

        0x52, 0x65, 0x76, 0x20, 0x36, 0x2e, 0x34, 0x32, 0x39, 0x39, 0x30, 0x33, 0x31, 0x36 };

unsigned char gdrom_71[] = { 0x3E, 0x0F, 0x90, 0xBE,  0x1D, 0xD9, 0x89, 0x04,  0x28, 0x3A, 0x8E, 0x26,  0x5C, 0x95, 0x10, 0x5A,

        0x0A, 0x99, 0xEE, 0xFB,  0x69, 0xCE, 0xD9, 0x63,  0x00, 0xF5, 0x0A, 0xBC,  0x2C, 0x0D, 0xF8, 0xE2,

        0x05, 0x02, 0x00, 0x7C,  0x03, 0x00, 0x3D, 0x08,  0xD8, 0x8D, 0x08, 0x7A,  0x6D, 0x00, 0x35, 0x06,

        0xBA, 0x66, 0x10, 0x00,  0x91, 0x08, 0x10, 0x29,  0xD0, 0x45, 0xDA, 0x00,  0x2D, 0x05, 0x69, 0x09,

        0x00, 0x5E, 0x0F, 0x70,  0x86, 0x12, 0x6C, 0x77,  0x5A, 0xFB, 0xCD, 0x56,  0xFB, 0xF7, 0xB7, 0x00,

        0x5D, 0x07, 0x19, 0x99,  0xF2, 0xAF, 0x00, 0x63,  0x03, 0x00, 0xF0, 0x10,  0xBE, 0xD7, 0xA0, 0x63,

        0xFA, 0x84, 0xA7, 0x74,  0x94, 0xEF, 0xAD, 0xC2,  0xAC, 0x00, 0x78, 0x07,  0x9F, 0x57, 0x0B, 0x62,

        0x00, 0xFE, 0x08, 0x08,  0x5D, 0x5A, 0x6A, 0x54,  0x00, 0xE2, 0x09, 0x93,  0x7E, 0x62, 0x2A, 0x5E,

        0xDA, 0x00, 0x7E, 0x0F,  0xF0, 0x07, 0x01, 0x6D,  0x50, 0x86, 0xDD, 0x4A,  0x15, 0x54, 0xC7, 0xEC,

        0x00, 0xF2, 0x0B, 0x07,  0xF8, 0x1A, 0xB0, 0x99,  0x3B, 0xF1, 0x36, 0x00,  0x94, 0x07, 0x34, 0xE3,

        0xBC, 0x6E, 0x00, 0x34,  0x0D, 0x6F, 0xDA, 0xBD,  0xEE, 0xF7, 0xCC, 0xCE,  0x39, 0x7E, 0xE3, 0x00,

        0x14, 0x08, 0xDC, 0xD2,  0xB9, 0xF9, 0x31, 0x00,  0xB0, 0x0C, 0x10, 0xA3,  0x45, 0x12, 0xC7, 0xCD,

        0xBF, 0x05, 0x37, 0x00,  0xC4, 0x0D, 0x5F, 0xE0,  0x59, 0xBB, 0x01, 0x59,  0x03, 0xD6, 0x29, 0x9C,

        0x00, 0x01, 0x0A, 0x09,  0xAA, 0xA8, 0xA8, 0x24,  0x0B, 0x66, 0x00, 0x5C,  0x05, 0xA5, 0xCE, 0x00,

        0xC1, 0x0B, 0xB7, 0xA0,  0x6F, 0xE9, 0x2B, 0xCC,  0xB5, 0xFC, 0x00, 0x8D,  0x05, 0xF4, 0xAC, 0x00,

        0x57, 0x04, 0xB6, 0x00,  0xFC, 0x03, 0x00, 0xC3,  0x10, 0x43, 0x3B, 0xBE,  0xA2, 0x96, 0xC3, 0x65,

        0x9F, 0x9A, 0x88, 0xD5,  0x49, 0x68, 0x00, 0xDC,  0x11, 0x56, 0x23, 0x2D,  0xF9, 0xFC, 0xF5, 0x8B,

        0x1B, 0xB1, 0xB7, 0x10,  0x21, 0x1C, 0x12, 0x00,  0x0D, 0x0D, 0xEB, 0x86,  0xA2, 0x49, 0x8D, 0x8D,

