IPT-C2H-NIOS Altera, IPT-C2H-NIOS Datasheet - Page 107

• Manufacturer Part Number: IPT-C2H-NIOS
• Description: C2H COMPILER FOR NIOS II
• Manufacturer: Altera
• Series: Nios®IIr
• Type: Nios IIr

Specifications of IPT-C2H-NIOS

• Function: C to Hardware Compiler
• License: Initial License
• Software Application: IP CORE, NIOS Processor And Functions
• Core Architecture: FPGA
• Core Sub-architecture: Cyclone
• Rohs Compliant: NA
• Lead Free Status / RoHS Status: Not applicable / Not applicable

Figure 4–5. CRC Dependency Graph
Altera Corporation
November 2009
lut_addr=(
crc
&0xFF)^*data++;
Since the critical path does not involve the pointer data the only
operations are on local scalar types and a read operation from the array
table. The calculation of lut_addr only depends on the scalar critical
loop variable crc, while the calculation of crc depends on a memory
reference to critical loop array variable table.
Each time the C2H accelerator finishes calculating the value of crc for
loop iteration n, it can start calculating crc for iteration n+1. On the same
clock cycle, it can also start calculating the value of lut_addr for
iteration n+2. This means that the accelerator always gets a one-loop head
start on calculating lut_addr. Thus, although the accelerator requires
lut_addr to calculate crc, lut_addr does not limit the loop speed,
because it is always ready as soon as crc is.
The report shows that the critical path is either 0--->6, or 6--->11.
Since the C2H Compiler pipelines the logic contained in loops, multiple
states are active concurrently.
of
the critical path, the accelerator begins each execution of that statement as
crc=(crc>>8)^table[
crc=(crc>>8)^
Example 4–2 on page
Nios II C2H Compiler User Guide
table
9.1
4–10. Notice that since the assignment of crc is
lut_addr=(crc&0xFF)^
[lut_addr];
lut_addr
Figure 4–6
represents the pipelined timing
];
Understanding the C2H View
*data++
4–13
;