From 56b7f4cf3100cd252a0325973fb9093ce0a629ee Mon Sep 17 00:00:00 2001 From: Sam Lantinga Date: Sat, 8 Jun 2019 14:40:27 -0700 Subject: [PATCH] Fixed bug 4583 - PollAllValues appears to use an incorrect index for all axes above 0x18 Noam Preil In src/joystick/linux/SDL_sysjoystick.c: The ConfigJoystick function's axes detection starts with a for loop using an index i for Linux's axes names. When i gets to ABS_HAT0X, it's set to ABS_HAT3Y and a continue statement appears, to skip the hats. This makes sense, as SDL handles hats separately from axes. However, in PollAllValues, *two* indices are used: a and b. Both start out the same, and remain so until the hats are reached. At that point, a becomes identical to the i from ConfigJoystick's loop, but b is equal to a - (ABS_HAT3Y - ABS_HAT0X), or a - 8. While all the joystick->hwdata->abs_* structures in ConfigJoystick used i - which would here be a - as both the index and the ioctl argument, PollAllValues uses b for the structure index and a as the ioctl argument. It would appear, however, that no joystick HAS such axes, and that the b index is entirely unnecessary. I tested three separate joysticks, and while that was far from a complete listing, I was unable to find a joystick with an axis above 0x08. --- src/joystick/linux/SDL_sysjoystick.c | 38 ++++++++++------------------ 1 file changed, 14 insertions(+), 24 deletions(-) diff --git a/src/joystick/linux/SDL_sysjoystick.c b/src/joystick/linux/SDL_sysjoystick.c index fd264158d9cda..0309f8c3e54e9 100644 --- a/src/joystick/linux/SDL_sysjoystick.c +++ b/src/joystick/linux/SDL_sysjoystick.c @@ -818,36 +818,26 @@ static SDL_INLINE void PollAllValues(SDL_Joystick * joystick) { struct input_absinfo absinfo; - int a, b = 0; + int i; /* Poll all axis */ - for (a = ABS_X; b < ABS_MAX; a++) { - switch (a) { - case ABS_HAT0X: - case ABS_HAT0Y: - case ABS_HAT1X: - case ABS_HAT1Y: - case ABS_HAT2X: - case ABS_HAT2Y: - case ABS_HAT3X: - case ABS_HAT3Y: - /* ingore hats */ - break; - default: - if (joystick->hwdata->abs_correct[b].used) { - if (ioctl(joystick->hwdata->fd, EVIOCGABS(a), &absinfo) >= 0) { - absinfo.value = AxisCorrect(joystick, b, absinfo.value); + for (i = ABS_X; i < ABS_MAX; i++) { + if (i == ABS_HAT0X) { + i = ABS_HAT3Y; + continue; + } + if (joystick->hwdata->abs_correct[i].used) { + if (ioctl(joystick->hwdata->fd, EVIOCGABS(i), &absinfo) >= 0) { + absinfo.value = AxisCorrect(joystick, i, absinfo.value); #ifdef DEBUG_INPUT_EVENTS - printf("Joystick : Re-read Axis %d (%d) val= %d\n", - joystick->hwdata->abs_map[b], a, absinfo.value); + printf("Joystick : Re-read Axis %d (%d) val= %d\n", + joystick->hwdata->abs_map[i], i, absinfo.value); #endif - SDL_PrivateJoystickAxis(joystick, - joystick->hwdata->abs_map[b], - absinfo.value); - } + SDL_PrivateJoystickAxis(joystick, + joystick->hwdata->abs_map[i], + absinfo.value); } - b++; } } }