Add GemDOS fonts (Joerg Jenderek)

diff --git a/magic/Magdir/fonts b/magic/Magdir/fonts
index 8967d19dd604a89c45ed48f4458aebba726128d5..f47736f4e4f4b0e2f3eb1b60f333c32042a7adfa 100644 (file)
--- a/magic/Magdir/fonts
+++ b/magic/Magdir/fonts
@@ -1,6 +1,6 @@
 
 #------------------------------------------------------------------------------
-# $File: fonts,v 1.40 2019/04/19 00:42:27 christos Exp $
+# $File: fonts,v 1.41 2019/05/05 16:44:04 christos Exp $
 # fonts:  file(1) magic for font data
 #
 0      search/1        FONT            ASCII vfont text
@@ -128,6 +128,58 @@
 7      belong          0x00564944      DOS code page font data (from Linux?)
 4098   string          DOSFONT         DOSFONT2 encrypted font data
 
+# From: Joerg Jenderek
+# URL: http://fileformats.archiveteam.org/wiki/GEM_bitmap_font
+# Reference: http://cd.textfiles.com/ataricompendium/BOOK/HTML/APPENDC.HTM#cnt
+#
+# usual case with lightening mask and skewing mask 5555h~UU
+62     ulelong         0x55555555
+>0     use             gdos-font
+# BOX18.GFT COWBOY30.GFT ROYALK30.GFT
+62     ulelong         0
+# skip ISO 9660 CD-ROM ./filesystem by looking for low positive face size
+>2     uleshort        >2
+# skip DOS 2.0 backup id file ./msdos by looking for face size lower/equal 48
+>>2    uleshort        <49
+# skip MS Windows ICO ./msdos by looking for valid face name
+>>>4   ubeshort        >0x1F00
+# skip DOS executable BACKM212.COM by looking for horizontal offset table after header
+#>>>>68        ulelong         >87             OFFSET_OK
+>>>>0  use             gdos-font
+0      name            gdos-font
+>0     uleshort        x               GEM GDOS font
+!:mime application/x-font-gdos
+# also .eps found like AA070GEP.EPS AI360GEP.EPS
+!:ext  fnt/gtf
+# font name like University Bold
+>4     string          x               %.32s
+# face size in points 3-48
+>2     uleshort        x               %u
+# face ID (must be unique)
+>0     uleshort        x               \b, ID 0x%4.4x
+# lowest character index in face (usually 32 for disk-loaded fonts).
+#>36   uleshort        x               \b, low character index %u
+# width of the widest character
+#>50   uleshort        x               \b, %u char width
+# width of the widest character cell
+#>52   uleshort        x               \b, %u cell width
+# thickening size
+#>58   uleshort        x               \b, %u thick
+# lightening mask to eliminate pixels, usually 5555h
+>62    uleshort        !0x5555         \b, lightening mask 0x%x
+# skewing mask to determine when to perform additional rotation when skewing, usually 5555h
+>64    uleshort        !0x5555         \b, skewing mask 0x%x
+# offset to horizontal offset table 58h~88 5eh
+#>68   ulelong         >88             \b, 0x%x horizontal table offset
+# offset character offset table
+#>72   ulelong         x               \b, 0x%x coffset
+# offset to font data
+#>72   ulelong         x               \b, 0x%x foffset
+# form width in bytes
+#>80   uleshort        x               \b, %u fwidth
+# pointer to the next font, set by GDOS after loading
+#>84   ulelong         x               \b, 0x%x noffset
+
 # downloadable fonts for browser (prints type) anthon@mnt.org
 # https://tools.ietf.org/html/rfc3073
 0      string          PFR1            Portable Font Resource font data (new)