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-- {name, top, bottom, fifo...}
fifomax = 5
function find_or_create_fifo(space, name)
local fifo = space:get{name}
if fifo == nil then
fifo = {}
for i = 1, fifomax do table.insert(fifo, 0) end
fifo = space:insert{name, 4, 4, unpack(fifo)}
end
return fifo
end
function fifo_push(space, name, val)
local fifo = find_or_create_fifo(space, name)
local top = fifo[2]
local bottom = fifo[3]
if top == fifomax+3 then -- % size
top = 4
elseif top ~= bottom then -- was not empty
top = top + 1
end
if bottom == fifomax + 3 then -- % size
bottom = 4
elseif bottom == top then
bottom = bottom + 1
end
return space:update({name}, {{'=', 2, top}, {'=', 3, bottom }, {'=', top, val}})
end
function fifo_top(space, name)
local fifo = find_or_create_fifo(space, name)
local top = fifo[2]
return fifo[top]
end
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