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Date: Tue, 25 Feb 2014 14:44:06 +0000
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Message-ID: <20140225144406.GC3656@work-vm>
References: <CAN7x1o79u9ZL9SqZ=YMPe0SjEfxiYOeYb8W5g6DPbTsNJmaq=g@mail.gmail.com>
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Subject: Re: [Qemu-devel] Some line of codes in a file that I cant understand
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To: Atlas Khan <atlaskhan90@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>

* Atlas Khan (atlaskhan90@gmail.com) wrote:
> I am watching i8259.c in \hw folder in QEMU. here is something like this
> 
> 
> static const VMStateDescription vmstate_pic = {
>     .name = "i8259",
>     .version_id = 1,
>     .minimum_version_id = 1,
>     .minimum_version_id_old = 1,
>     .fields = (VMStateField[]) {
>         VMSTATE_UINT8(last_irr, PicState),
>         VMSTATE_UINT8(irr, PicState),
>         VMSTATE_UINT8(imr, PicState),
>         VMSTATE_UINT8(isr, PicState),
>         VMSTATE_UINT8(priority_add, PicState),
>         VMSTATE_UINT8(irq_base, PicSthisate),
>         VMSTATE_UINT8(read_reg_select, PicState),
>         VMSTATE_UINT8(poll, PicState),
>         VMSTATE_UINT8(special_mask, PicState),
>         VMSTATE_UINT8(init_state, PicState),
>         VMSTATE_UINT8(auto_eoi, PicState),
>         VMSTATE_UINT8(rotate_on_auto_eoi, PicState),
>         VMSTATE_UINT8(special_fully_nested_mode, PicState),
>         VMSTATE_UINT8(init4, PicState),
>         VMSTATE_UINT8(single_mode, PicState),
>         VMSTATE_UINT8(elcr, PicState),
>         VMSTATE_END_OF_LIST()
>     }
> };
> 
> here what does this dot shows and what is this VMSTATE_UINT8 function?

The . is about assigning into named fields in a structure; it's just
neater than the old C way of having to keep all the fields in order.
See the def of VMStateDescription in include/migration/vmstate.h

The VMSTATE_UINT8 is a macro declaring that there is a byte/uint8 member
see ./include/migration/vmstate.h and docs/migration.txt for a bit
of a description.

Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK