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Remove floating point calculation in mouse move. Saves approx 650 bytes if no other floating point used.

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This commit is contained in:
Martin Sandiford 2017-08-15 10:38:29 +09:30 committed by Jack Humbert
parent b7d43ee253
commit c622423668
1 changed files with 11 additions and 3 deletions
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14
tmk_core/common/mousekey.c
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@ -55,6 +55,14 @@ uint8_t mk_wheel_time_to_max = MOUSEKEY_WHEEL_TIME_TO_MAX;
static uint16_t last_timer = 0;
inline int8_t times_inv_sqrt2(int8_t x)
{
// 181/256 is pretty close to 1/sqrt(2)
// 0.70703125 0.707106781
// 1 too small for x=99 and x=198
// This ends up being a mult and discard lower 8 bits
return (x * 181) >> 8;
}
static uint8_t move_unit(void)
{
@ -111,10 +119,10 @@ void mousekey_task(void)
if (mouse_report.y > 0) mouse_report.y = move_unit();
if (mouse_report.y < 0) mouse_report.y = move_unit() * -1;
/* diagonal move [1/sqrt(2) = 0.7] */
/* diagonal move [1/sqrt(2)] */
if (mouse_report.x && mouse_report.y) {
mouse_report.x *= 0.7;
mouse_report.y *= 0.7;
mouse_report.x = times_inv_sqrt2(mouse_report.x);
mouse_report.y = times_inv_sqrt2(mouse_report.y);
}
if (mouse_report.v > 0) mouse_report.v = wheel_unit();