Add CP437 (native Windows OEM) to unicode.lua

nselib/unicode.lua

@@ -189,6 +189,181 @@ function utf8_dec(buf, pos)
   return pos + 1 + n, cp
 end
 
+--Invert a one-to-one mapping
+local function invert(t)
+  local out = {}
+  for k, v in pairs(t) do
+    out[v] = k
+  end
+  return out
+end
+
+-- Code Page 437, native US-English Windows OEM code page
+local cp437_decode = {
+  [0x80] = 0x00c7,
+  [0x81] = 0x00fc,
+  [0x82] = 0x00e9,
+  [0x83] = 0x00e2,
+  [0x84] = 0x00e4,
+  [0x85] = 0x00e0,
+  [0x86] = 0x00e5,
+  [0x87] = 0x00e7,
+  [0x88] = 0x00ea,
+  [0x89] = 0x00eb,
+  [0x8a] = 0x00e8,
+  [0x8b] = 0x00ef,
+  [0x8c] = 0x00ee,
+  [0x8d] = 0x00ec,
+  [0x8e] = 0x00c4,
+  [0x8f] = 0x00c5,
+  [0x90] = 0x00c9,
+  [0x91] = 0x00e6,
+  [0x92] = 0x00c6,
+  [0x93] = 0x00f4,
+  [0x94] = 0x00f6,
+  [0x95] = 0x00f2,
+  [0x96] = 0x00fb,
+  [0x97] = 0x00f9,
+  [0x98] = 0x00ff,
+  [0x99] = 0x00d6,
+  [0x9a] = 0x00dc,
+  [0x9b] = 0x00a2,
+  [0x9c] = 0x00a3,
+  [0x9d] = 0x00a5,
+  [0x9e] = 0x20a7,
+  [0x9f] = 0x0192,
+  [0xa0] = 0x00e1,
+  [0xa1] = 0x00ed,
+  [0xa2] = 0x00f3,
+  [0xa3] = 0x00fa,
+  [0xa4] = 0x00f1,
+  [0xa5] = 0x00d1,
+  [0xa6] = 0x00aa,
+  [0xa7] = 0x00ba,
+  [0xa8] = 0x00bf,
+  [0xa9] = 0x2310,
+  [0xaa] = 0x00ac,
+  [0xab] = 0x00bd,
+  [0xac] = 0x00bc,
+  [0xad] = 0x00a1,
+  [0xae] = 0x00ab,
+  [0xaf] = 0x00bb,
+  [0xb0] = 0x2591,
+  [0xb1] = 0x2592,
+  [0xb2] = 0x2593,
+  [0xb3] = 0x2502,
+  [0xb4] = 0x2524,
+  [0xb5] = 0x2561,
+  [0xb6] = 0x2562,
+  [0xb7] = 0x2556,
+  [0xb8] = 0x2555,
+  [0xb9] = 0x2563,
+  [0xba] = 0x2551,
+  [0xbb] = 0x2557,
+  [0xbc] = 0x255d,
+  [0xbd] = 0x255c,
+  [0xbe] = 0x255b,
+  [0xbf] = 0x2510,
+  [0xc0] = 0x2514,
+  [0xc1] = 0x2534,
+  [0xc2] = 0x252c,
+  [0xc3] = 0x251c,
+  [0xc4] = 0x2500,
+  [0xc5] = 0x253c,
+  [0xc6] = 0x255e,
+  [0xc7] = 0x255f,
+  [0xc8] = 0x255a,
+  [0xc9] = 0x2554,
+  [0xca] = 0x2569,
+  [0xcb] = 0x2566,
+  [0xcc] = 0x2560,
+  [0xcd] = 0x2550,
+  [0xce] = 0x256c,
+  [0xcf] = 0x2567,
+  [0xd0] = 0x2568,
+  [0xd1] = 0x2564,
+  [0xd2] = 0x2565,
+  [0xd3] = 0x2559,
+  [0xd4] = 0x2558,
+  [0xd5] = 0x2552,
+  [0xd6] = 0x2553,
+  [0xd7] = 0x256b,
+  [0xd8] = 0x256a,
+  [0xd9] = 0x2518,
+  [0xda] = 0x250c,
+  [0xdb] = 0x2588,
+  [0xdc] = 0x2584,
+  [0xdd] = 0x258c,
+  [0xde] = 0x2590,
+  [0xdf] = 0x2580,
+  [0xe0] = 0x03b1,
+  [0xe1] = 0x00df,
+  [0xe2] = 0x0393,
