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Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
15 years ago

meaning of a pacKage

1)i dont understand the meaning of this package:

package body dwt2dpkg is

function dwt2dctrlvector(x : in type_dwt2d_ctrl_signal_enum) return type_dwt2d_ctrl_signal is

begin

return type_dwt2d_ctrl_signal(to_unsigned(type_dwt2d_ctrl_signal_enum'pos(x), cst_dwt2d_ctrl_sig_bus_width));

end;

end dwt2dpkg;:confused::eek:

2)i dont understand the utility of this code:

type type_dwt2d_state is (

ts2d_ready,

ts2d_init_horiz,

ts2d_start_horiz,

ts2d_continue_horiz,

ts2d_init_vert,

ts2d_start_vert,

ts2d_continue_vert,

ts2d_next_level,

ts2d_terminate

);:confused::confused:

can any one explain it to me.

Thinks

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Package is a support vhdl program that is not meant to be a module like other design module but to insert any constants, functions in a neat way. It is optional. Most people use one package per project to insert their constants and functions. Others go as far as one package per module...too excessive.

    type my_states is (s0, s1,s2....etc);

    signal state : my_states;

    means you create your own type, meaning a replacement for vhdl own types like std_logic etc. in order to help readability. For example it is convenient to use s0,s1,s2 than explicit binary value. The compiler then is free to encode the states.