-- EMACS settings: -*- tab-width: 2; indent-tabs-mode: t -*-
-- vim: tabstop=2:shiftwidth=2:noexpandtab
-- kate: tab-width 2; replace-tabs off; indent-width 2;
--
-- ============================================================================
-- Package: Common functions and types
--
-- Authors: Thomas B. Preusser
-- Martin Zabel
-- Patrick Lehmann
--
-- Description:
-- ------------------------------------
-- For detailed documentation see below.
--
-- License:
-- ============================================================================
-- Copyright 2007-2015 Technische Universitaet Dresden - Germany
-- Chair for VLSI-Design, Diagnostics and Architecture
--
-- Licensed under the Apache License, Version 2.0 (the "License");
-- you may not use this file except in compliance with the License.
-- You may obtain a copy of the License at
--
-- http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
-- ============================================================================
library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.numeric_std.all;
library PoC;
use PoC.my_config.all;
package utils is
-- PoC settings
-- ==========================================================================
constant POC_VERBOSE : BOOLEAN := MY_VERBOSE;
-- Environment
-- ==========================================================================
-- Distinguishes simulation from synthesis
constant SIMULATION : BOOLEAN; -- deferred constant declaration
-- Type declarations
-- ==========================================================================
--+ Vectors of primitive standard types +++++++++++++++++++++++++++++++++++++
type T_BOOLVEC is array(NATURAL range <>) of BOOLEAN;
type T_INTVEC is array(NATURAL range <>) of INTEGER;
type T_NATVEC is array(NATURAL range <>) of NATURAL;
type T_POSVEC is array(NATURAL range <>) of POSITIVE;
type T_REALVEC is array(NATURAL range <>) of REAL;
--+ Integer subranges sometimes useful for speeding up simulation ++++++++++
subtype T_INT_8 is INTEGER range -128 to 127;
subtype T_INT_16 is INTEGER range -32768 to 32767;
subtype T_UINT_8 is INTEGER range 0 to 255;
subtype T_UINT_16 is INTEGER range 0 to 65535;
--+ Enums ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- Intellectual Property (IP) type
type T_IPSTYLE is (IPSTYLE_HARD, IPSTYLE_SOFT);
-- Bit Order
type T_BIT_ORDER is (LSB_FIRST, MSB_FIRST);
-- Byte Order (Endian)
type T_BYTE_ORDER is (LITTLE_ENDIAN, BIG_ENDIAN);
-- rounding style
type T_ROUNDING_STYLE is (ROUND_TO_NEAREST, ROUND_TO_ZERO, ROUND_TO_INF, ROUND_UP, ROUND_DOWN);
type T_BCD is array(3 downto 0) of std_logic;
type T_BCD_VECTOR is array(NATURAL range <>) of T_BCD;
constant C_BCD_MINUS : T_BCD := "1010";
constant C_BCD_OFF : T_BCD := "1011";
-- Function declarations
-- ==========================================================================
--+ Division ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- Calculates: ceil(a / b)
function div_ceil(a : NATURAL; b : POSITIVE) return NATURAL;
--+ Power +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- is input a power of 2?
