pef20320 Infineon Technologies Corporation, pef20320 Datasheet - Page 189

• Manufacturer Part Number: pef20320
• Description: Multichannel Network Interface Controller For Hdlc With 32 Channels
• Manufacturer: Infineon Technologies Corporation

PEB 20320
Application Notes
DDS Tasks
The message transfer between the modules is the main task of the DDS, realized by
some service routines. DDMs and APMs are integrated in the DDS by executing a
Module Init Routine. The Module Init Routine is called by the DDS. Additionally the DDS
offers service routines for memory management. All service routines can be used by all
modules. Some memory management functions will be presented in more detail. For
detailed information about the other DDS service routines please refer to the SIPB 7520
Primary Rate User Board or EASY532 Datacom Userboard Documentation.
Memory Management
With the memory management functions the allocation of message descriptors,
1)
MUNICH32 receive/transmit descriptors
or LAN controller receive/transmit descriptors
is simplified. During initialization of the memory management module DDSM a pool of
descriptors is prepared in a linked list. The memory management functions allow to
allocate descriptors and to free descriptors. During initialization of the memory
management module DDSM a pool of descriptors is prepared in a linked list. The
memory management functions allow to allocate descriptors and to free descriptors.
During allocation a descriptor is taken from the prepared list. After utilization the
descriptor is given back to the descriptor pool. There is one pool for message descriptors
and one pool for MUNICH32 receive/transmit and LAN controller receive/transmit
descriptors. Because MUNICH32 transmit and receive descriptors differ and they both
differ from the LAN controller transmit and receive descriptors, there are service
functions available to convert the descriptor type.
1)
Refer to MUNICH32 Data Sheet.
User’s Manual
189
01.2000