Various fixes

Unicode:
Replace \0 with \xC0\x80
Limit max codepoint to 0xFFFF (Java chars are wonderful)
Fix wtrunc and math.huge
Fix wtrunc with a pos of 0 returning the entire string

GPU (not screen):
Simplify rdepthTbl
Add depth names table
return the old depth when changing depth
limit the resolution change correctly
allow gpu.get to work with a little over the max dimensions

Screen:
Don't modify characters if it's a wide character at the very edge of the
screen
Have getColor set the palette index instead
Return true in cec.fill
Floor the resolution when changing

src/apis/unicode.lua

@@ -3,12 +3,20 @@ local env = ...
 local utf8 = require("utf8")
 
 env.unicode = {
-	char = utf8.char,
 	len = utf8.len,
 	reverse = utf8.reverse,
 	sub = utf8.sub,
 }
 
+function env.unicode.char(...)
+	cprint("unicode.char", ...)
+	local args = table.pack(...)
+	for i = 1,args.n do
+		checkArg(i,args[i],"number")
+		args[i] = args[i]%0x10000
+	end
+	return utf8.char(table.unpack(args)):gsub("%z","\xC0\x80") .. ""
+end
 function env.unicode.lower(str)
 	cprint("unicode.lower", str)
 	if type(str) == "number" then str = tostring(str) end
@@ -52,6 +60,9 @@ function env.unicode.wtrunc(str, count)
 	cprint("unicode.wtrunc", str, count)
 	checkArg(1,str,"string")
 	checkArg(2,count,"number")
+	if count == math.huge then
+		count = 0
+	end
 	local width = 0
 	local pos = 0
 	local len = utf8.len(str)
@@ -62,5 +73,5 @@ function env.unicode.wtrunc(str, count)
 		end
 		width = width + getCharWidth(utf8.byte(str,pos,pos))
 	end
-	return utf8.sub(str, 1, pos-1)
+	return utf8.sub(str, 1, math.max(pos-1,0))
 end

src/component/gpu.lua

@@ -7,7 +7,8 @@ local lua_utf8 = require("utf8")
 
 local bindaddress
 local depthTbl = {1,4,8}
-local rdepthTbl = {1,nil,nil,2,nil,nil,nil,3}
+local rdepthTbl = {1,[4]=2,[8]=3}
+local depthNames = {"OneBit","FourBit","EightBit"}
 
 -- gpu component
 local obj = {}
@@ -82,7 +83,9 @@ function obj.setDepth(depth) -- Set the color depth. Returns the previous value.
 	if rdepthTbl[depth] == nil or rdepthTbl[depth] > math.max(scrmax, maxtier) then
 		error("unsupported depth",3)
 	end
-	return component.cecinvoke(bindaddress, "setDepth", rdepthTbl[depth])
+	local old = depthNames[component.cecinvoke(bindaddress, "getDepth")]
+	component.cecinvoke(bindaddress, "setDepth", rdepthTbl[depth])
+	return old
 end
 function obj.maxDepth() -- Get the maximum supported color depth.
 	cprint("gpu.maxDepth")
@@ -121,6 +124,11 @@ function obj.setResolution(width, height) -- Set the screen resolution. Returns
 	if bindaddress == nil then
 		return nil, "no screen"
 	end
+	local smw,smh = component.cecinvoke(bindaddress, "maxResolution")
+	smw,smh = math.min(smw,maxwidth),math.min(smh,maxheight)
+	if width <= 0 or width >= smw + 1 or height <= 0 or height >= smh + 1 then
+		error("unsupported resolution",3)
+	end
 	return component.cecinvoke(bindaddress, "setResolution", width, height)
 end
 function obj.maxResolution() -- Get the maximum screen resolution.
@@ -170,7 +178,7 @@ function obj.get(x, y) -- Get the value displayed on the screen at the specified
 		return nil, "no screen"
 	end
 	local w,h = component.cecinvoke(bindaddress, "getResolution")
-	if x < 1 or x > w or y < 1 or y > h then
+	if x < 1 or x >= w+1 or y < 1 or y >= h+1 then
 		error("index out of bounds",3)
 	end
 	return component.cecinvoke(bindaddress, "get", x, y)

src/component/screen_sdl2.lua

@@ -172,20 +172,22 @@ end
 local function setPos(x,y,c,fg,bg)
 	local renderchange = screen.txt[y][x] ~= utf8.char(c) or screen.bg[y][x] ~= scrbgc or (screen.txt[y][x] ~= " " and screen.fg[y][x] ~= scrfgc)
 	local charWidth = getCharWidth(c)
-	local renderafter = getCharWidth(utf8.byte(screen.txt[y][x])) > 1 and charWidth == 1 and x < width
+	if charWidth == 1 or x < width then
-	if x > 1 and getCharWidth(utf8.byte(screen.txt[y][x-1])) > 1 then
+		local renderafter = getCharWidth(utf8.byte(screen.txt[y][x])) > 1 and charWidth == 1 and x < width
-		renderchange = false
+		if x > 1 and getCharWidth(utf8.byte(screen.txt[y][x-1])) > 1 then
-	else
+			renderchange = false
-		screenSet(x,y,c)
+		else
-	end
+			screenSet(x,y,c)
-	if renderchange then
+		end
-		renderChar(c,(x-1)*8,(y-1)*16,fg,bg)
+		if renderchange then
-		if charWidth > 1 and x < width then
+			renderChar(c,(x-1)*8,(y-1)*16,fg,bg)
-			screenSet(x+1,y,32)
+			if charWidth > 1 then
+				screenSet(x+1,y,32)
+			end
+		end
+		if renderafter then
+			renderChar(32,x*8,(y-1)*16,screen.fg[y][x+1],screen.bg[y][x+1])
 		end
-	end
-	if renderafter then
-		renderChar(32,x*8,(y-1)*16,screen.fg[y][x+1],screen.bg[y][x+1])
 	end
 end
 
