Re: [Qemu-devel] [4249] Improve audio api use in WM8750.

[Jan Kiszka <jan.kiszka@web.de>]

[-- Attachment #1: Type: text/plain, Size: 2265 bytes --]

andrzej zaborowski wrote:
> 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.

True, that's redundant, let's fix it this way (this even obsoletes the
flush in out_cb):

Index: hw/wm8750.c
===================================================================
--- hw/wm8750.c	(Revision 4250)
+++ hw/wm8750.c	(Arbeitskopie)
@@ -73,14 +73,8 @@ 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;
-        wm8750_out_flush(s);
-    } else
-        s->req_out = free_b - s->idx_out;
- 
-    s->data_req(s->opaque, s->req_out >> 2, s->req_in >> 2);
+    s->req_out = free_b;
+    s->data_req(s->opaque, free_b >> 2, s->req_in >> 2);
 }
 
 struct wm_rate_s {
@@ -623,7 +617,7 @@ void wm8750_dac_dat(void *opaque, uint32
     *data = sample & s->outmask;
     s->req_out -= 4;
     s->idx_out += 4;
-    if (s->idx_out >= sizeof(s->data_out) || s->req_out <= 0)
+    if (s->idx_out >= sizeof(s->data_out)/2 || s->req_out <= 0)
         wm8750_out_flush(s);
 }
 


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 254 bytes --]