On 04/09/2012 14:53, Kostya Shishkov wrote:
First thing looks equally WTFy to me. One can easily replace
int bit = (((c->value - c->low) << 1) + 1) / range;
with
int bit = (((c->value - c->low) << 1) + 1) >= range;
But further simplifying that way is not obvious.
Starting with
int bit = ((c->value - c->low) << 1) + 1 >= range;
Replace range with its expression:
int bit = ((c->value - c->low) << 1) + 1 >= c->high - c->low + 1;
Subtract 1 on both sides:
int bit = (c->value - c->low) << 1 >= c->high - c->low;
Add c->low on both sides:
int bit = (c->value - c->low) << 1 + c->low >= c->high;
(Shift to multiplication)
int bit = 2 * (c->value - c->low) + c->low >= c->high;
Expand product:
int bit = 2 * c->value - 2 * c->low + c->low >= c->high;
Simplify:
int bit = 2 * c->value - c->low >= c->high;
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