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Subject: Re: unique function for each button
From: tp_at_diffenbach.org
Date: 2003-01-31


Er. Slimmer. But not much slower.

typedef int ( *rockbox_function )( int, void* ) ;
 
#define BUTTON_COUNT 10 ;
#define STATE_COUNT 10 ;

static rockbox_function known_rockbox_function[] = {
 &f_1, &f_2, ... } ;
// 4 bytes per func.

static unsigned char extra_level_of_indirection[ STATE_COUNT ][ BUTTON_COUNT ] = {
  1, 1, 2, 0, ...} ;
// 100 bytes total

 

// at global scope
rockbox_function current_state_buttons[ BUTTON_COUNT ] ;

void enter_state( int state ) {
  for( int i = 0 ; i < BUTTON_COUNT ; ++i ) {
    current_state_buttons[ i ] = known_rockbox_function[ extra_level_of_indirection[ state ][ i ] ] ;
  }
}
...

//button code

int pressed( int button ) {
  int extra_data_int = get_extra_data_int() ; // whatever
  void* extra_data_ptr = get_extra_data_ptr() ;
  return ( *( current_state_buttons[ button ] )( extra_data_int, extra_data_ptr ) ;
}

Quoting tp_at_diffenbach.org:

>
> Of course the Rockbox can be in different states, so you'd need to set
> the mapping per state. The recorder has 10 buttons so,
>
> typedef int ( *rockbox_function )( int, void* ) ;
>
> #define BUTTON_COUNT 10 ;
> #define STATE_COUNT 10 ;
>
> static rockbox_function[ STATE_COUNT ][ BUTTON_COUNT ] = {
> { &default_button_1, def_button_2, ... } } ;
>
>
> Now this is sizeof( func_ptr ) * STATE_COUNT * BUTTON_COUNT = 400 bytes,
> so we might want to investigate ways to slim it down.
>
> Of course, it also requites writing wrappers for all major functions to
> conform to the rockbox_function signature, or nasty casting.
>
>
> Quoting Gary Richardi <gary_pr_at_yahoo.com>:
>
> > Making all button functions configurable by the user is a GREAT
> idea!
> >
> > --- tp_at_diffenbach.org wrote:
> > >
> > > My two cents: what this (any?) button does should be customizable
> by
> > > the user.
> > >
> >
> >
> > =====
> > --- Gary ---
> > 4 Way Street (West) - CSN&Y Tribute band ---> http://4waystreet.net
> > My original music ---> http://www.mp3.com/gpr
> >
> > __________________________________________________
> > Do you Yahoo!?
> > Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
> > http://mailplus.yahoo.com
> >
>
>



Page was last modified "Jan 10 2012" The Rockbox Crew
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