Altera SCFIFO - Manual (Page 7)

Parameter Type Requir
ed
Description
lpm_numwords
Integer Yes Specifies the depths of the FIFO you require. The value
must be at least 4.
The value assigned must comply with this equation,
2LPM_WIDTHU
lpm_showahead
String Yes Specifies whether the FIFO is in normal mode (
OFF
) or
show-ahead mode (
ON
).
For normal mode, the FIFO IP core treats the
rdreq
port as a normal read request that only performs read
operation when the port is asserted.
For show-ahead mode, the FIFO IP core treats the
rdreq
port as a read-acknowledge that automatically
outputs the first word of valid data in the FIFO IP core
(when the
empty
or
rdempty
port is low) without
asserting the
rdreq
signal. Asserting the
rdreq
signal
causes the FIFO IP core to output the next data word, if
available.
If you set the parameter to ON, you may reduce
performance.
lpm_type
String No Identifies the library of parameterized modules (LPM)
entity name. The values are SCFIFO and DCFIFO.
maximize_speed
Integer No Specifies whether or not to optimize for area or speed.
The values are 0 through 10. The values 0, 1, 2, 3, 4,
and 5 result in area optimization, while the values 6, 7,
8, 9, and
10
result in speed optimization.
This parameter is applicable for Cyclone II and
Stratix II devices only.
overflow_checking
String No Specifies whether or not to enable the protection
circuitry for overflow checking that disables the
wrreq
port when the FIFO IP core is full. The values are ON
or OFF. If omitted, the default is ON.
underflow_checking
String No Specifies whether or not to enable the protection
circuitry for underflow checking that disables the
rdreq
port when the FIFO IP core is empty. The values are
ON or OFF. If omitted, the default is ON.
Note that reading from an empty SCFIFO gives
unpredictable results.
(5) Only applicable for the DCFIFO IP core.
UG-MFNALT_FIFO
2014.12.17
SCFIFO and DCFIFO Parameters 7
SCFIFO and DCFIFO IP Cores User Guide Altera Corporation
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