function is_pow2(int : NATURAL) return BOOLEAN;
-- round to next power of 2
function ceil_pow2(int : NATURAL) return POSITIVE;
-- round to previous power of 2
function floor_pow2(int : NATURAL) return NATURAL;
--+ Logarithm ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- Calculates: ceil(ld(arg))
function log2ceil(arg : positive) return natural;
-- Calculates: max(1, ceil(ld(arg)))
function log2ceilnz(arg : positive) return positive;
-- Calculates: ceil(lg(arg))
function log10ceil(arg : POSITIVE) return NATURAL;
-- Calculates: max(1, ceil(lg(arg)))
function log10ceilnz(arg : POSITIVE) return POSITIVE;
--+ if-then-else (ite) +++++++++++++++++++++++++++++++++++++++++++++++++++++
function ite(cond : BOOLEAN; value1 : BOOLEAN; value2 : BOOLEAN) return BOOLEAN;
function ite(cond : BOOLEAN; value1 : INTEGER; value2 : INTEGER) return INTEGER;
function ite(cond : BOOLEAN; value1 : REAL; value2 : REAL) return REAL;
function ite(cond : BOOLEAN; value1 : STD_LOGIC; value2 : STD_LOGIC) return STD_LOGIC;
function ite(cond : BOOLEAN; value1 : STD_LOGIC_VECTOR; value2 : STD_LOGIC_VECTOR) return STD_LOGIC_VECTOR;
function ite(cond : BOOLEAN; value1 : BIT_VECTOR; value2 : BIT_VECTOR) return BIT_VECTOR;
function ite(cond : BOOLEAN; value1 : UNSIGNED; value2 : UNSIGNED) return UNSIGNED;
function ite(cond : BOOLEAN; value1 : CHARACTER; value2 : CHARACTER) return CHARACTER;
function ite(cond : BOOLEAN; value1 : STRING; value2 : STRING) return STRING;
--+ Max / Min / Sum ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
function imin(arg1 : integer; arg2 : integer) return integer; -- Calculates: min(arg1, arg2) for integers
function rmin(arg1 : real; arg2 : real) return real; -- Calculates: min(arg1, arg2) for reals
function imin(vec : T_INTVEC) return INTEGER; -- Calculates: min(vec) for a integer vector
function imin(vec : T_NATVEC) return NATURAL; -- Calculates: min(vec) for a natural vector
function imin(vec : T_POSVEC) return POSITIVE; -- Calculates: min(vec) for a positive vector
function rmin(vec : T_REALVEC) return real; -- Calculates: min(vec) of real vector
function imax(arg1 : integer; arg2 : integer) return integer; -- Calculates: max(arg1, arg2) for integers
function rmax(arg1 : real; arg2 : real) return real; -- Calculates: max(arg1, arg2) for reals
function imax(vec : T_INTVEC) return INTEGER; -- Calculates: max(vec) for a integer vector
function imax(vec : T_NATVEC) return NATURAL; -- Calculates: max(vec) for a natural vector
function imax(vec : T_POSVEC) return POSITIVE; -- Calculates: max(vec) for a positive vector
function rmax(vec : T_REALVEC) return real; -- Calculates: max(vec) of real vector
function isum(vec : T_NATVEC) return NATURAL; -- Calculates: sum(vec) for a natural vector
function isum(vec : T_POSVEC) return natural; -- Calculates: sum(vec) for a positive vector
function isum(vec : T_INTVEC) return integer; -- Calculates: sum(vec) of integer vector
function rsum(vec : T_REALVEC) return real; -- Calculates: sum(vec) of real vector
--+ Conversions ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- to integer: to_int
function to_int(bool : BOOLEAN; zero : INTEGER := 0; one : INTEGER := 1) return INTEGER;
function to_int(sl : STD_LOGIC; zero : INTEGER := 0; one : INTEGER := 1) return INTEGER;
-- to std_logic: to_sl
function to_sl(Value : BOOLEAN) return STD_LOGIC;
function to_sl(Value : CHARACTER) return STD_LOGIC;
-- to std_logic_vector: to_slv
function to_slv(Value : NATURAL; Size : POSITIVE) return STD_LOGIC_VECTOR; -- short for std_logic_vector(to_unsigned(Value, Size))
-- TODO: comment
function to_index(slv : UNSIGNED; max : NATURAL := 0) return INTEGER;
function to_index(slv : STD_LOGIC_VECTOR; max : NATURAL := 0) return INTEGER;
-- is_*
function is_sl(c : CHARACTER) return BOOLEAN;
--+ Basic Vector Utilities +++++++++++++++++++++++++++++++++++++++++++++++++
-- Aggregate functions
function slv_or (vec : STD_LOGIC_VECTOR) return STD_LOGIC;
function slv_nor (vec : STD_LOGIC_VECTOR) return STD_LOGIC;
function slv_and (vec : STD_LOGIC_VECTOR) return STD_LOGIC;
function slv_nand(vec : STD_LOGIC_VECTOR) return STD_LOGIC;
function slv_xor (vec : std_logic_vector) return std_logic;
-- NO slv_xnor! This operation would not be well-defined as
-- not xor(vec) /= vec_{n-1} xnor ... xnor vec_1 xnor vec_0 iff n is odd.