@@ -214,7 +216,12 @@ local function searchPalette(value)
 	return index, score
 end
 
-local function getColor(value)
+local function getColor(value, sel)
+	if sel then
+		scrfgp = nil
+	else
+		scrbgp = nil
+	end
 	if tier == 3 then
 		local pi,ps = searchPalette(value)
 		local r,g,b = extract(value)
@@ -226,10 +233,21 @@ local function getColor(value)
 		if defs < ps then
 			return defc
 		else
+			if sel then
+				scrfgp = pi
+			else
+				scrbgp = pi
+			end
 			return palcol[pi]
 		end
 	elseif tier == 2 then
-		return palcol[searchPalette(value)]
+		local pi = searchPalette(value)
+		if sel then
+			scrfgp = pi
+		else
+			scrbgp = pi
+		end
+		return palcol[pi]
 	else
 		if value > 0 then
 			return 0xFFFFFF -- TODO: Configuration color
@@ -303,8 +321,8 @@ function cec.setForeground(value, palette) -- Sets the foreground color to the s
 	cprint("(cec) screen.setForeground", value, palette)
 	local oldc, oldp = scrrfc, scrfgp
 	scrrfc = palette and palcol[value] or value
-	scrfgc = palette and scrrfc or getColor(scrrfc)
 	scrfgp = palette and value
+	scrfgc = palette and scrrfc or getColor(scrrfc,true)
 	return oldc, oldp
 end
 function cec.getBackground() -- Get the current background color and whether it's from the palette or not.
@@ -315,8 +333,8 @@ function cec.setBackground(value, palette) -- Sets the background color to the s
 	cprint("(cec) screen.setBackground", value, palette)
 	local oldc, oldp = scrrbc, scrbgp
 	scrrbc = palette and palcol[value] or value
-	scrbgc = palette and scrrbc or getColor(scrrbc)
 	scrbgp = palette and value
+	scrbgc = palette and scrrbc or getColor(scrrbc,false)
 	return oldc, oldp
 end
 function cec.getDepth() -- Returns the currently set color depth.
@@ -329,8 +347,8 @@ function cec.setDepth(depth) -- Set the color depth. Returns the previous value.
 	if tier > 1 then
 		loadPalette()
 	end
-	scrfgc = getColor(scrrfc)
+	scrfgc = getColor(scrrfc,true)
-	scrfbc = getColor(scrrbc)
+	scrfbc = getColor(scrrbc,false)
 	-- TODO: Lowering the depth recolors the entire screen
 end
 function cec.maxDepth() -- Get the maximum supported color depth.
@@ -355,6 +373,7 @@ function cec.fill(x1, y1, w, h, char) -- Fills a portion of the screen at the sp
 			setPos(x,y,code,scrfgc,scrbgc)
 		end
 	end
+	return true
 end
 function cec.getResolution() -- Get the current screen resolution.
 	cprint("(cec) screen.getResolution")
@@ -362,8 +381,9 @@ function cec.getResolution() -- Get the current screen resolution.
 end
 function cec.setResolution(newwidth, newheight) -- Set the screen resolution. Returns true if the resolution changed.
 	cprint("(cec) screen.setResolution", newwidth, newheight)
+	newwidth,newheight = math.floor(newwidth),math.floor(newheight)
 	local oldwidth, oldheight = width, height
-	width, height = math.min(newwidth, maxwidth), math.min(newheight, maxheight)
+	width, height = newwidth, newheight
 	return oldwidth ~= width or oldheight ~= height
 end
 function cec.maxResolution() -- Get the maximum screen resolution.
@@ -444,8 +464,10 @@ function cec.copy(x1, y1, w, h, tx, ty) -- Copies a portion of the screen from t
 			copy.bgp[y-y1][x-x1] = screen.bgp[y][x]
 		end
 	end
-	for y = math.max(math.min(y1+ty, height), 1), math.max(math.min(y2+ty, height), 1) do
+	local my1,my2 = math.max(math.min(y1+ty, height), 1), math.max(math.min(y2+ty, height), 1)
-		for x = math.max(math.min(x1+tx, width), 1), math.max(math.min(x2+tx, width), 1) do
+	local mx1,mx2 = math.max(math.min(x1+tx, width), 1), math.max(math.min(x2+tx, width), 1)
+	for y = my1,my2 do
+		for x = mx1,mx2 do
 			screen.txt[y][x] = copy.txt[y-y1-ty][x-x1-tx]
 			screen.fg[y][x] = copy.fg[y-y1-ty][x-x1-tx]
 			screen.bg[y][x] = copy.bg[y-y1-ty][x-x1-tx]