zhcon-0.2.4.tar.gz_zhcon_zhcon 0.2.4_zhcon 0.2.4.tar._zhcon for

The PSF file-format for big charset (C) 2001 Hu Yong <ccpaging@online.sh.cn> This file documents the PSF file-format for big charset(called as BPSF as below), as understood by version 0.15 and above of zhcon, and zhcon is orient language envirment for linux console. This file is based on PSF format used in Linux console utilites by Yann Dirson <dirson@debian.org> This file has revision number 0.1, and is dated 2001/08/08. Any useful additional information on BPSF files would be great. 0. Changes: 1. Summary BPSF stands for PC Screen Font in orient language environment, and bases on PSF file format used in lct. We need understand PSF at first, and why we extend it? The PSF file basically contains one character-font, whose width is 8 pixels, i.e. each scan line in a character occupies 1 byte. It may contain characters of any height between 0 and 255, though character heights lower than 8 or greater than 32 are not attested to exist or even be useful [more info needed on this]. Fonts can contain either 256 or 512 characters. The file can optionally contain a unicode mapping-table, telling, for each character in the font, which UCS2 characters it can be used to display. The "file mode" byte controls font size (256/512) and whether file contains a unicode mapping table. When we developing zhcon, we have two main problems. The first is font width, we need to get more choice to display beautiful and more chars on console, the width may be any between 12 to 24, even 48. The second is chars count in font. Chinese charset is more then 8,000 chars, PSF can only hold 512 characters. According Yann Dirson's document, XPSF(the extend of PSF) can hold on big charset. We may change BPSF to XPSF in the future, but now we can not wait. You can not expect BPSF solve all problem for the console font, and it works for big charset only. BPSF extend "file mode" byte. BPSF is same as PSF when "file mode" between 0 to 3, and follow only one byte, char height. If "file mode" is 4 or 5, there is six bytes followed, include char width, char height, and number of chars. 2. History The PSF file format was designed by H. Peter Anvin <hpa@transmeta.com> in 1989 or so for his DOS screen font editor, FONTEDIT.EXE. When he became involved with Linux, he used it for the Linux font stuff he worked with, released a binary of FONTEDIT.EXE for free distribution, and added the Unicode table to the spec. 3. Known programs understanding this file-format. Only zhcon can read and/or write BPSF files. The program in the Linux console utilities, like: setfont (R/W) psfaddtable (R/W) psfstriptable (R/W) psfgettable (R) can read and/or write PSF files. Those program would show error message when involved in BPSF font file. 4. Technical data The file format is described here in sort-of EBNF notation. Upper-case WORDS represent terminal symbols, i.e. C types; lower-case words represent non-terminal symbols, i.e. symbols defined in terms of other symbols. [sym] is an optional symbol sym1 sym2 is sym1 followed by sym2 sym1 | sym2 is either sym1 or sym2 {sym} is a symbol that can be repeated 0 or more times {sym}*N is a symbol that must be repeated N times Comments are introduced with a # sign. # The data (U_SHORT's) are stored in LITTLE_ENDIAN byte order. psf_file = psf_header raw_fontdata [unicode_data] psf_header = CHAR = 0x36 CHAR = 0x04 # magic number filemode font info filemode = CHAR # 0 : 256 characters, no unicode_data # 1 : 512 characters, no unicode_data # 2 : 256 characters, with unicode_data # 3 : 512 characters, with unicode_data # 4 : big charset, no unicode_data # 5 : big charset, with unicode_data # file mode 4 or 5 is the extend of PSF font info : fontheight # filemode is between 0 to 3 | big_charset_info # filemode is between 4 to 5 fontheight = CHAR # measured in scan lines big_charset_info : charwidth charheight fontsize charwidth : u8 # char width in bits charheight : u8 # char height in bits fontsize : u32 # number of chars in font raw_fontdata = {char_data}*<fontsize> char_data = {row_data}*<charheight> row_data = scan line bits expand to byte, i.e., 1 byte when charwidth is less then 8, 2 bytes when charwidth between 9 to 16, and so on. The expand bit is 0. This may cost more memory, but it really efficent when display. # unicode_data is just behind raw_fontdata unicode_data = { unicode_array psf_separator }*<fontsize> unicode_array = { unicode } # any necessary number of times unicode = U_SHORT # UCS2 code psf_separator = unicode = 0xFFFF