-- Reverses the elements of the passed Vector.
--
-- @synthesis supported
--
function reverse(vec : std_logic_vector) return std_logic_vector;
function reverse(vec : bit_vector) return bit_vector;
function reverse(vec : unsigned) return unsigned;
-- Resizes the vector to the specified length. The adjustment is make on
-- on the 'high end of the vector. The 'low index remains as in the argument.
-- If the result vector is larger, the extension uses the provided fill value
-- (default: '0').
-- Use the resize functions of the numeric_std package for value-preserving
-- resizes of the signed and unsigned data types.
--
-- @synthesis supported
--
function resize(vec : bit_vector; length : natural; fill : bit := '0')
return bit_vector;
function resize(vec : std_logic_vector; length : natural; fill : std_logic := '0')
return std_logic_vector;
-- Shift the index range of a vector by the specified offset.
function move(vec : std_logic_vector; ofs : integer) return std_logic_vector;
-- Shift the index range of a vector making vec'low = 0.
function movez(vec : std_logic_vector) return std_logic_vector;
function ascend(vec : std_logic_vector) return std_logic_vector;
function descend(vec : std_logic_vector) return std_logic_vector;
-- Least-Significant Set Bit (lssb):
-- Computes a vector of the same length as the argument with
-- at most one bit set at the rightmost '1' found in arg.
--
-- @synthesis supported
--
function lssb(arg : std_logic_vector) return std_logic_vector;
function lssb(arg : bit_vector) return bit_vector;
-- Returns the index of the least-significant set bit.
--
-- @synthesis supported
--
function lssb_idx(arg : std_logic_vector) return integer;
function lssb_idx(arg : bit_vector) return integer;
-- Most-Significant Set Bit (mssb): computes a vector of the same length
-- with at most one bit set at the leftmost '1' found in arg.
function mssb(arg : std_logic_vector) return std_logic_vector;
function mssb(arg : bit_vector) return bit_vector;
function mssb_idx(arg : std_logic_vector) return integer;
function mssb_idx(arg : bit_vector) return integer;
-- Swap sub vectors in vector (endian reversal)
function swap(slv : STD_LOGIC_VECTOR; Size : POSITIVE) return STD_LOGIC_VECTOR;
-- generate bit masks
function genmask_high(Bits : NATURAL; MaskLength : POSITIVE) return STD_LOGIC_VECTOR;
function genmask_low(Bits : NATURAL; MaskLength : POSITIVE) return STD_LOGIC_VECTOR;
--+ Encodings ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-- One-Hot-Code to Binary-Code.
function onehot2bin(onehot : std_logic_vector) return unsigned;
-- Converts Gray-Code into Binary-Code.
--
-- @synthesis supported
--
function gray2bin (gray_val : std_logic_vector) return std_logic_vector;
-- Binary-Code to One-Hot-Code
function bin2onehot(value : std_logic_vector) return std_logic_vector;
-- Binary-Code to Gray-Code
function bin2gray(value : std_logic_vector) return std_logic_vector;
end package;
package body utils is
-- Environment
-- ==========================================================================
function is_simulation return boolean is
variable ret : boolean;
begin
ret := false;
--synthesis translate_off
if Is_X('X') then ret := true; end if;
--synthesis translate_on
return ret;
end function;
-- deferred constant assignment
constant SIMULATION : BOOLEAN := is_simulation;
-- Divisions: div_*
function div_ceil(a : NATURAL; b : POSITIVE) return NATURAL is -- calculates: ceil(a / b)
begin
return (a + (b - 1)) / b;
end function;
-- Power functions: *_pow2
-- ==========================================================================
-- is input a power of 2?
