Add string encoding IBM720 alias CP720 (#3803)

The mapping table is generated from the ICU project:
  https://github.com/unicode-org/icu/blob/master/icu4c/source/data/mappings/ibm-720_P100-1997.ucm

Fixes bug 16233 : https://bugs.ruby-lang.org/issues/16233

3 files changed, 126 insertions, 1 deletions

diff --git a/enc/ascii.c b/enc/ascii.c
index 8b32c414fe..a2fef2f879 100644
--- a/enc/ascii.c
+++ b/enc/ascii.c
@@ -61,6 +61,8 @@ OnigEncodingDefine(ascii, ASCII) = {
 ENC_ALIAS("BINARY", "ASCII-8BIT")
 ENC_REPLICATE("IBM437", "ASCII-8BIT")
 ENC_ALIAS("CP437", "IBM437")
+ENC_REPLICATE("IBM720", "ASCII-8BIT")
+ENC_ALIAS("CP720", "IBM720")
 ENC_REPLICATE("IBM737", "ASCII-8BIT")
 ENC_ALIAS("CP737", "IBM737")
 ENC_REPLICATE("IBM775", "ASCII-8BIT")
diff --git a/enc/trans/ibm720-tbl.rb b/enc/trans/ibm720-tbl.rb
new file mode 100644
index 0000000000..558684d649
--- /dev/null
+++ b/enc/trans/ibm720-tbl.rb
@@ -0,0 +1,122 @@
+IBM720_TO_UCS_TBL = [
+  ["FF",0xA0],
+  ["9C",0xA3],
+  ["94",0xA4],
+  ["AE",0xAB],
+  ["F8",0xB0],
+  ["FD",0xB2],
+  ["E6",0xB5],
+  ["FA",0xB7],
+  ["AF",0xBB],
+  ["85",0xE0],
+  ["83",0xE2],
+  ["87",0xE7],
+  ["8A",0xE8],
+  ["82",0xE9],
+  ["88",0xEA],
+  ["89",0xEB],
+  ["8C",0xEE],
+  ["8B",0xEF],
+  ["93",0xF4],
+  ["97",0xF9],
+  ["96",0xFB],
+  ["98",0x621],
+  ["99",0x622],
+  ["9A",0x623],
+  ["9B",0x624],
+  ["9D",0x625],
+  ["9E",0x626],
+  ["9F",0x627],
+  ["A0",0x628],
+  ["A1",0x629],
+  ["A2",0x62A],
+  ["A3",0x62B],
+  ["A4",0x62C],
+  ["A5",0x62D],
+  ["A6",0x62E],
+  ["A7",0x62F],
+  ["A8",0x630],
+  ["A9",0x631],
+  ["AA",0x632],
+  ["AB",0x633],
+  ["AC",0x634],
+  ["AD",0x635],
+  ["E0",0x636],
+  ["E1",0x637],
+  ["E2",0x638],
+  ["E3",0x639],
+  ["E4",0x63A],
+  ["95",0x640],
+  ["E5",0x641],
+  ["E7",0x642],
+  ["E8",0x643],
+  ["E9",0x644],
+  ["EA",0x645],
+  ["EB",0x646],
+  ["EC",0x647],
+  ["ED",0x648],
+  ["EE",0x649],
+  ["EF",0x64A],
+  ["F1",0x64B],
+  ["F2",0x64C],
+  ["F3",0x64D],
+  ["F4",0x64E],
+  ["F5",0x64F],
+  ["F6",0x650],
+  ["91",0x651],
+  ["92",0x652],
+  ["FC",0x207F],
+  ["F9",0x2219],
+  ["FB",0x221A],
+  ["F7",0x2248],
+  ["F0",0x2261],
+  ["C4",0x2500],
+  ["B3",0x2502],
+  ["DA",0x250C],
+  ["BF",0x2510],
+  ["C0",0x2514],
+  ["D9",0x2518],
+  ["C3",0x251C],
+  ["B4",0x2524],
+  ["C2",0x252C],
+  ["C1",0x2534],
+  ["C5",0x253C],
+  ["CD",0x2550],
+  ["BA",0x2551],
+  ["D5",0x2552],
+  ["D6",0x2553],
+  ["C9",0x2554],
+  ["B8",0x2555],
+  ["B7",0x2556],
+  ["BB",0x2557],
+  ["D4",0x2558],
+  ["D3",0x2559],
+  ["C8",0x255A],
+  ["BE",0x255B],
+  ["BD",0x255C],
+  ["BC",0x255D],
+  ["C6",0x255E],
+  ["C7",0x255F],
+  ["CC",0x2560],
+  ["B5",0x2561],
+  ["B6",0x2562],
+  ["B9",0x2563],
+  ["D1",0x2564],
+  ["D2",0x2565],
+  ["CB",0x2566],
+  ["CF",0x2567],
+  ["D0",0x2568],
+  ["CA",0x2569],
+  ["D8",0x256A],
+  ["D7",0x256B],
+  ["CE",0x256C],
+  ["DF",0x2580],
+  ["DC",0x2584],
+  ["DB",0x2588],
+  ["DD",0x258C],
+  ["DE",0x2590],
+  ["B0",0x2591],
+  ["B1",0x2592],
+  ["B2",0x2593],
+  ["FE",0x25A0],
+]
diff --git a/enc/trans/single_byte.trans b/enc/trans/single_byte.trans
index cf521bed38..0d5407b918 100644
--- a/enc/trans/single_byte.trans
+++ b/enc/trans/single_byte.trans
@@ -51,8 +51,9 @@
   transcode_tblgen_singlebyte "WINDOWS-1256"
   transcode_tblgen_singlebyte "WINDOWS-1257"
   transcode_tblgen_singlebyte "IBM437"
-  transcode_tblgen_singlebyte "IBM775"
+  transcode_tblgen_singlebyte "IBM720"
   transcode_tblgen_singlebyte "IBM737"
+  transcode_tblgen_singlebyte "IBM775"
   transcode_tblgen_singlebyte "IBM852"
   transcode_tblgen_singlebyte "IBM855"
   transcode_tblgen_singlebyte "IBM857"