EOR - AND mask inconsistency

[John Tytgat]

Various RISC OS API calls uses the EOR/AND mask principle to partially
update bits of a word and/or read bits of its old value.  The OSLib API
is not consistent for all these calls :

1) EOR/AND values for IN and OLD/NEW values for OUT:

E.g.
extern os_error *xosserialop_status (bits eor_mask,
      bits and_mask,
      bits *old_value,
      bits *new_value);

extern os_error *xparallelop_write_control (bits eor_mask,
      bits and_mask,
      bits *old_control,
      bits *new_control);

extern os_error *xportable_speed (bits eor_mask,
      bits and_mask,
      portable_processor_speed *old_speed,
      portable_processor_speed *new_speed);

extern os_error *xportable_control (bits eor_mask,
      bits and_mask,
      portable_control_flags *old_control,
      portable_control_flags *new_control);

2) EOR/AND values for IN but only OLD value for OUT:

E.g.
extern os_error *xos_mmu_control (bits eor_mask,
      bits and_mask,
      bits *old_value);

extern os_error *xhourglass_leds (bits eor_mask,
      bits and_mask,
      bits *old_leds);

extern os_error *xeconet_set_protection (econet_protection eor_mask,
      econet_protection and_mask,
      econet_protection *old_protection);

extern os_error *xcache_control (bits eor_mask,
      bits and_mask,
      bits *old_state);

extern os_error *xcache_cacheable (bits eor_mask,
      bits and_mask,
      bits *old_state);

extern os_error *xcache_updateable (bits eor_mask,
      bits and_mask,
      bits *old_state);

extern os_error *xcache_disruptive (bits eor_mask,
      bits and_mask,
      bits *old_state);

As the NEW value for OUT is easily derivable from EOR/AND values for IN and
the OLD value for OUT, this isn't a real issue.

3) EOR/AND values for IN only:

extern os_error *xbuffer_modify_flags (buffer_b b,
      bits eor_mask,
      bits and_mask);

But this is bad because this API doesn't allow me to read any of the
current buffer flag bits...

Could this be fixed please ?

John.
-- 
John Tytgat, in his comfy chair at home                                 BASS
John.Tytgat at aaug.net                             ARM powered, RISC OS driven