-- +---------------------------+
-- |   Copyright 1996 DOULOS   |
-- |      Generic Library      |
-- |    opened: 16 Feb 1995    |
-- +---------------------------+

library ieee;
library vfp;

package body generic_functions is
  use ieee.std_logic_1164.all;
      
-- ancillary function required in order to 
-- enable the "+" and "-" operators in std_operators 
-- to work with different length vectors.

-- NON-SYNTHESISABLE VHDL BEGIN
function longest (                      -- 27.02.95
  a, b: std_ulogic_vector 
) return integer is
  variable y: integer;
begin
  if (a'length >= b'length) then
    y := a'length;
  else
    y := b'length;
  end if;
  return y;
end longest;
-- NON-SYNTHESISABLE VHDL END

function longest (                      -- 27.02.95
  a, b: std_logic_vector 
) return integer is
  variable y: integer;
begin
  if (a'length >= b'length) then
    y := a'length;
  else
    y := b'length;
  end if;
  return y;
end longest;

function longest (                      -- 25.11.95
  a, b: twos_complement 
) return integer is
  variable y: integer;
begin
  if (a'length >= b'length) then
    y := a'length;
  else
    y := b'length;
  end if;
  return y;
end longest;

function is_factor_of_32 (a: integer) return boolean is       -- 15.11.95
begin
  case a is
    when 1 | 2 | 4 | 8 | 16 | 32 =>
      return TRUE;
    when others =>
      return FALSE;
  end case;
end is_factor_of_32;

function is_power_of_2 (a: integer) return boolean is       -- 15.11.95
begin
  case a is
    when 1 | 2 | 4 | 8 | 16 | 32 | 64 | 128 | 256 | 512 | 1024 | 2048 |
         4096 | 8192 | 16384 | 32768 | 65536 | 131072 | 262144 | 524288 |
         1048576 | 2097152 | 4194304 | 8388608 | 16777216 | 33554432 |
         67108864 | 134217728 | 268435456 | 536870912 | 1073741824 =>
      return TRUE;
    when others =>
      return FALSE;
  end case;
end is_power_of_2;

function log_2 (a: integer) return integer is       -- 15.11.95
  variable remainder : integer;
  variable log_2 : integer;
begin
  if a > 0  then
    return integer_wordlength(a) - 2;
  else
    assert FALSE
      report "log_2(a) returns an out-of-range value"
      severity warning;
    return integer'low; -- a stupid value => a 2**32-bit vector 
                        -- with an LSB of 1 !!!
  end if;
end log_2;

function log_2 (a: std_ulogic_vector) return integer is       -- 15.11.95
  variable index : integer;
begin
  index := a'length - 1;
  while index > -1 loop
    if a(index) = '1' then
      return index;
      index := -1; -- required in order to exit the loop
    else
      index := index - 1;
      if index = -1 then  -- catches the case when a has no '1's in it
        assert FALSE
          report "log_2(a) returns an out-of-range value"
          severity warning;
        return integer'low; -- a stupid value => a 2**32-bit vector 
                            -- with an LSB of 1 !!!
      end if;
    end if;
      -- if a >= 1, index goes to -1 in order to exit the loop after returning index=0
      -- if a = 0, index goes to -1, return value = -integer'low
      -- if a is not bit_vector pattern, (i.e., contains non-0,1 values)
      --   the U,X,W,H,L,Z,- are also treated as 0
  end loop;
end log_2;

-- NON-SYNTHESISABLE VHDL BEGIN
function longest (                      -- 10.05.95
  a, b: time 
) return time is
  variable y: time;
begin
  if (a >= b) then
    y := a;
  else
    y := b;
  end if;
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c: time 
) return time is
  variable ab: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (ab >= c) then
		y := ab;      
  else
    y := c;       
  end if; 
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c, d: time 
) return time is
  variable ab: time;
  variable cd: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (c >= d) then
    cd := c;
  else
    cd := d;
  end if;
  if (ab >= cd) then
		y := ab;
  else
    y := cd;
  end if;   
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c, d, e: time 
) return time is
  variable ab: time;
  variable cd: time;
  variable cde: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (c >= d) then
    cd := c;
  else
    cd := d;
  end if;
  if (cd >= e) then
		cde := cd;      
  else
    cde := e;       
  end if; 
  if (ab >= cde) then
		y := ab;
  else
    y := cde;
  end if;   
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c, d, e, f: time 
) return time is
  variable ab: time;
  variable cd: time;
  variable ef: time;
  variable abcd: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (c >= d) then
    cd := c;
  else
    cd := d;
  end if;
  if (e >= f) then
    ef := e;
  else
    ef := f;
  end if;
  if (ab >= cd) then
		abcd := ab;
  else
    abcd := cd;
  end if;   
  if (abcd >= ef) then
		y := abcd;
  else
    y := ef;
  end if;   
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c, d, e, f, g: time 
) return time is
  variable ab: time;
  variable cd: time;
  variable ef: time;
  variable efg: time;
  variable abcd: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (c >= d) then
    cd := c;
  else
    cd := d;
  end if;
  if (e >= f) then
    ef := e;
  else
    ef := f;
  end if;
  if (ef >= g) then
		efg := ef;       
  else
    efg := g;        
  end if; 
  if (ab >= cd) then
		abcd := ab;
  else
    abcd := cd;
  end if;   
  if (abcd >= efg) then
		y := abcd;
  else
    y := efg;
  end if;   
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c, d, e, f, g, h: time 
) return time is
  variable ab: time;
  variable cd: time;
  variable ef: time;
  variable gh: time;
  variable abcd: time;
  variable efgh: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (c >= d) then
    cd := c;
  else
    cd := d;
  end if;
  if (e >= f) then
    ef := e;
  else
    ef := f;
  end if;
  if (g >= h) then
    gh := g;         -- g > h
  else               
    gh := h;         -- h > g 
  end if;
  if (ab >= cd) then
		abcd := ab;
  else
    abcd := cd;
  end if;   
  if (ef >= gh) then
		efgh := ef;
  else
    efgh := gh;
  end if;   
  if (abcd >= efgh) then
		y := abcd;
  else
    y := efgh;
  end if;   
  return y;
end longest;

