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Diffstat (limited to 'testsuite/vests/vhdl-ams/ashenden/compliant/access-types/bounded_buffer_adt.vhd')
-rw-r--r-- | testsuite/vests/vhdl-ams/ashenden/compliant/access-types/bounded_buffer_adt.vhd | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/testsuite/vests/vhdl-ams/ashenden/compliant/access-types/bounded_buffer_adt.vhd b/testsuite/vests/vhdl-ams/ashenden/compliant/access-types/bounded_buffer_adt.vhd new file mode 100644 index 000000000..3041d0380 --- /dev/null +++ b/testsuite/vests/vhdl-ams/ashenden/compliant/access-types/bounded_buffer_adt.vhd @@ -0,0 +1,114 @@ + +-- Copyright (C) 2002 Morgan Kaufmann Publishers, Inc + +-- This file is part of VESTs (Vhdl tESTs). + +-- VESTs is free software; you can redistribute it and/or modify it +-- under the terms of the GNU General Public License as published by the +-- Free Software Foundation; either version 2 of the License, or (at +-- your option) any later version. + +-- VESTs is distributed in the hope that it will be useful, but WITHOUT +-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or +-- FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +-- for more details. + +-- You should have received a copy of the GNU General Public License +-- along with VESTs; if not, write to the Free Software Foundation, +-- Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + +package bounded_buffer_adt is + + subtype byte is bit_vector(0 to 7); + + type bounded_buffer_object; -- private + + type bounded_buffer is access bounded_buffer_object; + + function new_bounded_buffer ( size : in positive ) return bounded_buffer; + -- creates a bounded buffer object with 'size' bytes of storage + + procedure test_empty ( variable the_bounded_buffer : in bounded_buffer; + is_empty : out boolean ); + -- tests whether the bounded buffer is empty (i.e., no data to read) + + procedure test_full ( variable the_bounded_buffer : in bounded_buffer; + is_full : out boolean ); + -- tests whether the bounded buffer is full (i.e., no data can be written) + + procedure write ( the_bounded_buffer : inout bounded_buffer; data : in byte ); + -- if the bounded buffer is not full, writes the data + -- if it is full, assertion violation with severity failure + + procedure read ( the_bounded_buffer : inout bounded_buffer; data : out byte ); + -- if the bounded buffer is not empty, read the first byte of data + -- if it is empty, assertion violation with severity failure + +---------------------------------------------------------------- + + -- the following types are private to the ADT + + type store_array is array (natural range <>) of byte; + + type store_ptr is access store_array; + + type bounded_buffer_object is record + byte_count : natural; + head_index, tail_index : natural; + store : store_ptr; + end record bounded_buffer_object; + +end package bounded_buffer_adt; + + + +package body bounded_buffer_adt is + + function new_bounded_buffer ( size : in positive ) return bounded_buffer is + begin + return new bounded_buffer_object'( + byte_count => 0, head_index => 0, tail_index => 0, + store => new store_array(0 to size - 1) ); + end function new_bounded_buffer; + + procedure test_empty ( variable the_bounded_buffer : in bounded_buffer; + is_empty : out boolean ) is + begin + is_empty := the_bounded_buffer.byte_count = 0; + end procedure test_empty; + + procedure test_full ( variable the_bounded_buffer : in bounded_buffer; + is_full : out boolean ) is + begin + is_full := the_bounded_buffer.byte_count = the_bounded_buffer.store'length; + end procedure test_full; + + procedure write ( the_bounded_buffer : inout bounded_buffer; data : in byte ) is + variable buffer_full : boolean; + begin + test_full(the_bounded_buffer, buffer_full); + if buffer_full then + report "write to full bounded buffer" severity failure; + else + the_bounded_buffer.store(the_bounded_buffer.tail_index) := data; + the_bounded_buffer.tail_index := (the_bounded_buffer.tail_index + 1) + mod the_bounded_buffer.store'length; + the_bounded_buffer.byte_count := the_bounded_buffer.byte_count + 1; + end if; + end procedure write; + + procedure read ( the_bounded_buffer : inout bounded_buffer; data : out byte ) is + variable buffer_empty : boolean; + begin + test_empty(the_bounded_buffer, buffer_empty); + if buffer_empty then + report "read from empty bounded buffer" severity failure; + else + data := the_bounded_buffer.store(the_bounded_buffer.head_index); + the_bounded_buffer.head_index := (the_bounded_buffer.head_index + 1) + mod the_bounded_buffer.store'length; + the_bounded_buffer.byte_count := the_bounded_buffer.byte_count - 1; + end if; + end procedure read; + +end package body bounded_buffer_adt; |