[Qemu-devel] Re: [PATCH 2/9] eepro100: Simplify status handling

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Apr 06, 2010 at 04:29:45PM +0200, Stefan Weil wrote:
> Michael S. Tsirkin schrieb:
> > On Tue, Apr 06, 2010 at 01:44:02PM +0200, Stefan Weil wrote:
> >   
> >> Signed-off-by: Stefan Weil <weil@mail.berlios.de>
> >> ---
> >>  hw/eepro100.c |    9 +++++----
> >>  1 files changed, 5 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/hw/eepro100.c b/hw/eepro100.c
> >> index 0415132..741031c 100644
> >> --- a/hw/eepro100.c
> >> +++ b/hw/eepro100.c
> >> @@ -175,6 +175,7 @@ typedef enum {
> >>  } scb_command_bit;
> >>  
> >>  typedef enum {
> >> +    STATUS_NOT_OK = 0,
> >>      STATUS_C = BIT(15),
> >>      STATUS_OK = BIT(13),
> >>  } scb_status_bit;
> >>     
> >
> > 0 is not a bit, I would just use 0 as a constant below.
> >   
> 
> In a philosophical way, not a bit is some kind of a bit.
> 
> I think ok_status = STATUS_NOT_OK is clearer than
> ok_status = 0.

The reason it's not clear is because STATUS_OK | STATUS_NOT_OK
is not a valid combination. IOW, each enum should be:
- a set of bits. 0 is not a bit, you write 0 to say "no bits".
  you can | the values.
- a set of values. you can not | values together.

So either we have ok_status = 0 -> no bits set, and then
ok_status | STATUS_C, or

      STATUS_NOT_OK = BIT(15)
      STATUS_OK = BIT(13) | BIT(15),

and then just use ok_status.

> >   
> >> @@ -882,7 +883,7 @@ static void action_command(EEPRO100State *s)
> >>          bool bit_s;
> >>          bool bit_i;
> >>          bool bit_nc;
> >> -        bool success = true;
> >> +        uint16_t ok_status = STATUS_OK;
> >>          s->cb_address = s->cu_base + s->cu_offset;
> >>          read_cb(s);
> >>          bit_el = ((s->tx.command & COMMAND_EL) != 0);
> >> @@ -915,7 +916,7 @@ static void action_command(EEPRO100State *s)
> >>          case CmdTx:
> >>              if (bit_nc) {
> >>                  missing("CmdTx: NC = 0");
> >> -                success = false;
> >> +                ok_status = STATUS_NOT_OK;
> >>                  break;
> >>              }
> >>              tx_command(s);
> >> @@ -932,11 +933,11 @@ static void action_command(EEPRO100State *s)
> >>              break;
> >>          default:
> >>              missing("undefined command");
> >> -            success = false;
> >> +            ok_status = STATUS_NOT_OK;
> >>              break;
> >>          }
> >>          /* Write new status. */
> >> -        stw_phys(s->cb_address, s->tx.status | STATUS_C | (success ? STATUS_OK : 0));
> >> +        stw_phys(s->cb_address, s->tx.status | ok_status | STATUS_C);
> >>          if (bit_i) {
> >>              /* CU completed action. */
> >>              eepro100_cx_interrupt(s);
> >> -- 
> >> 1.7.0
> >>