From: Allan Peramaki <aperamak@pp1.inet.fi>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Trivial <qemu-trivial@nongnu.org>,
QEMU Developers <qemu-devel@nongnu.org>,
Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [PATCH] hw/audio/gus: Fix registers 32-bit access
Date: Thu, 18 Jun 2020 02:10:31 +0300 [thread overview]
Message-ID: <06bdf82f-858a-6b28-a9f9-e85154ac9c5d@pp1.inet.fi> (raw)
In-Reply-To: <87e628f4-6c0e-c4a2-daba-57cb1e508b77@pp1.inet.fi>
On 18/06/2020 01:25, Allan Peramaki wrote:
> On 17/06/2020 23:23, Peter Maydell wrote:
>> Are these accesses all guaranteed to be correctly aligned
>> to be 16 or 32 bit loads/stores ? Otherwise it would be
>> better to use the ldl_p/stl_p/ldw_p/stw_p/etc accessors,
>> which correctly handle possibly misaligned pointers.
>
> Yes (assuming compiler aligns struct fields properly.) It is not obvious
> though (and easy to break), so I suppose refactoring much of the GUS
> code would be nice. For example, the few places where GUSregd(position)
> is used, position is 2 (mod 4). On the other hand, gusptr is also 2 (mod
> 4) bytes (making gusptr+position = 0 (mod 4)), because we have the struct
It is aligned, but my reasoning had a mistake. Both gusptr and position
(GUSDRAMPOS24bit and voicewavetableirq) are 0 (mod 4). (mixbuf is a
pointer.) Sorry.
>
> typedef struct GUSState {
> ISADevice dev;
> GUSEmuState emu;
> QEMUSoundCard card;
> uint32_t freq;
> uint32_t port;
> int pos, left, shift, irqs;
> int16_t *mixbuf;
> uint8_t himem[1024 * 1024 + 32 + 4096];
> int samples;
> SWVoiceOut *voice;
> int64_t last_ticks;
> qemu_irq pic;
> IsaDma *isa_dma;
> PortioList portio_list1;
> PortioList portio_list2;
> } GUSState;
>
>
Best regards,
Allan
next prev parent reply other threads:[~2020-06-17 23:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 20:17 [PATCH] hw/audio/gus: Fix registers 32-bit access Allan Peramaki
2020-06-17 19:58 ` Volker Rümelin
2020-06-17 20:23 ` Peter Maydell
2020-06-17 22:25 ` Allan Peramaki
2020-06-17 23:10 ` Allan Peramaki [this message]
2020-06-18 4:57 ` Thomas Huth
2020-06-18 9:13 ` Peter Maydell
2020-06-18 10:22 ` Philippe Mathieu-Daudé
2020-06-18 10:23 ` Peter Maydell
2020-06-18 10:35 ` Philippe Mathieu-Daudé
2020-06-18 4:59 ` Thomas Huth
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