        0xBE, 0xA1, 0x6D, 0x53,  0x00, 0xE1, 0x0A, 0x8E,  0x67, 0xAA, 0x16, 0x79,  0x39, 0x59, 0x00, 0x36,

        0x0B, 0x2A, 0x4E, 0xAE,  0x51, 0x4B, 0xD0, 0x66,  0x33, 0x00, 0x8A, 0x07,  0xCD, 0x6F, 0xBA, 0x92,

        0x00, 0x1A, 0x0E, 0xDF,  0x4A, 0xB3, 0x77, 0x1F,  0xA5, 0x90, 0x19, 0xFA,  0x59, 0xD7, 0x00, 0x04,

        0x0F, 0xAC, 0xCA, 0x9F,  0xA4, 0xFC, 0x6D, 0x90,  0x86, 0x9E, 0x1F, 0x44,  0x40, 0x00, 0x9F, 0x04,

        0x56, 0x00, 0x22, 0x03,  0x00, 0xB8, 0x10, 0x2C,  0x7A, 0x53, 0xA4, 0xBF,  0xA3, 0x90, 0x90, 0x14,

        0x9D, 0x46, 0x6C, 0x96,  0x00, 0xC6, 0x0B, 0x9B,  0xBB, 0xB0, 0xAE, 0x60,  0x92, 0x8E, 0x0C, 0x00,

        0x14, 0x06, 0x4B, 0xAE,  0x7F, 0x00, 0x5C, 0x0B,  0x23, 0xFA, 0xE7, 0x51,  0xDA, 0x61, 0x49, 0x5E,

        0x00, 0xD7, 0x0B, 0x01,  0xFC, 0x55, 0x31, 0x84,  0xC5, 0x0C, 0x98, 0x00,  0x97, 0x50, 0x6E, 0xF9,

        0xEE, 0x75, 0x92, 0x53,  0xD3, 0x66, 0xA4, 0xAF,  0x3B, 0xFE, 0x7B, 0x27,  0x30, 0xBB, 0xB6, 0xF2,

        0x76, 0x22, 0x45, 0x42,  0xCA, 0xF9, 0xF0, 0xDE,  0x9F, 0x45, 0x16, 0x68,  0x22, 0xB9, 0x84, 0x28,

        0x8F, 0x2B, 0xB5, 0x5C,  0xD2, 0xF5, 0x45, 0x36,  0x3E, 0x76, 0xC6, 0xBF,  0x32, 0x5C, 0x41, 0xA6,

        0x26, 0xC7, 0x82, 0x2F,  0x2E, 0xB5, 0x75, 0xC6,  0xE6, 0x67, 0x9E, 0x77,  0x94, 0xAF, 0x6A, 0x05,

        0xC0, 0x05, 0x61, 0x71,  0x89, 0x5A, 0xB1, 0xD0,  0xFC, 0x7E, 0xC0, 0x9B,  0xCB, 0x3B, 0x69, 0xD9,

        0x5F, 0xAF, 0xCA, 0xAB,  0x25, 0xD5, 0xBE, 0x8A,  0x6B, 0xB0, 0xFB, 0x61,  0x6C, 0xEB, 0x85, 0x6E,

        0x7A, 0x48, 0xFF, 0x97,  0x91, 0x06, 0x3D, 0x4D,  0x68, 0xD3, 0x65, 0x83,  0x90, 0xA0, 0x08, 0x5C,

        0xFC, 0xEE, 0x7C, 0x33,  0x43, 0x7F, 0x80, 0x52,  0x8B, 0x19, 0x72, 0xF2,  0xC9, 0xAB, 0x93, 0xAF,

        0x16, 0xED, 0x36, 0x48,  0xAB, 0xC9, 0xD1, 0x03,  0xB3, 0xDC, 0x2F, 0xF2,  0x92, 0x3F, 0x0A, 0x19,

        0x25, 0xE2, 0xEF, 0x7A,  0x22, 0xDA, 0xDB, 0xCB,  0x32, 0x12, 0x61, 0x49,  0x5B, 0x74, 0x7C, 0x65,

