GambitNds

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(New page: This will be a page describing the efforts to build a version of Gambit optimized for NDS development. Right now it will just point to the Distributions page, and contain a few notes....)
(Add note about removing bignum algorithms, and a note about simplifying the "radical surgery")
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This will be a page describing the efforts to build a version of Gambit optimized for NDS development.
+
This will be a page describing the efforts to build a version of Gambit optimized for NDS (Nintendo DS) development.
Right now it will just point to the [[Distributions]] page, and contain a few notes.
Right now it will just point to the [[Distributions]] page, and contain a few notes.
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== Decreasing the size of the Gambit executable ==
== Decreasing the size of the Gambit executable ==
-
One of the Biggest challenges is the RAM limitation on the DS (4 megs).  Gambit, even when properly compressed will take 3 of those.   
+
 
 +
One of the Biggest challenges is the RAM limitation on the DS (4 megs).  Gambit, even when properly compressed will take 3 of those.
 +
 
 +
=== Get rid of the fancy bignum algorithms ===
 +
 
 +
Gambit includes fast algorithms for large integer multiplication, division, and gcd.
 +
 
 +
You probably don't need them on the NDSTo remove them from the executable, after you've done
 +
a "make bootstrap" change the line
 +
<pre>
 +
(##define-macro (use-fast-bignum-algorithms) #t)
 +
</pre>
 +
in _num.scm to
 +
<pre>
 +
(##define-macro (use-fast-bignum-algorithms) #f)
 +
</pre>
 +
and do another "make".  Gambit's constant propagation and dead-code elimination will eliminate all
 +
the code (and tables) for the fancy bignum algorithms.
 +
 
 +
=== Radical surgery on the Gambit runtime ===
 +
 
 +
(Note: In revision 207, _kernel.scm was changed so that these warnings do not occur, and you don't have to provide your own
 +
versions of ##map, ##string->symbol, ##+, and ##*.)
Recently Marc sent a message about how to radically decrease the size of the executable:
Recently Marc sent a message about how to radically decrease the size of the executable:
 +
<pre>
Actually there is another one, which consists in eliminating the whole   
Actually there is another one, which consists in eliminating the whole   
Gambit library, except for the "essentials" (lib/_kernel.scm and some   
Gambit library, except for the "essentials" (lib/_kernel.scm and some   
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% ./hw
% ./hw
hello world
hello world
 +
</pre>

Revision as of 04:15, 8 October 2008

This will be a page describing the efforts to build a version of Gambit optimized for NDS (Nintendo DS) development.

Right now it will just point to the Distributions page, and contain a few notes.


Decreasing the size of the Gambit executable

One of the Biggest challenges is the RAM limitation on the DS (4 megs). Gambit, even when properly compressed will take 3 of those.

Get rid of the fancy bignum algorithms

Gambit includes fast algorithms for large integer multiplication, division, and gcd.

You probably don't need them on the NDS. To remove them from the executable, after you've done a "make bootstrap" change the line

(##define-macro (use-fast-bignum-algorithms) #t)

in _num.scm to

(##define-macro (use-fast-bignum-algorithms) #f)

and do another "make". Gambit's constant propagation and dead-code elimination will eliminate all the code (and tables) for the fancy bignum algorithms.

Radical surgery on the Gambit runtime

(Note: In revision 207, _kernel.scm was changed so that these warnings do not occur, and you don't have to provide your own versions of ##map, ##string->symbol, ##+, and ##*.)

Recently Marc sent a message about how to radically decrease the size of the executable:

Actually there is another one, which consists in eliminating the whole  
Gambit library, except for the "essentials" (lib/_kernel.scm and some  
of the C files in lib/ which implement the GC, C-interface,
initialization code, etc).

Using this technique (see trace below) I managed to build a 300 kB  
executable on MacOS X from the v4.2.9 tarball.  This could be reduced  
some more by removing some functionality.  Anyway, this is just a  
quick-and-dirty experiment.

