user
215 lines
7.8 KiB
TeX
215 lines
7.8 KiB
TeX
\documentclass[10pt]{article}
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\usepackage[T1]{fontenc}\usepackage[utf8]{inputenc}\usepackage[polish]{babel}
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\usepackage[a4paper,margin=1.55cm]{geometry}
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\usepackage{array,tabularx,booktabs,amsmath,amssymb,xcolor,listings,hyperref,fancyhdr,lastpage,enumitem}
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\definecolor{accent}{HTML}{16324A}\definecolor{accentlight}{HTML}{EEF3F7}\definecolor{rulegray}{HTML}{D7DEE5}
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\hypersetup{colorlinks=true,linkcolor=accent,urlcolor=blue}
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\IfFileExists{build-meta.tex}{\input{build-meta.tex}}{\newcommand{\BuildCommit}{local}}
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\newcommand{\PublisherDomain}{mpabi}
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\newcommand{\CardArea}{inf}
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\newcommand{\CardSeries}{freertos-cpp}
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\newcommand{\CardNumber}{10}
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\newcommand{\CardCount}{16}
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\newcommand{\CardSlug}{queue}
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\newcommand{\CardVersion}{v00.01}
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\newcommand{\DocumentUUID}{66967c2d-bb34-4344-8064-f54d06cce47a}
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\newcommand{\blank}[1]{\rule{#1}{.2pt}}
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\lstset{language=C++,basicstyle=\ttfamily\scriptsize,columns=fullflexible,keepspaces=true,frame=single,breaklines=true,showstringspaces=false,numbers=none,backgroundcolor=\color{accentlight},rulecolor=\color{rulegray}}
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\pagestyle{fancy}\fancyhf{}
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\lhead{\textbf{K10 · FreeRTOS C++ · typed queue}}\rhead{\small L09 · byte-copy contract}
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\lfoot{\scriptsize commit \BuildCommit}\cfoot{\scriptsize \thepage/\pageref{LastPage}}\rfoot{\scriptsize V11.3.0 / \CardVersion}
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\setlength{\headheight}{14pt}\setlength{\footskip}{19pt}
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\setlist[itemize]{nosep,leftmargin=1.45em}\setlist[enumerate]{nosep,leftmargin=1.65em}
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\begin{document}\sloppy
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\begin{center}
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{\LARGE\bfseries \texttt{Queue<T>} i \texttt{StaticQueue<T,N>}}\par
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\vspace{.25em}{\large typowana granica nad kopiowaniem bajtów FreeRTOS}\par
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\end{center}
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\noindent\begin{tabularx}{\textwidth}{@{}p{1.65cm}Xp{1.9cm}X@{}}
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\toprule
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Karta & K10 / \CardCount & Czas & 30 minut \\
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Platforma & Hazard3 / RV32I & Wiadomość & \texttt{Sample}, 12 B \\
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Capacity & 2 elementy & Timeout & jawny, 0 lub 2 ticki \\
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Wersja & \CardVersion & UUID karty & \texttt{66967c2d-...} \\
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\bottomrule
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\end{tabularx}
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\section*{Kontrakt typu przed uruchomieniem}
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\begin{lstlisting}
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static_assert(std::is_trivially_copyable<T>::value,
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"Queue<T> requires T to be trivially copyable");
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\end{lstlisting}
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Kernel zapamiętuje \texttt{sizeof(T)} bajtów. Nie wywołuje konstruktora,
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destruktora ani operacji kopiowania C++. Dlatego owning \texttt{VectorV1} nie
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może być wiadomością by value.
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\noindent\fcolorbox{accent}{accentlight}{\begin{minipage}{.94\textwidth}
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\textbf{Kontrakt K10.} \texttt{send} kopiuje bajty w chwili wywołania. Późniejsza
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zmiana źródła nie może zmienić elementu w kolejce. Timeout jest jawny; wrapper
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nie ukrywa \texttt{portMAX\_DELAY}.
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\end{minipage}}
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\section*{Plan 30 minut}
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\noindent\begin{tabularx}{\textwidth}{@{}p{1.35cm}p{3.1cm}X@{}}
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\toprule
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Czas & Tryb & Dowód \\
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\midrule
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0--5 & gate & trivial Sample przechodzi; VectorV1 nie \\
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5--10 & create & dynamic heap cost kontra static delta 0 \\
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10--15 & copy & send, mutate, receive oryginalnej wartości \\
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15--20 & bytes & snapshot 12 B caller storage \\
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20--25 & full & trzeci send odmawia po 2 tickach \\
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25--30 & FIFO & drain 0x2222, 0x3333; empty receive=false \\
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\bottomrule
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\end{tabularx}
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\section*{Predykcja}
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\texttt{sizeof(Sample)} = \blank{2cm} B. Po wysłaniu wartości \texttt{0x1111}
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i zmianie źródła na \texttt{0xDEAD} odbiorę: \blank{3cm}.
