Transactional memory that performs an atomic metering command

1. A transactional memory comprising:

a memory that stores a table including a plurality of meter pairs, each meter pair including a long term credit value and a short term credit value;

means for receiving an Atomic Metering Command (AMC) and in response performing an AMC operation such that the transactional memory does not fetch instructions, wherein a memory address is included in the AMC, wherein the memory address is used to read a word out of the memory, and wherein the word includes the long term credit value and the short term credit value; and

means for subtracting an input value from the long term credit value and the short term credit value, thereby generating a pair of decremented credit values.

2. The transactional memory of claim 1 , wherein the means include a hardware engine and a data bus interface, wherein the means is also for causing a result value to be output from the transactional memory via the data bus interface, and wherein the result value indicates a meter color.

3. A method comprising:

(a) receiving an Atomic Metering Command (AMC) from a first processor onto a second processor, wherein a memory unit is coupled to the second processor;

(b) receiving an input value (IV);

(c) using a memory address to read a word out of the memory unit, wherein the memory address is included in the AMC, and wherein the word includes a plurality of credit values;

(d) storing the plurality of credit values and the IV into a storage device coupled to the second processor;

(e) selecting a pair of credit values from the plurality of credit values;

(f) subtracting the IV from the pair of credit values, thereby generating a pair of decremented credit values;

(g) determining if each of the decremented credit values generated in (f) is greater than a threshold value; and

(h) determining a meter color based upon the determination in (g) and returning a result value representing the meter color to the first processor; wherein (b) through (h) are performed by the second processor.

4. The method of claim 3 , wherein the command information includes the memory address and a meter pair indicator value, wherein the IV is a byte count value that represents the number of bytes to be transmitted by the first processor, and wherein the meter pair indicator value identifies the pair of credit values within the plurality of credit values in the word.

5. The method of claim 3 , wherein the selecting of (e) is performed by the second processor, wherein the second processor receives the plurality of credit values and a meter pair indicator value, wherein the second processor selects the pair of credit values, and wherein the pair of credit values selected by the second processor is determined by the meter pair indicator value.

6. The method of claim 3 , wherein the subtracting of (f) is performed by the second processor, wherein the second processor receives the pair of credit values and the IV, and wherein the second processor generates the pair of decremented credit values.

7. The method of claim 3 , wherein the determining of (g) is performed by the second processor, wherein the second processor receives the pair of decremented credit values and the threshold value, wherein the second processor generates a pair of indicator values, and wherein the pair of indicator values are determined by the comparison of the threshold value with each of the decremented credit values.

8. The method of claim 3 , wherein the determining of (h) is performed by the second processor, wherein the second processor receives a pair of indicator values, wherein the second processor determines the meter color based upon the pair of indicator values, and wherein the second processor outputs the result value.

9. The method of claim 3 , wherein the determining of (h) is performed by the second processor, wherein the second processor receives the pair of indicator values and a packet color indicator value, wherein the second processor determines the meter color based upon the pair of indicator values and the packet color indicator value, and wherein the second processor outputs the result value.

10. The method of claim 3 , further comprising:

(i) selecting a plurality of selected credit values that are written back to the memory unit based upon the meter color determined in (h).

11. The method of claim 10 , wherein the selecting of (i) is performed by the second processor, wherein the second processor receives the plurality of credit values, the pair of decremented credit values, and a selector value, wherein the second processor selects a plurality of selected credit values that are selected from both the plurality of credit values and the pair of decremented credit values, and wherein the plurality of selected credit values are determined by the selector value.

12. The method of claim 3 , wherein the AMC is received onto the second processor via a bus, the method further comprising:

(j) outputting the result value onto the bus.

13. The method of claim 3 , wherein the IV of (b) is received onto the second processor via a bus in response to receiving the AMC.

14. The method of claim 3 , wherein the bus is a command/push/pull (CPP) bus, and wherein the second processor initiates a pull bus transaction and thereby receives the IV via the bus.

15. The method of claim 3 , wherein the storage device is taken from the group consisting of: a register, a plurality of registers.