/**

  * $Id: ide.c,v 1.18 2006-12-19 09:52:56 nkeynes Exp $

  *

  * 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 "asic.h"

 #include "gdrom/ide.h"

 #include "gdrom/gdrom.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 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 );

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

 				       NULL, ide_save_state, ide_load_state };

 struct ide_registers idereg;

 unsigned char *data_buffer = NULL;

 uint32_t data_buffer_len = 0;

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

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

 /* "\0\0\0\0\xb4\x19\0\0\x08SE      REV 6.42990316" */

 unsigned char gdrom_ident[] = { 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 };

 static void ide_init( void )

 {

     ide_reset();

     data_buffer_len = DEFAULT_DATA_SECTORS; 

     data_buffer = malloc( MAX_SECTOR_SIZE * data_buffer_len ); 

     assert( data_buffer != NULL );

 }

 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 = 0x50;

     idereg.device = 0x00;

     idereg.disc = gdrom_is_mounted() ? (IDE_DISC_CDROM|IDE_DISC_READY) : IDE_DISC_NONE;

     idereg.state = IDE_STATE_IDLE;

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

     idereg.data_offset = -1;

     idereg.data_length = -1;

     idereg.last_read_track = 1;

     idereg.last_read_lba = 150;

     idereg.last_read_count = 0;

 }

 static void ide_save_state( FILE *f )

 {

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

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

     fwrite( data_buffer, MAX_SECTOR_SIZE, data_buffer_len, f );

 }

 static int ide_load_state( FILE *f )

 {

     uint32_t length;

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

     fread( &length, sizeof(uint32_t), 1, f );

     if( length > data_buffer_len ) {

 	if( data_buffer != NULL )

 	    free( data_buffer );

 	data_buffer = malloc( MAX_SECTOR_SIZE * length  );

 	assert( data_buffer != NULL );

 	data_buffer_len = length;

     }

     fread( data_buffer, MAX_SECTOR_SIZE, length, 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;

     if( result != 0 ) {

 	idereg.status = 0x51;

 	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 = IDE_STATUS_DRDY | IDE_STATUS_DRQ;

     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 read from the device. The data is assumed to already be

  * in the buffer at this point.

  */

 static void ide_start_read( int length, int blocksize, 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 = IDE_STATUS_DRDY | IDE_STATUS_DRQ;

 	idereg.lba1 = length & 0xFF;

 	idereg.lba2 = (length >> 8) & 0xFF;

 	//	idereg.lba1 = blocksize & 0xFF;

 	//	idereg.lba2 = blocksize >> 8; 

 	idereg.block_length = blocksize;

 	idereg.block_left = blocksize;

 	ide_raise_interrupt( );

     }

 }

 static void ide_start_packet_read( int length, int blocksize )

 {

     ide_set_packet_result( PKT_ERR_OK );

     ide_start_read( length, blocksize, (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;

 	idereg.block_left -= 2;

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

 	    idereg.state = IDE_STATE_IDLE;

 	    idereg.status &= ~IDE_STATUS_DRQ;

 	    idereg.data_offset = -1;

 	    ide_raise_interrupt();

 	} else if( idereg.block_left <= 0 ) {

 	    idereg.block_left = idereg.block_length;

 	    ide_raise_interrupt();

 	}

 	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 )

 {

     if( idereg.state == IDE_STATE_DMA_READ ) {

 	int xferlen = length;

 	int remaining = idereg.data_length - idereg.data_offset;

 	if( xferlen > remaining )

 	    xferlen = remaining;

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

 	idereg.data_offset += xferlen;

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

 	    idereg.data_offset = -1;

 	    idereg.state = IDE_STATE_IDLE;

 	    idereg.status = 0x50;

 	    ide_raise_interrupt();

 	    asic_event( EVENT_IDE_DMA );

 	}

 	return xferlen;

     }

     return 0;

 }

 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);

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

 	    idereg.state = IDE_STATE_BUSY;

 	    idereg.data_offset = -1;

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

 	    /* ??? - no data writes yet anyway */

 	}

     }

 }

 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 );

 	}

 	ide_raise_interrupt( );

 	break;

     default:

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

     }

     idereg.status = (idereg.status | IDE_STATUS_DRDY | IDE_STATUS_SERV) & (~IDE_STATUS_CHK);

 }

 /**

  * 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, datalen;

     uint32_t lba, status;

     int mode;

     int blocksize = idereg.lba1 + (idereg.lba2<<8);

     /* 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] );

     switch( cmd[0] ) {

     case PKT_CMD_TEST_READY:

 	if( !gdrom_is_mounted() ) {

 	    ide_set_packet_result( PKT_ERR_NODISC );

 	} else {

 	    ide_set_packet_result( 0 );

 	    ide_raise_interrupt();

 	    idereg.status = 0x50;

