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| 1676 | tullio | 1 | %---------------------------------------------------------------------------- |
| 2 | \chapter{The File Management} |
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| 3 | %---------------------------------------------------------------------------- |
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| 4 | |||
| 5 | S.Ha.R.K. provides a built-in File System that currently supports Hard Disk |
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| 6 | Drivers and FAT16 partitions. |
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| 7 | |||
| 8 | If you are using the DOS eXtender X to run the application, you can use some |
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| 9 | callback to the DOS 0x21 interrupt, to write/read some bytes from the |
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| 10 | filesystem \footnote{These callbacks are useful when you don't have any |
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| 11 | partition that can be read by the filesystem... for example when running |
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| 12 | S.Ha.R.K. applications from a FAT32 filesystem!}. These functions directly |
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| 13 | interact with the underlying DOS, and can not be used when the system is in |
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| 14 | protected mode. In particular, you can only use these functions into the |
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| 15 | \_\_kernel\_register\_levels\_\_() function and in the RUNLEVEL\_AFTER\_EXIT |
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| 16 | exit functions. |
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| 17 | |||
| 18 | In the case of errors, a \texttt{NULL} or zero value is returned; |
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| 19 | \texttt{DOS\_ferror()} can be used to get the DOS error code; the header file |
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| 20 | \texttt{<ll/i386/x-dos.h>} must be included to use these functions. A running |
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| 21 | (we hope) well documented example can be foun in the \texttt{demos/dosfs} |
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| 22 | directory. |
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| 23 | |||
| 24 | \vspace{7mm} |
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| 25 | |||
| 26 | \begin{intest} |
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| 27 | DOS\_FOPEN\index{DOS\_fopen()} |
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| 28 | \end{intest} |
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| 29 | |||
| 30 | \begin{description} |
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| 31 | \item [\textbf{DOS\_FILE {*}DOS\_fopen(char {*}name, char {*}mode);}] |
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| 32 | \item [\textbf{Description:}] It opens a file and returns a pointer to a file structure. |
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| 33 | The \texttt{name} parameter contains the name of the file to be opened. The |
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| 34 | \texttt{mode} parameter contains a string whose value can be one of the |
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| 35 | following constants: {}``r'' to read, {}``w'' to write, and {}``rw'' to read and |
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| 36 | write. In the case of error, \texttt{NULL} is returned; otherwise the returned |
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| 37 | value can be used as last parameter in the functions listed below. |
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| 38 | \end{description} |
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| 39 | |||
| 40 | \begin{intest} |
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| 41 | DOS\_FCLOSE\index{DOS\_fclose()} |
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| 42 | \end{intest} |
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| 43 | |||
| 44 | \begin{description} |
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| 45 | \item [\textbf{void DOS\_fclose(DOS\_FILE {*}f);}] |
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| 46 | \item [\textbf{Description:}] It closes the specified file and releases all allocated DOS |
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| 47 | resources. |
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| 48 | \end{description} |
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| 49 | |||
| 50 | \begin{intest} |
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| 51 | DOS\_FREAD\index{DOS\_fread()} |
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| 52 | \end{intest} |
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| 53 | |||
| 54 | \begin{description} |
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| 55 | \item [\textbf{DWORD DOS\_fread(void {*}buf, DWORD size, DWORD num, DOS\_FILE {*}f);}] |
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| 56 | \item [\textbf{Description:}] It reads \texttt{num} objects of \texttt{size} bytes from |
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| 57 | file \texttt{f} and place them in a buffer pointed by \texttt{buf}. This |
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| 58 | function returns the actual number of bytes read from the file (it can be less |
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| 59 | than $num*size$ bytes). Zero is returned if an error occurs or |
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| 60 | \textit{end-of-file} is found. |
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| 61 | \end{description} |
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| 62 | |||
| 63 | \begin{intest} |
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| 64 | DOS\_FWRITE\index{DOS\_fwrite()} |
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| 65 | \end{intest} |
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| 66 | |||
| 67 | \begin{description} |
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| 68 | \item [\textbf{DWORD DOS\_fwrite(void {*}buf,DWORD size,DWORD num,DOS\_FILE {*}f);}] |
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| 69 | \item [\textbf{Description:}] It writes \texttt{num} objects of \texttt{size} bytes into |
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| 70 | file \texttt{f}. Data are picked from the buffer pointed by \texttt{buf}. This |
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| 71 | function returns the actual number of bytes written (it can be less than |
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| 72 | $num*size$ bytes). Zero is returned if an error occurs. |
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| 73 | \end{description} |
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| 74 | |||
| 75 | \begin{intest} |
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| 76 | DOS\_ERROR\index{DOS\_error()} |
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| 77 | \end{intest} |
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| 78 | |||
| 79 | \begin{description} |
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| 80 | \item [\textbf{unsigned DOS\_error(void);}] |
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| 81 | \item [\textbf{Description:}] Returns the error code of the latest \texttt{DOS\_xxx} |
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| 82 | function. |
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| 83 | \end{description} |
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| 84 |