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Date: Fri, 25 Apr 2008 02:23:36 +0200
From: "andrzej zaborowski" <balrogg@gmail.com>
Subject: Re: [Qemu-devel] [4249] Improve audio api use in WM8750.
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To: qemu-devel@nongnu.org

On 25/04/2008, Jan Kiszka <jan.kiszka@web.de> wrote:
> Jan Kiszka wrote:
>  > Nothing is crawling here, just use a reasonable threshold for flushing
>  > _after_ the callback. Need to check, but maybe we can even wait the a
>  > full buffer.
>
>
> Of course not the full buffer, but its half is fine as it generally
>  leaves enough time to the guest to refill the other half:
>
>  Index: hw/wm8750.c
>  ===================================================================
>  --- hw/wm8750.c (Revision 4250)
>  +++ hw/wm8750.c (Arbeitskopie)
>  @@ -73,14 +73,10 @@ static void wm8750_audio_out_cb(void *op
>
>  {
>      struct wm8750_s *s = (struct wm8750_s *) opaque;
>
>
> -    if (s->idx_out >= free_b) {
>  -        s->idx_out = free_b;
>  -        s->req_out = 0;
>
> +    s->req_out = free_b;
>  +    s->data_req(s->opaque, free_b >> 2, s->req_in >> 2);
>
> +    if (s->idx_out >= sizeof(s->data_out)/2)

The checking of whether the guest filled enough data happens in
wm8750_dac_dat(), I don't see why do it second time here.  The only
place we need an additional check is before s->dat_req call, which you
remove.

Regards
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