 	}

 	break;

     case PKT_CMD_IDENTIFY:

 	lba = cmd[2];

 	if( lba >= sizeof(gdrom_ident) ) {

 	    ide_set_error(PKT_ERR_BADFIELD);

 	} else {

 	    length = cmd[4];

 	    if( lba+length > sizeof(gdrom_ident) )

 		length = sizeof(gdrom_ident) - lba;

 	    memcpy( data_buffer, gdrom_ident + lba, length );

 	    ide_start_packet_read( length, blocksize );

 	}

 	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, blocksize );

 	break;

     case PKT_CMD_READ_TOC:

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

 	if( length > sizeof(struct gdrom_toc) )

 	    length = sizeof(struct gdrom_toc);

 	status = gdrom_get_toc( data_buffer );

 	if( status != PKT_ERR_OK ) {

 	    ide_set_packet_result( status );

 	} else {

 	    ide_start_packet_read( length, blocksize );

 	}

 	break;

     case PKT_CMD_SESSION_INFO:

 	length = cmd[4];

 	if( length > 6 )

 	    length = 6;

 	status = gdrom_get_info( data_buffer, cmd[2] );

 	if( status != PKT_ERR_OK ) {

 	    ide_set_packet_result( status );

 	} else {

 	    ide_start_packet_read( length, blocksize );

 	}

 	break;

     case PKT_CMD_READ_SECTOR:

 	lba = cmd[2] << 16 | cmd[3] << 8 | cmd[4];

 	length = cmd[8] << 16 | cmd[9] << 8 | cmd[10]; /* blocks */

 	switch( cmd[1] ) {

 	case 0x20: mode = GDROM_MODE1; break;     /* TODO - might be unchecked? */

 	case 0x24: mode = GDROM_GD; break;

 	case 0x28: mode = GDROM_MODE2_XA1; break; /* ??? */

 	case 0x30: mode = GDROM_RAW; break;

 	default:

 	    ERROR( "Unrecognized read mode '%02X' in GD-Rom read request", cmd[1] );

 	    ide_set_packet_result( PKT_ERR_BADFIELD );

 	    return;

 	}

 	if( length > data_buffer_len ) {

 	    do {

 		data_buffer_len = data_buffer_len << 1;

 	    } while( data_buffer_len < length );

 	    data_buffer = realloc( data_buffer, MAX_SECTOR_SIZE * data_buffer_len );

 	}

 	datalen = data_buffer_len;

 	status = gdrom_read_sectors( lba, length, mode, data_buffer, &datalen );

 	if( status != 0 ) {

 	    ide_set_packet_result( status );

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

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

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

 	} else {

 	    idereg.last_read_count += length;

 	    idereg.last_read_lba = lba + length;

 	    idereg.last_read_track = gdrom_get_track_no_by_lba( idereg.last_read_lba );

 	    ide_start_packet_read( datalen, blocksize );

 	}

 	break;

     case PKT_CMD_SPIN_UP:

 	/* do nothing? */

 	ide_set_packet_result( PKT_ERR_OK );

 	ide_raise_interrupt();

 	break;

     case PKT_CMD_STATUS:

 	length = cmd[4];

 	if( !gdrom_is_mounted() ) {

 	    ide_set_packet_result( PKT_ERR_NODISC );

 	} else {

 	    switch( cmd[1] ) {

 	    case 0:

 		break;

 	    case 1:

 		if( length > 16 ) {

 		    length = 16;

 		}

 		data_buffer[0] = 0x00;

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

 		data_buffer[2] = 0x00;

 		data_buffer[3] = 0x0E;

 		data_buffer[4] = gdrom_get_track(idereg.last_read_track)->flags;

 		data_buffer[5] = idereg.last_read_track;

 		data_buffer[6] = 0x01; /* ?? */

 		data_buffer[7] = (idereg.last_read_count >> 16) & 0xFF;

 		data_buffer[8] = (idereg.last_read_count >> 8) & 0xFF;

 		data_buffer[9] = idereg.last_read_count & 0xFF;

 		data_buffer[10] = (idereg.last_read_lba >> 24) & 0xFF;

 		data_buffer[11] = (idereg.last_read_lba >> 16) & 0xFF;

 		data_buffer[12] = (idereg.last_read_lba >> 8) & 0xFF;

 		data_buffer[13] = idereg.last_read_lba & 0xFF;

 		data_buffer[14] = 0x00;

 		data_buffer[15] = 0x00;

 		ide_start_packet_read( length, blocksize );

 		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

 	 */

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

 	ide_start_packet_read( sizeof(gdrom_71), blocksize );

 	break;

     default:

 	ide_set_packet_result( PKT_ERR_BADCMD ); /* Invalid command */

 	return;

     }

 }