Unshare pointer pragma, Unshare pointer pragma –5 – Altera Nios II C2H Compiler User Manual
Page 123
Altera Corporation
9.1
6–5
November 2009
Nios II C2H Compiler User Guide
Pragma Reference
Example 6–4. Interrupt Header File
#ifndef ALT_C2H_COPROCESS_IRQ_H
#define ALT_C2H_COPROCESS_IRQ_H
#include "io.h"
#include "c2h_accelerator_base_addresses.h"
#define ACCELERATOR_MY_PROJECT_COPROCESS_GET_RETURN_VALUE() \
(( int ) IORD_32DIRECT ( \
ACCELERATOR_MY_PROJECT_COPROCESS_CPU_INTERFACE0_BASE, \
(1*sizeof(int))))
#define ACCELERATOR_MY_PROJECT_COPROCESS_CLEAR_IRQ() \
( IOWR_32DIRECT ( \
ACCELERATOR_MY_PROJECT_COPROCESS_CPU_INTERFACE0_BASE, \
(0*sizeof(int)), 0))
#define ACCELERATOR_MY_PROJECT_COPROCESS_BUSY() \
( IORD_32DIRECT ( \
ACCELERATOR_MY_PROJECT_COPROCESS_CPU_INTERFACE0_BASE, \
((0*sizeof(int))) & 1) ^ 1)
#endif /* ALT_C2H_COPROCESS_IRQ_H */
The hardware accelerator does not have an IRQ level so you must open
the system in SOPC Builder and manually assign this value. After
assigning the IRQ level press the generate button because this is a change
outside of the Nios II IDE. You only have to do this manual step once. In
addition, you can use the
accelerate_my_project_coprocess_busy
macro in a non-
interrupt based system in which the user code pulls for the
done
bit,
rather than using the automatically generated C wrapper.
f
Refer to the
f the
more information about creating interrupt service routines.
Unshare Pointer
Pragma
As discussed in
chapter, the C2H compiler automatically shares a master port
for multiple pointer dereference operations that connect to the same slave
port or group of slave ports. In certain cases, this causes a reduction in
performance. For example, in
both
ptr_a
and
ptr_b
must
be connected to both onchip_memory_0 and onchip_memory_1, but they
never access the same memory at the same time. By default, the C2H
compiler will attempt to share a single master between
ptr_a
and
ptr_b
, preventing these dereference operations from being scheduled
concurrently and possibly degrading performance.