maple/visio.c: Refine and support more key sequence varieties. [ref: …

…PttBBS 'common/sys/vtkbd.c']

* maple/visio.c: `vkey()`: Add comments about current key sequences for conditions.
* maple/visio.c: `vkey()`: Fix any key sequence of "<Esc> [ <12> ch" being processed as `KEY_F*` keys.
* maple/visio.c: Reorder comment about "Home" key group to match the order of key values.
     "Ins Del Home End PgUp PgDn" => "Home Ins Del End PgUp PgDn"
* maple/visio.c: Support more key sequence varieties. [ref: PttBBS 'common/sys/vtkbd.c']

maple/visio.c

@@ -2361,51 +2361,82 @@ vkey(void)
             return ch;
         }
 #endif
-        else if (mode == 1)
+        else if (mode == 1)   /* "<Esc> `ch`" */
         {                               /* Escape sequence */
-            if (ch == '[' || ch == 'O')
+            if (ch == '[' || ch == 'O')       /* "<Esc> <[O>" */
                 mode = 2;
-            else if (ch == '1' || ch == '4')
-                mode = 3;
             else
             {
                 return Meta(ch);
             }
         }
-        else if (mode == 2)
+        else if (mode == 2)   /* "<Esc> <[O> `ch`" */
         {
-            if (ch >= 'A' && ch <= 'D')      /* Cursor key */
+            if (ch >= 'A' && ch <= 'D')       /* "<Esc> <[O> <A-D>" */ /* Cursor key */
                 return KEY_UP + (ch - 'A');
-            else if (last == 'O')
+            else switch (ch)  /* "<Esc> <[O> <HF>" */ /* Home Ens (xterm) */
+            {
+              case 'H':
+                return KEY_HOME;
+              case 'F':
+                return KEY_END;
+            }
+            /* else */ if (last == 'O')             /* "<Esc> O `ch`" */
             {
-                if (ch >= 'P' && ch <= 'S')  /* F1 - F4 */
+                if (ch >= 'P' && ch <= 'S')   /* "<Esc> O <PQRS>" */ /* F1 - F4 */
                     return KEY_F1 + (ch - 'P');
+                else if (ch == 'w')           /* "<Esc> O w" */ /* END (PuTTY-rxvt) */
+                    return KEY_END;
                 else
                     return ch;
             }
-            else if (ch == 'Z')              /* Shift-Tab */
-                return KEY_STAB;
-            else if (ch >= '1' && ch <= '6')
+            else if (ch >= '1' && ch <= '8')  /* "<Esc> [ <1-8>" */
                 mode = 3;
-            else
+            else switch (ch)                  /* "<Esc> [ `ch`" */
+            {
+                                              /* "<Esc> [ <GIL>" */ /* PgDn PgUp Ins (SCO) */
+              case 'G':
+                return KEY_PGDN;
+              case 'I':
+                return KEY_PGUP;
+              case 'L':
+                return KEY_INS;
+
+              case 'Z':                       /* "<Esc> [ Z" */ /* Shift-Tab */
+                return KEY_STAB;
+
+              default:
                 return ch;
+            }
         }
-        else if (mode == 3)
-        {                               /* Ins Del Home End PgUp PgDn */
-            if (ch == '~')
-                return KEY_HOME + (last - '1');
-            else if (last >= '1' && last <= '2')
+        else if (mode == 3)   /* "<Esc> [ <1-8> `ch`" */
+        {                               /* Home Ins Del End PgUp PgDn */
+            if (ch == '~')              /* "<Esc> [ <1-8> ~" */
+            {
+                if (last <= '6')        /* "<Esc> [ <1-6> ~" */
+                    return KEY_HOME + (last - '1');
+                else switch (last)      /* "<Esc> [ <78> ~" */ /* Home End (rxvt) */
+                {
+                  case '7':
+                    return KEY_HOME;
+                  case '8':
+                    return KEY_END;
+                  default:
+                    return ch;
+                }
+            }
+            else if (ch >= '0' && ch <= '9')      /* "<Esc> [ <1-6> <0-9>" */
                 mode = 4;
             else
                 return ch;
         }
-        else if (mode == 4)
+        else if (mode == 4)   /* "<Esc> [ <1-6> <0-9> `ch`" */
         {                               /* F1 - F12 */
-            if (ch == '~')
+            if (ch == '~')              /* "<Esc> [ <1-6> <0-9> ~" */
             {
-                if (last2 == '1')       /* F1 - F8 */
+                if (last2 == '1')       /* "<Esc> [ 1 `last` ~" */ /* F1 - F8 */
                     return KEY_F1 + (last - '1') - (last > '6');
-                else if (last2 == '2')  /* F9 - F12 */
+                else if (last2 == '2')  /* "<Esc> [ 2 `last` ~" */ /* F9 - F12 */
                     return KEY_F9 + (last - '0') - (last > '2');
                 else
                     return ch;