        0x20, 0x89, 0x54, 0x9E,  0x0E, 0xC9, 0x52, 0xE3,  0xC9, 0x9A, 0x44, 0xC9,  0x5D, 0xA6, 0x77, 0xC0,

        0xE7, 0x60, 0x91, 0x80,  0x50, 0x1F, 0x33, 0xB1,  0xCD, 0xAD, 0xF4, 0x0D,  0xBB, 0x08, 0xB1, 0xD0,

        0x13, 0x95, 0xAE, 0xC9,  0xE2, 0x64, 0xA2, 0x65,  0xFB, 0x8F, 0xE9, 0xA2,  0x8A, 0xBC, 0x98, 0x81,

        0x45, 0xB4, 0x55, 0x4E,  0xB9, 0x74, 0xB4, 0x50,  0x76, 0xBF, 0xF0, 0x45,  0xE7, 0xEE, 0x41, 0x64,

        0x9F, 0xB5, 0xE0, 0xBB,  0x1C, 0xBB, 0x28, 0x66,  0x1B, 0xDD, 0x2B, 0x02,  0x66, 0xBF, 0xFD, 0x7D,

        0x37, 0x35, 0x1D, 0x76,  0x21, 0xC3, 0x8F, 0xAF,  0xF6, 0xF9, 0xE9, 0x27,  0x48, 0xE7, 0x3D, 0x95,

        0x74, 0x0C, 0x77, 0x88,  0x56, 0xD9, 0x84, 0xC8,  0x7D, 0x20, 0x31, 0x43,  0x53, 0xF1, 0xC1, 0xC7,

        0xC9, 0xF7, 0x5C, 0xC0,  0xA6, 0x5A, 0x27, 0x0A,  0x41, 0xD4, 0x44, 0x94,  0x65, 0x4F, 0xE2, 0x53,

        0x60, 0x0B, 0xD1, 0x23,  0x6C, 0x0C, 0xBC, 0x70,  0x6C, 0x26, 0x1A, 0x61,  0x1D, 0x35, 0x88, 0xEC,

        0xB8, 0x15, 0xE3, 0xB4,  0x82, 0xEE, 0xB3, 0x21,  0xAC, 0x6C, 0xB7, 0x33,  0x6D, 0x78, 0x0C, 0x0D,

        0xB4, 0x0B, 0x29, 0xF2,  0xD4, 0x8C, 0x3F, 0xDD,  0x3F, 0x47, 0xDD, 0xF2,  0xD8, 0x39, 0x57, 0x20,

        0x28, 0xD8, 0xDD, 0x32,  0xE2, 0x6A, 0x47, 0x53,  0x57, 0xC6, 0xFA, 0x7A,  0x38, 0x30, 0x31, 0x8F,

        0xE7, 0xD3, 0x84, 0x2B,  0x5D, 0x4F, 0x95, 0x98,  0xED, 0x0B, 0xD7, 0x50,  0x0C, 0x49, 0xDA, 0x59,

        0x15, 0xF1, 0x39, 0xF3,  0x40, 0xDC, 0xDC, 0x25,  0x24, 0x56, 0x6E, 0xA9,  0x2F, 0xF0, 0x00, 0x00 };

char gdrom_status[] = { 

        0x00, 0x15, 0x00, 0x64, 0x00, 0x40, 0x00, 0x00, 

        0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00,

        0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,

        0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00,

        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

        0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00,

        0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,

        0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x40, 0x40,

        0x40, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00,

        0x00, 0x40, 0x40, 0x00, 0x00, 0x00, 0x40, 0x40,

        0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x40, 0x00,

        0x00, 0x40, 0x00, 0x00 };

static void ide_init( void )

{

    ide_reset();

}

static void ide_reset( void )

{

    ide_clear_interrupt();

    idereg.error = 0x01;

    idereg.count = 0x01;

    idereg.lba0 = /* 0x21; */ 0x81;

    idereg.lba1 = 0x14;

    idereg.lba2 = 0xeb;

    idereg.feature = 0; /* Indeterminate really */

    idereg.status = 0x00;

    idereg.device = 0x00;

    idereg.state = IDE_STATE_IDLE;

    memset( idereg.gdrom_sense, '\0', 10 );

    memcpy( idereg.gdrom_mode, default_gdrom_mode, GDROM_MODE_LENGTH );

    idereg.data_offset = -1;

    idereg.data_length = -1;

    idereg.last_read_track = 1;

    idereg.current_lba = 150;

    idereg.current_mode = 0x28;

    idereg.sectors_left = 0;

    idereg.was_reset = TRUE;

