Altera Integer Arithmetic IP - Manual (Page 33)

The LPM_MULT megafunction can be implemented using either logic resources or dedicated multiplier
circuitry in Altera devices. Typically, the LPM_MULT megafunction is translated to the dedicated
multiplier circuitry when it is available because it provides better performance and resource utilization. If
all of the input data widths are smaller than or equal to nine bits, the function uses the 9 × 9 multiplier
configuration in the dedicated multiplier. Otherwise, 18 × 18 multipliers are used to process data with
widths between 10 bits and 18 bits.
For information about the architecture of the DSP blocks and embedded multipliers, and for detailed
information about the hardware conversion process, refer to the DSP block and embedded multiplier
chapters in the Stratix device series, Stratix II, Stratix III, and Cyclone II handbooks on the Literature and
Technical Documentation page.
The following table provides resource utilization and performance information for the LPM_MULT
megafunction.
Table 4-1: LPM_MULT Resource Utilization and Performance
Device family
Input data
width
Output
latency
Logic Usage
18-bit DSP f
MAX
(MHz) (2)
Adaptive
Look-Up
Table
(ALUT)
Dedicated
Logic
Register
(DLR)
Adaptive
Logic
Module
(ALM)
Stratix III 8 × 8 0 0 0 0 1
N/A 16 × 16 0 0 0 0 2
32 × 32 0 0 0 0 4
16 × 16 3 0 0 0 2 645
32 × 32 3 0 0 0 4 454
64 × 64 3 92 128 82 16 191
Verilog HDL Prototype
The following Verilog HDL prototype is located in the Verilog Design File (.v) lpm.v in the
installation directory>\eda\synthesis directory.
module lpm_mult ( result, dataa, datab, sum, clock, clken, aclr )
parameter lpm_type = "lpm_mult";
parameter lpm_widtha = 1;
parameter lpm_widthb = 1;
parameter lpm_widths = 1;
parameter lpm_widthp = 1;
parameter lpm_representation = "UNSIGNED";
parameter lpm_pipeline = 0;
parameter lpm_hint = "UNUSED";
input clock;
input clken;
input aclr;
input [lpm_widtha-1:0] dataa;
input [lpm_widthb-1:0] datab;
(2) The performance of the megafunction is dependant on the value of the maximum allowable ceiling f
MAX
that the selected device can achieve. Therefore, results may vary from the numbers stated in this column.
4-2 Verilog HDL Prototype
UG-01063
2014.12.19
Altera Corporation LPM_MULT (Multiplier)
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