function is_pow2(int : NATURAL) return BOOLEAN is
begin
return ceil_pow2(int) = int;
end function;
-- round to next power of 2
function ceil_pow2(int : NATURAL) return POSITIVE is
begin
return 2 ** log2ceil(int);
end function;
-- round to previous power of 2
function floor_pow2(int : NATURAL) return NATURAL is
variable temp : UNSIGNED(30 downto 0);
begin
temp := to_unsigned(int, 31);
for i in temp'range loop
if (temp(i) = '1') then
return 2 ** i;
end if;
end loop;
return 0;
end function;
-- Logarithms: log*ceil*
-- ==========================================================================
function log2ceil(arg : positive) return natural is
variable tmp : positive;
variable log : natural;
begin
if arg = 1 then return 0; end if;
tmp := 1;
log := 0;
while arg > tmp loop
tmp := tmp * 2;
log := log + 1;
end loop;
return log;
end function;
function log2ceilnz(arg : positive) return positive is
begin
return imax(1, log2ceil(arg));
end function;
function log10ceil(arg : positive) return natural is
variable tmp : positive;
variable log : natural;
begin
if arg = 1 then return 0; end if;
tmp := 1;
log := 0;
while arg > tmp loop
tmp := tmp * 10;
log := log + 1;
end loop;
return log;
end function;
function log10ceilnz(arg : positive) return positive is
begin
return imax(1, log10ceil(arg));
end function;
-- if-then-else (ite)
-- ==========================================================================
function ite(cond : BOOLEAN; value1 : BOOLEAN; value2 : BOOLEAN) return BOOLEAN is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : INTEGER; value2 : INTEGER) return INTEGER is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : REAL; value2 : REAL) return REAL is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : STD_LOGIC; value2 : STD_LOGIC) return STD_LOGIC is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : STD_LOGIC_VECTOR; value2 : STD_LOGIC_VECTOR) return STD_LOGIC_VECTOR is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : BIT_VECTOR; value2 : BIT_VECTOR) return BIT_VECTOR is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : UNSIGNED; value2 : UNSIGNED) return UNSIGNED is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : CHARACTER; value2 : CHARACTER) return CHARACTER is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
function ite(cond : BOOLEAN; value1 : STRING; value2 : STRING) return STRING is
begin
if cond then
return value1;
else
return value2;
end if;
end function;
-- *min / *max / *sum
-- ==========================================================================
function imin(arg1 : integer; arg2 : integer) return integer is
begin
if arg1 < arg2 then return arg1; end if;
return arg2;
end function;
function rmin(arg1 : real; arg2 : real) return real is
begin
if arg1 < arg2 then return arg1; end if;
return arg2;
end function;
function imin(vec : T_INTVEC) return INTEGER is
variable Result : INTEGER;
begin
Result := INTEGER'high;
for i in vec'range loop
if (vec(I) < Result) then
Result := vec(I);
end if;
end loop;
return Result;
end function;
function imin(vec : T_NATVEC) return NATURAL is
variable Result : NATURAL;
begin
Result := NATURAL'high;
for i in vec'range loop
if (vec(I) < Result) then
Result := vec(I);
end if;
end loop;
return Result;
end function;
function imin(vec : T_POSVEC) return POSITIVE is
variable Result : POSITIVE;
begin
Result := POSITIVE'high;
for i in vec'range loop
if (vec(I) < Result) then
Result := vec(I);
end if;
end loop;
return Result;
end function;
function rmin(vec : T_REALVEC) return REAL is
variable Result : REAL;
begin
Result := REAL'high;
for i in vec'range loop
if vec(i) < Result then
Result := vec(i);
end if;
end loop;
return Result;
end function;
function imax(arg1 : integer; arg2 : integer) return integer is
begin
if arg1 > arg2 then return arg1; end if;
return arg2;
end function;
function rmax(arg1 : real; arg2 : real) return real is
begin
if arg1 > arg2 then return arg1; end if;
return arg2;
end function;
function imax(vec : T_INTVEC) return INTEGER is
variable Result : INTEGER;
