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Unformatted text preview: dest of length n to zero. Our measurements for the ﬁrst version show a CPE of 2.00. Since each iteration requires a store operation, it is clear that the processor can begin a new store operation at least once every two cycles. To probe further, we try unrolling the loop eight times, as shown in the code for array_clear_8. For this one we measure a CPE of 1.25. That is, each iteration requires around ten cycles and issues eight store operations. Thus, we have nearly achieved the optimum limit of one new store operation per cycle. Unlike the other operations we have considered so far, the store operation does not affect any register values. Thus, by their very nature a series of store operations must be independent from each other. In fact, only a load operation is affected by the result of a store operation, since only a load can read back the memory location that has been written by the store. The function write_read shown in Figure 5.33 illustrates the potential interactions between loads and stores. This ﬁgure also s...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.
 Spring '10
 Schultz
 The American, Gulliver's Travels, 2.2.5 2.2.6 2.2.7 2.3 2.3.1 2.3.2 2.3.3 2.3.4 2.3.5

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