library ieee; use ieee.std_logic_1164.all; package QueueP is generic ( type QUEUE_TYPE; MAX_LEN : natural := 64; function to_string(d : in QUEUE_TYPE) return string ); -- simple queue interface type t_simple_queue is protected procedure push (data : in QUEUE_TYPE); procedure pop (data : out QUEUE_TYPE); procedure init (logging : in boolean := false); impure function is_empty return boolean; impure function is_full return boolean; impure function fillstate return natural; end protected t_simple_queue; -- linked list queue interface type t_list_queue is protected procedure push (data : in QUEUE_TYPE); procedure pop (data : out QUEUE_TYPE); procedure init (logging : in boolean := false); impure function is_empty return boolean; impure function is_full return boolean; impure function fillstate return natural; end protected t_list_queue; end package QueueP; package body QueueP is -- simple queue implementation -- inspired by noasic article http://noasic.com/blog/a-simple-fifo-using-vhdl-protected-types/ type t_simple_queue is protected body type t_queue_array is array (0 to MAX_LEN-1) of QUEUE_TYPE; variable v_queue : t_queue_array; variable v_count : natural range 0 to t_queue_array'length := 0; variable v_head : natural range 0 to t_queue_array'high := 0; variable v_tail : natural range 0 to t_queue_array'high := 0; variable v_logging : boolean := false; -- write one entry into queue procedure push (data : in QUEUE_TYPE) is begin assert not(is_full) report "push into full queue -> discarded" severity failure; v_queue(v_head) := data; v_head := (v_head + 1) mod t_queue_array'length; v_count := v_count + 1; if v_logging then report t_simple_queue'instance_name & " pushed 0x" & to_string(data) & " into queue"; end if; end procedure push; -- read one entry from queue procedure pop (data : out QUEUE_TYPE) is variable v_data : QUEUE_TYPE; begin assert not(is_empty) report "pop from empty queue -> discarded" severity failure; v_data := v_queue(v_tail); v_tail := (v_tail + 1) mod t_queue_array'length; v_count := v_count - 1; if v_logging then report t_simple_queue'instance_name & " popped 0x" & to_string(v_data) & " from queue"; end if; data := v_data; end procedure pop; -- returns true if queue is empty, false otherwise impure function is_empty return boolean is begin return v_count = 0; end function is_empty; -- returns true if queue is full, false otherwise impure function is_full return boolean is begin return v_count = t_queue_array'length; end function is_full; -- returns number of filled slots in queue impure function fillstate return natural is begin return v_count; end function fillstate; -- returns number of free slots in queue impure function freeslots return natural is begin return t_queue_array'length - v_count; end function freeslots; procedure init (logging : in boolean := false) is begin v_logging := logging; end procedure init; end protected body t_simple_queue; -- linked liste queue implementation type t_list_queue is protected body type t_entry; type t_entry_ptr is access t_entry; type t_data_ptr is access QUEUE_TYPE; type t_entry is record data : t_data_ptr; last_entry : t_entry_ptr; next_entry : t_entry_ptr; end record t_entry; variable v_head : t_entry_ptr; variable v_tail : t_entry_ptr; variable v_count : natural := 0; variable v_logging : boolean := false; -- write one entry into queue by -- creating new entry at head of list procedure push (data : in QUEUE_TYPE) is variable v_entry : t_entry_ptr; begin if (not(is_full)) then if (v_count /= 0) then v_entry := new t_entry; v_entry.data := new QUEUE_TYPE'(data); v_entry.last_entry := v_head; v_entry.next_entry := null; v_head := v_entry; v_head.last_entry.next_entry := v_head; else v_head := new t_entry; v_head.data := new QUEUE_TYPE'(data); v_head.last_entry := null; v_head.next_entry := null; v_tail := v_head; end if; v_count := v_count + 1; if v_logging then report t_list_queue'instance_name & " pushed 0x" & to_string(data) & " into queue"; end if; else assert false report "Push to full queue -> discared" severity warning; end if; end procedure push; -- read one entry from queue at tail of list and -- delete that entry from list after read procedure pop (data : out QUEUE_TYPE) is variable v_entry : t_entry_ptr := v_tail; variable v_data : QUEUE_TYPE; begin assert not(is_empty) report "pop from empty queue -> discarded" severity failure; v_data := v_tail.data.all; v_tail := v_tail.next_entry; deallocate(v_entry.data); deallocate(v_entry); v_count := v_count - 1; if v_logging then report t_list_queue'instance_name & " popped 0x" & to_string(v_data) & " from queue"; end if; data := v_data; end procedure pop; procedure init (logging : in boolean := false) is begin v_logging := logging; end procedure init; -- returns true if queue is full, false otherwise impure function is_full return boolean is begin return v_count = MAX_LEN; end function is_full; -- returns true if queue is empty, false otherwise impure function is_empty return boolean is begin return v_tail = null; end function is_empty; -- returns number of filled slots in queue impure function fillstate return natural is begin return v_count; end function fillstate; end protected body t_list_queue; end package body QueueP;