function longest (                      -- 31.05.95
  a, b, c, d, e, f, g, h, i: time 
) return time is
  variable ab: time;
  variable cd: time;
  variable ef: time;
  variable gh: time;
  variable ghi: time;
  variable abcd: time;
  variable efghi: time;
  variable y: time;
begin
  if (a >= b) then
    ab := a;
  else
    ab := b;
  end if;
  if (c >= d) then
    cd := c;
  else
    cd := d;
  end if;
  if (e >= f) then
    ef := e;
  else
    ef := f;
  end if;
  if (g >= h) then
    gh := g;         -- g > h
  else               
    gh := h;         -- h > g 
  end if;
  if (gh >= i) then
		ghi := gh;       --  ">"(g,h) > i
  else
    ghi := i;        -- i > g,h
  end if; 
  if (ab >= cd) then
		abcd := ab;
  else
    abcd := cd;
  end if;   
  if (ef >= ghi) then
		efghi := ef;
  else
    efghi := ghi;
  end if;   
  if (abcd >= efghi) then
		y := abcd;
  else
    y := efghi;
  end if;   
  return y;
end longest;
-- NON-SYNTHESISABLE VHDL END

-- ancillary function required in order to 
-- enable the integer -> ? functions in generic_conversions 
-- to be completed with only the required number of
-- bits of precision in the length of the vectors.

function integer_wordlength (
  a: integer        
) return integer is           
  variable wordlength: integer;    
begin
  if (a >= -2) and (a <= 1) then
    wordlength := 2;
  elsif (a >= -4) and (a <= 3) then  
    wordlength := 3;
  elsif (a >= -8) and (a <= 7) then  
    wordlength := 4;
  elsif (a >= -16) and (a <= 15) then  
    wordlength := 5;
  elsif (a >= -32) and (a <= 31) then  
    wordlength := 6;
  elsif (a >= -64) and (a <= 63) then  
    wordlength := 7;
  elsif (a >= -128) and (a <= 127) then  
    wordlength := 8;
  elsif (a >= -256) and (a <= 255) then  
    wordlength := 9;
  elsif (a >= -512) and (a <= 511) then  
    wordlength := 10;
  elsif (a >= -1024) and (a <= 1023) then  
    wordlength := 11;
  elsif (a >= -2048) and (a <= 2047) then  
    wordlength := 12;
  elsif (a >= -4096) and (a <= 4095) then  
    wordlength := 13;
  elsif (a >= -8192) and (a <= 8191) then  
    wordlength := 14;
  elsif (a >= -16384) and (a <= 16383) then  
    wordlength := 15;
  elsif (a >= -32768) and (a <= 32767) then  
    wordlength := 16;
  elsif (a >= -65536) and (a <= 65535) then  
    wordlength := 17;
  elsif (a >= -131072) and (a <= 131071) then  
    wordlength := 18;
  elsif (a >= -262144) and (a <= 262143) then  
    wordlength := 19;
  elsif (a >= -524288) and (a <= 524287) then  
    wordlength := 20;
  elsif (a >= -1048576) and (a <= 1048575) then  
    wordlength := 21;
  elsif (a >= -2097152) and (a <= 2097151) then  
    wordlength := 22;
  elsif (a >= -4194304) and (a <= 4194303) then  
    wordlength := 23;
  elsif (a >= -8388608) and (a <= 8388607) then  
    wordlength := 24;
  elsif (a >= -16777216) and (a <= 16777215) then  
    wordlength := 25;
  elsif (a >= -33554432) and (a <= 33554431) then  
    wordlength := 26;
  elsif (a >= -67108864) and (a <= 67108863) then  
    wordlength := 27;
  elsif (a >= -134217728) and (a <= 134217727) then  
    wordlength := 28;
  elsif (a >= -268435456) and (a <= 268435455) then  
    wordlength := 29;
  elsif (a >= -536870912) and (a <= 536870911) then  
    wordlength := 30;
  elsif (a >= -1073741824) and (a <= 1073741823) then  
    wordlength := 31;
  elsif (a >= integer'low) and (a <= integer'high) then  -- i'low = -2147483647
    wordlength := 32;                                    -- or -2147483648
  end if;                                                -- depending upon implementation
  return wordlength;
end integer_wordlength;

