Altera Nios II C2H Compiler Uživatelský manuál stáhnout pdf (Strana 121)

Altera Corporation 9.1 6–3

November 2009 Nios II C2H Compiler User Guide

Pragma Reference

master port when it begins a sequence of transfer requests. The

arbitration share of a shared Avalon-MM master port is the sum of the

arbitration shares of all master-slave pairs associated with the master

port.

The connection pragma with additional terms for arbitration share is

defined as follows, where <shares> is a positive integer from 1 to 100:

#pragma altera_accelerate connect_variable \

<function name>/<variable name> to \

<module>[/<slave name>] arbitration_share <shares>

Example 6–3 connects the variable x in function myfunc to the memory

module named sdram with an arbitration share of 16.

Example 6–3. Pragma Specifying Arbitration Share

#pragma altera_accelerate connect_variable myfunc/x to sdram \

arbitration_share 16

Flow Control

Pragma

Avalon-MM transfers with flow control force a master port to obey flow

control signals controlled by a slave port. For example, a slave FIFO might

assert flow control signals to prevent write transfers when the FIFO

memory is full. The C2H Compiler provides a flow control pragma which

enables flow control for all master ports related to a specific pointer

variable.

The flow control pragma is defined as follows:

#pragma altera_accelerate \

enable_flow_control_for_pointer

The flow control pragma must be placed outside the function to

accelerate in the same file. <function name> and <variable name> are the

exact names of the accelerated function and the pointer variable.

1 Using the flow control pragma might result in an accelerator

that functions differently from the original function running on

the Nios II processor.

f For details about Avalon-MM flow control, refer to the Avalon Memory-

Mapped Interface Specification.

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Altera Nios II C2H Compiler Uživatelský manuál Strana 121