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Integrated JPEG CODEC

6.11.1 Data Corruption during Decompression

If during the decompression of a field the ZR36060 senses a

data corruption event, it immediately asserts DATERR, then

continues the decompression process until it senses the EOI

(End Of Image) marker or the end of the active video area

(whichever occurs later). At this time it asserts END and enters

the IDLE state. The deassertion of END (upon START for the

next field) deasserts the DATERR signal.

1) If DATERR is not enabled as an interrupt requesting event

(i.e., it is cleared in the Interrupt Mask register), then the

ZR36060 samples START again, and if START is asserted a

new process begins.

2) If DATERR is enabled as an interrupt requesting event, JIRQ

is asserted together with the assertion of DATERR, and when

the ZR36060 completes the current process it enters the WAIT-

ISR state and remains “frozen” (without regard for START) until

the host reads the Interrupt Status register. At this time the

ZR36060 goes back to IDLE and is again ready to start a new

process, waiting for START.

In decompression the ZR36060 identifies a data corruption con-

dition if the strip buffer underflows, i.e.- insufficient blocks of

decompressed data to start outputting the first video line of a

strip when required.

3

Figure 38. Examples of ZR36060 Decompression (After Host Loaded Parameters & Load Command)

VSYNC

_active

_state

START

FRAME

RTBSY

DATERR

CSS

(code master)

CBUSY

(code slave)

DATA Bus

(CODE bus)

END

JIRQ

1

2

3

4

5

6

7

8

9

10

11

12

ODD

EVEN

ODD

EVEN

ODD

EVEN

ODD

EVEN

ODD

EVEN

ODD

EVEN

IDLE

WaitACT

EXP

i

i

IDLE

EXP

EXP

i

i

EXP

(w/error)

i

EXP

i

WaitISR

EXP

(w/error)

EXP

3

4

7

8

11

In field #1, START & FRAME asserted indicate to decompress on next ODD VSYNC (field #3). Code can be input immediately after START

assertion (filling CFIFO), to decode and fill with 8 lines of video the 1st. strip buffer before active video time arrive. After the 1st. strip is

completed, code is no longer fetched, and the ZR36060 waits for the active area of the next ODD field.

Field #3 decompression continues and complete, issue END and return to IDLE. RTBSY goes low after active area completes indicating

strip memory empty.

Field #4 is decompressed normally.

Begin field decompression, but system is too slow to feed new code data, so DATERR is asserted. Sampling of END and DATERR inform

the system of an illegal field. Since interrupt request on data error is enabled, ZR36060 assert JIRQ and wait until the host acknowledge the

JIRQ by reading the associated interrupt status register.

During this field, the host service the interrupt (ZR36060 de-assert JIRQ) and assert again START (w/o FRAME) for next field compression.

In this example, the host also disables interrupts after servicing this one.

Field #7 is decompressed. After END , system assert START for next field.

In Field #8 start to input code, but somewhere during the active area, the system is busy (without feeding new code) long enough that the

ZR36060 issue a DATERR (no JIRQ here since interrupts are disabled). Despite this situation the system continue to feed new code to the

ZR36060 until END which occurs only after next field #9 beginning (VSYNC assertion). Now START is sensed low meaning that next

decompression will happen on field #10 (skipping field #9).

Fields are decompressed normally. START is not asserted during field #11, therefore after END assertion the ZR36060 returns to IDLE and

wait for next operation.

1, 2.

3.

4.

5.

6.

7.

8, 9.

10, 11.

Notes:

i = go through IDLE & WAITACT)

5

8

10