From: Nathaniel Wesley Filardo <nwfilardo@gmail.com>
Date: Wed, 14 Mar 2018 18:04:01 +0000 (-0400)
Subject: linux-draw-xpm: ws2812:shift negative
X-Git-Url: https://hydra-www.ietfng.org/gitweb/?a=commitdiff_plain;h=0637802af8f658e9cad2b0ad619b95cf9df47c5e;p=acmetensortoys-esp-lua_lamp

linux-draw-xpm: ws2812:shift negative
---

diff --git a/linux-draw-xpm.lua b/linux-draw-xpm.lua
index 2f881cf..04bc269 100644
--- a/linux-draw-xpm.lua
+++ b/linux-draw-xpm.lua
@@ -42,13 +42,21 @@ function remotefb.shift(self,n,m,i,j)
 
   if m == nil then m = remotefb.SHIFT_LOGICAL end
 
-  local ix
-
-  for ix = 1, n do
-    local v = table.remove(self,j)
-    if m == ws2812.SHIFT_LOGICAL then v = string.char(0,0,0) end
-
-    table.insert(self,i,v)
+  if n == 0 then return
+  elseif n > 0 then
+    local ix
+    for ix = 1, n do
+      local v = table.remove(self,j)
+      if m == ws2812.SHIFT_LOGICAL then v = string.char(0,0,0) end
+      table.insert(self,i,v)
+    end
+  elseif n < 0 then
+    local ix
+    for ix = 1, -n do
+      local v = table.remove(self,i)
+      if m == ws2812.SHIFT_LOGICAL then v = string.char(0,0,0) end
+      table.insert(self,j,v)
+    end
   end
 end
 remotefb:fill(0,0,0)