Altera Nios II C2H Compiler Bedienungsanleitung PDF herunterladen (Seite 122)

6–4 9.1 Altera Corporation

Nios II C2H Compiler User Guide November 2009

Interrupt Pragma

Interrupt

Pragma

To use a hardware accelerator in interrupt mode, add the following line

to your function source code:

#pragma altera_accelerate \

enable_interrupt_for_function <function name>

At the next software compilation, the C2H Compiler creates a new header

file containing all the macros needed to use the accelerator and service the

interrupts it generates.

This pragma causes the function (which is assumed to be a top-level

accelerated function, not an accelerated subfunction) to be an interrupt-

mode accelerator. Specifically, the following things change:

■ The accelerator's control slave has an IRQ signal, which is asserted

every time the function has completed execution.

■ The polling loop in the generated driver file is removed. When the

function is called, the CPU immediately returns after launching the

accelerator.

■ A header file is generated, providing macros and definitions

required for you to write an ISR. The macros are summarized in

Table 6–1.

An example of this header file is shown in Example 6–4 for an

accelerated function called coprocess() in a Nios II IDE project

called my_project. The file is generated in <Project Path>/

<Configuration>, where <Project Path> is the software project

directory, and <Configuration> is the project configuration name

(Release or Debug). The file name is ACCELERATOR_<Project

Name>_<Function Name>_IRQ.h, where <Project Name> is the name

of the project (usually the same as <Project Path>), and <Function

Name> is the name of the function you are accelerating.

Table 6–1. C2H Accelerator Interrupt Macros

Purpose Macro Name

Return value

ACCELERATOR_<Project Name>_<Function Name>_GET_RETURN_VALUE()

Interrupt clear

ACCELERATOR_<Project Name>_<Function Name>_CLEAR_IRQ()

Check status

ACCELERATOR_<Project Name>_<Function Name>_BUSY()

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Altera Nios II C2H Compiler Bedienungsanleitung Seite 122