[Feature] Swap buttons on PS2 Mouse/Trackball

[jkutianski]

Description

This add the config parameter PS2_MOUSE_INVERT_BUTTONS that invert the left & right button on the PS2 mouse.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

• [Feature Request] Swap buttons on PS2 Mouse/Trackball #9204

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[zvecr]

Not a fan of the new proposed logic. Its far more complex than just swapping two bits. I dont have time to profile it, but i cant imagine its much faster/smaller.

[jkutianski]

Yes I tried to found a simple solution but I cant see it. I'm not a fan of complexity too.

buttons ^= 1 << PS2_MOUSE_BTN_LEFT; 
buttons ^= 1 << PS2_MOUSE_BTN_RIGHT;

This code doesn't work as intented. Just works with 2 buttons mouses partially.
If you press left and right at the same time the result is no press at all.

With 3 buttons:
If you press just the middle button is like press all the buttons (left, middle and right)
If you press the 3 buttons is like press only the middle one.

If you try to implement the 4th and 5th button of MS Intellimouse Explorer this mess up the Z3, Z1 & Z0.

/*
 * Data format:
 * byte|7       6       5       4       3       2       1       0
 * ----+----------------------------------------------------------------
 *    0|[Yovflw][Xovflw][Ysign ][Xsign ][ 1    ][Middle][Right ][Left  ]
 *    1|[                    X movement(0-255)                         ]
 *    2|[                    Y movement(0-255)                         ]
 *    3|[ 0    ][ 0    ][ 5th  ][ 4th  ][  Z3  ][  Z2  ][  Z1  ][  Z0  ]
 */

Z0-Z3 is a 2's complement number which represents the amount
of movement that has occurred since the last data report. 
Valid values range from -8 to +7.

I think the most performant and simple solution is a look up table. Something like:

static const __swap_btn_lut uint8_t swap_btn[8] = {0b000, 0b010, 0b001, 0b011, 0b100, 0b101, 0b110, 0b111};

[jkutianski]

I changed the logic to a LUT.
Looks easy to understand and more cleaner than use binary operators.

[zvecr]

Looks easy to understand and more cleaner than use binary operators.

However the lookup table still suffers from assumptions in the value of PS2_MOUSE_BTN_LEFT and PS2_MOUSE_BTN_RIGHT.

[jkutianski]

I return to the idea of operators. I tried to think another approach.
This new one looks more clear and no macros needed.
Hope this fits.
Tell me if this is OK and I will clean up this a little bit before to merge.

[drashna]

Also, (@noroadsleft ) I think this should be retargeted to the develop branch, and rebased.