It's not using the BIOS fonts (unless I'm misunderstanding your point). There's a file, font.pak on the ISO that contains the compressed fonts. The decompression and loading into RAM is done through a system call rather than a decompression routine in the game code.
The .pak file is structured like this:
address size
0x0000 0x0004 little endian representation of 0x1 (not sure of meaning, possibly that there's only one file)
0x0004 0x0004 little endian representation of size of filename (0x9 in this instance)
0x0008 0x0009 filename (font.bin_ in this case)
0x0011 0x0004 little endian representation of size of compressed data (0x4DE31 in this instance)
0x0015 0x0004 little endian representation of size of decompressed data (0x9BACC in this instance)
0x0019 0x4DE31 the payload. The first three bytes are 00. That may be part of the data, or it may be padding to get the compressed data PPC word aligned.
There was no yaz or yay magic word in the header, but I'll work through the first few bits of data and see if it matches.
The .pak file is structured like this:
address size
0x0000 0x0004 little endian representation of 0x1 (not sure of meaning, possibly that there's only one file)
0x0004 0x0004 little endian representation of size of filename (0x9 in this instance)
0x0008 0x0009 filename (font.bin_ in this case)
0x0011 0x0004 little endian representation of size of compressed data (0x4DE31 in this instance)
0x0015 0x0004 little endian representation of size of decompressed data (0x9BACC in this instance)
0x0019 0x4DE31 the payload. The first three bytes are 00. That may be part of the data, or it may be padding to get the compressed data PPC word aligned.
There was no yaz or yay magic word in the header, but I'll work through the first few bits of data and see if it matches.