StupidFS/docs/book/main.tex

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  pdftitle={StupidFS},
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\date{\today}
\title{%
	StupidFS Algorithm \& Data Structure \\
	\large 1st Edition}
\author{d0p1}

\lowertitleback{Copyright \copyright{} 2022 d0p1
    \medskip\\
    \begin{tabular}{lp{.8\textwidth}}
        \raisebox{-12pt}{\includegraphics[height=18pt]{fig/gfdl}} &
        Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.3
    or any later version published by the Free Software Foundation;
    with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. \\
    \end{tabular}
}

\begin{document}
	\frontmatter
	
	\maketitle
	\tableofcontents

	\mainmatter

	\chapter{File, file system, and memory size limits}

	\chapter{Magic Numbers}

	\begin{center}
		\begin{tabular}{ |c|c|c|c| } 
 			\hline
 			\textbf{Flag} & \textbf{Hexadecimal} & \textbf{ASCII} & \textbf{Data structure}  \\ 
			\hline
 			STPDFS\_SB\_MAGIC & 0x44505453 & STPD & Superblock \\
			STDFS\_BLOCK\_SIZE & 512 & &  Block size\\ 
 			\hline
		\end{tabular}
	\end{center}

	\chapter{Structures}

	\section{Superblock}

	\subsection{free list}

	\begin{lstlisting}[language=C]
struct stpdfs_free {
	uint32_t free[100];
	uint8_t nfree;
};
	\end{lstlisting}

	\subsection{superblock}

	\begin{lstlisting}[language=C]

#define STPDFS_SB_MAGIC 0x44505453
#define STPDFS_REV      STPDFS_REV_1
#define STPDFS_REV_1    0x1

struct stpdfs_sb {
	uint32_t magic;
	uint32_t isize;
	uint32_t fsize;
	uint32_t free[100];
	uint8_t nfree;
	uint8_t revision;
	uint16_t state;
	uint64_t time;
};
	\end{lstlisting}

	\section{INodes}

	\begin{lstlisting}[language=C]
struct inode {
	uint16_t mode;
	uint16_t nlink;
	uint16_t uid;
	uint16_t gid;
	uint16_t flags;
	uint32_t size;
	uint32_t zones[10];
	uint64_t actime;
	uint64_t modtime;
};
	\end{lstlisting}
	
	\subsection{flags}

	\begin{center}
		\begin{tabular}{ |c|c|c|c| } 
 			\hline
	 		\textbf{flags} & \textbf{value} & \textbf{Description}  \\ 
			\hline
			STPDFS\_INODE\_ALLOCATED & 1 << 15 & if set inode is allocated \\
			STPDFS\_INODE\_LZP & 1 << 0 & if set data are compressed \\
			STPDFS\_INODE\_ENC &  1 << 1 & if set data are encrypted \\
 		\hline
		\end{tabular}
	\end{center}

	\begin{center}
		\begin{tabular}{ |c|c| }
			zone 0-6 & direct \\
			zone 7 & indirect \\
			zone 8 & double indirect \\
			zone 9 & triple indirect \\
		\end{tabular}
	\end{center}

	\subsection{mode}

	\begin{center}
		\begin{tabular}{ |c|c|c|c| } 
 			\hline
 			\textbf{mode} & \textbf{value} & \textbf{Description}  \\ 
			STPDFS\_S\_IFSOCK & 0xA000 & \\
			STPDFS\_S\_IFLNK  & 0xC000 & \\
			STPDFS\_S\_IFREG & 0x8000 & \\
			STPDFS\_S\_IFBLK  & 0x6000 & \\
			STPDFS\_S\_IFDIR &  0x4000 & \\
 			\hline
		\end{tabular}
	\end{center}

	\section{Dirent}

	\begin{lstlisting}[language=C]
struct stpdfs_dirent {
	ino_t inode;
	char filename[STPDFS_NAME_MAX];
};
	\end{lstlisting}

	\appendix

	\chapter{LZP implementation}

	\section{Compression}

	\begin{lstlisting}[language=C]
#include <stdint.h>
#include <string.h>

#define LZP_HASH_ORDER 16
#define LZP_HASH_SIZE  (1 << LZP_HASH_ORDER)

#define HASH(h, x) ((h << 4) ^ x)

void
lzp_compress(uint8_t *out, size_t *outsz, const uint8_t *in, size_t insz)
{
	uint8_t c;
	uint16_t hash;
	uint32_t mask;
	uint8_t table[LZP_HASH_SIZE] = { 0 };
	size_t i, j;
	size_t inpos;
	size_t outpos;
	uint8_t buff[9];

	inpos = 0;
	outpos = 0;
	hash = 0;
	while (inpos < insz)
	{
		j = 1;
		mask = 0;
		for (i = 0; i < 8; i++)
		{
			if (inpos >= insz)
			{
				break;
			}

			c = in[inpos++];

			if (table[hash] == c)
			{
				mask |= 1 << i;
			}
			else
			{
				table[hash] = c;
				buff[j++] = c;
			}

			hash = HASH(hash, c);
		}

		if (i > 0)
		{
			buff[0] =  mask;
			if (out != NULL)
			{
				memcpy(out + outpos, buff, j);
			}
			outpos += j;
		}
	}

	*outsz = outpos;
}
	\end{lstlisting}
	\section{Decompression}
	\begin{lstlisting}[language=C]
void
lzp_decompress(uint8_t *out, size_t *outsz, const uint8_t *in, size_t insz)
{
	uint8_t c;
	uint16_t hash = 0;
	uint32_t mask = 0;
	uint8_t table[LZP_HASH_SIZE] = { 0 };
	size_t i, j;
	size_t inpos;
	size_t outpos;
	uint8_t buff[9];

	inpos = 0;
	outpos = 0;
	while (inpos < insz)
	{
		j = 0;
		if (inpos >= insz)
		{
			break;
		}

		mask = in[inpos++];

		for (i = 0; i < 8; i++)
		{
			if ((mask & (1 << i)) != 0)
			{
				c = table[hash];
			}
			else
			{
				if (inpos >= insz)
				{
					break;
				}
				c = in[inpos++];
				table[hash] = c;
			}
			buff[j++] = c;
			hash = HASH(hash, c);
		}

		if (j > 0)
		{
			if (out != NULL)
			{
				memcpy(out + outpos, buff, j);
			}
			outpos += j;
		}
	}

	*outsz = outpos;
}
	\end{lstlisting}

\end{document}