TX4939 Datasheet, PDF (266/756 Pages) Toshiba Semiconductor – 64-Bit TX System RISC

Video Port
Toshiba RISC Processor
TX4939
Example:
Memoy has the following byte data:
byte # - 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
data - a b c d e f g h i j k l m n o p q r s t u v w x y z A B C
byte # - 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
data - D E F G H I J K L M N O P Q R S T U V W
With validCount[11:0] = 10(11 bytes), Offset[11:0] = 4 (5 bytes) and Bcount[22:0] = 32(33 bytes) data send out by VPC will
have the following pattern assuming dma address(DMAGA[31:0] = 0) is pointing to byte 0:
abcdefghij kqrstuvwxyzAG H I J K L M N O P Q
Bytes #10 to #15 and #27 to #31 are skipped because of the Offset[11:0] = 4.
In this example, Bcount[22:0] can be up to
8 Mbyte - (8Mbyte % 11) - 1 = 8388599 (0x7FFFF7)
MPEG Transmit
If VPC is programmed to transmit packet in MPEG format with Vddata = 187(188 byte data packet) and Bcount[22:0]
greater than 187(more than 188 bytes), the number of packets will be sent by VPC is
((Bcount + 1) / (Vddata + 1)) + ((((Bcount + 1) % (Vddata + 1)) != 0) ? 1 : 0)
For example, if vdfor = 1, Vddata = 187 and bcount = 189 (190 bytes), 2 packets will be sent out by VPC. Second packet
will have 0s after 2 bytes of valid data:
12
0
1 2 3 4 … 187
packet #0 D0 D1 D2 D3 D4 … D187
packet #1 D188 D189 0 0 0 …
0
Rev. 3.3 May 18, 2007
12-8