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\newpage
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\section{Dynamiczna i statyczna własność}
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\noindent\begin{tabularx}{\textwidth}{@{}p{4.1cm}p{4.5cm}X@{}}
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\toprule
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Właściwość & \texttt{Queue<Sample>} & \texttt{StaticQueue<Sample,2>} \\
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\midrule
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create API & \texttt{xQueueCreate} & \texttt{xQueueCreateStatic} \\
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control & heap & caller \texttt{StaticQueue\_t} \\
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item bytes & heap & caller \texttt{uint8\_t[24]} \\
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item size & \texttt{sizeof(Sample)} & \texttt{sizeof(Sample)} \\
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destructor & delete + heap free & delete, bez free caller bytes \\
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\bottomrule
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\end{tabularx}
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\section*{Pomiar heap i adresów}
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\noindent\begin{tabularx}{\textwidth}{@{}p{5.5cm}p{3.5cm}X@{}}
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\toprule
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Pomiar & Predykcja & Odczyt \\
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\midrule
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dynamic cost & $>0$ & \blank{3cm} B \\
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static create delta & 0 & \blank{3cm} B \\
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heap po obu destruktorach & baseline & \blank{3cm} \\
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static handle & control address & \blank{3cm} \\
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control/storage domain & .bss, poza heap & \blank{3cm} \\
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\bottomrule
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\end{tabularx}
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\section{Kopia jest snapshotem}
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\begin{lstlisting}
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Sample source{1, 0x1111, 3, 0x55};
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dynamic.send(source, 0);
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source.value = 0xDEAD;
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dynamic.receive(received, 0);
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\end{lstlisting}
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\noindent\begin{tabularx}{\textwidth}{@{}p{4.5cm}p{3.5cm}X@{}}
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\toprule
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Wartość & Źródło po mutate & Odebrana kopia \\
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\midrule
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\texttt{value} & \texttt{0xDEAD} & \blank{3cm} \\
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\texttt{flags} & \texttt{0xAA} & \blank{3cm} \\
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\bottomrule
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\end{tabularx}
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Co byłoby błędem przy \texttt{xQueueCreate(2,sizeof(Sample*))}, gdy send dostaje
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\texttt{\&sample} zamiast \texttt{\&samplePointer}?\\[.5em]\blank{16cm}
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\newpage
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\section{Full, timeout, FIFO i empty}
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\begin{center}
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\texttt{send(first,0)} $\rightarrow$ count 1\\
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\texttt{send(second,0)} $\rightarrow$ count 2 / FULL\\
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\texttt{send(third,2)} $\rightarrow$ task blokuje maks. 2 ticki / false\\
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\texttt{receive} $\rightarrow$ first, potem second\\
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\texttt{receive(empty,0)} $\rightarrow$ false
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\end{center}
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\noindent\begin{tabularx}{\textwidth}{@{}p{4.8cm}p{3.6cm}X@{}}
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\toprule
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Dowód & Predykcja & Odczyt \\
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\midrule
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count przed trzecim send & 2 & \blank{2.5cm} \\
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third send result & false & \blank{2.5cm} \\
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tick delta & $\geq2$ & \blank{2.5cm} \\
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FIFO first value & \texttt{0x2222} & \blank{2.5cm} \\
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FIFO second value & \texttt{0x3333} & \blank{2.5cm} \\
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empty receive, timeout 0 & false & \blank{2.5cm} \\
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\bottomrule
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\end{tabularx}
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\section{Zajrzyj do caller storage}
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Po pierwszym static send porównaj pierwsze 12 bajtów
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\texttt{g\_static\_queue\_storage.bytes} z reprezentacją \texttt{first}.
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\noindent\begin{tabularx}{\textwidth}{@{}p{3cm}p{4cm}X@{}}
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\toprule
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Pole & Wartość & Little-endian bytes \\
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\midrule
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sequence & 2 & \blank{5cm} \\
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value & \texttt{0x2222} & \blank{5cm} \\
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channel/flags & 4 / \texttt{0x10} & \blank{5cm} \\
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\bottomrule
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\end{tabularx}
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\section*{Ćwiczenie typu}
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Zaprojektuj trivial UART message: kierunek, długość, maks. 8 bajtów payload i
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sequence. Zapisz definicję oraz policz \texttt{sizeof}:\\[.5em]
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\blank{16cm}\\[1em]\blank{16cm}
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Dlaczego sam fakt, że wskaźnik jest trivially copyable, nie rozwiązuje lifetime
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wskazywanego obiektu?\\[.5em]\blank{16cm}
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\newpage
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\section{Hazard3/GDB i zaliczenie}
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\begin{lstlisting}[language=bash]
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make check
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riscv64-unknown-elf-gdb build/task01_queue/prog.elf
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b queue_debug_checkpoint
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\end{lstlisting}
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\begin{lstlisting}
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p g_dynamic_queue_cost
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p g_static_control_address
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p g_static_bytes_address
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p g_static_first_item_bytes
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p g_copy_source_after_mutation
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p g_copy_received_value
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p g_full_count
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p g_timeout_ticks
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p g_fifo_values
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p g_queue_pass
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\end{lstlisting}
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\section*{Negatywny test jest częścią kontraktu}
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\begin{lstlisting}
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struct VectorV1 {
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unsigned* data;
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~VectorV1() { data = nullptr; }
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};
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freertos::Queue<VectorV1> forbidden{2}; // must not compile
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\end{lstlisting}
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Oczekiwana przyczyna, nie przypadkowy błąd linkera:
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\texttt{Queue<T> requires T to be trivially copyable}.
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\section*{Zaliczenie}
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\begin{itemize}
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\item $\square$ wyjaśniam byte copy i gate trivially-copyable;
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\item $\square$ pokazuję 128 B dynamic cost i 0 B static delta;
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\item $\square$ dowodzę snapshot 0x1111 po mutate do 0xDEAD;
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\item $\square$ wiążę 12 B item size z typed API i storage;
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\item $\square$ pokazuję full, timeout 2, FIFO i empty=false;
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\item $\square$ negatywny test VectorV1 kończy się właściwym static assert.
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\end{itemize}
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\section*{Wyjście}
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Kiedy przesyłać wartość, a kiedy wskaźnik? Jak udokumentować ownership?\\[.5em]
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\blank{16cm}\\[1em]\blank{16cm}
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\vfill
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\noindent\textbf{Następna karta K11:} \texttt{Mutex}, własny
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\texttt{LockGuard} i obserwowalne dziedziczenie priorytetu.
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\end{document}
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