gas/NOTES.config

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   2                       The GAS Configuration Plan
   3
   4 Theory:
   5
   6 The goal of the new configuration scheme is to bury all object format
   7 and target processor dependancies in object and target specific files.
   8 That is, to move all #ifdef's out of the gas common code.
   9
  10 Here's how it works.  There is a .h and a .c file for each object file
  11 format and a .h and a .c file for each target processor.  The
  12 configure script creates symlinks in the current directory to the
  13 appropriate files in the config directory.  configure also serves as a
  14 list of triplets {host, target, object-format} that have been tested
  15 at one time or another.  I also recommend that configure be used to
  16 document triplet specific notes as to purpose of the triplet, etc.
  17
  18 Implementation:
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  20 obj-format.h is a {sym}link to .../config/obj-something.h.  It is intended
  21
  22 All gas .c files include as.h.
  23
  24 as.h #define's "gas", includes host.h, defines a number of gas
  25 specific structures and types, and then includes tp.h, obj.h, and
  26 target-environment.h.
  27
  28 target-environment.h defines a target environment specific
  29 preprocessor flag, eg, TE_SUN, and then includes obj-format.h.
  30
  31 obj-format.h defines an object format specific preprocessor flag, eg,
  32 OBJ_AOUT, OBJ_BOUT, OBJ_COFF, includes "target-processor.h", and then
  33 defines the object specific macros, functions, types, and structures.
  34
  35 target-processor.h
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  37 target-processor.
  38
  39 Porting:
  40
  41 There appear to be four major types of ports; new hosts, new target
  42 processors, new object file formats, and new target environments.