begin
Result := INTEGER'low;
for i in vec'range loop
if (vec(I) > Result) then
Result := vec(I);
end if;
end loop;
return Result;
end function;
function imax(vec : T_NATVEC) return NATURAL is
variable Result : NATURAL;
begin
Result := NATURAL'low;
for i in vec'range loop
if (vec(I) > Result) then
Result := vec(I);
end if;
end loop;
return Result;
end function;
function imax(vec : T_POSVEC) return POSITIVE is
variable Result : POSITIVE;
begin
Result := POSITIVE'low;
for i in vec'range loop
if (vec(I) > Result) then
Result := vec(I);
end if;
end loop;
return Result;
end function;
function rmax(vec : T_REALVEC) return REAL is
variable Result : REAL;
begin
Result := REAL'low;
for i in vec'range loop
if vec(i) > Result then
Result := vec(i);
end if;
end loop;
return Result;
end function;
function isum(vec : T_INTVEC) return INTEGER is
variable Result : INTEGER;
begin
Result := 0;
for i in vec'range loop
Result := Result + vec(i);
end loop;
return Result;
end function;
function isum(vec : T_NATVEC) return NATURAL is
variable Result : NATURAL;
begin
Result := 0;
for i in vec'range loop
Result := Result + vec(I);
end loop;
return Result;
end function;
function isum(vec : T_POSVEC) return natural is
variable Result : natural;
begin
Result := 0;
for i in vec'range loop
Result := Result + vec(I);
end loop;
return Result;
end function;
function rsum(vec : T_REALVEC) return REAL is
variable Result : REAL;
begin
Result := 0.0;
for i in vec'range loop
Result := Result + vec(i);
end loop;
return Result;
end function;
-- Vector aggregate functions: slv_*
-- ==========================================================================
function slv_or(vec : STD_LOGIC_VECTOR) return STD_LOGIC is
variable Result : STD_LOGIC;
begin
Result := '0';
for i in vec'range loop
Result := Result or vec(i);
end loop;
return Result;
end function;
function slv_nor(vec : STD_LOGIC_VECTOR) return STD_LOGIC is
begin
return not slv_or(vec);
end function;
function slv_and(vec : STD_LOGIC_VECTOR) return STD_LOGIC is
variable Result : STD_LOGIC;
begin
Result := '1';
for i in vec'range loop
Result := Result and vec(i);
end loop;
return Result;
end function;
function slv_nand(vec : STD_LOGIC_VECTOR) return STD_LOGIC is
begin
return not slv_and(vec);
end function;
function slv_xor(vec : std_logic_vector) return std_logic is
variable res : std_logic;
begin
res := '0';
for i in vec'range loop
res := res xor vec(i);
end loop;
return res;
end slv_xor;
-- Convert to integer: to_int
function to_int(bool : BOOLEAN; zero : INTEGER := 0; one : INTEGER := 1) return INTEGER is
begin
return ite(bool, one, zero);
end function;
function to_int(sl : STD_LOGIC; zero : INTEGER := 0; one : INTEGER := 1) return INTEGER is
begin
if (sl = '1') then
return one;
end if;
return zero;
end function;
-- Convert to bit: to_sl
-- ==========================================================================
function to_sl(Value : BOOLEAN) return STD_LOGIC is
begin
return ite(Value, '1', '0');
end function;
function to_sl(Value : CHARACTER) return STD_LOGIC is
begin
case Value is
when 'U' => return 'U';
when '0' => return '0';
when '1' => return '1';
when 'Z' => return 'Z';
when 'W' => return 'W';
when 'L' => return 'L';
when 'H' => return 'H';
when '-' => return '-';
when OTHERS => return 'X';
end case;
end function;
-- Convert to vector: to_slv
-- ==========================================================================
-- short for std_logic_vector(to_unsigned(Value, Size))
-- the return value is guaranteed to have the range (Size-1 downto 0)
function to_slv(Value : NATURAL; Size : POSITIVE) return STD_LOGIC_VECTOR is
constant res : std_logic_vector(Size-1 downto 0) := std_logic_vector(to_unsigned(Value, Size));
begin
return res;
end function;
function to_index(slv : UNSIGNED; max : NATURAL := 0) return INTEGER is
variable res : integer;
begin
if (slv'length = 0) then return 0; end if;
res := to_integer(slv);
if SIMULATION and max > 0 then
res := imin(res, max);
end if;
return res;
end function;
