-- +---------------------------+
-- | Copyright 1996 DOULOS |
-- | Generic Library |
-- | opened: 26 Nov 1995 |
-- +---------------------------+
-- Synthesis script: read -f vhdl gen_conv.bdy
library ieee;
library vfp;
package body generic_conversions is
use ieee.std_logic_1164.all;
use vfp.twos_complement_types.all;
use vfp.generic_functions.all;
-- std_ulogic_vector -> integer
function to_integer (
a: std_ulogic_vector
) return integer is
variable y: integer := 0;
begin
y := 0;
if (a'length < 32) then
for i in a'length-1 downto 0 loop
y := y * 2;
if (a(i) = '1') or (a(i) = 'H') then
y := y + 1;
elsif (a(i) = 'U') or (a(i) = 'X') or (a(i) = 'Z') or
(a(i) = 'W') or (a(i) = '-') then
y := y + 0;
-- assert false
-- report "Error 0001." &
-- "Library = vfp." &
-- "Package Body = generic_conversions." &
-- "Function = to_integer." &
-- "The std_ulogic_vector input to this function MUST contain 0, 1, L, or H."
-- severity error;
-- upon this assertion, 0 will have effectively been added to y
-- else y := y + 0; thus there's no update to y for this "bit" anyway
end if;
end loop;
else
assert false
report "Error 0002." &
"Library = vfp." &
"Package Body = generic_conversions." &
"Function = to_integer." &
"The std_ulogic_vector input to this function MUST be less than 32 bits."
severity error;
end if;
return y; -- y returns 0 if std_ulogic_vector is > 31 bits
end to_integer;
-- std_logic_vector -> integer
function to_integer (
a: std_logic_vector
) return integer is
variable y: integer := 0;
begin
y := 0;
if (a'length < 32) then
for i in a'length-1 downto 0 loop
y := y * 2;
if (a(i) = '1') or (a(i) = 'H') then
y := y + 1;
elsif (a(i) = 'U') or (a(i) = 'X') or (a(i) = 'Z') or
(a(i) = 'W') or (a(i) = '-') then
y := y + 0;
-- assert false
-- report "Error 0001." &
-- "Library = vfp." &
-- "Package Body = generic_conversions." &
-- "Function = to_integer." &
-- "The std_logic_vector input to this function MUST contain 0, 1, L, or H."
-- severity error;
-- upon this assertion, 0 will have effectively been added to y
-- else y := y + 0; thus there's no update to y for this "bit" anyway
end if;
end loop;
else
assert false
report "Error 0002." &
"Library = vfp." &
"Package Body = generic_conversions." &
"Function = to_integer." &
"The std_logic_vector input to this function MUST be less than 32 bits."
severity error;
end if;
return y; -- y returns 0 if std_logic_vector is > 31 bits
end to_integer;
-- 2's complement -> integer
function to_integer (
a: twos_complement
) return integer is
variable y: integer := 0;
begin
if (a(a'length-1) = '1') or (a(a'length-1) = 'H') then
y := -1;
elsif (a(a'length-1) = 'U') or (a(a'length-1) = 'X') or (a(a'length-1) = 'Z') or
(a(a'length-1) = 'W') or (a(a'length-1) = '-') then
y := 0; -- was integer'low
-- assert false
-- report "Warning 0001." &
-- "Library = vfp." &
-- "Package Body = generic_conversions." &
-- "Function = to_integer (input = 2's complement)." &
-- "The 2's complement input to this function MUST contain 0, 1, L, or H."
-- severity warning;
-- upon this assertion, y will still be uninitialized
else -- a(i'length-1) is '0' or 'L'
y := 0;
end if;
for i in a'length-2 downto 0 loop
y := y * 2;
if (a(i) = '1') or (a(i) = 'H') then
y := y + 1;
elsif (a(i) = 'U') or (a(i) = 'X') or (a(i) = 'Z') or
(a(i) = 'W') or (a(i) = '-') then
y := y + 0;
-- assert false
-- report "Warning 0002." &
-- "Library = vfp." &
-- "Package Body = generic_conversions." &
-- "Function = to_integer (input = 2's complement)." &
-- "The 2's complement input to this function MUST contain 0, 1, L, or H."
