ZR36057 Просмотр технического описания (PDF) - Zoran Corporation

Номер в каталоге

Компоненты Описание

Список матч

ZR36057

ENHANCED PCI BUS MULTIMEDIA CONTROLLER

Zoran Corporation 

Enhanced PCI Bus Multimedia Controller

mand” information, written by the host, for the next available

buffer. Table 10 shows the interpretation for this

case.

Table 10: STAT_COM entry content, when

STAT_BIT=0

Bit

31:2

1

0

Content

FRAG_TAB_PTR[31:2]

FRAG_TAB_PTR [1]

STAT_BIT

Description

The address pointer to the

fragment table of the next buffer

to be used. The 2 l.s. bits of the

address must be ‘0’ - that is, the

address must be doubleword

aligned.

Must to be ‘0‘.

Must be ‘0’ to indicate that the

table entry is a command.

If the STAT_BIT=‘1‘, the content of the entry is the “status” infor-

mation, written by the ZR36057, of the most recently processed

field or frame. Table 11 shows the interpretation for this case.

Table 11: STAT_COM entry content, when

STAT_BIT=1

Bit

Content

31:24 F_CNT[7:0]

23

22:1 F_LENGTH[21:0]

0 STAT_BIT

Description

The serial number, modulo 256, of the

most recent field or frame. Used in

compression only.

Reserved, set to ‘0’.

The length of the most recently com-

pressed field or frame in bytes, used in

compression only. The length is dou-

bleword aligned, so bits 2..1 are

always ‘0‘.

‘1‘, indicating that this table entry is a

status written by the ZR36057.

9.2 Fragment Table

The Fragment Table defines the structure of the allocated

memory for each code buffer. The table has N entries for N allo-

cated fragments. Each entry holds two doublewords:

• first doubleword - the physical address of the fragment (must

be doubleword aligned),

• second doubleword - the fragment length in doublewords

(must be doubleword aligned).

The l.s. bit of the second doubleword is the FINAL bit, indicating

(when ‘1’) that the current fragment entry defines the last

fragment of the buffer.

9.3 JPEG Compression Modes

The sequence of actions performed by the host software and the

ZR36057 is as follows:

• The host allocates the first four code buffers and writes out

the code buffer table and the fragment table.

• The host loads the ZR36057’s I_STAT_COM_PTR register

with the base address of the code buffer table.

• After the start of the compression process, the ZR36057

starts filling the fragments of the first code buffer with the

compressed data of the first field or frame.

• After successfully completing transfer of the compressed

data of a field or frame, the ZR36057 writes the status infor-

mation back to the STAT_COM entry of the current buffer. It

sets the STATUS_BIT in the STAT_COM entry, declaring its

content as status. It then issues an interrupt, and starts the

next field or frame process.

• If a new code buffer is unavailable at the beginning of a field

or frame process (that is, if the STATUS_BIT of the next

buffer entry is ‘1’), the ZR36057 polls the STAT_COM entry

until the buffer is available.

• When the host receives the interrupt, it checks the

STAT_COM entries in the code buffer table. For each entry

whose STAT_BIT=’1’, the host checks F_CNT to determine

whether any fields/frames were dropped. It records the code

buffer information, updates the fragment table and

STAT_COM entry of the code buffer, and returns it by reset-

ting STAT_BIT to ‘0’.

Several scenarios might cause a field or frame process to be

unsuccessful:

• The allocated code buffer memory was smaller than the ac-

tual field/frame code volume (the ZR36057 fills the final

fragment, but the field/frame code transfer is not complete).

• A ZR36016 strip memory overflow occurs during the field/

frame compression (might be caused by very large PCI bus

latency)

After an unsuccessful field/frame process in compression, the

ZR36057 does not issue an interrupt, and restarts with the next

field or frame.

9.4 JPEG Decompression Modes.

The sequence of actions performed by the host software and the

ZR36057 is as follows:

• The host allocates the first four code buffers and writes out

the code buffer table and the fragment table.

• The host fills the allocated fragments with the code to be

decompressed.

• The host loads the ZR36057’s I_STAT_COM_PTR register

with the base address of the code buffer table.

• After the start of the decompression process, the ZR36057

starts reading the code of the first field or frame from the

code buffer fragments.

• After completing decompression of the field or frame, the

ZR36057 sets the STATUS_BIT in the STAT_COM register,

21

Share Link: