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local function trigram_to_value (a, b, c)
return a * 25 + b * 5 + c
end
local function next_trigram (message, index)
index = (index or 0) + 1
local offset = (index - 1) * 3
local a = message[offset + 1]
if not a then
return nil
end
return index, a, message[offset + 2], message[offset + 3]
end
local function next_value (message, index)
local a, b, c
index, a, b, c = next_trigram(message, index)
if not index then
return nil
end
return index, trigram_to_value(a, b, c)
end
local reading = {
trigram_to_value = trigram_to_value,
next_trigram = next_trigram,
next_value = next_value,
}
function reading.trigrams (message, start)
return next_trigram, message, start or 0
end
function reading.values (message, start)
return next_value, message, start or 0
end
function reading.tvalues (message)
local values = {}
for _, value in reading.values(message) do
table.insert(values, value)
end
return values
end
return reading
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