Altera Nios II C2H Compiler Uživatelský manuál stáhnout pdf (Strana 82)

3–42 9.1 Altera Corporation

Nios II C2H Compiler User Guide November 2009

Scheduling

Memory Transfers

Avalon-MM system interconnect fabric manages arbitration between

multiple Avalon-MM master ports that access a single slave port. A

master port might have to wait several clock cycles before beginning a

transfer due to arbitration. If a master port on an accelerator is being

forced to wait, the state machine for the accelerator stalls until the transfer

can proceed.

Loop Pipelining

The C2H Compiler structures the state machine for a loop so that

iterations of the loop are pipelined. In other words, consecutive iterations

of the loop can begin before prior iterations have completed.

Pipelining Loop Iterations

Figure 3–20 shows the dependency graph for the loop block in

Example 3–35.

Example 3–35. Loop Block

int mac(int *data_array, int *coef_array, int len)

{

int sum = 0;

{

int x = *data_array++;

int c = *coef_array++;

int prod = c * x;

sum += prod;

} while (i++ < len);

return sum;

}

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Altera Nios II C2H Compiler Uživatelský manuál Strana 82