Altera Nios II C2H Compiler - Manual (Page 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
< function name >/< variable name >
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 .