-- ancillary function required in order to 
-- enable the integer -> ? functions in generic_conversions 
-- to be completed with only the required number of
-- bits of precision in the length of the vectors.

function next_greater_binary_power_minus_1 (
  a: integer        
) return integer is           
  variable power_minus_1: integer;    
begin
  if (a >= -2) and (a <= 1) then
    power_minus_1 := 1;
  elsif (a >= -4) and (a <= 3) then  
    power_minus_1 := 3;
  elsif (a >= -8) and (a <= 7) then  
    power_minus_1 := 7;
  elsif (a >= -16) and (a <= 15) then  
    power_minus_1 := 15;
  elsif (a >= -32) and (a <= 31) then  
    power_minus_1 := 31;
  elsif (a >= -64) and (a <= 63) then  
    power_minus_1 := 63;
  elsif (a >= -128) and (a <= 127) then  
    power_minus_1 := 127;
  elsif (a >= -256) and (a <= 255) then  
    power_minus_1 := 255;
  elsif (a >= -512) and (a <= 511) then  
    power_minus_1 := 511;
  elsif (a >= -1024) and (a <= 1023) then  
    power_minus_1 := 1023;
  elsif (a >= -2048) and (a <= 2047) then  
    power_minus_1 := 2047;
  elsif (a >= -4096) and (a <= 4095) then  
    power_minus_1 := 4095;
  elsif (a >= -8192) and (a <= 8191) then  
    power_minus_1 := 8191;
  elsif (a >= -16384) and (a <= 16383) then  
    power_minus_1 := 16383;
  elsif (a >= -32768) and (a <= 32767) then  
    power_minus_1 := 32767;
  elsif (a >= -65536) and (a <= 65535) then  
    power_minus_1 := 65535;
  elsif (a >= -131072) and (a <= 131071) then  
    power_minus_1 := 131071;
  elsif (a >= -262144) and (a <= 262143) then  
    power_minus_1 := 262143;
  elsif (a >= -524288) and (a <= 524287) then  
    power_minus_1 := 524287;
  elsif (a >= -1048576) and (a <= 1048575) then  
    power_minus_1 := 1048575;
  elsif (a >= -2097152) and (a <= 2097151) then  
    power_minus_1 := 2097151;
  elsif (a >= -4194304) and (a <= 4194303) then  
    power_minus_1 := 4194303;
  elsif (a >= -8388608) and (a <= 8388607) then  
    power_minus_1 := 8388607;
  elsif (a >= -16777216) and (a <= 16777215) then  
    power_minus_1 := 16777215;
  elsif (a >= -33554432) and (a <= 33554431) then  
    power_minus_1 := 33554431;
  elsif (a >= -67108864) and (a <= 67108863) then  
    power_minus_1 := 67108863;
  elsif (a >= -134217728) and (a <= 134217727) then  
    power_minus_1 := 134217727;
  elsif (a >= -268435456) and (a <= 268435455) then  
    power_minus_1 := 268435455;
  elsif (a >= -536870912) and (a <= 536870911) then  
    power_minus_1 := 536870911;
  elsif (a >= -1073741824) and (a <= 1073741823) then  
    power_minus_1 := 1073741823;
  elsif (a >= integer'low) and (a <= integer'high) then  -- i'low = -2147483647
    power_minus_1 := 2147483647;                                    -- or -2147483648
  end if;                                                -- depending upon implementation
  return power_minus_1;
end next_greater_binary_power_minus_1;

-- NON-SYNTHESISABLE VHDL BEGIN
function posedge (
  signal a: std_ulogic
) return boolean is
  variable y: boolean;
begin
  if (a = '1') and a'event then
    y := true;
  else
	   y := false;
  end if;
  return y; 
end posedge;

function negedge (
  signal a: std_ulogic
) return boolean is
  variable y: boolean;
begin
  if (a = '0') and a'event then
    y := true;
  else
	  y := false;
  end if;
  return y; 
end negedge;
-- NON-SYNTHESISABLE VHDL END

function abs_wordlength (
  a: twos_complement
) return integer is
  variable any_1s: std_ulogic;
  variable y: integer;
begin
  any_1s := '0';
-- all bits excpet the MSB are tested for being 1
-- if none are 1, all bits are 0, and any_1s is 0
-- hence either 0 or -2(N-1) has been found
-- if this function is only called when a is -ve
-- it finds if a is -2(N-1)
  for i in 0 to a'length-2 loop    -- unary OR operation
    any_1s := a(i) or any_1s; 
  end loop;
  if ((a(a'length-1) = '1') and (any_1s = '0')) then
    y := a'length + 1;
  else
    y := a'length;
  end if;
  return y;
end abs_wordlength; 

end generic_functions;


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