#define TF_BASE 0xDA0000
#define WORD_WIDE unsigned short int
#define BYTE_WIDE unsigned char
#define REG_INC 4
#define CS0 0x0000
#define CS1 0x8000
#define Y 0

#define TF_DATA     (*(volatile WORD_WIDE *)(TF_BASE+ 0x0 * REG_INC + CS0))
#define TF_DATA_8BIT (*(volatile BYTE_WIDE *)(Y+TF_BASE+ 0x0 * REG_INC + CS0))
#define TF_ERROR    (*(volatile BYTE_WIDE *)(Y+TF_BASE+ 0x1 * REG_INC + CS0))
#define TF_FEATURES (*(volatile BYTE_WIDE *)(Y+TF_BASE+ 0x1 * REG_INC + CS0))
#define TF_SECTOR_COUNT  (*(BYTE_WIDE *)(Y+TF_BASE+ 0x2 * REG_INC + CS0))
#define TF_SECTOR_NUMBER (*(BYTE_WIDE *)(Y+TF_BASE+ 0x3 * REG_INC + CS0))
#define TF_CYLINDER_LOW  (*(BYTE_WIDE *)(Y+TF_BASE+ 0x4 * REG_INC + CS0))
#define TF_CYLINDER_HIGH (*(BYTE_WIDE *)(Y+TF_BASE+ 0x5 * REG_INC + CS0))
#define TF_DRIVE_HEAD    (*(BYTE_WIDE *)(Y+TF_BASE+ 0x6 * REG_INC + CS0))
#define TF_STATUS  (*(volatile BYTE_WIDE *)(Y+TF_BASE+ 0x7 * REG_INC + CS0))
#define TF_COMMAND (*(volatile BYTE_WIDE *)(Y+TF_BASE+ 0x7 * REG_INC + CS0))
#define TF_ALTERNATE_STATUS\
                   (*(volatile BYTE_WIDE *)(Y+TF_BASE+ 0x6 * REG_INC + CS1))
#define TF_DEVICE_CONTROL TF_ALTERNATE_STATUS
#define TF_DRIVE_ADDRESS\
           (*(volatile BYTE_WIDE *)(TF_BASE+ 0x7 * REG_INC + CS1))

/* Bit names for general use */
#define bit7    0x80
#define bit6    0x40
#define bit5    0x20
#define bit4    0x10
#define bit3    0x08
#define bit2    0x04
#define bit1    0x02
#define bit0    0x01

/* status register */
#define BSY    bit7 /*Busy*/
#define DRDY   bit6 /*drive ready*/
#define DWF    bit5 /*drive write fault*/
#define DF     DWF
#define DSC    bit4 /*drive seek complete*/
#define SKC    DSC  
#define DRQ    bit3 /*data request*/
#define CORR   bit2 /*corrected data*/
#define IDX    bit1 /*index*/
#define ERR    bit0 /*error*/

/* device control register */
#define SRST   bit2 /*software reset*/
#define nIEN   bit1 /*interrupt enable*/

/* error register */
#define BBK    bit7 /*bad block detected*/
#define UNC    bit6 /*uncorrectable data error*/
#define MC     bit5 /*media changed*/
#define IDNF   bit4 /*ID Not Found*/
#define ABRT   bit3 /*aborted command*/
#define MCR    bit2 /*Media Change Requested*/
#define TK0NF  bit1 /*Track 0 Not Found*/
#define AMNF   bit0 /*Address Mark Not Found*/

/* drive / head register */
#define L      bit6 /*L=0.CHS , L=1.LBA*/
#define DRV    bit4 /*drive select 0=drive0*/
#define DRV0   0
#define DRV1   DRV
#define HS3    bit3 /* Head select / LBA bits 24-27*/
#define HS2    bit2 /**/
#define HS1    bit1
#define HS0    bit0

/* commands */
#define ATA_IDENTIFY_DRIVE 0xEC
#define ATA_EXECUTE_DRIVE_DIAGNOSTIC 0x90
#define ATA_SLEEP  0xE6
#define ATA_SEEK 0x70
#define ATA_READ_SECTORS 0x20
#define ATA_WRITE_SECTORS 0x30
#define ATA_NOP 0
#define ATA_IDLE 0xE3 /*0x97*/
#define ATA_IDLE_IMMEDIATE 0xE1 /*0x95*/
#define ATA_STANDBY_IMMEDIATE 0xE0
#define ATA_INIIIALIZE_DRIVE_PARAMETERS 0x91
#define ATA_SET_FEATURES 0xEF
#define ATA_CHECK_POWER_MODE 0xE5

/* features */
#define FEATURE_8BIT_ON    0x01
#define FEATURE_8BIT_OFF   0x81