}

static uint32_t ide_run_slice( uint32_t nanosecs )

{

    if( gdrom_disc != NULL && gdrom_disc->run_time_slice != NULL ) {

        gdrom_disc->run_time_slice(gdrom_disc, nanosecs);

    }

    return nanosecs;

}

static void ide_save_state( FILE *f )

{

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

    fwrite( data_buffer, MAX_SECTOR_SIZE, 1, f );

}

static int ide_load_state( FILE *f )

{

    fread( &idereg, sizeof(idereg), 1, f );

    fread( data_buffer, MAX_SECTOR_SIZE, 1, f );

    return 0;

}

/************************ State transitions *************************/

void ide_set_packet_result( uint16_t result )

{

    idereg.gdrom_sense[0] = 0xf0;

    idereg.gdrom_sense[2] = result & 0xFF;

    idereg.gdrom_sense[8] = (result >> 8) & 0xFF;

    idereg.error = (result & 0x0F) << 4;

    idereg.count = 3;

    if( result != 0 ) {

        idereg.status = 0x51;

        idereg.state = IDE_STATE_IDLE;

        ide_raise_interrupt();

    } else {

        idereg.status = idereg.status & ~(IDE_STATUS_BSY|IDE_STATUS_CHK);

    }

}

/**

 * Begin command packet write to the device. This is always 12 bytes of PIO data

 */

static void ide_start_command_packet_write( )

{

    idereg.state = IDE_STATE_CMD_WRITE;

    idereg.status = 0x58;

    idereg.error = idereg.feature & 0x03; /* Copy values of OVL/DMA */

    idereg.count = IDE_COUNT_CD;

    idereg.data_offset = 0;

    idereg.data_length = 12;

}

/**

 * Begin PIO/DMA read from the device. The data is assumed to already be

 * in the buffer at this point.

 */

static void ide_start_read( int length, gboolean dma ) 

{

    idereg.count = IDE_COUNT_IO;

    idereg.data_length = length;

    idereg.data_offset = 0;

    if( dma ) {

        idereg.state = IDE_STATE_DMA_READ;

        idereg.status = 0xD0;

    } else {

        idereg.state = IDE_STATE_PIO_READ;

        idereg.status = 0x58;

        idereg.lba1 = length & 0xFF;

        idereg.lba2 = length >> 8; 

        ide_raise_interrupt( );

    }

}

static void ide_start_write( int length, gboolean dma )

{

    idereg.count = 0;

    idereg.data_length = length;

    idereg.data_offset = 0;

    if( dma ) {

        idereg.state = IDE_STATE_DMA_WRITE;

        idereg.status = 0xD0;

    }  else {

        idereg.state = IDE_STATE_PIO_WRITE;

        idereg.status = 0x58;

        idereg.lba1 = length & 0xFF;

        idereg.lba2 = length >> 8;

        ide_raise_interrupt( );

    }

}

static void ide_start_packet_read( int length, int sector_count )

{

    idereg.sectors_left = sector_count;

    ide_set_packet_result( PKT_ERR_OK );

    ide_start_read( length, (idereg.feature & IDE_FEAT_DMA) ? TRUE : FALSE );

}

static void ide_start_packet_write( int length, int sector_count )

{

    idereg.sectors_left = sector_count;

    ide_set_packet_result( PKT_ERR_OK );

    ide_start_write( length, (idereg.feature & IDE_FEAT_DMA) ? TRUE : FALSE );

}

static void ide_raise_interrupt( void )

{

    if( idereg.intrq_pending == 0 ) {

        idereg.intrq_pending = 1;

        if( IS_IDE_IRQ_ENABLED() )

            asic_event( EVENT_IDE );

    }

}

static void ide_clear_interrupt( void ) 

{

    if( idereg.intrq_pending != 0 ) {

        idereg.intrq_pending = 0;

        if( IS_IDE_IRQ_ENABLED() )

            asic_clear_event( EVENT_IDE );

    }

}

static void ide_set_error( int error_code )

