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Newsgroups: comp.lang.ada
Date: Mon, 25 Mar 2019 07:09:18 -0700 (PDT)
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Subject: Re: differences between Ada and C in gnat forcing me to use C instead
 of Ada
From: matthewbrentmccarty@gmail.com
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Xref: reader01.eternal-september.org comp.lang.ada:55954
Date: 2019-03-25T07:09:18-07:00
List-Id: <comp.lang.ada>

Hi all:
"gnat-gps" on my machine Windows 10 (debian subsystem for Linux) (see https=
://docs.microsoft.com/en-us/windows/wsl/install-win10 ) gives me "raised ST=
ORAGE_ERROR : s-intman.adb:139 explicit raise" yet the same software works =
fine on my "real" debian machine. The compiler works but gant-gps doesn't.=
=20


For some reason when I call sane_get_devices as in:

      type Sane_Device_Ptr is access all sane_sane_h.SANE_Device;
      for Sane_Device_Ptr'Size use Standard'Address_Size;
      pragma Convention (C, Sane_Device_Ptr);

      type Device_Array is array (Integer range <>) of aliased Sane_Device_=
Ptr;
      pragma Convention (C, Device_Array);
      ...
      devices :  aliased  Device_Array (1..5);
      Status :=3D sane_sane_h.sane_get_devices (devices(1)'Address, sane_sa=
ne_h.SANE_Bool(SANE_TRUE));

I get back garbage but in C, it works. Oh, now that makes sense about 'Size=
 returning bits and sizeof in C returning bytes. 256 bits is indeed 32 byte=
s. I wonder why I'm getting back garbage. InterfaceS.C.Strings.chars_ptr'Si=
ze=3D64 and sizeof(char *)=3D8 are equivalent.

Thanks. I guess I got some more digging to do as to my garbage.

Regards,
Matthew McCarty