function to_index(slv : STD_LOGIC_VECTOR; max : NATURAL := 0) return INTEGER is
begin
return to_index(unsigned(slv), max);
end function;
-- is_*
-- ==========================================================================
function is_sl(c : CHARACTER) return BOOLEAN is
begin
case c is
when 'U'|'X'|'0'|'1'|'Z'|'W'|'L'|'H'|'-' => return true;
when OTHERS => return false;
end case;
end function;
-- Reverse vector elements
function reverse(vec : std_logic_vector) return std_logic_vector is
variable res : std_logic_vector(vec'range);
begin
for i in vec'low to vec'high loop
res(vec'low + (vec'high-i)) := vec(i);
end loop;
return res;
end function;
function reverse(vec : bit_vector) return bit_vector is
variable res : bit_vector(vec'range);
begin
res := to_bitvector(reverse(to_stdlogicvector(vec)));
return res;
end reverse;
function reverse(vec : unsigned) return unsigned is
begin
return unsigned(reverse(std_logic_vector(vec)));
end function;
-- Swap sub vectors in vector
-- ==========================================================================
function swap(slv : STD_LOGIC_VECTOR; Size : POSITIVE) return STD_LOGIC_VECTOR IS
CONSTANT SegmentCount : NATURAL := slv'length / Size;
variable FromH : NATURAL;
variable FromL : NATURAL;
variable ToH : NATURAL;
variable ToL : NATURAL;
variable Result : STD_LOGIC_VECTOR(slv'length - 1 DOWNTO 0);
begin
for i in 0 TO SegmentCount - 1 loop
FromH := ((I + 1) * Size) - 1;
FromL := I * Size;
ToH := ((SegmentCount - I) * Size) - 1;
ToL := (SegmentCount - I - 1) * Size;
Result(ToH DOWNTO ToL) := slv(FromH DOWNTO FromL);
end loop;
return Result;
end function;
-- generate bit masks
-- ==========================================================================
function genmask_high(Bits : NATURAL; MaskLength : POSITIVE) return STD_LOGIC_VECTOR IS
begin
if (Bits = 0) then
return (MaskLength - 1 DOWNTO 0 => '0');
else
return (MaskLength - 1 DOWNTO MaskLength - Bits + 1 => '1') & (MaskLength - Bits DOWNTO 0 => '0');
end if;
end function;
function genmask_low(Bits : NATURAL; MaskLength : POSITIVE) return STD_LOGIC_VECTOR is
begin
if (Bits = 0) then
return (MaskLength - 1 DOWNTO 0 => '0');
else
return (MaskLength - 1 DOWNTO Bits => '0') & (Bits - 1 DOWNTO 0 => '1');
end if;
end function;
-- binary encoding conversion functions
-- ==========================================================================
-- One-Hot-Code to Binary-Code
function onehot2bin(onehot : std_logic_vector) return unsigned is
variable res : unsigned(log2ceilnz(onehot'high+1)-1 downto 0);
variable chk : natural;
begin
res := (others => '0');
chk := 0;
for i in onehot'range loop
if onehot(i) = '1' then
res := res or to_unsigned(i, res'length);
chk := chk + 1;
end if;
end loop;
if SIMULATION and chk /= 1 then
report "Broken 1-Hot-Code with "&integer'image(chk)&" bits set."
severity error;
end if;
return res;
end onehot2bin;
-- Gray-Code to Binary-Code
function gray2bin(gray_val : std_logic_vector) return std_logic_vector is
variable res : std_logic_vector(gray_val'range);
begin -- gray2bin
res(res'left) := gray_val(gray_val'left);
for i in res'left-1 downto res'right loop
res(i) := res(i+1) xor gray_val(i);
end loop;
return res;
end gray2bin;
-- Binary-Code to One-Hot-Code
function bin2onehot(value : std_logic_vector) return std_logic_vector is
variable result : std_logic_vector(2**value'length - 1 downto 0);
begin
result := (others => '0');
result(to_index(value, 0)) := '1';
return result;
end function;
-- Binary-Code to Gray-Code
function bin2gray(value : std_logic_vector) return std_logic_vector is
variable result : std_logic_vector(value'range);
begin
result(result'left) := value(value'left);
for i in (result'left - 1) downto result'right loop
result(i) := value(i) xor value(i + 1);
end loop;
return result;
end function;
-- bit searching / bit indices
-- ==========================================================================
-- Least-Significant Set Bit (lssb): computes a vector of the same length with at most one bit set at the rightmost '1' found in arg.
