Altera Nios II C2H Compiler Bedienungsanleitung PDF herunterladen (Seite 58)

3–18 9.1 Altera Corporation

Nios II C2H Compiler User Guide November 2009

Memory Accesses

Example 3–10 shows two dereferences that are identical inside of a loop.

The C2H Compiler consolidates them into a single master port.

Example 3–10. Equivalent Pointers in a Loop

void equivalent_pointers(char *packed_data, int len)

{

int i = 0;

while (i < len)

{

char ms_nibble = *(packed_data) >> 4;

char ls_nibble = *(packed_data++) & 0x0f;

...

i++;

}

}

Example 3–11 demonstrates a case of non equivalent pointers.

Example 3–11 is similar to Example 3–10, but packed_data increments

between the two pointer dereferences. In this case the address

expressions have different values, which translate to two separate master

ports.

Example 3–11. Nonequivalent Pointers

void nonequivalent_pointers(char *packed_data, int len)

{

int i = 0;

while (i < len)

{

char ms_nibble = *(packed_data++) >> 4;

char ls_nibble = *(packed_data) & 0x0f;

...

i++;

}

}

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