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Date: Tue, 15 Jun 2010 16:28:21 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH] Fix comparison which always returned false
References: <1276635808-7315-1-git-send-email-weil@mail.berlios.de>
In-Reply-To: <1276635808-7315-1-git-send-email-weil@mail.berlios.de>
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To: Stefan Weil <weil@mail.berlios.de>
Cc: Anthony Liguori <aliguori@us.ibm.com>, QEMU Developers <qemu-devel@nongnu.org>, Gleb Natapov <gleb@redhat.com>

On 06/15/2010 04:03 PM, Stefan Weil wrote:
> Comparing an 8 bit value with ~0 does not work as expected.
> Replace ~0 by UINT8_MAX in comparison and also in assignment
> (and fix coding style, too).
>    

Because when the uint8_t gets promoted, it doesn't get zero filled.  I'd 
rather something a bit more obvious like HPET_INVALID_COUNT.

Regards,

Anthony Liguori

> Cc: Gleb Natapov<gleb@redhat.com>
> Cc: Anthony Liguori<aliguori@us.ibm.com>
> Signed-off-by: Stefan Weil<weil@mail.berlios.de>
> ---
>   hw/hpet.c |    6 ++++--
>   1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/hpet.c b/hw/hpet.c
> index 0c80ee5..d5c406c 100644
> --- a/hw/hpet.c
> +++ b/hw/hpet.c
> @@ -74,7 +74,7 @@ typedef struct HPETState {
>       uint8_t  hpet_id;           /* instance id */
>   } HPETState;
>
> -struct hpet_fw_config hpet_cfg = {.count = ~0};
> +struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
>
>   static uint32_t hpet_in_legacy_mode(HPETState *s)
>   {
> @@ -682,8 +682,10 @@ static int hpet_init(SysBusDevice *dev)
>       int i, iomemtype;
>       HPETTimer *timer;
>
> -    if (hpet_cfg.count == ~0) /* first instance */
> +    if (hpet_cfg.count == UINT8_MAX) {
> +        /* first instance */
>           hpet_cfg.count = 0;
> +    }
>
>       if (hpet_cfg.count == 8) {
>           fprintf(stderr, "Only 8 instances of HPET is allowed\n");
>