MIMEMap

MimeMap and DOSMap

Traditionally many applications have used the DOSMap settings to determine the RISC OS filetype corresponding to a PC file extension. This is now deprecated and applications should be converted to use the MimeMap module instead.

DOSMap is still available in DOSFS and may be used to override the setting given in the MimeMap file, but it is only for DOSFS to use. DOSFS now behaves as follows:

Look for filetype information in the reserved fields in the directory structure. If Acorn filetype is found, then use that (i.e. if DOS disc was written using an Acorn system).
Look up file extension in DOSMap settings and map to Acorn filetype if one is defined.
Look up file extension in MimeMap and map to Acorn filetype if one is defined.
Nothing available so use type DOS.

The MimeMap module provides a MimeMap_Translate SWI to convert between RISC OS filetypes, MIME content type and file type suffix:

     MimeMap_Translate (&50B00)

On entry:    R0 = input format (see below)
   R1 = filetype (if R0=0), or pointer to string buffer (if R0>0)
   R2 = output format (see below)
   R3 = output buffer, if needed (i.e. if R2 = 1, 2 or 3)
On exit:    R0-R2 preserved
   R3 = result (if R2=0), or pointer to buffer (if R2>0)

This SWI may be used to convert between RISC OS file types, MIME content types and 'dot' extensions to file names. An error will be returned if the translation cannot be performed. Strings are always null-terminated.

The MimeMap translation formats are:

Format    Name    Meaning
0    MMM_TYPE_RISCOS    Filetype as a number
1    MMM_TYPE_RISCOS_STRING    Filetype as string
2    MMM_TYPE_MIME    Content type as string
3    MMM_TYPE_DOT_EXTN    Extension as string
others       reserved