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The GAS Configuration Plan
Theory:
The goal of the new configuration scheme is to bury all object format
and target processor dependancies in object and target specific files.
That is, to move all #ifdef's out of the gas common code.
Here's how it works. There is a .h and a .c file for each object file
format and a .h and a .c file for each target processor. The
configure script creates symlinks in the current directory to the
appropriate files in the config directory. configure also serves as a
list of triplets {host, target, object-format} that have been tested
at one time or another. I also recommend that configure be used to
document triplet specific notes as to purpose of the triplet, etc.
Implementation:
obj-format.h is a {sym}link to .../config/obj-something.h. It is intended
All gas .c files include as.h.
as.h #define's "GAS", includes config.h, defines a number of gas
specific structures and types, and then includes tc.h, obj.h, and
targ-env.h.
targ-env.h defines a target environment specific preprocessor flag,
eg, TE_SUN, and then includes obj-format.h.
obj-format.h defines an object format specific preprocessor flag, eg,
OBJ_AOUT, OBJ_BOUT, OBJ_COFF, includes "targ-cpu.h", and then defines
the object specific macros, functions, types, and structures.
targ-cpu.h
targ-cpu.c
Porting:
There appear to be four major types of ports; new hosts, new target
processors, new object file formats, and new target environments.
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