mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 481

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

16.3.3.2 MODULO ADDRESSING. The input and output buffers are circular within a
certain programmable size that must be a multiple of 2
buffer must be aligned on its natural size boundary. For example, if your input buffer size is
128 bytes, your base address must be aligned on a 128-byte boundary. In other words, the
lower boundary (base address) of a circular buffer containing modulus (M) bytes must have
zeros in the k LSBs of the base address, where 2
2
M-1). Once M is chosen, a sequential series of memory blocks (each of length 2
where these circular buffer can be located. If M
sequential M-sized circular buffers and M must be a multiple of four. See Figure 16-9 for
details.
16.3.3.2.1 DSP Function Descriptors. Each function descriptor is composed of eight
16-bit half-words. The first half-word contains the function opcode as well as status and
control bits and the other half-words contain the function’s parameter packet. Each function
has its own parameter packet.
S—STOP
Bits 1 and 4–10—Reserved
These bits are reserved and must be set to 0.
OFFSET + E
OFFSET + 0
OFFSET + 2
k
. The upper boundary is the lower boundary, plus the size minus one (base address +
• • •
• • •
• • •
0 = Do not stop after executing this function descriptor.
1 = Stop after executing this function descriptor.
0
S
RES
1
ADDRESS
POINTER
W
2
Freescale Semiconductor, Inc.
For More Information On This Product,
3
I
Figure 16-9. Circular Buffer
MPC823 REFERENCE MANUAL
4
Go to: www.freescale.com
5
CIRCULAR
BUFFER
6
RESERVED
PARAMETER 1
PARAMETER 7
7
• • •
• • •
• • •
k
2
k
, there is a 2
8
M, and therefore must be a multiple of
k
UPPER BOUNDARY
LOWER BOUNDARY
. The base address of the circular
9
M = MODULUS
Communication Processor Module
10
k
-M space between the
11
12
OPCODE
13
k
) is created
14
16-29
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