{

    idereg.status = 0x51;

    idereg.error = error_code;

}

uint8_t ide_read_status( void ) 

{

    if( (idereg.status & IDE_STATUS_BSY) == 0 )

        ide_clear_interrupt();

    return idereg.status;

}

uint16_t ide_read_data_pio( void ) {

    if( idereg.state == IDE_STATE_PIO_READ ) {

        uint16_t rv = READ_BUFFER();

        idereg.data_offset += 2;

        if( idereg.data_offset >= idereg.data_length ) {

            idereg.state = IDE_STATE_IDLE;

            idereg.status &= ~IDE_STATUS_DRQ;

            idereg.data_offset = -1;

            idereg.count = 3; /* complete */

            ide_raise_interrupt();

            if( idereg.sectors_left > 0 ) {

                ide_read_next_sector();

            }

        }

        return rv;

    } else {

        return 0xFFFF;

    }

}

/**

 * DMA read request

 *

 * This method is called from the ASIC side when a DMA read request is

 * initiated. If there is a pending DMA transfer already, we copy the

 * data immediately, otherwise we record the DMA buffer for use when we

 * get to actually doing the transfer.

 * @return number of bytes transfered

 */

uint32_t ide_read_data_dma( uint32_t addr, uint32_t length )

{

    uint32_t xfercount = 0;

    while( xfercount < length && idereg.state == IDE_STATE_DMA_READ ) {

        int xferlen = length - xfercount;

        int remaining = idereg.data_length - idereg.data_offset;

        if( xferlen > remaining ) {

            xferlen = remaining;

        }

        mem_copy_to_sh4( addr, (data_buffer + idereg.data_offset), xferlen );

        xfercount += xferlen;

        addr += xferlen;

        idereg.data_offset += xferlen;

        if( idereg.data_offset >= idereg.data_length ) {

            if( idereg.sectors_left > 0 ) {

                ide_read_next_sector();

            } else {

                idereg.data_offset = -1;

                idereg.state = IDE_STATE_IDLE;

                idereg.status = 0x50;

                idereg.count = 0x03;

                ide_raise_interrupt();

                asic_event( EVENT_IDE_DMA );

                break;

            }

        }

    }

    return xfercount;

}

void ide_write_data_pio( uint16_t val ) {

    if( idereg.state == IDE_STATE_CMD_WRITE ) {

        WRITE_BUFFER(val);

        idereg.data_offset+=2;

        if( idereg.data_offset >= idereg.data_length ) {

            idereg.state = IDE_STATE_BUSY;

            idereg.status = (idereg.status & ~IDE_STATUS_DRQ) | IDE_STATUS_BSY;

            idereg.data_offset = -1;

            ide_packet_command(data_buffer);

        }

    } else if( idereg.state == IDE_STATE_PIO_WRITE ) {

        WRITE_BUFFER(val);

        idereg.data_offset +=2;

        if( idereg.data_offset >= idereg.data_length ) {

            idereg.state = IDE_STATE_IDLE;

            idereg.status &= ~IDE_STATUS_DRQ;

            idereg.data_offset = -1;

            idereg.count = 3; /* complete */

            ide_raise_interrupt();

            ide_write_buffer( data_buffer, idereg.data_length );

        }

    }

}

void ide_write_control( uint8_t val ) {

    if( IS_IDE_IRQ_ENABLED() ) {

        if( (val & 0x02) != 0 && idereg.intrq_pending != 0 )

            asic_clear_event( EVENT_IDE );

    } else {

        if( (val & 0x02) == 0 && idereg.intrq_pending != 0 )

            asic_event( EVENT_IDE );

    }

    idereg.control = val;

}

void ide_write_command( uint8_t val ) {

    ide_clear_interrupt();

    idereg.command = val;

    switch( val ) {

    case IDE_CMD_NOP: /* Effectively an "abort" */

        idereg.state = IDE_STATE_IDLE;

        idereg.status = 0x51;

        idereg.error = 0x04;

        idereg.data_offset = -1;

        ide_raise_interrupt();

        return;

    case IDE_CMD_RESET_DEVICE:

        ide_reset();

        break;

    case IDE_CMD_PACKET:

        ide_start_command_packet_write();

        break;

    case IDE_CMD_SET_FEATURE:

        switch( idereg.feature ) {

        case IDE_FEAT_SET_TRANSFER_MODE:

            switch( idereg.count & 0xF8 ) {

            case IDE_XFER_PIO:

