From 771e9b120f05cc6b900e50618d6fbfd06f96e1ff Mon Sep 17 00:00:00 2001
From: "Paul \"LeoNerd\" Evans" <leonerd@leonerd.org.uk>
Date: Tue, 6 Sep 2022 16:00:35 +0100
Subject: [PATCH] Also accept the DECSGR sequences for superscript/subscript
 control, for greater compatibility

---
 doc/seqs.txt |  1 +
 src/state.c  | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/doc/seqs.txt b/doc/seqs.txt
index 16bfee26..27f28b91 100644
--- a/doc/seqs.txt
+++ b/doc/seqs.txt
@@ -122,6 +122,7 @@ x = xterm
 123x   CSI l            = RM, Reset mode
 123x   CSI ? l          = DECRM, DEC reset mode
 123x   CSI m            = SGR, Set Graphic Rendition
+       CSI ? m          = DECSGR, private Set Graphic Rendition
 123x   CSI   n          = DSR, Device Status Report
  23x       5            =   operating status
  23x       6            =   CPR = cursor position
diff --git a/src/state.c b/src/state.c
index 302ec0f1..ccc69817 100644
--- a/src/state.c
+++ b/src/state.c
@@ -1341,6 +1341,29 @@ static int on_csi(const char *leader, const long args[], int argcount, const cha
     vterm_state_setpen(state, args, argcount);
     break;
 
+  case LEADER('?', 0x6d): // DECSGR
+    /* No actual DEC terminal recognised these, but some printers did. These
+     * are alternative ways to request subscript/superscript/off
+     */
+    for(int argi = 0; argi < argcount; argi++) {
+      long arg;
+      switch(arg = CSI_ARG(args[argi])) {
+        case 4: // Superscript on
+          arg = 73;
+          vterm_state_setpen(state, &arg, 1);
+          break;
+        case 5: // Subscript on
+          arg = 74;
+          vterm_state_setpen(state, &arg, 1);
+          break;
+        case 24: // Super+subscript off
+          arg = 75;
+          vterm_state_setpen(state, &arg, 1);
+          break;
+      }
+    }
+    break;
+
   case 0x6e: // DSR - ECMA-48 8.3.35
   case LEADER('?', 0x6e): // DECDSR
     val = CSI_ARG_OR(args[0], 0);