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factor out duplicated sign-extension code to new sext module

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This commit is contained in:
Mikael Pettersson
2025-08-11 16:41:55 +02:00
parent 1f230f9e61
commit fc3bd12e7c
5 changed files with 37 additions and 16 deletions
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2
erlang/apps/lib/src/libelf.erl
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@@ -707,7 +707,7 @@ read_Word(FP) -> read_uint36(FP).
read_sint36(FP) ->
case read_uint36(FP) of
{ok, UInt36} -> {ok, (UInt36 bxor (1 bsl 35)) - (1 bsl 35)}; % sign-extend
{ok, UInt36} -> {ok, sext:sext(UInt36, 36)};
{error, _Reason} = Error -> Error
end.

30
erlang/apps/lib/src/sext.erl Normal file
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@@ -0,0 +1,30 @@
%%% -*- erlang-indent-level: 2 -*-
%%%
%%% Sign-extend integers of given widths.
%%% Copyright (C) 2013-2025 Mikael Pettersson
%%%
%%% This file is part of pdp10-tools.
%%%
%%% pdp10-tools is free software: you can redistribute it and/or modify
%%% it under the terms of the GNU General Public License as published by
%%% the Free Software Foundation, either version 3 of the License, or
%%% (at your option) any later version.
%%%
%%% pdp10-tools is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
%%% GNU General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License
%%% along with pdp10-tools. If not, see <http://www.gnu.org/licenses/>.
-module(sext).
-export([ sext/2
]).
-spec sext(non_neg_integer(), pos_integer()) -> integer().
sext(Word, Width) ->
SignBit = 1 bsl (Width - 1),
Max = (1 bsl Width) - 1,
((Word band Max) bxor SignBit) - SignBit.

9
erlang/apps/od/src/od.erl
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@@ -1,7 +1,7 @@
%%% -*- erlang-indent-level: 2 -*-
%%%
%%% 'od' for files with 9-bit bytes
%%% Copyright (C) 2013-2023 Mikael Pettersson
%%% Copyright (C) 2013-2025 Mikael Pettersson
%%%
%%% This file is part of pdp10-tools.
%%%
@@ -333,7 +333,7 @@ print_number(Opts, UInt) ->
OutputType = Opts#options.output_type,
Number =
case OutputType of
$d -> sign_extend(UInt, 9 * Opts#options.bytes_per_datum);
$d -> sext:sext(UInt, 9 * Opts#options.bytes_per_datum);
_ -> UInt
end,
{Base, Pad} =
@@ -345,11 +345,6 @@ print_number(Opts, UInt) ->
end,
io:format(" ~*.*.*B", [Opts#options.chars_per_datum, Base, Pad, Number]).
sign_extend(UInt, NrBits) ->
Max = (1 bsl NrBits) - 1,
SignBit = 1 bsl (NrBits - 1),
((UInt band Max) bxor SignBit) - SignBit.
bytes_to_uint(B1, B2) -> % PDP10 has big-endian byte order
((B1 band 16#1FF) bsl 9) bor (B2 band 16#1FF).

6
erlang/apps/sim/src/sim_arithmetic.erl
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@@ -1,7 +1,7 @@
%%% -*- erlang-indent-level: 2 -*-
%%%
%%% simulator for pdp10-elf
%%% Copyright (C) 2020 Mikael Pettersson
%%% Copyright (C) 2020-2025 Mikael Pettersson
%%%
%%% This file is part of pdp10-tools.
%%%
@@ -933,9 +933,7 @@ sub1(Word) ->
%% Sign-extend a uint36_t() to the full width of its representation type.
-spec sext36(uint36_t()) -> integer().
sext36(X) ->
UInt36Sbit = 1 bsl (36 - 1),
UInt36Max = (1 bsl 36) - 1,
((X band UInt36Max) bxor UInt36Sbit) - UInt36Sbit.
sext:sext(X, 36).
set_non_zero_ac(Core, IR, Word) ->
case IR band 8#17 of

6
erlang/apps/sim/src/sim_core.erl
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@@ -1,7 +1,7 @@
%%% -*- erlang-indent-level: 2 -*-
%%%
%%% simulator for pdp10-elf
%%% Copyright (C) 2018-2020 Mikael Pettersson
%%% Copyright (C) 2018-2025 Mikael Pettersson
%%%
%%% This file is part of pdp10-tools.
%%%
@@ -606,9 +606,7 @@ bit36(X, BIT) -> bits36(X, BIT, BIT).
%% Sign-extend a uint18_t() to the full width of its representation type.
-spec sext18(uint18_t()) -> integer().
sext18(X) ->
UInt18Sbit = 1 bsl (18 - 1),
UInt18Max = (1 bsl 18) - 1,
((X band UInt18Max) bxor UInt18Sbit) - UInt18Sbit.
sext:sext(X, 18).
%% This implements Word := C(E).
-spec c(#core{}, sim_mem:mem(), #ea{})