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CHAPTER 5 SAR FUNCTION
174
<2>
BATCH SIZE
This field specifies the number of buffers in one batch located in this pool.
Setting: The end of a batch is always a "batch link pointer." This field specifies the number of buffers n,
excluding the batch link pointer. The amount of system memory actually used by one batch is
equal to the number of buffers, plus "link pointer," i.e., 2n + 1 words. The value of n must be
set to 1 or greater. The
μ
PD98405 recognizes the position of the link pointer from the contents
of this "BATCH SIZE" field.
<3>
REMAINING NUMBER OF BATCHES
The host writes the number of batches n, prepared in the pool, to this field during initialization. This field
is then managed by the
μ
PD98405 and indicates the number of batches remaining in the pool. The
μ
PD98405 subtracts the value in this field each time it fetches a batch from the pool, and adds it each
time it receives the Add_Batches command.
<4>
ADDRESS
The host sets the first address of the first batch in the pool to this field during initialization.
Subsequently, the
μ
PD98405 uses this field as a pointer to the next batch.
(3) Pool for storing raw cell
The
μ
PD98405 uses different pool numbers depending on the type of the data it receives. When AAL-5-
type data is received, the user can specify any of pools 0 through 31 for each VC. If raw cell data is
received, any of pools 0 through 7 can be specified. When OAM F5 or RM cell is received, however, the
μ
PD98405 unconditionally stores that cell to pool 0. If the reception of an OAM F5 or RM cell has been
set, the user must always set the storing of raw cell data of the OAM or RM cell to pool 0.
Table 5-5. Types of Receive Data and Pools Used
Data type
Pool used
AAL-5-type packet reception
Pool 0 to 31
Raw cell data
Pool 0 to 7
OAM F5 or RM cell data
Pool 0 only
In the case of a pool that is used to store raw cell data, the RQA interrupt function that indicates the
number of remaining batches is ineffective, and the
μ
PD98405 ignores the setting of the "ALERT LEVEL"
field.
The
μ
PD98405 stores the data of a single raw cell, consisting of 64 bytes, to each free buffer. For a pool
used to store raw cell data, therefore, set the size of a free buffer to 64 bytes. If the free buffer size is set
to more than 64 bytes, the
μ
PD98405 ignores the area. Even if the free buffer size is set to less than 64
bytes, the
μ
PD98405 assumes the actual buffer size to be 64 bytes.