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% \iffalse meta-comment
%
%% File: l3alloc.dtx Copyright (C) 1990-2012,2014-2017 The LaTeX3 Project
%
% It may be distributed and/or modified under the conditions of the
% LaTeX Project Public License (LPPL), either version 1.3c of this
% license or (at your option) any later version. The latest version
% of this license is in the file
%
% https://www.latex-project.org/lppl.txt
%
% This file is part of the "l3kernel bundle" (The Work in LPPL)
% and all files in that bundle must be distributed together.
%
% -----------------------------------------------------------------------
%
% The development version of the bundle can be found at
%
% https://github.com/latex3/latex3
%
% for those people who are interested.
%
%<*driver>
\documentclass[full,kernel]{l3doc}
\begin{document}
\DocInput{\jobname.dtx}
\end{document}
%</driver>
% \fi
%
% \title{^^A
% The \pkg{l3alloc} package\\ Register allocation^^A
% }
%
% \author{^^A
% The \LaTeX3 Project\thanks
% {^^A
% E-mail:
% \href{mailto:latex-team@latex-project.org}
% {latex-team@latex-project.org}^^A
% }^^A
% }
%
% \date{Released 2017/12/16}
%
% \maketitle
%
% \begin{documentation}
%
% This module provides the basic mechanism for allocating \TeX{}'s
% registers when operating in format mode. When loaded as a package on
% an existing format, the mechanisms from the latter are used.
%
% The approach used here is informed by the mechanisms used in plain
% \TeX{}/\LaTeX{} but noting that newer engines provide us much more
% flexibility. In addition to this, we do not need allocators for all
% register types: for example \texttt{toks} are not used by \LaTeX3 whilst
% reads/writes are handled using a pool and thus do not need a classical
% allocator.
%
% In classical (non-\LuaTeX{}) engines, there are various restriction on
% registers, for example |\box255| is hard-coded as the output box and
% inserts have to be allocated below this (not in the extended pool). Rather
% than worry about this, allocations for the registers affected (\TeX{}
% |box|, |count|, |dimen| and |skip| types) are simply made only from the
% extended pool. (There is a performance impact in engines other than
% \LuaTeX{} but the free use of registers in \pkg{expl3} means that code
% cannot be sure of obtaining a low-numbered register in any case.)
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3alloc} implementation}
%
% \begin{macrocode}
%<*initex>
% \end{macrocode}
%
% \begin{macrocode}
%<@@=alloc>
% \end{macrocode}
%
% \begin{variable}
% {
% \g_@@_int_int ,
% \g_@@_dim_int ,
% \g_@@_muskip_int ,
% \g_@@_int_int ,
% \g_@@_box_int
% }
% The core register tracking is done using the same raw \TeX{} count
% registers as reserved by plain \TeX{} and \LaTeXe{}, as there may be the
% odd piece of generic code that needs to work by number. However, as not
% all of our variables work the same way, some of the older registers are
% simply ignored. For the same reason, there is no special status for the
% low-numbers registers other than counts. To avoid having to worry about
% inserts and reflecting the register availability in \eTeX{}, the lower
% register space is unused here (though is available for hard-coded
% use).
% \begin{macrocode}
\tex_countdef:D \g_@@_int_int = 10 ~
\tex_countdef:D \g_@@_dim_int = 11 ~
\tex_countdef:D \g_@@_skip_int = 12 ~
\tex_countdef:D \g_@@_muskip_int = 13 ~
\tex_countdef:D \g_@@_box_int = 14 ~
\g_@@_int_int = 255 ~
\g_@@_dim_int = 255 ~
\g_@@_skip_int = 255 ~
\g_@@_muskip_int = 0 ~
\g_@@_box_int = 255 ~
% \end{macrocode}
% \end{variable}
%
% \begin{variable}
% {
% \g_@@_attribute_int ,
% \g_@@_bytecode_int ,
% \g_@@_chunkname_int ,
% \g_@@_whatsit_int
% }
% To allow \LuaTeX{} to load |ltluatex.lua| for generic \Lua{} support, a
% small number of counts have to be correctly named at the \TeX{} level.
% At present there are no \pkg{expl3} allocators for these concepts so the
% names and numbers of the tracking variables may change.
% \begin{macrocode}
\etex_ifdefined:D \luatex_luatexversion:D
\tex_global:D \tex_countdef:D \g_@@_attribute_int = 21 ~
\tex_global:D \tex_countdef:D \g_@@_bytecode_int = 22 ~
\tex_global:D \tex_countdef:D \g_@@_chunkname_int = 23 ~
\tex_global:D \tex_countdef:D \g_@@_whatsit_int = 24 ~
\tex_fi:D
% \end{macrocode}
% \end{variable}
%
% \begin{macro}
% {\box_new:N, \dim_new:N, \int_new:N, \muskip_new:N \skip_new:N}
% Each of the public allocators is a wrapper around the one internal
% function needed here.
% \begin{macrocode}
\cs_new_protected:Npx \box_new:N #1
{
\exp_not:N \@@_reg:nNnN { box }
\cs_if_exist:NTF \luatex_luatexversion:D
{ \tex_chardef:D }
{ \tex_mathchardef:D }
\c_max_register_int
#1
}
\cs_new_protected:Npn \dim_new:N #1
{ \@@_reg:nNnN { dim } \tex_dimendef:D \c_max_register_int #1 }
\cs_new_protected:Npn \int_new:N #1
{ \@@_reg:nNnN { int } \tex_countdef:D \c_max_register_int #1 }
\cs_new_protected:Npn \muskip_new:N #1
{ \@@_reg:nNnN { muskip } \tex_muskipdef:D \c_max_register_int #1 }
\cs_new_protected:Npn \skip_new:N #1
{ \@@_reg:nNnN { skip } \tex_skipdef:D \c_max_register_int #1 }
% \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@@_reg:nNNN}
% The allocator itself is modelled somewhat on \LaTeXe{}'s \tn{e@alloc},
% though there is no need to set \tn{allocationnumber}.
% \begin{macrocode}
\cs_new_protected:Npn \@@_reg:nNnN #1#2#3#4
{
\__chk_if_free_cs:N #4
\int_compare:nNnTF { \int_use:c { g_@@_ #1 _int } } < {#3}
{
\int_gincr:c { g_@@_ #1 _int }
\tex_global:D #2 #4 \int_use:c { g_@@_ #1 _int }
\iow_log:x
{
\token_to_str:N #4 ~=~ #1 ~register~
\int_use:c { g_@@_ #1 _int }
}
}
{ \__msg_kernel_fatal:nnx { kernel } { out-of-registers } {#1} }
}
% \end{macrocode}
% \end{macro}
%
% \begin{macrocode}
%</initex>
% \end{macrocode}
%
% \end{implementation}
%
% \PrintIndex
|
