Texas Instruments TMS320 Series, User Manual

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Streaming DEV Structures
7-30
7.10 Streaming DEV Structures
The DEV_Fxns structure contains pointers to internal driver functions
corresponding to generic I/O operations as shown in Example 7-19.
Example 7-19. The DEV_Fxns Structure
Device frames are structures of type DEV_Frame used by SIO and device
drivers to enqueue/dequeue stream buffers. The device
→
todevice and
device
→
fromdevice queues contain elements of this type (Example 7-20).
Example 7-20. The DEV_Frame Structure
Example 7-20 has the following parameters:
❏
link is used by QUE_put and QUE_get to enqueue/dequeue the frame.
❏
addr contains the address of the stream buffer.
❏
size contains the logical size of the stream buffer. The logical size can be
less than the physical buffer size.
❏
misc is an extra field which is reserved for use by a device.
❏
arg is an extra field available for you to associate information with a
particular frame of data. This field should be preserved by the device.
❏
cmd is a command code for use with mini-drivers that use the IOM model
described in the DSP/BIOS Driver Developer's Guide (SPRU616). The
command code tells the mini-driver what action to perform.
❏
status is a field set by an IOM mini-driver before calling a callback
function.
typedef struct DEV_Fxns {
Int (*close)(DEV_Handle);
Int (*ctrl)(DEV_Handle, Uns, Arg);
Int (*idle)(DEV_Handle, Bool);
Int (*issue(DEV_Handle);
Int (*open)(DEV_Handle, String);
Bool (*ready)(DEV_Handle, SEM_Handle);
Int (*reclaim)(DEV_Handle);
} DEV_Fxns;
typedef struct DEV_Frame { /* frame object */
QUE_Elem link; /* queue link */
Ptr addr; /* buffer address */
Uns size; /* buffer size */
Arg misc; /* reserved for driver */
Arg arg; /* user argument */
Uns cmd; /* mini-driver command */
Int status; /* status of command */
} DEV_Frame;