+  [0xe3] = 0x03c0,
+  [0xe4] = 0x03a3,
+  [0xe5] = 0x03c3,
+  [0xe6] = 0x00b5,
+  [0xe7] = 0x03c4,
+  [0xe8] = 0x03a6,
+  [0xe9] = 0x0398,
+  [0xea] = 0x03a9,
+  [0xeb] = 0x03b4,
+  [0xec] = 0x221e,
+  [0xed] = 0x03c6,
+  [0xee] = 0x03b5,
+  [0xef] = 0x2229,
+  [0xf0] = 0x2261,
+  [0xf1] = 0x00b1,
+  [0xf2] = 0x2265,
+  [0xf3] = 0x2264,
+  [0xf4] = 0x2320,
+  [0xf5] = 0x2321,
+  [0xf6] = 0x00f7,
+  [0xf7] = 0x2248,
+  [0xf8] = 0x00b0,
+  [0xf9] = 0x2219,
+  [0xfa] = 0x00b7,
+  [0xfb] = 0x221a,
+  [0xfc] = 0x207f,
+  [0xfd] = 0x00b2,
+  [0xfe] = 0x25a0,
+  [0xff] = 0x00a0,
+}
+local cp437_encode = invert(cp437_decode)
+
+---Encode a Unicode code point to CP437
+--
+-- Returns nil if the code point cannot be found in CP437
+--@param cp The Unicode code point as a number
+--@return A string containing the related CP437 character
+function cp437_enc(cp)
+  if cp < 0x80 then
+    return char(cp)
+  else
+    local bv = cp437_encode[cp]
+    if bv == nil then
+      return nil
+    else
+      return char(bv)
+    end
+  end
+end
+
+---Decodes a CP437 character
+--@param buf A string containing the character
+--@param pos The index in the string where the character begins
+--@return pos The index in the string where the character ended
+--@return cp The code point of the character as a number
+function cp437_dec(buf, pos)
+  pos = pos or 1
+  local bv = byte(buf, pos)
+  if bv < 0x80 then
+    return pos + 1, bv
+  else
+    return pos + 1, cp437_decode[bv]
+  end
+end
+
 ---Helper function for the common case of UTF-16 to UTF-8 transcoding, such as
 --from a Windows/SMB unicode string to a printable ASCII (subset of UTF-8)
 --string.
@@ -235,5 +410,7 @@ test_suite:add_test(unittest.table_equal(decode("\x08\xD8\x45\xDF=\0R\0a\0", utf
 test_suite:add_test(unittest.table_equal(decode("\xD8\x08\xDF\x45\0=\0R\0a", utf16_dec, true), {0x12345,61,82,97}),"decode utf-16, big-endian")
 test_suite:add_test(unittest.equal(utf16to8("\x08\xD8\x45\xDF=\0R\0a\0"), "\xF0\x92\x8D\x85=Ra"),"utf16to8")
 test_suite:add_test(unittest.equal(utf8to16("\xF0\x92\x8D\x85=Ra"), "\x08\xD8\x45\xDF=\0R\0a\0"),"utf8to16")
+test_suite:add_test(unittest.equal(encode({0x221e, 0x2248, 0x30}, cp437_enc), "\xec\xf70"), "encode cp437")
+test_suite:add_test(unittest.table_equal(decode("\x81ber", cp437_dec), {0xfc, 0x62, 0x65, 0x72}), "decode cp437")
 
 return _ENV