Convert lex and dix constant tables into a series of packed bytes to save memory.

Author: Lethja

arch/INFLATE.LUA

@@ -226,57 +226,13 @@ function inflate(r, w, z)
 				h = mh(ll) d = mh(dl)
 			end
 
-			-- lex = length extra
-			-- dix = dist extra
-			local lex, dix = {
-				[257]={3,0},[258]={4,0},[259]={5,0},[260]={6,0},[261]={7,0},
-				[262]={8,0},[263]={9,0},[264]={10,0},[265]={11,1},[266]={13,1},
-				[267]={15,1},[268]={17,1},[269]={19,2},[270]={23,2},[271]={27,2},
-				[272]={31,2},[273]={35,3},[274]={43,3},[275]={51,3},[276]={59,3},
-				[277]={67,4},[278]={83,4},[279]={99,4},[280]={115,4},[281]={131,5},
-				[282]={163,5},[283]={195,5},[284]={227,5},[285]={258,0}
-			},{
-				{1,0},{2,0},{3,0},{4,0},
-				{5,1},{7,1},
-				{9,2},{13,2},
-				{17,3},{25,3},
-				{33,4},{49,4},
-				{65,5},{97,5},
-				{129,6},{193,6},
-				{257,7},{385,7},
-				{513,8},{769,8},
-				{1025,9},{1537,9},
-				{2049,10},{3073,10},
-				{4097,11},{6145,11},
-				{8193,12},{12289,12},
-				{16385,13},{24577,13},
-
-				-- Inflate64 below
-				{32769,14},{49153,14},
-				{65537,15},{98305,15},
-				{131073,16},{196609,16},
-				{262145,17},{393217,17},
-				{524289,18},{786433,18},
-				{1048577,19},{1572865,19},
-				{2097153,20},{3145729,20},
-				{4194305,21},{6291457,21},
-				{8388609,22},{12582913,22},
-				{16777217,23},{25165825,23},
-				{33554433,24},{50331649,24},
-				{67108865,25},{100663297,25},
-				{134217729,26},{201326593,26},
-				{268435457,27},{402653185,27},
-				{536870913,28},{805306369,28},
-				{1073741825,29},{1610612737,29},
-				{2147483649,30},{3221225473,30},
-			}
-
-			-- Strip addition table values out when not in inflate64 mode
-			if not z then
-				for _ = 1, 33 do
-					table.remove(dix)
-				end
-			end
+			-- lex = length base & extra bits (pairs of bytes)
+			-- dix = distance extra bits (1 byte per entry)
+			-- dib = distance base (packed 32-bit LE)
+			local lex, dix, dib =
+			"\003\000\004\000\005\000\006\000\007\000\008\000\009\000\010\000\011\001\013\001\015\001\017\001\019\002\023\002\027\002\031\002\035\003\043\003\051\003\059\003\067\004\083\004\099\004\115\004\131\005\163\005\195\005\227\005\002\000",
+			"\000\000\000\000\001\001\002\002\003\003\004\004\005\005\006\006\007\007\008\008\009\009\010\010\011\011\012\012\013\013\014\014\015\015\016\016\017\017\018\018\019\019\020\020\021\021\022\022\023\023\024\024\025\025\026\026\027\027\028\028\029\029\030\030",
+			"\001\000\000\000\002\000\000\000\003\000\000\000\004\000\000\000\005\000\000\000\007\000\000\000\009\000\000\000\013\000\000\000\017\000\000\000\025\000\000\000\033\000\000\000\049\000\000\000\065\000\000\000\097\000\000\000\129\000\000\000\193\000\000\000\001\001\000\000\129\001\000\000\001\002\000\000\001\003\000\000\001\004\000\000\001\006\000\000\001\008\000\000\001\012\000\000\001\016\000\000\001\024\000\000\001\032\000\000\001\048\000\000\001\064\000\000\001\096\000\000\001\128\000\000\001\192\000\000\001\000\001\000\001\128\001\000\001\000\002\000\001\128\002\000\001\000\004\000\001\128\004\000\001\000\008\000\001\128\008\000\001\000\016\000\001\128\16\000\001\000\032\000\001\128\032\000\001\000\064\000\001\128\064\000\001\000\128\000\001\128\128\000\001\000\000\001\001\128\000\001\001\000\000\002\001\128\000\002\001\000\000\004\001\128\000\004\001\000\000\008\001\128\000\008\001\000\000\016\001\128\000\016\001\000\000\032\001\128\000\032\001\000\000\064\001\128\000\064\001\000\000\128\001\128\000\128\001\000\000\000\192"
 
 			while true do
 				-- s = sym
@@ -287,27 +243,28 @@ function inflate(r, w, z)
 					break
 				else
 
-					-- e = entry
 					-- b = base
 					-- x = extra
 					-- a = add
 					-- l = length
-					-- ds = dsym
-					-- de = dentry
-					-- db = dbase
-					-- dx = dextra
-					-- da = dadd
-					local e, b, x, a, l, ds, de, db, dx, da, dv = lex[s]
-
-					b, x = e[1], e[2]
-					a = x > 0 and bs.r(x) or 0
-					l = b + a
+					local li, b, x, l = (s - 257) * 2 + 1
+					b, x = lex:byte(li), lex:byte(li + 1)
+					if s == 285 then b = 258 end
+
+					l = b + (x > 0 and bs.r(x) or 0)
+
 					if d.max > 0 and #d.tab > 0 then
-						ds = rh(d)
-						de = dix[ds + 1]
-						db, dx = de[1], de[2]
-						da = dx > 0 and bs.r(dx) or 0
-						dv = db + da
+
+						-- ds = distance symbol
+						-- db = distance base
+						-- dx = distance extra bits
+						-- dv = distance value
+						local ds, db, dx, dv = rh(d)
+
+						-- Extract 32-bit unsigned little-endian integer (I4) and extra bits byte
+						db = string.unpack("<I4", dib, ds * 4 + 1)
+						dx = dix:byte(ds + 1)
+						dv = db + (dx > 0 and bs.r(dx) or 0)
 
 						if dv <= 0 or dv > op then
 							print("!Distance", dv, Z, op) os.exit(1)