OpenCores
URL https://opencores.org/ocsvn/encore/encore/trunk

Subversion Repositories encore

[/] [encore/] [trunk/] [fpmult/] [src/] [fpmult_stage_pre.vhdl] - Blame information for rev 11

Details | Compare with Previous | View Log

Line No. Rev Author Line
1 11 aloy.amber 
library ieee;
2 
use ieee.std_logic_1164.all;
3 
use ieee.numeric_std.all;
4 
use work.fp_generic.all;
5 
use work.fpmult_stage_pre_comp.all;
6 
 
7 
entity fpmult_stage_pre is
8 
  port(
9 
    clk:in std_logic;
10 
    d:in fpmult_stage_pre_in_type;
11 
    q:out fpmult_stage_pre_out_type
12 
  );
13 
end;
14 
 
15 
architecture twoproc of fpmult_stage_pre is
16 
  type reg_type is record
17 
    a:fp_type;
18 
    b:fp_type;
19 
  end record;
20 
  signal r,rin:reg_type;
21 
begin
22 
  comb:process(d,r)
23 
    variable v:reg_type;
24 
    variable a_is_normal,b_is_normal:boolean;
25 
    variable a_is_subnormal,b_is_subnormal:boolean;
26 
    variable a_is_zero,b_is_zero:boolean;
27 
    variable a_is_infinite,b_is_infinite:boolean;
28 
    variable a_is_nan,b_is_nan:boolean;
29 
    variable is_normal:boolean;
30 
    variable is_zero:boolean;
31 
    variable is_infinite:boolean;
32 
    variable is_nan:boolean;
33 
  begin
34 
    -- sample register outputs
35 
    v:=r;
36 
 
37 
    -- overload
38 
    a_is_normal:=fp_is_normal(d.a);
39 
    b_is_normal:=fp_is_normal(d.b);
40 
    a_is_subnormal:=fp_is_subnormal(d.a);
41 
    b_is_subnormal:=fp_is_subnormal(d.b);
42 
    a_is_zero:=fp_is_zero(d.a);
43 
    b_is_zero:=fp_is_zero(d.b);
44 
    a_is_infinite:=fp_is_infinite(d.a);
45 
    b_is_infinite:=fp_is_infinite(d.b);
46 
    a_is_nan:=fp_is_nan(d.a);
47 
    b_is_nan:=fp_is_nan(d.b);
48 
 
49 
    -- This implementation does not support subnormal numbers.
50 
    -- They are treated as zero.
51 
    -- This is not in conformance with IEEE-754 but greatly simplifies the implementation
52 
    --
53 
    -- +-----------+------+----------+-----------+----------+------+
54 
    -- |           | zero |  normal  | subnormal | infinite | NaN  |
55 
    -- +-----------+------+----------+-----------+----------+------+
56 
    -- |   zero    | zero |   zero   |   zero    |   qNaN   | qNaN |
57 
    -- |  normal   | zero |  A * B   |   zero    | infinite | qNaN |
58 
    -- | subnormal | zero |   zero   |   zero    |   qNaN   | qNaN |
59 
    -- | infinite  | qNaN | infinite |   qNaN    | infinite | qNaN |
60 
    -- |    NaN    | qNaN |   qNaN   |   qNaN    |   qNaN   | qNaN |
61 
    -- +-----------+------+----------+-----------+----------+------+
62 
 
63 
    is_normal:=false;
64 
    is_zero:=false;
65 
    is_infinite:=false;
66 
    is_nan:=false;
67 
    if a_is_zero or b_is_zero then
68 
      if a_is_zero and b_is_zero then
69 
        is_zero:=true;
70 
      end if;
71 
      if a_is_normal or b_is_normal then
72 
        is_zero:=true;
73 
      end if;
74 
      if a_is_subnormal or b_is_subnormal then
75 
        is_zero:=true;
76 
      end if;
77 
      if a_is_infinite or b_is_infinite then
78 
        is_nan:=true;
79 
      end if;
80 
      if a_is_nan or b_is_nan then
81 
        is_nan:=true;
82 
      end if;
83 
    end if;
84 
 
85 
    if a_is_normal or b_is_normal then
86 
      if a_is_normal and b_is_normal then
87 
        is_normal:=true;
88 
      end if;
89 
      if a_is_subnormal or b_is_subnormal then
90 
        is_zero:=true;
91 
      end if;
92 
      if a_is_infinite or b_is_infinite then
93 
        is_infinite:=true;
94 
      end if;
95 
      if a_is_nan or b_is_nan then
96 
        is_nan:=true;
97 
      end if;
98 
    end if;
99 
 
100 
    if a_is_subnormal or b_is_subnormal then
101 
      if a_is_subnormal and b_is_subnormal then
102 
        is_zero:=true;
103 
      end if;
104 
      if a_is_infinite or b_is_infinite then
105 
        is_nan:=true;
106 
      end if;
107 
      if a_is_nan or b_is_nan then
108 
        is_nan:=true;
109 
      end if;
110 
    end if;
111 
 
112 
    if a_is_infinite or b_is_infinite then
113 
      if a_is_infinite and b_is_infinite then
114 
        is_infinite:=true;
115 
      end if;
116 
      if a_is_nan or b_is_nan then
117 
        is_nan:=true;
118 
      end if;
119 
    end if;
120 
 
121 
    if a_is_nan and b_is_nan then
122 
      is_nan:=true;
123 
    end if;
124 
 
125 
    if is_zero or is_infinite or is_nan then
126 
      v.b:=d.b(31)&"01111111"&"00000000000000000000000";  -- 1.0
127 
    end if;
128 
    if is_normal then
129 
      v.b:=d.b;
130 
    end if;
131 
 
132 
    if is_zero then
133 
      v.a:=d.a(31)&"00000000"&"00000000000000000000000";  -- 0.0
134 
    end if;
135 
    if is_infinite then
136 
      v.a:=d.a(31)&"11111111"&"00000000000000000000000";  -- infinite
137 
    end if;
138 
    if is_nan then
139 
      v.a:=d.a(31)&"11111111"&"10000000000000000000000";  -- qNaN
140 
    end if;
141 
    if is_normal then
142 
      v.a:=d.a;
143 
    end if;
144 
 
145 
    -- drive register inputs
146 
    rin<=v;
147 
 
148 
    -- drive outputs
149 
    q.a<=r.a;
150 
    q.b<=r.b;
151 
  end process;
152 
 
153 
  seq:process(clk,rin)
154 
  begin
155 
    if rising_edge(clk) then
156 
      r<=rin;
157 
    end if;
158 
  end process;
159 
end;

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.