                INFO( "Set PIO default mode: %d", idereg.count&0x07 );

                break;

            case IDE_XFER_PIO_FLOW:

                INFO( "Set PIO Flow-control mode: %d", idereg.count&0x07 );

                break;

            case IDE_XFER_MULTI_DMA:

                INFO( "Set Multiword DMA mode: %d", idereg.count&0x07 );

                break;

            case IDE_XFER_ULTRA_DMA:

                INFO( "Set Ultra DMA mode: %d", idereg.count&0x07 );

                break;

            default:

                INFO( "Setting unknown transfer mode: %02X", idereg.count );

                break;

            }

            break;

            default:

                WARN( "IDE: unimplemented feature: %02X", idereg.feature );

        }

        idereg.status = 0x50;

        idereg.error = 0x00;

        idereg.lba1 = 0x00;

        idereg.lba2 = 0x00;

        ide_raise_interrupt();

        break;

        default:

            WARN( "IDE: Unimplemented command: %02X", val );

    }

}

uint8_t ide_get_drive_status( void )

{

    if( gdrom_disc == NULL ) {

        return IDE_DISC_NONE;

    } else {

        return gdrom_disc->drive_status(gdrom_disc);

    }

}

#define REQUIRE_DISC() if( gdrom_disc == NULL ) { ide_set_packet_result( PKT_ERR_NODISC ); return; }

/**

 * Read the next sector from the active read, if any

 */

static void ide_read_next_sector( void )

{

    uint32_t sector_size;

    REQUIRE_DISC();

    gdrom_error_t status = 

        gdrom_disc->read_sector( gdrom_disc, idereg.current_lba, idereg.current_mode, 

                data_buffer, &sector_size );

    if( status != PKT_ERR_OK ) {

        ide_set_packet_result( status );

        idereg.gdrom_sense[5] = (idereg.current_lba >> 16) & 0xFF;

        idereg.gdrom_sense[6] = (idereg.current_lba >> 8) & 0xFF;

        idereg.gdrom_sense[7] = idereg.current_lba & 0xFF;

        WARN( " => Read CD returned sense key %02X, %02X", status & 0xFF, status >> 8 );

    } else {

        idereg.current_lba++;

        idereg.sectors_left--;

        ide_start_read( sector_size, (idereg.feature & IDE_FEAT_DMA) ? TRUE : FALSE );

    }

}

/**

 * Execute a packet command. This particular method is responsible for parsing

 * the command buffers (12 bytes), and generating the appropriate responses, 

 * although the actual implementation is mostly delegated to gdrom.c

 */

void ide_packet_command( unsigned char *cmd )

{

    uint32_t length;

    uint32_t lba, status;

    /* Okay we have the packet in the command buffer */

    INFO( "ATAPI packet: %02X %02X %02X %02X  %02X %02X %02X %02X  %02X %02X %02X %02X", 

          cmd[0], cmd[1], cmd[2], cmd[3], cmd[4], cmd[5], cmd[6], cmd[7],

          cmd[8], cmd[9], cmd[10], cmd[11] );

    if( cmd[0] != PKT_CMD_SENSE && idereg.was_reset ) {

        ide_set_packet_result( PKT_ERR_RESET );

        idereg.was_reset = FALSE;

        return;

    }

    switch( cmd[0] ) {

    case PKT_CMD_TEST_READY:

        REQUIRE_DISC();

        ide_set_packet_result( 0 );

        ide_raise_interrupt();

        idereg.status = 0x50;

        break;

    case PKT_CMD_MODE_SENSE:

        lba = cmd[2];

        if( lba >= GDROM_MODE_LENGTH ) {

            ide_set_error(PKT_ERR_BADFIELD);

        } else {

            length = cmd[4];

            if( lba+length > GDROM_MODE_LENGTH )

                length = GDROM_MODE_LENGTH - lba;

            memcpy( data_buffer, idereg.gdrom_mode + lba, length );

            ide_start_packet_read( length, 0 );

