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comparison util/hex.lua @ 6545:ec566d7cd518

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util.hex: Pedantic optimization, 1 table lookup per byte instead of 3 function calls makes it go faster
author Kim Alvefur <zash@zash.se>
date Mon, 12 Jan 2015 15:10:37 +0100
parents 3f4809d01783
children 442019e955dc
comparison
equal deleted inserted replaced
6544:2f709bc35575 6545:ec566d7cd518
1 local s_char = string.char; 1 local s_char = string.char;
2 local s_format = string.format;
3 local s_gsub = string.gsub;
2 4
3 local function char_to_hex(c) 5 local char_to_hex = {};
4 return ("%02x"):format(c:byte()) 6 local hex_to_char = {};
5 end
6 7
7 local function hex_to_char(h) 8 do
8 return s_char(tonumber(h, 16)); 9 local char, hex;
10 for i = 0,255 do
11 char, hex = s_char(i), s_format("%02x", i);
12 char_to_hex[char] = hex;
13 hex_to_char[hex] = char;
14 end
9 end 15 end
10 16
11 local function to(s) 17 local function to(s)
12 return s:gsub(".", char_to_hex); 18 return (s_gsub(s, ".", char_to_hex));
13 end 19 end
14 20
15 local function from(s) 21 local function from(s)
16 return s:gsub("..", hex_to_char); 22 return (s_gsub(s, "..", hex_to_char));
17 end 23 end
18 24
19 return { to = to, from = from } 25 return { to = to, from = from }