Altera Reed-Solomon Compiler - Manual (Page 24)

3–6 Chapter 3: Functional Description
Interfaces
Reed-Solomon Compiler December 2014 Altera Corporation
User Guide
Figure 3–5 on page 3–6 shows the error symbol output.
Whenever rserr is not 0 (while decfail is 0), an error correction successfully takes
place. The rsout is the rserr XORed with the corresponding rsin, where XOR is done
for each bit, so you know that the respective symbol has been corrected. The value of
rserr
shows which bits of the symbol have been corrected. For each bit of rserr that
is 1, the corresponding bit of rsout is corrected.
The rsout and the corresponding rserr value appear at the output at the same clock
cycle.
Bit Error Count
The decoder can provide the bit error count found in the correction process. The bit
error count has the following options:
■ Full count. The output num_err_bit is connected, which shows the valid value.
■ Split count. The outputs num_err_bit0 and num_err_bit1 are connected, which
show the valid values
For information about these outputs, refer to Table 3–8 on page 3–10 .
Interfaces
The RS encoder and decoder use the Avalon ® Streaming (Avalon-ST) interface for data
input and output. The input is an Avalon-ST sink and the output is an Avalon-ST
source. The Avalon-ST interface READY_LATENCY parameter is set to 1. The Avalon-ST
interfaces allow for flow control.
The Avalon-ST interface is an evolution of the Atlantic ™ interface. The Avalon-ST
interface defines a standard, flexible, and modular protocol for data transfers from a
source interface to a sink interface and simplifies the process of controlling the flow of
data in a datapath. The Avalon-ST interface signals can describe traditional streaming
interfaces supporting a single stream of data without knowledge of channels or
packet boundaries. Such interfaces typically contain data, ready, and valid signals.
The Avalon-ST interface can also support more complex protocols for burst and
packet transfers with packets interleaved across multiple channels. The Avalon-ST
interface inherently synchronizes multi-channel designs, which allows you to achieve
efficient, time-multiplexed implementations without having to implement complex
control logic.
Figure 3–5. Error Symbol Output
Memory
& Control
Syndrome
Calculation
rsin rserr
rsout
Solve Key
Equation
Chien Search
& Forney's
Algorithm