extmod/utime_mphal: ticks_diff(): Optimize to avoid if conditions.
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@ -89,12 +89,10 @@ STATIC mp_obj_t time_ticks_diff(mp_obj_t end_in, mp_obj_t start_in) {
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// we assume that the arguments come from ticks_xx so are small ints
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uint32_t start = MP_OBJ_SMALL_INT_VALUE(start_in);
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uint32_t end = MP_OBJ_SMALL_INT_VALUE(end_in);
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int32_t diff = end - start;
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if (diff < (signed)-(MICROPY_PY_UTIME_TICKS_PERIOD / 2)) {
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diff += MICROPY_PY_UTIME_TICKS_PERIOD;
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} else if (diff >= (signed)(MICROPY_PY_UTIME_TICKS_PERIOD / 2)) {
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diff -= MICROPY_PY_UTIME_TICKS_PERIOD;
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}
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// Optimized formula avoiding if conditions. We adjust difference "forward",
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// wrap it around and adjust back.
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int32_t diff = ((end - start + MICROPY_PY_UTIME_TICKS_PERIOD / 2) & (MICROPY_PY_UTIME_TICKS_PERIOD - 1))
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- MICROPY_PY_UTIME_TICKS_PERIOD / 2;
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return MP_OBJ_NEW_SMALL_INT(diff);
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}
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MP_DEFINE_CONST_FUN_OBJ_2(mp_utime_ticks_diff_obj, time_ticks_diff);
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