Altera Nios II C2H Compiler - Manual (Page 63)

Altera Corporation 9.1 3–23
November 2009 Nios II C2H Compiler User Guide
C-to-Hardware Mapping Reference
The write-data signal for the Avalon-MM master port is computed and
registered in parallel with the address assignment. As soon as
ptr_to_int_i_addr and ptr_to_int_i_writedata are valid,
write-enable control logic asserts the signal ptr_to_int_i_write ,
which initiates a transfer on the master port.
Figure 3–11 shows the logic created for the following write operation to a
dereferenced pointer. Translation of the data-computation logic follows
the rules described in section
“Assignments” on page 3–2 .
*(ptr_to_int + i) = a*x + y;
Figure 3–11. Complex Write Operation
Master-Slave Connections
The C2H Compiler uses pragmas that allow user control of master-slave
connections and arbitration shares. This section describes the pragmas to
control master-slave connections.
The C language specification dictates that when a compiler
implementation encounters a
pragma directive it does not recognize, the
compiler ignores the pragma. By using pragmas, you can write directives
to optimize the C2H Compiler results, without making the C code
incompatible with other compilers.