        }

        break;

    case PKT_CMD_MODE_SELECT:

        lba = cmd[2];

        if( lba >= GDROM_MODE_LENGTH ) {

            ide_set_error(PKT_ERR_BADFIELD);

        } else {

            length = cmd[4];

            if( lba+length > GDROM_MODE_LENGTH )

                length = GDROM_MODE_LENGTH - lba;

            idereg.current_lba = lba;

            ide_start_packet_write( length, 0 );

        }

        break;

    case PKT_CMD_SENSE:

        length = cmd[4];

        if( length > 10 )

            length = 10;

        memcpy( data_buffer, idereg.gdrom_sense, length );

        ide_start_packet_read( length, 0 );

        break;

    case PKT_CMD_READ_TOC:

        REQUIRE_DISC();

        length = (cmd[3]<<8) | cmd[4];

        if( length > sizeof(struct gdrom_toc) )

            length = sizeof(struct gdrom_toc);

        status = gdrom_disc->read_toc( gdrom_disc, data_buffer );

        if( status != PKT_ERR_OK ) {

            ide_set_packet_result( status );

        } else {

            ide_start_packet_read( length, 0 );

        }

        break;

    case PKT_CMD_SESSION_INFO:

        REQUIRE_DISC();

        length = cmd[4];

        if( length > 6 )

            length = 6;

        status = gdrom_disc->read_session( gdrom_disc, cmd[2], data_buffer );

        if( status != PKT_ERR_OK ) {

            ide_set_packet_result( status );

        } else {

            ide_start_packet_read( length, 0 );

        }

        break;

    case PKT_CMD_PLAY_AUDIO:

        REQUIRE_DISC();

        ide_set_packet_result( 0 );

        ide_raise_interrupt();

        idereg.status = 0x50;

        break;

    case PKT_CMD_READ_SECTOR:

        REQUIRE_DISC();

        idereg.current_lba = cmd[2] << 16 | cmd[3] << 8 | cmd[4];

        idereg.sectors_left = cmd[8] << 16 | cmd[9] << 8 | cmd[10]; /* blocks */

        idereg.current_mode = cmd[1];

        ide_read_next_sector();

        break;

    case PKT_CMD_SPIN_UP:

        REQUIRE_DISC();

        /* do nothing? */

        ide_set_packet_result( PKT_ERR_OK );

        ide_raise_interrupt();

        break;

    case PKT_CMD_STATUS:

        REQUIRE_DISC();

        length = cmd[4];

        switch( cmd[1] ) {

        case 0:

            if( length > sizeof(gdrom_status) ) {

                length = sizeof(gdrom_status);

            }

            memcpy( data_buffer, gdrom_status, length );

            ide_start_packet_read( length, 0 );

            break;

        case 1:

            if( length > 14 ) {

                length = 14;

            }

            gdrom_disc->read_position( gdrom_disc, idereg.current_lba, data_buffer );

            data_buffer[0] = 0x00;

            data_buffer[1] = 0x15; /* audio status ? */

            data_buffer[2] = 0x00;

            data_buffer[3] = 0x0E;

            ide_start_packet_read( length, 0 );

            break;

        }

        break;

        case PKT_CMD_71:

            /* This is a weird one. As far as I can tell it returns random garbage

             * (and not even the same length each time, never mind the same data).

             * For sake of something to do, it returns the results from a test dump

             */

            REQUIRE_DISC();

            memcpy( data_buffer, gdrom_71, sizeof(gdrom_71) );

            ide_start_packet_read( sizeof(gdrom_71), 0 );

            break;

        default:

            ide_set_packet_result( PKT_ERR_BADCMD ); /* Invalid command */

            return;

    }

    idereg.last_packet_command = cmd[0];

}

void ide_write_buffer( unsigned char *data, uint32_t length )

{

    switch( idereg.last_packet_command ) {

    case PKT_CMD_MODE_SELECT:

        if( idereg.current_lba < 10 ) {

            if( idereg.current_lba + length > 10 ) {

                length = 10 - idereg.current_lba;

            }

            memcpy( idereg.gdrom_mode + idereg.current_lba, data, length );

        }

        break;

    default:

        WARN( "Don't know what to do with received data buffer for command %02X", idereg.last_packet_command );

    }

}