EP3C16F256I7N Altera, EP3C16F256I7N Datasheet - Page 94

• Manufacturer Part Number: EP3C16F256I7N
• Description: Cyclone III
• Manufacturer: Altera

Embedded Multipliers in Cyclone III Devices
5–6
Cyclone III Device Handbook, Volume 1
Table 5–3. Multiplier Sign Representation
signa Value
Unsigned
Unsigned
Signed
Signed
Data A
Logic Level
Refer to
Each multiplier operand can be a unique signed or unsigned number.
Two signals, signa and signb, control an input of a multiplier and
determine if the value is signed or unsigned. If the signa signal is high,
the data A operand is a signed number. If the signa signal is low, the
data A operand is an unsigned number.
multiplication result for the various operand sign representations. The
result of the multiplication is signed if any one of the operands is a signed
value.
Each embedded multiplier block has only one signa and one signb
signal to control the sign representation of the input data to the block. If
the embedded multiplier block has two 9 × 9 multipliers, the data A
input of both multipliers share the same signa signal, and the data B
input of both multipliers share the same signb signal. You can change
the signa and signb signals dynamically to modify the sign
representation of the input operands at run time. You can send the signa
and signb signals through a dedicated input register. The multiplier
offers full precision, regardless of the sign representation.
1
Output Registers
You can choose to register the embedded multiplier output using the
output registers in 18- or 36-bit sections, depending on the operational
mode of the multiplier. The following control signals are available to each
output register within the embedded multiplier:
■
■
■
High
High
Low
Low
clock
clock enable
asynchronous clear
“Operational Modes” on page 5–7
When the signa and signb signals are unused, the Quartus II
software sets the multiplier to perform unsigned multiplication
by default.
signb Value
Unsigned
Unsigned
Signed
Signed
Data B
Logic Level
High
High
Low
Low
Table 5–3
Altera Corporation-Preliminary
for multiplier details.
shows the sign of the
Unsigned
Signed
Signed
Signed
Result
March 2007