VSC7511 datasheet(205/324 Pages) MICROSEMI

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VCore-Ie System and CPU Interfaces

VMDS-10488 VSC7511 Datasheet Revision 4.2

190

written (before stating a data block), the BLOCKO is cleared, so by default all blocks have 0 byte offset.

The offset can be written multiple times; the last value takes effect.

The CPU can abort frames that it has already started to read out by writing the extraction status field with

the ABORT field set. All other status-word fields will be ignored. This causes the extraction logic to

discard the active frame and remove it from the queuing system.

Reading of block data does not have to be done in one burst. As long as the status word is not read,

multiple reads from the extraction region are treated as belonging to the same block.

4.7.7.2

Manual Injection

Injection is done by writing one or more blocks of data to the injection memory area. A block of data is

defined by writing an injection status word followed by writing one or more data words. The injection

memory area is 16 kilobytes and is implemented as a replicated register region MANUAL_INJ. The first

following:

•

Number of bytes to be injected

•

Optional byte offset before injection data

•

SOF and EOF indications

•

Optional ABORT indication

Note In general, it makes sense to inject frames as a single large block of data (containing both SOF

and EOF). However, because offset/length can be specified individually for each block, injecting frames

through several blocks is useful when compensating for offset/word misalignment. For example, when

building a frame from different memory regions in the CPU main memory.

Figure 70 •

Injection Status Word Encoding

Injection logic updates the PD field of the status word. The status word can be read at any time during

injection without affecting current data block transfers. However, a CPU is able to calculate how much

data that is required to inject a complete block of data (at least BLOCKO + BLOCKL bytes), so reading

the status word is for software development and debug only. Writing status word before finishing a

previous data block will cause that frame to be aborted. Frames are also aborted if they do not start with

SOF or end with EOF indications.

As long as the status word is not written, multiple writes to the injection region are treated as data

belonging to the same block. This means multiple bursts of data words can be written between each

injection status word update.

[31:20]

[15:0]

BLOCKL: The amount of frame data (bytes) that

will be written for this block. The CPU is allowed to

write more data than this, additional data will be

ignored.

SOF: Start of frame, set to indicate that this block

contains start of a frame.

EOF: End of frame, set to indicate that this block

contains end of a frame.

ABORT: Set to abort active frame transfer. The

current frame will be aborted and removed from

Queuing System.

PD: Injection done, is set by the injection logic

when enough data has been received for this block

of data (BLOCKO+BLOCKL). If set when writing

status word, then this is treated as if ABORT had

been set.

BLOCKO: The amount of dummy bytes (non-frame

data) to expect before the frame data. The dummy

data will be ignored.

BLOCKL

BLOCKO

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