Re: [PATCH 5/5] xinput: Fix axis scaling arithmetic.

[Aric Stewart]

Signed-off-by: Aric Stewart

On 2/12/19 12:06 AM, Zebediah Figura wrote:
> Cast difference to ULONGLONG to ensure unsigned division, and correct
> off-by-one error present when inverting axes (previously hidden by signed
> division bug).
>
> Fixes a regression introduced by bd9e130ee5b569433f2c847c5b2b562f0ae35ac5.
>
> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=46623
> Signed-off-by: Zebediah Figura
>
> dlls/xinput1_3/hid.c | 23 +++++++++++++++--------
>   1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/dlls/xinput1_3/hid.c b/dlls/xinput1_3/hid.c
> index 7553aaba63..c0c405fbdb 100644
> --- a/dlls/xinput1_3/hid.c
> +++ b/dlls/xinput1_3/hid.c
> @@ -318,8 +318,15 @@ void HID_destroy_gamepads(xinput_controller *devices)
>       LeaveCriticalSection(&hid_xinput_crit);
>   }
>
> -#define SCALE_SHORT(v,r) (SHORT)((((0xffff)*(v - (r).min))/(r).range)-32767)
> -#define SCALE_BYTE(v,r) (BYTE)((((0xff)*(v - (r).min))/(r).range))
> +static SHORT scale_short(LONG value, const struct axis_info *axis)
> +{
> - return ((((ULONGLONG)(value - axis->min)) * 0xffff) / axis->range) - 32768;
>
> +}
> -
>
> +static BYTE scale_byte(LONG value, const struct axis_info *axis)
> +{
> - return (((ULONGLONG)(value - axis->min)) * 0xff) / axis->range;
>
> +}
>
> void HID_update_state(xinput_controller* device)
>   {
> @@ -382,22 +389,22 @@ void HID_update_state(xinput_controller* device)
>       }
>   HidP_GetScaledUsageValue(HidP_Input, HID_USAGE_PAGE_GENERIC, 0, HID_USAGE_GENERIC_X, &value, private->ppd, target_report, private->report_length);
> - device->state.Gamepad.sThumbLX = SCALE_SHORT(value, private->lx);
> -
>
> device->state.Gamepad.sThumbLX = scale_short(value, &private->lx);
>
> HidP_GetScaledUsageValue(HidP_Input, HID_USAGE_PAGE_GENERIC, 0, HID_USAGE_GENERIC_Y, &value, private->ppd, target_report, private->report_length);
> - device->state.Gamepad.sThumbLY = -SCALE_SHORT(value, private->ly);
> -
>
> device->state.Gamepad.sThumbLY = -scale_short(value, &private->ly) - 1;
>
> HidP_GetScaledUsageValue(HidP_Input, HID_USAGE_PAGE_GENERIC, 0, HID_USAGE_GENERIC_RX, &value, private->ppd, target_report, private->report_length);
> - device->state.Gamepad.sThumbRX = SCALE_SHORT(value, private->rx);
> -
>
> device->state.Gamepad.sThumbRX = scale_short(value, &private->rx);
>
> HidP_GetScaledUsageValue(HidP_Input, HID_USAGE_PAGE_GENERIC, 0, HID_USAGE_GENERIC_RY, &value, private->ppd, target_report, private->report_length);
> - device->state.Gamepad.sThumbRY = -SCALE_SHORT(value, private->ry);
> -
>
> device->state.Gamepad.sThumbRY = -scale_short(value, &private->ry) - 1;
>
> HidP_GetScaledUsageValue(HidP_Input, HID_USAGE_PAGE_GENERIC, 0, HID_USAGE_GENERIC_RZ, &value, private->ppd, target_report, private->report_length);
> - device->state.Gamepad.bRightTrigger = SCALE_BYTE(value, private->rtrigger);
> -
>
> device->state.Gamepad.bRightTrigger = scale_byte(value, &private->rtrigger);
>
> HidP_GetScaledUsageValue(HidP_Input, HID_USAGE_PAGE_GENERIC, 0, HID_USAGE_GENERIC_Z, &value, private->ppd, target_report, private->report_length);
> - device->state.Gamepad.bLeftTrigger = SCALE_BYTE(value, private->ltrigger);
> - device->state.Gamepad.bLeftTrigger = scale_byte(value, &private->ltrigger);
>  LeaveCriticalSection(&private->crit);
> }