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src/shiftOut.lua

@@ -0,0 +1,61 @@
+shiftOut = {}
+
+local GPIO = require('periphery').GPIO
+local bit = require("bit")
+
+LSBFIRST = 1
+MSBFIRST = 0
+
+function shiftOut:new(latchPin, dataPin, clockPin)
+
+    local obj = {}
+    obj.latchGPIO = GPIO(latchPin, "out")
+    obj.dataGPIO = GPIO(dataPin, "out")
+    obj.clockGPIO = GPIO(clockPin, "out")
+
+    obj.latchGPIO:write(false)
+    obj.dataGPIO:write(false)
+    obj.clockGPIO:write(false)
+
+    function obj:shiftOut(value, bitOrder)
+        if bitOrder == nil then
+            bitOrder = MSBFIRST
+        end
+
+        if type(value) == "number" then -- decimal
+            for i = 1, 8 do
+                if bitOrder == LSBFIRST then
+                    self.dataGPIO:write(bit.band(value, 1))
+                    value = bit.rshift(value, 1)
+                else
+                    self.dataGPIO:write(bit.band(value, 128) ~= 0)
+                    value = bit.lshift(value, 1)
+                end
+
+                self.clockGPIO:write(true)
+                self.clockGPIO:write(false)
+            end
+        elseif type(value) == "string" then -- string bits (Ex: "10100001")
+            if bitOrder == LSBFIRST then
+                value = string.reverse(value)
+            end
+
+            for i = 1, 8 do
+                self.dataGPIO:write(string.sub(value, i, i) == "1")
+
+                self.clockGPIO:write(true)
+                self.clockGPIO:write(false)
+            end
+
+        end
+
+        self.latchGPIO:write(true)
+        self.latchGPIO:write(false)
+    end
+
+    setmetatable(obj, self)
+    self.__index = self;
+    return obj
+end
+
+return shiftOut