• Miguel F. Simoes (10/10) Jun 07 2005 How can I emulate in D this C code?
• Phoenix (6/21) Jun 08 2005 struct _name {
• =?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= (15/30) Jun 08 2005 struct name
• Miguel F. Simoes (5/35) Jun 08 2005 Ok. Thanks. I will try.
• Stewart Gordon (8/18) Jun 08 2005 But _should_ it work? AIUI that's not indicated in the spec.
• =?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= (7/10) Jun 08 2005 Beats me, the "bit" type is lame anyway :-)
• Stewart Gordon (20/33) Jun 08 2005 Yes. But that isn't really necessary. How about making them only as

"Miguel F. Simoes" <Kobold netcabo.pt> writes:

How can I emulate in D this C code?
 (I don't know the right way to convert the numbers after the colon)

typedef struct _name {
    DWORD fieldA :1
    DWORD fieldB :1
    ...
    ...
} name;


Thanks
Miguel Ferreira Simoes 

Phoenix <phoenix flareware.cz> writes:

Miguel F. Simoes napsal(a):
 How can I emulate in D this C code?
  (I don't know the right way to convert the numbers after the colon)
 
 typedef struct _name {
     DWORD fieldA :1
     DWORD fieldB :1
     ...
     ...
 } name;
 
 
 Thanks
 Miguel Ferreira Simoes 
 
 

struct _name {
  bit fieldA;
  bit fieldB;
}

what about this? but i`m not sure..

=?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= <afb algonet.se> writes:

Miguel F. Simoes wrote:

 How can I emulate in D this C code?
  (I don't know the right way to convert the numbers after the colon)
 
 typedef struct _name {
     DWORD fieldA :1
     DWORD fieldB :1
     ...
     ...
 } name;

struct name
{
       uint field;

       bit fieldA() { return cast(bit) (field >> 31) & 1; }
       void fieldA(bit b) { field = (field &~ 1<<31) | (b << 31); }
       bit fieldB() { return cast(bit) (field >> 30) & 1; }
       void fieldB(bit b) { field = (field &~ 1<<30) | (b << 30); }
}

Something like that... Not sure if the C bit order is defined ?
(so you might need some kind of bitsex versioning in D as well)

Phoenix wrote:

 struct _name {
  bit fieldA;
  bit fieldB;
 }
 
 what about this? but i`m not sure..

No, that does not work. Single bits are the size of "byte"...
(bit[32] might, but then only for even multiples of 32 bits)

--anders

"Miguel F. Simoes" <Kobold netcabo.pt> writes:

Ok. Thanks. I will try.
My goal is just to port the DCB windows struct to D.

Miguel

"Anders F Björklund" <afb algonet.se> escreveu na mensagem 
news:d86j62$1hsq$1 digitaldaemon.com...
 Miguel F. Simoes wrote:

 How can I emulate in D this C code?
  (I don't know the right way to convert the numbers after the colon)

 typedef struct _name {
     DWORD fieldA :1
     DWORD fieldB :1
     ...
     ...
 } name;

 struct name
 {
       uint field;

       bit fieldA() { return cast(bit) (field >> 31) & 1; }
       void fieldA(bit b) { field = (field &~ 1<<31) | (b << 31); }
       bit fieldB() { return cast(bit) (field >> 30) & 1; }
       void fieldB(bit b) { field = (field &~ 1<<30) | (b << 30); }
 }

 Something like that... Not sure if the C bit order is defined ?
 (so you might need some kind of bitsex versioning in D as well)

 Phoenix wrote:

 struct _name {
  bit fieldA;
  bit fieldB;
 }

 what about this? but i`m not sure..

 No, that does not work. Single bits are the size of "byte"...
 (bit[32] might, but then only for even multiples of 32 bits)

 --anders 

Stewart Gordon <smjg_1998 yahoo.com> writes:

Anders F Björklund wrote:
<snip>
 Phoenix wrote:
 
 struct _name {
  bit fieldA;
  bit fieldB;
 }

 what about this? but i`m not sure..

 
 No, that does not work. Single bits are the size of "byte"...

But _should_ it work?  AIUI that's not indicated in the spec.

http://www.digitalmars.com/drn-bin/wwwnews?digitalmars.D/10198

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on 
the 'group where everyone may benefit.

=?ISO-8859-1?Q?Anders_F_Bj=F6rklund?= <afb algonet.se> writes:

Stewart Gordon wrote:

 No, that does not work. Single bits are the size of "byte"...

 
 But _should_ it work?  AIUI that's not indicated in the spec.

Beats me, the "bit" type is lame anyway :-)


I think it will have to occupy (at least) one byte, in order to
be addressable ? (for use as pointer targets or inout parameters)

Maybe the compiler could concatenate single bits next to each other
into bit arrays or something. But then those are 32-bit aligned now?

--anders

Stewart Gordon <smjg_1998 yahoo.com> writes:

Anders F Björklund wrote:
 Stewart Gordon wrote:
 
 No, that does not work. Single bits are the size of "byte"...

 
 But _should_ it work?  AIUI that's not indicated in the spec.

 
 Beats me, the "bit" type is lame anyway :-)
 
 I think it will have to occupy (at least) one byte, in order to
 be addressable ? (for use as pointer targets or inout parameters)
 
 Maybe the compiler could concatenate single bits next to each other
 into bit arrays or something. But then those are 32-bit aligned now?

Yes.  But that isn't really necessary.  How about making them only as 
many bytes as necessary, and obeying the alignment setting?

Even if there would be a performance hit:
- it would at least make it possible to use bit arrays to wrap bit flags 
in structs
- instances that aren't in structs, or happen to be 32-bit aligned, can 
still use the efficient implementation for this case.

I guess a good course of action would be to make this change to bit 
arrays, and to have consecutive bit members of a struct implemented as a 
bit array internally.  Of course they won't be addressable, but that's a 
necessary side effect under the current constraints.  And if people want 
to use bytes instead, then they can.

We'd also need to consider what happens to endianness from a portability 
POV.  FTM I just tested it with gdc on Mac OS X - a big-endian platform 
but bit arrays seem to be little-endian nonetheless (albeit left-aligned).

Stewart.

-- 
My e-mail is valid but not my primary mailbox.  Please keep replies on 
the 'group where everyone may benefit.