CDA CD 60 Especificações descarregar pdf (Página 20)

PCI CD and PCI CDa

Document Number: 008-00965-06 EDT Public Revision: I December 2004

Template: edt.dot

Page 20

Return

The return value from read, normally the number of bytes read; –1 is returned in case of error. Call

edt_perror() to get the system error message.

Note

If using timeouts, call edt_timeouts after edt_read returns to see if the number of timeouts

has incremented. If it has incremented, call edt_get_timeout_count to get the number of

bytes transferred into the buffer. DMA does not automatically continue on to the next buffer,

so you need to call edt_start_buffers to move on to the next buffer in the ring.

edt_write

Description

Perform a write on the EDT Product. For those on UNIX systems, the UNIX 2 GB file offset bug is

avoided during large amounts of input or output; that is, writing past 231 does not fail. This call is not

multibuffering, and no transfer is active when it completes.

Syntax

#include "edtinc.h"

int edt_write(EdtDev *edt_p, void *buf, int size);

Arguments

edt_p

device handle returned from edt_open or edt_open_channel

buf

address of buffer to write from

size

size of write in bytes

Return

The return value from write; –1 is returned in case of error. Call edt_perror() to get the system error

message.

Note

If using timeouts, call edt_timeouts after edt_write returns to see if the number of timeouts

has incremented. If it has incremented, call edt_get_timeout_count to get the number of

bytes transferred into the buffer. DMA does not automatically continue on to the next buffer,

so you need to call edt_start_buffers to move on to the next buffer in the ring.

edt_start_buffers

Description

Starts DMA to the specified number of buffers. If you supply a number greater than the number of

buffers set up, DMA continues looping through the buffers until the total count has been satisfied.

Syntax

#include "edtinc.h"

int edt_start_buffers(EdtDev *edt_p, int bufnum);

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CDA CD 60 Especificações Página 20