15 / 36 · 概念

Comparators and boundary conditions

Connect equality and magnitude comparisons to boundary tests.

译文尚未提供，以下显示课时原文。 (English)

Learning goals

Explain equality versus magnitude comparison.
Test minimum, maximum and equal values.

Turn the specification into a condition.

a==b is 1 for equal values; a<b is 1 when a is smaller. A counter limit may require count==limit or count>=limit: choose based on the specification.

Testing only equality can miss the stopping condition if updates may skip over the limit. Review the update rule and allowed range alongside the comparison.

Align widths and signedness.

Comparing 1111 with 0001 gives 15>1 when unsigned and −1<1 when signed. The declared interpretation changes the result.

Test zero against zero, equal maxima, adjacent values and both sides of the sign boundary. This lesson assumes 0/1 inputs and does not cover four-state X/Z comparisons.

自己试试

If count increases by two and limit=3, will count==limit reliably stop it?

阅读解释

Starting at zero gives 0,2,4 and skips three. If the specification says stop at or above the limit, consider >= together with the allowed range.