NAME
        availfonts -- inquire available memory & disk fonts.

   SYNOPSIS
        error = AvailFonts(buffer, bufBytes, flags);
                           A0      D0        D1

        long availfonts( struct availfontsheader *buffer, long bufbytes
                ULONG flags );

   FUNCTION
        availfonts fills a user supplied buffer with the structure,
        described below, that contains information about all the
        fonts available in memory and/or on disk.  Those fonts
        available on disk need to be loaded into memory and opened
        via opendiskfont, those already in memory are accessed via
        openfont.  the textattr structure required by the open calls
        is part of the information availfonts supplies.

        When availfonts fails, it returns the number of extra bytes
        it needed to complete the command.  Add this number to your
        current buffer size, allocate a new buffer, and try again.

   INPUTS
        buffer - memory to be filled with struct availfontsheader
                followed by an array of availfonts elements, which
                contains entries for the available fonts and their
                names.

        bufBytes - the number of bytes in the buffer
        flags - AFF_MEMORY is set to search memory for fonts to fill
                the structure, AFF_DISK is set to search the disk for
                fonts to fill the structure.  AFF_SCALED is set to
                not filter out memory fonts that are not designed.
                AFF_BITMAP is set to filter out fonts that are not
                stored in Amiga font format, i.e. to filter out
                outline fonts.  Any combination may be specified.
                AFF_TAGGED is set to fill the buffer with tavailfonts
                elements instead of availfonts elements.

   RESULTS
        buffer - filled with struct availfontsheader followed by the
                [T]AvailFonts elements, There will be duplicate entries
                for fonts found both in memory and on disk, differing
                only by type.  The existance of a disk font in the
                buffer indicates that it exists as an entry in a font
                contents file -- the underlying font file has not been
                checked for validity, thus an opendiskfont of it may
                fail.
        error - if non-zero, this indicates the number of bytes needed
                for availfonts in addition to those supplied.  thus
                structure elements were not returned because of
                insufficient bufBytes.

   EXAMPLE
        int afShortage, afSize;
        struct availfontsheader *afh;

        ...

        afSize = 400;
        do {
            afh = (struct availfontsheader *) allocmem(afsize, 0);
            if (afh) {
                afShortage = AvailFonts(afh, afSize, AFF_MEMORY|AFF_DISK);
                if (afShortage) {
                    FreeMem(afh, afSize);
                    afSize += afShortage;
                }
            }
            else {
                fail("AllocMem of availfonts buffer afh failedn");
                break;
            }
        }
            while (afShortage);

        /*
         * if (afh) non-zero here, then:
         * 1. it points to a valid availfontsheader
         * 2. it must have FreeMem(afh, afSize) called for it after use
         */