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2 - A File Pick Dialog
To start, we can look at a bit of code for file management. This column's sample program (along with source code) contains a dialog that simply lists all the programs (.FXE files) in the system, and allows a selection. Although it's ready for reuse, it also lends itself well to tinkering, and can be a starting point for your own file dialog. Calling it is a matter of including the dlg_file.cpp file in your project, and calling one function:bool OpenDialog(ebo_enumerator_t *info,const char *ext);
You pass a pointer to an ebo_enumerator_t structure and an extension string (case insensitive) and get back a filled structure and true, or false if no selection made. This dialog scans the MMC and main RAM, or just main RAM if there is no MMC, making this a good general-purpose dialog for file selection.
To understand the results returned, we need to delve into the ebm code internals a little, starting with the ebo_enumerator_t structure:
struct ebo_enumerator_t
{
int index; // file system index
ebo_name_t name; // file name struct
EBO_U32 publisher_revision; // publisher info
EBO_U32 size; // file size
EBO_U32 flags; // various flags
EBO_U32 minimum_os; // OS requirement
EBO_U32 mod_cnt; // modification count
EBO_U32 modh_cnt; // mod. count (header)
EBO_U32 vdev; // file device
};
Some interesting fields in this structure: 'index', which indicates where in the file system this entry exists; 'size', which is the file size (not necessarily rounded to a page size); and 'vdev', which tells us the location of the file (zero if in RAM, non-zero otherwise). For our dialog, this entry makes for a handy way to test if a file resides in RAM or on the MMC.
Finally, another important field, 'name' is actually the ebo_name_t structure, which provides a great deal of file information, and which we've seen before:
struct ebo_name_t
{
char secure_type[EBO_LEN_STYPE];
char publisher[EBO_LEN_PUB];
char name[EBO_LEN_NAME];
char extension[EBO_LEN_EXT];
};
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