-- severity warning;
-- upon this assertion, 0 will have effectively been added to y
-- else y := y + 0; thus there's no update to y for this "bit" anyway
end if;
end loop;
return y;
end to_integer;
-- integer -> std_ulogic_vector
function to_std_ulogic_vector (
a: integer
) return std_ulogic_vector is
constant y_length: integer := integer_wordlength (a);
constant a_threshold: integer := next_greater_binary_power_minus_1 (a);
variable y_ref: integer;
variable y: integer;
variable y_std_ulogic_vector: std_ulogic_vector(y_length-1 downto 0);
begin
y := a; -- y is a temp variable for conversion
if (a >= 0) then
y_ref := (a_threshold / 2) + 1; -- set the initial threshold for comparison
y_std_ulogic_vector(y_length-1) := '0';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of positive
if (y < y_ref) then
y_std_ulogic_vector(i) := '0';
else
y := y - y_ref; -- y = 0 signifies the end of the process
y_std_ulogic_vector(i) := '1';
end if;
y_ref := y_ref / 2;
end loop;
else
y_ref := -(a_threshold / 2) - 1; -- set the initial threshold for comparison
y_std_ulogic_vector(y_length-1) := '1';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of negative
if (y >= y_ref) then
y_std_ulogic_vector(i) := '1';
else
y := y - y_ref; -- y = -1 at the end of the process
y_std_ulogic_vector(i) := '0';
end if;
y_ref := y_ref / 2;
end loop;
end if;
return y_std_ulogic_vector;
end to_std_ulogic_vector;
-- integer -> std_logic_vector
function to_std_logic_vector (
a: integer
) return std_logic_vector is
constant y_length: integer := integer_wordlength (a);
constant a_threshold: integer := next_greater_binary_power_minus_1 (a);
variable y_ref: integer;
variable y: integer;
variable y_std_logic_vector: std_logic_vector(y_length-1 downto 0);
begin
y := a; -- y is a temp variable for conversion
if (a >= 0) then
y_ref := (a_threshold / 2) + 1; -- set the initial threshold for comparison
y_std_logic_vector(y_length-1) := '0';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of positive
if (y < y_ref) then
y_std_logic_vector(i) := '0';
else
y := y - y_ref; -- y = 0 signifies the end of the process
y_std_logic_vector(i) := '1';
end if;
y_ref := y_ref / 2;
end loop;
else
y_ref := -(a_threshold / 2) - 1; -- set the initial threshold for comparison
y_std_logic_vector(y_length-1) := '1';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of negative
if (y >= y_ref) then
y_std_logic_vector(i) := '1';
else
y := y - y_ref; -- y = -1 at the end of the process
y_std_logic_vector(i) := '0';
end if;
y_ref := y_ref / 2;
end loop;
end if;
return y_std_logic_vector;
end to_std_logic_vector;
-- integer -> std_ulogic_vector
function to_std_ulogic_vector (
a: integer;
width: integer
) return std_ulogic_vector is
constant y_length: integer := width;
constant a_threshold: integer := 2 ** (width-2);
variable y_ref: integer;
variable y: integer;
variable y_std_ulogic_vector: std_ulogic_vector(y_length-1 downto 0);
begin
y := a; -- y is a temp variable for conversion
if (a >= 0) then
y_ref := a_threshold; -- set the initial threshold for comparison
y_std_ulogic_vector(y_length-1) := '0';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of positive
if (y < y_ref) then
y_std_ulogic_vector(i) := '0';
else
y := y - y_ref; -- y = 0 signifies the end of the process
y_std_ulogic_vector(i) := '1';
end if;
y_ref := y_ref / 2;
end loop;
else
y_ref := -a_threshold; -- set the initial threshold for comparison
y_std_ulogic_vector(y_length-1) := '1';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of negative
if (y >= y_ref) then
y_std_ulogic_vector(i) := '1';
else
y := y - y_ref; -- y = -1 at the end of the process
y_std_ulogic_vector(i) := '0';
end if;
y_ref := y_ref / 2;
end loop;
end if;
return y_std_ulogic_vector;
end to_std_ulogic_vector;
-- 2's complement -> std_ulogic_vector
function to_std_ulogic_vector (
a: twos_complement
) return std_ulogic_vector is
variable y: std_ulogic_vector(a'length-1 downto 0);
begin
for i in a'length-1 downto 0 loop
y(i) := a(i);
end loop;
return y;
end to_std_ulogic_vector;
-- integer -> 2's complement
function to_twos_complement (
a: integer
) return twos_complement is
constant y_length: integer := integer_wordlength (a);
constant a_threshold: integer := next_greater_binary_power_minus_1 (a);
variable y_ref: integer;
variable y: integer;
variable y_2sC: twos_complement(y_length-1 downto 0);
begin
y := a; -- y is a temp variable for conversion
if (a >= 0) then
y_ref := (a_threshold / 2) + 1; -- set the initial threshold for comparison
y_2sC(y_length-1) := '0';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of positive
if (y < y_ref) then
y_2sC(i) := '0';
else
y := y - y_ref; -- y = 0 signifies the end of the process
y_2sC(i) := '1';
end if;
y_ref := y_ref / 2;
end loop;
else
y_ref := -(a_threshold / 2) - 1; -- set the initial threshold for comparison
y_2sC(y_length-1) := '1';
for i in y_length-2 downto 0 loop -- perform algorithmic conversion of negative
if (y >= y_ref) then
y_2sC(i) := '1';
else
y := y - y_ref; -- y = -1 at the end of the process
y_2sC(i) := '0';
end if;
y_ref := y_ref / 2;
end loop;
end if;
return y_2sC;
end to_twos_complement;
-- std_ulogic_vector -> 2's complement
function to_twos_complement (
a: std_ulogic_vector
) return twos_complement is
variable y: twos_complement(a'length-1 downto 0);
begin
for i in a'length-1 downto 0 loop
y(i) := a(i);
end loop;
return y;
end to_twos_complement;
end generic_conversions;
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