Atari resource structure (file)

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atari

 · 11 Jan 2021

Resource structure (file)

A resource file (*.RSC) is normally loaded with ~RSRC_LOAD(filenamne), which allocates memory for the file, and then performs:

• internal AES pointer initialization (ADDROUT(0)= tree%)
• conversion of character coordinates to pixel coordinates in the current resolution (ie ~RSRC_OBFIX(tree%,obj%) for each object)
• pointer conversion (L:ob_spec and others) from file relative to memory absolute (see file structure below)

The RSC-file is structured as at least five distinct blocks:

• a file header (18 words, 36 bytes)
• a text block with all strings, masks and type info
• an info block with L:pointers (TEDINFO to texts...)
• a tree info block (L:ob_spec pointers) (n x 24 bytes)
• a relocation table (L: rel ptrs, n x 4 bytes)

It should be noted that the program variable tree% obtained with the function ~RSRC_GADDR(0,0,tree%) points to the (first) tree info block, not the beginning of the file as located in memory. Filestart is thus at:

  
   <tree%> - <W:rsh_vrsn> 

 File header (18 words) 
   +00   1  W:rsh_vrsn (editor ID#, usually 0 or 1) 
   --- offset pointers 
   +02   2  W:rsh_object (relative) to (first) tree info (object field) 
         3  W:rsh_tedinfo  position of the TEDINFo structs 
         4  W:rsh_iconblk  position of the ICONBLK structs 
         5  W:rsh_bitblk   position of the BITBLK struct 
         6  W:rsh_frstr    position of the free strings 
         7  W:rsh_string   position of fixed strings 
         8  W:rsh_imdata   position of imagedata 
         9  W:rsh_frimg    position of the free images 
        10  W:rsh_trindex  (relative) to relocation table 
   --- structure info 
   +20  11  W:rsh_nobs     total number of objects 
        12  W:rsh_ntree    Obj trees (must be >=1 for valid RSC-file) 
        13  W:rsh_nted     total number of TEDINFO structs 
        14  W:rsh_nib      total number of ICONBLK structs 
        15  W:rsh_nbb      total number of BITBLK structs 
        16  W:rsh_nstring  total number of strings 
        17  W:rsh_nimages  total number of images 
        18  W:rsh_rssize   file length (should be same as LOF when loading) 
   --- --- --- 
   +36 start of text strings 
 

Notes:

• K saves with W(1) id#=1.
• K-resource rejects files if W(18)<>LOF().W(18) may be poked to correct (actual) size to fix this.