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Upd clogb2 info

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This commit is contained in:
Konstantin Pavlov 2023-04-25 15:24:36 +03:00
parent 93bb8db9b8
commit 9d51a2b2d2
1 changed files with 24 additions and 1 deletions
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clogb2.svh
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@ -7,6 +7,28 @@
// INFO ------------------------------------------------------------------------
// Calculates counter/address width based on specified vector/RAM depth
//
// see also: http://www.sunburst-design.com/papers/CummingsHDLCON2001_Verilog2001.pdf
//
// Compared with system function $clog2():
// =======================================
// $clog2(0) = 0; clogb2(0) = 0;
// $clog2(1) = 0; clogb2(1) = 1;
// $clog2(2) = 1; clogb2(2) = 2;
// $clog2(3) = 2; clogb2(3) = 2;
// $clog2(4) = 2; clogb2(4) = 3;
// $clog2(5) = 3; clogb2(5) = 3;
// $clog2(6) = 3; clogb2(6) = 3;
// $clog2(7) = 3; clogb2(7) = 3;
// $clog2(8) = 3; clogb2(8) = 4;
// $clog2(9) = 4; clogb2(9) = 4;
// $clog2(10)= 4; clogb2(10)= 4;
// $clog2(11)= 4; clogb2(11)= 4;
// $clog2(12)= 4; clogb2(12)= 4;
// $clog2(13)= 4; clogb2(13)= 4;
// $clog2(14)= 4; clogb2(14)= 4;
// $clog2(15)= 4; clogb2(15)= 4;
// $clog2(16)= 4; clogb2(16)= 5;
//
// Function should be instantiated inside a module
// But you are free to call it from anywhere by its hierarchical name
//
@ -15,10 +37,11 @@
//
function integer clogb2;
input integer depth;
input [31:0] depth;
for( clogb2=0; depth>0; clogb2=clogb2+1 ) begin
depth = depth >> 1;
end
endfunction