Verilog Math Functions - ChipVerify

• Integer Math Functions
• Real Math Functions

Verilog math functions can be used in place of constant expressions and supports both integer and real maths.

Integer Math Functions

The function $clog2 returns the ceiling of log2 of the given argument. This is typically used to calculate the minimum width required to address a memory of given size.

For example, if the design has 7 parallel adders, then the minimum number of bits required to represent all 7 adders is $clog2 of 7 that yields 3.

module des #(parameter NUM_UNITS = 7) // Use of this system function helps to reduce the // number of input wires to this module (input [$clog2(NUM_UNITS)-1:0] active_unit); initial $monitor("active_unit = %d", active_unit); endmodule `define NUM_UNITS 5 module tb; integer i; reg [`NUM_UNITS-1:0] active_unit; des #(.NUM_UNITS(`NUM_UNITS)) u0(active_unit); initial begin active_unit = 1; #10 active_unit = 7; #10 active_unit = 8; end endmodule

Note that the signal active_unit has 3-bits to store total 5 units.

Output xcelium> run active_unit = 001 active_unit = 111 active_unit = 000 xmsim: *W,RNQUIE: Simulation is complete.

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Real Math Functions

These system functions accept real arguments and return a real number.

Function	Description
$ln(x)	Natural logarithm log(x)
$log10(x)	Decimal Logarithm log10(x)
exp(x)	Exponential of x (ex) where e=2.718281828...
sqrt(x)	Square root of x
$pow(x, y)	xy
$floor(x)	Floor x
$ceil(x)	Ceiling x
$sin(x)	Sine of x where x is in radians
$cos(x)	Cosine of x where x is in radians
$tan(x)	Tangent of x where x is in radians
$asin(x)	Arc-Sine of x
$acos(x)	Arc-Cosine of x
$atan(x)	Arc-tangent of x
$atan2(x, y)	Arc-tangent of x/y
$hypot(x, y)	Hypotenuse of x and y : sqrt(xx + yy)
$sinh(x)	Hyperbolic Sine of x
$cosh(x)	Hyperbolic-Cosine of x
$tanh(x)	Hyperbolic-Tangent of x
$asinh(x)	Arc-hyperbolic Sine of x
$acosh(x)	Arc-hyperbolic Cosine of x
$atanh(x)	Arc-hyperbolic tangent of x

module tb; real x, y; initial begin x = 10000; $display("$log10(%0.3f) = %0.3f", x, $log10(x)); x = 1; $display("$ln(%0.3f) = %0.3f", x, $ln(x)); x = 2; $display("$exp(%0.3f) = %0.3f", x, $exp(x)); x = 25; $display("$sqrt(%0.3f) = %0.3f", x, $sqrt(x)); x = 5; y = 3; $display("$pow(%0.3f, %0.3f) = %0.3f", x, y, $pow(x, y)); x = 2.7813; $display("$floor(%0.3f) = %0.3f", x, $floor(x)); x = 7.1111; $display("$ceil(%0.3f) = %0.3f", x, $ceil(x)); x = 30 * (22.0/7.0) / 180; // convert 30 degrees to radians $display("$sin(%0.3f) = %0.3f", x, $sin(x)); x = 90 * (22.0/7.0) / 180; $display("$cos(%0.3f) = %0.3f", x, $cos(x)); x = 45 * (22.0/7.0) / 180; $display("$tan(%0.3f) = %0.3f", x, $tan(x)); x = 0.5; $display("$asin(%0.3f) = %0.3f rad, %0.3f deg", x, $asin(x), $asin(x) * 7.0/22.0 * 180); x = 0; $display("$acos(%0.3f) = %0.3f rad, %0.3f deg", x, $acos(x), $acos(x) * 7.0/22.0 * 180); x = 1; $display("$atan(%0.3f) = %0.3f rad, %f deg", x, $atan(x), $atan(x) * 7.0/22.0 * 180); end endmodule Output xcelium> run $log10(10000.000) = 4.000 $ln(1.000) = 0.000 $exp(2.000) = 7.389 $sqrt(25.000) = 5.000 $pow(5.000, 3.000) = 125.000 $floor(2.781) = 2.000 $ceil(7.111) = 8.000 $sin(0.524) = 0.500 $cos(1.571) = -0.001 $tan(0.786) = 1.001 $asin(0.500) = 0.524 rad, 29.988 deg $acos(0.000) = 1.571 rad, 89.964 deg $atan(1.000) = 0.785 rad, 44.981895 deg xmsim: *W,RNQUIE: Simulation is complete.