Optimize matrix scanning by removing variable shifts #14947
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AVR does not include a barrel shifter. Variable shifts compile into loops that carry the bits across multiple 8-bit registers. This small optimization increases the matrix scan rate on my keyboard from 598 to 628.
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Note that the per-key debouncers would also benefit from this optimization, but the impact is smaller. |
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Retargeted against |
tzarc
approved these changes
Oct 26, 2021
drashna
approved these changes
Oct 26, 2021
cadusk
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to cadusk/qmk_firmware
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Oct 27, 2021
* qmk/develop: (24 commits) [Keyboard] add Lefty keyboard (qmk#14898) [Keyboard] Add support for bm65rgb, a revival of qmk#13361 (qmk#14800) [Keymap] Add personal lily58 keymap (qmk#14834) [Keyboard] binepad bn009 (qmk#14881) [Keyboard] Add MW65 Series PCB (qmk#14939) [Docs] Add instructions to create keymap before proceeding (qmk#14945) [Keyboard] Cradio keyboard (qmk#14946) [Keyboard] update(readme): with PCB reset instructions (qmk#14961) [Keymap] Add VLC keymap (qmk#14956) [Keyboard] Docs/folder organization and info json fixed (qmk#14239) Fix white spacing issues in kb files (qmk#14963) Optimize matrix scanning by removing variable shifts (qmk#14947) [Keymap] Add planck/pjanx and keebio/nyquist/pjanx keymaps (qmk#13115) [Keyboard] add ProjectCain Vault35; update Vault45 (qmk#13652) Add MAGIC_TOGGLE_GUI line to main keycode documentation (qmk#14959) Document `MAGIC` feature (qmk#14301) [Keyboard] Add minimon/Index tab 13x6 ortho (qmk#14765) [Keyboard] add support for Phoenix45_Ortho PCB (qmk#14798) [Keymap] Add via keymap for meishi2 (qmk#14892) Update mcu_selection.mk with current ChibiOS path (qmk#14909) ...
ptrxyz
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to ptrxyz/qmk_firmware
that referenced
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Apr 9, 2022
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Description
AVR does not include a barrel shifter. Variable shifts compile into
loops that carry the bits across multiple 8-bit registers.
This small optimization increases the matrix scan rate on my keyboard
from 598 to 628.
Types of Changes
Issues Fixed or Closed by This PR
Checklist