PATH Hardware Documentation > Device Managers and Drivers > ATA Devices > ATA Device Software Guide

ATA_ExecIO

You can use the ATA_ExecIO function to perform all data I/O transfers to or from an ATA device. Your application must provide all of the parameters needed to complete the transaction prior to calling the ATA Manager. On return, the parameter block contains the result of the request.

A prior call to the ATA_SetDevConfig function is recommended to obtain the optimal performance from the device. See ATA_SetDevConfig for information about the ATA_SetDevConfig function.

The manager function code for the ATA_ExecIO function is $01.

The parameter block associated with the ATA_ExecIO function is defined below:

Field descriptions

ataPBHdr

See the definition of the ataPBHdr parameter block.

ataStatusReg

This field contains the last device status register image. See the ATA-2 specification for status register bit definitions.

ataErrorReg

This field contains the last device error register image. This field is valid only if the error bit (bit 0) of the Status register is set. See the ATA-2 specification for error register bit definitions.

ataReserved

Reserved. All reserved fields are set to 0 for future compatibility.

BlindTxSize

This field specifies the maximum number of bytes that can be transferred for each interrupt or detection of a data request. Bytes are transferred in blind mode (no byte level handshake). Once an interrupt or a data request condition is detected, the ATA Manager transfers up to the number of bytes specified in the field from or to the selected device. The typical number is 512 bytes.

The BlindTxSize field is used only for PIO transfers. It is ignored for DMA data transfers.

This field is ignored for ATAPI commands. For the ATAPI ptotocol, the dynamic byte transfer count is specified in the cylinder registers (big-endian format) at the beginning of each interrupt. See the Cylinders field in the definition of the devicePB structure for the RegBlock field.

ioBuffer

This field contains either the host buffer address for the number of bytes specified in the ioReqCount field and the requested transfer length, or a pointer to a scatter gather list and the number of scatter gather entries. If the SGType bits of the ataFlags field are set, an IOBlk structure contains the scatter gather information. The IOBlk is defined as follows:

typedef		struct
{
	UInt8*	ioBuffer;	/* --> Data buffer ptr */
	UInt32	ioReqCount;	/* --> Transfer length */
} IOBlk;

ioBuffer

This field contains the host buffer address for the number of bytes specified in the ioReqCount field. On returning, the ioBuffer field is updated to reflect data transfers. When the SGType bits of the ataFlags field are set, the ioBuffer field points to a scatter gather list. The scatter gather list consists of a series of IOBlk entries.

ioReqCount

This field contains the number of bytes to transfer either from or to the buffer specified in ioBuffer . On returning, the ioReqCount field is updated to reflect data transfers (0 if successful; otherwise, the number of bytes that remained to be transferred prior to the error condition). When the SGType bits of the ataFlags field are set, the ioReqCount field contains the number of scatter gather entries in the list pointed to by the ioBuffer field.

ioReqCount

This field contains the number of bytes to transfer either from or to the buffer specified in ioBuffer . On returning, this field is updated to reflect data transfers (0 if successful; otherwise, the number of bytes that remained to be transferred prior to the error condition). When the SGType bits of the ataFlags field are set, the ioReqCount field contains the number of scatter gather entries in the list pointed to by the ioBuffer field.

ataActualTxCnt

This field contains the total number of bytes transferred for this request.

ataReserved2

This field is reserved. To ensure future compatibility, all reserved fields should be set to 0.

RegBlock

This field contains the ATA device register image structure. Values contained in this structure are written out to the device during the command delivery state. The caller must provide the image prior to calling the ATA Manager. The ATA device register image structure is defined as follows:

typedef		struct	/* Device register images */
{
	UIntt8	Features;	/* --> Features register */
	UIntt8	Count;	/* <--> Sector count */
			/*image */
	UIntt8	Sector;	/* <--> Sector start/finish */
	UIntt8	Reserved;	/* Reserved */
	UIntt16	Cylinder;	/* <-->*/ Cylinder in big */ /* endian format */
	UIntt8	SDH;	/* <--> SDH register image */
	UIntt8	Command;	/* --> Command register image */
} devicePB;

For ATAPI commands, the Cylinder image must contain the preferred PIO DRQ packet size which is written out to the Cylinder High/Low registers at command phase.

packetCDBPtr

This field contains the pointer to the ATAPICmdPtr packet structure for the ATAPI protocol. The ATAPI bit of the ProtocolType field in the ataPBHdr must be set for this field to be valid. Setting the ATAPI protocol bit also signals the ATA Manager to initiate the transaction without the DRDY bit set in the status register of the device. The ATAPICmdPtr structure is defined as follows:

typedef		struct	/* ATAPI command packet */;
{
	SInt16	packetSize;	/* Size of command in */ /* bytes (exclude size) */
	SInt16	command[8];	/* The actual ATAPI */ /* command packet */
} ATAPICmdPacket;

For ATA commands, this field should contain 0 in order to ensure compatibility in the future.

ataReserved3[6]

These fields are reserved. To ensure future compatibility, all reserved fields should be set to 0.

RESULT CODES

© 1999 Apple Computer, Inc. — (Last Updated 30 Oct 97)

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