[PATCH 0/1] MR8780: winbus: SDL backend FF effect angle requires 32 bits

[Tyson Whitehead (＠twhitehead)]

@rbernon had also noticed that under the SDL backend, effects with a direction of mostly right with a bit of up played mostly up/down and not right/left as would be expected.

Traced this down using a `INT16` for the rotation angle in the SDL backend, which isn't large enough to represent 36000. Overflowing would effectively subtract 66536, amounting to a 65536 % 36000 = 29536 centi-degree rotation. End effect was effects mostly right with a bit of up (those over 327 degrees) where changed to mostly up with a bit of right (rotated counter-clockwise 65 degrees).

This patch changes the local computation variable to INT32, which also matches what is used by the SDL library.

[PATCH 1/1] winbus: SDL backend FF effect angle requires 32 bits

[Tyson Whitehead]

From: Tyson Whitehead

The max value of a INT16 is 32768, which is less than the 36000
required for a full rotation angle. Change type to INT32 as that
is what the underlying SDL paramerter is.

Rotate by +270 instead of -90 to elimante negative value fixup too.
---
 dlls/winebus.sys/bus_sdl.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/dlls/winebus.sys/bus_sdl.c b/dlls/winebus.sys/bus_sdl.c
index 91cb785fdff..ddc32f7243f 100644
--- a/dlls/winebus.sys/bus_sdl.c
+++ b/dlls/winebus.sys/bus_sdl.c
@@ -652,7 +652,7 @@ static NTSTATUS sdl_device_physical_effect_update(struct unix_device *iface, BYT
     struct sdl_device *impl = impl_from_unix_device(iface);
     int id = impl->effect_ids[index];
     SDL_HapticEffect effect = {0};
-    INT16 direction;
+    INT32 direction;
     NTSTATUS status;

TRACE("iface %p, index %u, params %p.\n", iface, index, params);
@@ -662,8 +662,7 @@ static NTSTATUS sdl_device_physical_effect_update(struct unix_device *iface, BYT

/* The first direction we get from PID is in polar coordinate space, so we need to
      * remove 90° to make it match SDL spherical coordinates. */
-    direction = (params->direction[0] - 9000) % 36000;
-    if (direction < 0) direction += 36000;
+    direction = (params->direction[0] + (36000-9000)) % 36000;

switch (params->effect_type)
     {

[PATCH 0/1] MR8780: winbus: SDL backend FF effect angle requires 32 bits - closed

[Rémi Bernon (＠rbernon)]

This merge request was closed by Rémi Bernon.