function lssb(arg : std_logic_vector) return std_logic_vector is
variable res : std_logic_vector(arg'range);
begin
res := arg and std_logic_vector(unsigned(not arg)+1);
return res;
end function;
function lssb(arg : bit_vector) return bit_vector is
variable res : bit_vector(arg'range);
begin
res := to_bitvector(lssb(to_stdlogicvector(arg)));
return res;
end lssb;
-- Most-Significant Set Bit (mssb): computes a vector of the same length with at most one bit set at the leftmost '1' found in arg.
function mssb(arg : std_logic_vector) return std_logic_vector is
begin
return reverse(lssb(reverse(arg)));
end function;
function mssb(arg : bit_vector) return bit_vector is
begin
return reverse(lssb(reverse(arg)));
end mssb;
-- Index of lssb
function lssb_idx(arg : std_logic_vector) return integer is
begin
return to_integer(onehot2bin(lssb(arg)));
end function;
function lssb_idx(arg : bit_vector) return integer is
variable slv : std_logic_vector(arg'range);
begin
slv := to_stdlogicvector(arg);
return lssb_idx(slv);
end lssb_idx;
-- Index of mssb
function mssb_idx(arg : std_logic_vector) return integer is
begin
return to_integer(onehot2bin(mssb(arg)));
end function;
function mssb_idx(arg : bit_vector) return integer is
variable slv : std_logic_vector(arg'range);
begin
slv := to_stdlogicvector(arg);
return mssb_idx(slv);
end mssb_idx;
function resize(vec : bit_vector; length : natural; fill : bit := '0') return bit_vector is
constant high2b : natural := vec'low+length-1;
constant highcp : natural := imin(vec'high, high2b);
variable res_up : bit_vector(vec'low to high2b);
variable res_dn : bit_vector(high2b downto vec'low);
begin
if vec'ascending then
res_up := (others => fill);
res_up(vec'low to highcp) := vec(vec'low to highcp);
return res_up;
else
res_dn := (others => fill);
res_dn(highcp downto vec'low) := vec(highcp downto vec'low);
return res_dn;
end if;
end resize;
function resize(vec : std_logic_vector; length : natural; fill : std_logic := '0') return std_logic_vector is
constant high2b : natural := vec'low+length-1;
constant highcp : natural := imin(vec'high, high2b);
variable res_up : std_logic_vector(vec'low to high2b);
variable res_dn : std_logic_vector(high2b downto vec'low);
begin
if vec'ascending then
res_up := (others => fill);
res_up(vec'low to highcp) := vec(vec'low to highcp);
return res_up;
else
res_dn := (others => fill);
res_dn(highcp downto vec'low) := vec(highcp downto vec'low);
return res_dn;
end if;
end resize;
-- Move vector boundaries
-- ==========================================================================
function move(vec : std_logic_vector; ofs : integer) return std_logic_vector is
variable res_up : std_logic_vector(vec'low +ofs to vec'high+ofs);
variable res_dn : std_logic_vector(vec'high+ofs downto vec'low +ofs);
begin
if vec'ascending then
res_up := vec;
return res_up;
else
res_dn := vec;
return res_dn;
end if;
end move;
function movez(vec : std_logic_vector) return std_logic_vector is
begin
return move(vec, -vec'low);
end movez;
function ascend(vec : std_logic_vector) return std_logic_vector is
variable res : std_logic_vector(vec'low to vec'high);
begin
res := vec;
return res;
end ascend;
function descend(vec : std_logic_vector) return std_logic_vector is
variable res : std_logic_vector(vec'high downto vec'low);
begin
res := vec;
return res;
end descend;
end package body;