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Merge pull request #12 from ErikBuer/nrzi
add NRZI encoding // decoding
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# Assumes it's being run from project root. | ||
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using Pkg | ||
Pkg.activate("docs/") | ||
Pkg.instantiate() | ||
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ENV["LOCAL"] = "true" | ||
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include("make.jl") |
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""" | ||
encodeNRZI(bits::AbstractVector, transitions::Symbol=:low)::AbstractVector | ||
Map a bit sequence to Non-Return-to-Zero Inverted (NRZI) encoded bits. | ||
Expects a vector of bits, e.g. `[0, 1, 1, 0, 0, 1, 0, 1, 0, 1]`. | ||
# Arguments | ||
- `bits::AbstractVector`: Vector of bits to encode. | ||
- `transitions::Symbol`: Symbol indicating the symbol to transition on (`:low`/`:high`). Defaults to `:low`. | ||
# Returns | ||
- `encoded_bits::AbstractVector`: Vector of encoded bits. | ||
# Examples | ||
```jldoctest | ||
julia> encoded_bits = encodeNRZI(Int32[0, 1, 1, 0, 0, 1], :low); | ||
julia> transpose(encoded_bits) | ||
1×6 transpose(::Vector{Int32}) with eltype Int32: | ||
1 1 1 0 1 1 | ||
``` | ||
The example below shows how the `transitions` argument affects the encoded bit sequence. | ||
```jldoctest | ||
julia> encoded_bits = encodeNRZI(Int32[0, 1, 1, 0, 0, 1], :high); | ||
julia> transpose(encoded_bits) | ||
1×6 transpose(::Vector{Int32}) with eltype Int32: | ||
0 1 0 0 0 1 | ||
``` | ||
""" | ||
function encodeNRZI(bits::AbstractVector, transitions::Symbol=:low)::AbstractVector | ||
encoded_bits = similar(bits) | ||
encodeNRZI!(encoded_bits,bits,transitions) | ||
return encoded_bits | ||
end | ||
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function encodeNRZI!(encoded_bits::AbstractVector,bits::AbstractVector,transitions::Symbol=:low) | ||
@assert size(encoded_bits) == size(bits) "With NRZI encoding, input and output should have same size ($(size(encoded_bits)) ≂̸ $(size(bits))" | ||
last_bit = 0 | ||
transition_bit = (transitions == :high) ? 1 : 0 | ||
for n ∈ eachindex(bits) | ||
if bits[n] == transition_bit | ||
last_bit = last_bit ⊻ 1 | ||
end | ||
encoded_bits[n] = last_bit | ||
end | ||
return nothing | ||
end | ||
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""" | ||
decodeNRZI(bits::AbstractVector, transitions::Symbol=:low)::AbstractVector | ||
Decode a Non-Return-to-Zero Inverted (NRZI) encoded bit sequence. | ||
Expects a vector of bits, e.g. `[0, 1, 1, 0, 0, 1, 0, 1, 0, 1]`. | ||
# Arguments | ||
- `bits::AbstractVector`: Vector of bits to encode. | ||
- `transitions::Symbol`: Symbol represented by a transition in the NRZI coded sequence (`:low`/`:high`). Defaults to `:low`. | ||
# Returns | ||
- `decoded_bits::AbstractVector`: Vector of decoded bits. The first bit of the output depends on a value of a memory bit in the decoder. | ||
this value is set to `0`. | ||
# Examples | ||
```jldoctest | ||
julia> decoded_bits = decodeNRZI(Int32[1, 1, 1, 0, 1, 1], :low); | ||
julia> transpose(decoded_bits) | ||
1×6 transpose(::Vector{Int32}) with eltype Int32: | ||
0 1 1 0 0 1 | ||
``` | ||
The example below shows how the `transitions` argument affects the decoded bit sequence. | ||
```jldoctest | ||
julia> decoded_bits = decodeNRZI(Int32[0, 1, 0, 0, 0, 1], :high); | ||
julia> transpose(decoded_bits) | ||
1×6 transpose(::Vector{Int32}) with eltype Int32: | ||
0 1 1 0 0 1 | ||
``` | ||
""" | ||
function decodeNRZI(encoded_bits::AbstractVector, transitions::Symbol=:low)::AbstractVector | ||
decoded_bits = similar(encoded_bits) | ||
decodeNRZI!(decoded_bits,encoded_bits,transitions) | ||
return decoded_bits | ||
end | ||
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function decodeNRZI!(decoded_bits::AbstractVector,encoded_bits::AbstractVector, transitions::Symbol=:low) | ||
@assert size(encoded_bits) == size(decoded_bits) "With NRZI encoding, input and output should have same size ($(size(decoded_bits)) ≂̸ $(size(encoded_bits))" | ||
last_bit = 0 | ||
transition_bit = (transitions == :high) ? 1 : 0 | ||
for n ∈ eachindex(encoded_bits) | ||
current_bit = encoded_bits[n] | ||
if current_bit != last_bit | ||
decoded_bit = transition_bit | ||
else | ||
decoded_bit = 1 - transition_bit | ||
end | ||
last_bit = current_bit | ||
decoded_bits[n] = decoded_bit | ||
end | ||
return nothing | ||
end |
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# ---------------------------------------------------- | ||
# --- Import modules | ||
# ---------------------------------------------------- | ||
using DigitalComm | ||
using Test | ||
# ---------------------------------------------------- | ||
# --- Tests | ||
# ---------------------------------------------------- | ||
# Note --> The mapping system is described in bitMapping.jl | ||
println("Tests for symbol mapper with NRZI sequences"); | ||
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@testset "NRZI" begin | ||
# Create a bit squence (already tested) | ||
nbBits = 2 * 2048; | ||
bitSeq = genBitSequence(nbBits); | ||
# Pass trough the function | ||
buff = zeros(Complex{Float64},nbBits) | ||
# Call | ||
encodeNRZI!(buff,bitSeq); | ||
buff2 = encodeNRZI(bitSeq); | ||
@test all( buff .== buff2) | ||
# Ensure Tx // Rx is Ok | ||
@test all(bitSeq .== decodeNRZI(encodeNRZI(bitSeq))) | ||
@test all(bitSeq .== decodeNRZI(encodeNRZI(bitSeq,:high),:high)) | ||
# Some manual check for both transitions | ||
buff = [0x01;0x00;0x00;0x01;0x00;0x00;0x00;0x01 ]; | ||
@test all( encodeNRZI(buff,:low) .== [0;1;0;0;1;0;1;1]) # Transitions on 0 | ||
@test all( encodeNRZI(buff,:high) .== [1;1;1;0;0;0;0;1]) # Transitions on 1 | ||
end |