1#!/usr/bin/env escript
2%% -*- erlang -*-
3%%! +A0
4%%
5%% %CopyrightBegin%
6%%
7%% Copyright Ericsson AB 2017-2019. All Rights Reserved.
8%%
9%% Licensed under the Apache License, Version 2.0 (the "License");
10%% you may not use this file except in compliance with the License.
11%% You may obtain a copy of the License at
12%%
13%%     http://www.apache.org/licenses/LICENSE-2.0
14%%
15%% Unless required by applicable law or agreed to in writing, software
16%% distributed under the License is distributed on an "AS IS" BASIS,
17%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18%% See the License for the specific language governing permissions and
19%% limitations under the License.
20%%
21%% %CopyrightEnd%
22%%
23
24-mode(compile).
25
26-define(MOD, "io_lib_format_ryu_table").
27
28-define(TABLE_SIZE, 326).
29-define(INV_TABLE_SIZE, 342).
30
31-define(POW5_BITCOUNT, 125).
32-define(POW5_INV_BITCOUNT, 125).
33
34main(_) ->
35    Values = [ values(X) || X <- lists:seq(0, ?TABLE_SIZE - 1)],
36    InvValues = [ inv_values(X) || X <- lists:seq(0, ?INV_TABLE_SIZE - 1)],
37
38    %% Make module
39    {ok, Out} = file:open("../src/" ++ ?MOD ++ ".erl", [write]),
40    gen_file(Out, Values, InvValues),
41    ok = file:close(Out),
42    ok.
43
44%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
45
46inv_values(X) ->
47  Pow = pow5(X),
48  Pow5len = log2floor(Pow),
49  J = Pow5len + ?POW5_INV_BITCOUNT - 1,
50  Inv = ((1 bsl J) div Pow) + 1,
51  {X, Inv}.
52
53values(X) ->
54  Pow = pow5(X),
55  Pow5len = log2floor(Pow),
56  Pow5 = Pow bsr (Pow5len - ?POW5_BITCOUNT),
57  {X, Pow5}.
58
59pow5(0) ->
60  1;
61pow5(1) ->
62  5;
63pow5(X) ->
64  5 * pow5(X - 1).
65
66log2floor(Int) when is_integer(Int), Int > 0 ->
67    log2floor(Int, 0).
68
69log2floor(0, N) ->
70    N;
71log2floor(Int, N) ->
72    log2floor(Int bsr 1, 1 + N).
73
74%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
75
76gen_file(Fd, Values, InvValues) ->
77    gen_header(Fd),
78    gen_pow5_static(Fd),
79    gen_table(Fd, Values),
80    gen_inv_table(Fd, InvValues),
81    ok.
82
83gen_header(Fd) ->
84    io:put_chars(Fd, "%%\n%% this file is generated do not modify\n"),
85    io:put_chars(Fd, "%% see ../script/generate_ryu_table.escript\n\n"),
86    io:put_chars(Fd, "-module(" ++ ?MOD ++").\n"),
87    io:put_chars(Fd, "-export([pow5_bitcount/0, pow5_inv_bitcount/0, value/1, inv_value/1]).\n\n"),
88    ok.
89
90gen_pow5_static(Fd) ->
91    io:put_chars(Fd, "-spec pow5_bitcount() -> integer().\n"),
92    io:format(Fd, "pow5_bitcount() -> ~p.~n~n", [?POW5_BITCOUNT]),
93    io:put_chars(Fd, "-spec pow5_inv_bitcount() -> integer().\n"),
94    io:format(Fd, "pow5_inv_bitcount() -> ~p.~n~n", [?POW5_INV_BITCOUNT]),
95    ok.
96
97gen_table(Fd, Values) ->
98    io:put_chars(Fd, "-spec value(integer()) -> integer().\n"),
99    [io:format(Fd, "value(~p) -> ~p;~n", [Key, Val]) || {Key,Val} <- Values],
100    io:put_chars(Fd, "value(_) -> error(function_clause).\n\n"),
101    ok.
102
103gen_inv_table(Fd, Values) ->
104    io:put_chars(Fd, "-spec inv_value(integer()) -> integer().\n"),
105    [io:format(Fd, "inv_value(~p) -> ~p;~n", [Key, Val]) || {Key,Val} <- Values],
106    io:put_chars(Fd, "inv_value(_) -> error(function_clause).\n"),
107    ok.
108
109