Comparing central time stamp bits from bus and client circuitry
This invention is time stamping subsystem of an electronic apparatus. A time stamp generator generates a multibit time stamp value including a predetermined number of least significant bits overlapping a predetermined number of most significant bits. Each client receives the least significant bits. Each client associates captured data with a corresponding set of the least significant bits in a message. A central scheduling unit associates most significant bits of the time stamp value with the least significant bits of the message. This associating compares overlap bits of the most significant bits and least significant bits. The most significant bits are decremented until the overlap bits are equal.
1. An integrated circuit comprising:
A. functional circuitry having functional leads;
B. time stamp generator circuitry having time stamp bit leads, the time stamp bit leads including a group of most significant bit leads carrying most significant bits, a group of least significant bit leads carrying least significant bits, and a group of central bit leads, that carry central bits, that include some of the most significant bit leads and some of the least significant bit leads;
C. a first bus of time stamp bit leads connected to the time stamp bit leads of the time stamp generator circuitry, the first bus including the most significant bit leads and the central bit leads;
D. a second bus of time stamp bit leads connected to the time stamp bit leads of the time stamp generator circuitry, the second bus including the least significant bit leads and the central bit leads;
E. client circuitry that has functional inputs coupled to the functional leads, time stamp inputs connected to only the second bus, the client circuitry including data circuitry capturing data from the functional leads with time stamp data from the time stamp inputs, and the client circuitry having scheduling outputs that output the captured data with time stamp data; and
F. scheduling circuitry having time stamp inputs connected to only the first bus and client inputs connected to the scheduling outputs, the scheduling circuitry including comparator circuitry having first inputs coupled to the central bits from the first bus and second inputs coupled to the central bits from the scheduling outputs to determine a full time stamp of the captured data.
2. The integrated circuit of claim 1 in which the functional circuitry includes a central processing unit.
3. The integrated circuit of claim 1 in which the time stamp bit leads of the time stamp generator circuitry are numbered from n to 0, the most significant bit leads are numbered from n to m and m−1 to p, the central bit leads are numbered from m−1 to p, and the least significant bit leads are numbered from m−1 to p and p−1 to 0.
4. The integrated circuit of claim 1 in which the client circuitry includes plural client circuits.
5. The integrated circuit of claim 1 in which the client circuitry includes at least one of emulation circuitry and debug circuitry.
6. The integrated circuit of claim 1 in which the client circuitry includes at least one of bus event detectors, trigger builders, trace collection circuitry, data export circuitry, and scan adaptor circuitry.