From: tmoran@bix.com
Subject: Re: C struct import
Date: 2000/01/27
Date: 2000-01-27T00:00:00+00:00 [thread overview]
Message-ID: <%hOj4.120$hb5.4849@nnrp3-w.snfc21.pbi.net> (raw)
In-Reply-To: vhi3drkqqo7.fsf@grotte.ifi.uio.no
Assuming the unused things are really unused, the 1 bit flags
are Booleans, and Uint32 and SDL_PixelFormat types are elsewhere
defined, you might say:
type Access_SDL_Pixel_Format is access all SDL_PixelFormat;
type SDL_VideoInfo is record
hw_available, -- Can you create hardware surfaces?
wm_available, -- Can you talk to a window manager?
blit_hw, -- Accelerated blits HW --> HW
blit_hw_CC, -- Accelerated blits with Colorkey
blit_hw_A, -- Accelerated blits with Alpha
blit_sw, -- Accelerated blits SW --> HW
blit_sw_CC, -- Accelerated blits with Colorkey
blit_sw_A, -- Accelerated blits with Alpha
blit_fill : Boolean; -- Accelerated color fill
video_mem : Uint32; -- The total amount of video memory (in K)
vfmt : Access_SDL_Pixel_Format; -- Value: The format of the video surface
end record;
If you not only need a record with these things, but you need the bits
to occur at specific places in the bytes (if you're interfacing to
hardware or an OS, say), then you'll have to find out just where
your C compiler puts things (since that's implementation dependent)
and then include a record representation clause to ensure the Ada
compiler puts things in the same places. My Microsoft VC++ says
that it allocates bit fields from the right. My Windows targetted
Ada compilers label bit locations Low_Order_First. So to make sure
the Ada structure, using such an Ada compiler, matches the C ordering,
using the Microsoft compiler, you would include:
for SDL_VideoInfo use record
hw_available at 0 range 0 .. 0;
wm_available at 0 range 1 .. 1;
blit_hw at 1 range 1 .. 1;
blit_hw_CC at 1 range 2 .. 2;
blit_hw_A at 1 range 3 .. 3;
blit_sw at 1 range 4 .. 4;
blit_sw_CC at 1 range 5 .. 5;
blit_sw_A at 1 range 6 .. 6;
blit_fill at 1 range 7 .. 7;
video_mem at 4 range 0 .. 31;
vfmt at 8 range 0 .. 31; -- Assuming Access types are 32 bits.
end record;
next parent reply other threads:[~2000-01-27 0:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <vhi3drkqqo7.fsf@grotte.ifi.uio.no>
2000-01-27 0:00 ` tmoran [this message]
2000-01-27 0:00 ` C struct import David C. Hoos, Sr.
[not found] ` <vhi1z73r5cc.fsf@grotte.ifi.uio.no>
2000-01-30 0:00 ` Mario Klebsch
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