Re: [Amforth] int_restore, etc.

[Matthias T. <mt...@we...>]

Hi,

> "-int" (int-off.asm) counterpart is "int_restore" (int-restore.asm). So,
> why is this "int_restore" header commented out, i.e., not available to
> the high level?

uhm. yes. These words are one of very first ones, that fell out of
scope later on.


> Candidly, as "+int" (int-on.asm) is a simple SEI instruction (Set Global
> Interrupt Flag) one would expect "-int" to be a simple CLI (Clear Global
> Interrupt Flag) but this is not the case...
> 
> May I suggest:
> 
> +int → SEI
> -int → CLI

Thats fine.
> int_suspend → ( -- SREG ) CLI
> int_restore → ( SREG -- )

These words are not really needed.

\ get the I flag as a forth flag
: int? SREG c@ SREG_I and 0> ;

\ to be used in pairs within the same colon definition
\ can be nested
: critical[
    int? r> swap >r >r \ keep the current state
    -int \ turn interrupts off
    drop \ currently the content of SREG.
;

: ]critical
    r> r> if +int then >r \ will crash if not matched
;

\ test case. foo prints bar-1 baz0 qux-1

: bar ." bar" int? . ;
: baz ." baz" int? . ;
: qux ." qux" int? . ;

: foo
  bar
  critical[
    \ nothing will disturb us here
    baz
  ]critical \ now interrupts or other things may happen again
  qux ;