NEC Network Controller uPD98502 - Manual (Page 261)

CHAPTER 4 ATM CELL PROCESSOR
Preliminary User’s Manual S15543EJ1V0UM 261
4.7.5 Add_Buffers command
The Add_Buffers command is used to add unused buffer directories to a single receive free buffer pool.
In this command, when ATM Cell Processor detects some errors, it writes E bit in A_CMR. This command has the
following format:
Figure 4-22. Add_Buffers Command
[Add_Buffers command]
CMR
0 1 1 0 1 0 Pool No. Number of Buffer Directories
31 30 29 28 27 26 25 21 20 16 15 0
CER
Buffer Directory Pointer
31 0
[Add_Buffers command indication]
CMR
0 1 1 0 1 0 E 0 Pool No. Number of Buffer Directories
31 30 29 28 27 26 25 24 23 21 20 16 15 0
Add_Buffers command
Pool No. Number of the pool to which buffer directories are to be added. Since ATM Cell
Processor supports only 8 pools (0 to 7), Bit 19 and 20 should be set to a ‘0’.
Number of Buffer Directories Number of new buffer directories to be added
Buffer Directory Pointer Start address of the first buffer directory in the list of new buffer directories to be
added
Add_Buffers command indication
E Error bit. If detects an error, sets this bit to a ‘1’. When V R 4120A issues this
command, this bit has to be a ‘0’. The possible error is the number of buffer
directories after this command is executed exceeds 65535.
Pool No. Number of the pool to which new buffer directories are just added
Number of Buffer Directories Number of new buffer directories just added