PNX1302EH NXP Semiconductors, PNX1302EH Datasheet - Page 245

• Manufacturer Part Number: PNX1302EH
• Manufacturer: NXP Semiconductors

Specifications of PNX1302EH

• Lead Free Status / RoHS Status: Not Compliant

Philips Semiconductors
15.9
15.9.1
This register indicates the next action to be taken by the
VLD. Some commands have an associated count which
resides in the least significant 8 bits of this register. There
are currently five commands recognized by the VLD
block:
• Shift the bitstream by ‘count’ bits (‘count’ must be
• Parse ‘count’ un-skipped macroblocks
• Search for the next start code
• Reset the VLD
• Flush the VLD output buffers
The DSPCPU must wait for the VLD to halt before the
next command can be issued. Note that there are sever-
al ways in which a command may complete. Only a suc-
Table 15-6. VLD Commands
15.9.2
This read only register is a shadow of the VLD’s opera-
tional shift register. Tt allows the DSPCPU to access the
bitstream through the VLD. Bits 0 through 15 are the cur-
rent contents of the VLD shift register. Bits 16 to 31 are
RESERVED and should be treated as undefined by the
programmer.
Shift the bitstream
by ‘count’ bits
Search for the
next start code
Reset the VLD
Parse for a given
number of mac-
roblocks
Flush the VLD out-
put buffer
less than or equal to 15)
Command
VLD OPERATIONAL REGISTERS
VLD Command (VLD_COMMAND)
VLD Shift Register (VLD_SR)
coding
Field
1
3
4
2
8
COMMAND_DONE
or
DMA_IN_DONE
STARTCODE
or
COMMAND_DONE
or
DMA_IN_DONE
None
COMMAND_DONE
or
STARTCODE
or
ERROR
or
DMA_IN_DONE
COMMAND_DONE
Completion of the
Flags Set after
Command
VLD shifts the number of bits in its internal shift register. The shift register value
is available in the VLD_SR register.
The DMA_IN_DONE flag will be set when VLD runs out of data from input FIFO.
The flag is reset by issuing the new command.
VLD search for a start code. The search code has 0x000001 prefix and an addi-
tional 8-bit value.
The DMA_IN_DONE flag will be set when VLD runs out of data from input FIFO.
The STARTCODE detected flag is reset by writing a ‘1’ value to the flag.
The COMMAND_DONE flag is reset by issuing the new command.
Refer section
VLD parses for a given number of un-skipped macroblocks and the associated
run-level values. COUNT will indicate the remaining macroblocks to parse. Note
that this number is slightly inaccurate since a parsed macroblock can still be in
internal 64-byte FIFO.
If VLD encounters a start code, the parsing action will be terminated and VLD
sets only the STARTCODE detected flag. If VLD parses the given number of un-
skipped macroblocks without encountering a start code, VLD will set the
COMMAND_DONE flag.
The ERROR flag will be set when VLD encounters an error while parsing the bit-
stream.
The DMA_IN_DONE flag will be set when VLD runs out of data from input FIFO.
The STARTCODE detected flag is reset by writing a ‘1’ value to the flag.
The COMMAND_DONE flag is reset by issuing the new command.
VLD flushes the remaining macroblock header data and the remaining run-level
data to SDRAM. The highway byte-enables will be used in order to write only the
valid data to SDRAM. Only the valid word count values written to SDRAM will be
subtracted from the VLD_MBH_CNT and the VLD_RL_CNT registers.
15.12
cessful
COMMAND_DONE bit in the status register. A command
may complete unsuccessfully if a start code or an error is
encountered before the requested number of items has
been processed. Note also that expiration of a DMA
count does not constitute completion of a command.
When a DMA count expires the VLD is stalled as it waits
for a new DMA to be initiated. It is not halted. Default val-
ue (after hardware reset) is ‘0’. VLD_COMMAND fields
are described in
explained in
Table 15-5. VLD Command Register
15.9.3
This 5-bit register contains the quantization scale code
(from the slice header) to be output by the VLD until it is
overridden by a macroblock quantizer scale code. The
quantizer scale code is part of the macroblock header
output.
PRELIMINARY SPECIFICATION
COUNT
COMMAND
for more details
Name
VLD Quantizer Scale (VLD_QS)
completion
Table
Description
Table 15-5
15-6.
(bits)
Size
8
4
Variable Length Decoder
is
and the different commands
Count for current command
VLD command to be exe-
cuted
indicated
Description
by
15-7
the