The downside of course is that you have to implement yourself whatever  
you need in your application.  You only have very basic functionality  
(the inlinable primitives like ##fx+, ##cons, ##car).  This is like  
reinventing the wheel... but I'm sure some users will appreciate the  
hack value!

Marc

% tar zxf gambc-v4_2_9.tgz
% cd gambc-v4_2_9
% ./configure --enable-single-host
% make bootstrap
% ################ Now edit lib/makefile.in .
% diff lib/makefile.in lib/makefile.in-orig
< MODULES = _kernel
< MODULES_SCM = _kernel.scm
< MODULES_C = _kernel.c
< MODULES_O = _kernel@obj@
< MODULES_O_PLUS = +_kernel@obj@
< MODULES_O_COMMA = _kernel@obj@
---
MODULES = _kernel _system _num _std \
_eval _io _nonstd _thread _repl
MODULES_SCM = _kernel.scm _system.scm _num.scm _std.scm \
_eval.scm _io.scm _nonstd.scm _thread.scm _repl.scm
MODULES_C = _kernel.c _system.c _num.c _std.c \
_eval.c _io.c _nonstd.c _thread.c _repl.c
MODULES_O = _kernel@obj@ _system@obj@ _num@obj@ _std@obj@ \
_eval@obj@ _io@obj@ _nonstd@obj@ _thread@obj@ _repl@obj@
MODULES_O_PLUS = +_kernel@obj@ +_system@obj@ +_num@obj@ +_std@obj@ \
+_eval@obj@ +_io@obj@ +_nonstd@obj@ +_thread@obj@ +_repl@obj@
MODULES_O_COMMA = _kernel@obj@,_system@obj@,_num@obj@,_std@obj@,\
+_eval@obj@,_io@obj@,_nonstd@obj@,_thread@obj@,_repl@obj@
81c87,88
< MODULES_O_IN_COMPILE_ORDER = _kernel@obj@
---
MODULES_O_IN_COMPILE_ORDER = _io@obj@ _num@obj@ _std@obj@ \
_kernel@obj@ _nonstd@obj@ _repl@obj@ _eval@obj@ _thread@obj@  
_system@obj@
% make clean
% make
making all in include
...
making all in lib
...
../gsc-comp -:=.. -f -link -flat -o _gambc.c _kernel.c
*** WARNING -- "##*" is not defined,
***            referenced in: ("_kernel.c")
*** WARNING -- "##+" is not defined,
***            referenced in: ("_kernel.c")
*** WARNING -- "##map" is not defined,
***            referenced in: ("_kernel.c")
*** WARNING -- "##string->symbol" is not defined,
***            referenced in: ("_kernel.c")
% ################ Note that lib/_kernel.scm depends on some Gambit
% ################ library procedures that are not defined in
% ################ lib/_kernel.scm.  This will be fixed so that
% ################ lib/_kernel.scm is self contained, as it should.
% ################ Now create hw.scm .
% cat hw.scm
;; Make sure the compiler does not assume the standard library is
;; linked in.
(declare
   (block)
   (not inline)
   (not inline-primitives)
   (inlining-limit 0)
   (not run-time-bindings)
)

;; Supply the procedures lib/_kernel.scm needs (this dependency should
;; be removed since it is gratuitous).
(define (##map f lst) '()) ;; I'm lazy
(define (##string->symbol str) 'foo)
(define (##+ x y) 0)
(define (##* x y) 0)

;; The "hello world" program:

(c-declare "#include <stdio.h>")

(define puts (c-lambda (char-string) int "puts"))

(puts "hello world")
% ./gsc-comp -:=. -c hw.scm
% ./gsc-comp -:=. -link hw.c
% gcc -Iinclude -D___SINGLE_HOST hw_.c hw.c lib/libgambc.a -o hw
% strip hw
% ls -l hw
-rwxr-xr-x  1 feeley  feeley  300384 Oct  4 09:22 hw
% ./hw
hello world
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