Merge remote-tracking branch 'upstream/master' into mix_20240309HEADrahm

1 files changed, 2467 insertions, 0 deletions

diff --git a/src/nvim/vterm/state.c b/src/nvim/vterm/state.c
new file mode 100644
index 0000000000..0e43107347
--- /dev/null
+++ b/src/nvim/vterm/state.c
@@ -0,0 +1,2467 @@
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "nvim/grid.h"
+#include "nvim/mbyte.h"
+#include "nvim/vterm/encoding.h"
+#include "nvim/vterm/parser.h"
+#include "nvim/vterm/pen.h"
+#include "nvim/vterm/state.h"
+#include "nvim/vterm/vterm.h"
+#include "nvim/vterm/vterm_internal_defs.h"
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "vterm/state.c.generated.h"
+#endif
+
+#define strneq(a, b, n) (strncmp(a, b, n) == 0)
+
+// Some convenient wrappers to make callback functions easier
+
+static void putglyph(VTermState *state, const schar_T schar, int width, VTermPos pos)
+{
+  VTermGlyphInfo info = {
+    .schar = schar,
+    .width = width,
+    .protected_cell = state->protected_cell,
+    .dwl = state->lineinfo[pos.row].doublewidth,
+    .dhl = state->lineinfo[pos.row].doubleheight,
+  };
+
+  if (state->callbacks && state->callbacks->putglyph) {
+    if ((*state->callbacks->putglyph)(&info, pos, state->cbdata)) {
+      return;
+    }
+  }
+
+  DEBUG_LOG("libvterm: Unhandled putglyph U+%04x at (%d,%d)\n", chars[0], pos.col, pos.row);
+}
+
+static void updatecursor(VTermState *state, VTermPos *oldpos, int cancel_phantom)
+{
+  if (state->pos.col == oldpos->col && state->pos.row == oldpos->row) {
+    return;
+  }
+
+  if (cancel_phantom) {
+    state->at_phantom = 0;
+  }
+
+  if (state->callbacks && state->callbacks->movecursor) {
+    if ((*state->callbacks->movecursor)(state->pos, *oldpos, state->mode.cursor_visible,
+                                        state->cbdata)) {
+      return;
+    }
+  }
+}
+
+static void erase(VTermState *state, VTermRect rect, int selective)
+{
+  if (rect.end_col == state->cols) {
+    // If we're erasing the final cells of any lines, cancel the continuation marker on the
+    // subsequent line
+    for (int row = rect.start_row + 1; row < rect.end_row + 1 && row < state->rows; row++) {
+      state->lineinfo[row].continuation = 0;
+    }
+  }
+
+  if (state->callbacks && state->callbacks->erase) {
+    if ((*state->callbacks->erase)(rect, selective, state->cbdata)) {
+      return;
+    }
+  }
+}
+
+static VTermState *vterm_state_new(VTerm *vt)
+{
+  VTermState *state = vterm_allocator_malloc(vt, sizeof(VTermState));
+
+  state->vt = vt;
+
+  state->rows = vt->rows;
+  state->cols = vt->cols;
+
+  state->mouse_col = 0;
+  state->mouse_row = 0;
+  state->mouse_buttons = 0;
+
+  state->mouse_protocol = MOUSE_X10;
+
+  state->callbacks = NULL;
+  state->cbdata = NULL;
+
+  state->selection.callbacks = NULL;
+  state->selection.user = NULL;
+  state->selection.buffer = NULL;
+
+  vterm_state_newpen(state);
+
+  state->bold_is_highbright = 0;
+
+  state->combine_pos.row = -1;
+
+  state->tabstops = vterm_allocator_malloc(state->vt, ((size_t)state->cols + 7) / 8);
+
+  state->lineinfos[BUFIDX_PRIMARY] = vterm_allocator_malloc(state->vt,
+                                                            (size_t)state->rows *
+                                                            sizeof(VTermLineInfo));
+  // TODO(vterm): Make an 'enable' function
+  state->lineinfos[BUFIDX_ALTSCREEN] = vterm_allocator_malloc(state->vt,
+                                                              (size_t)state->rows *
+                                                              sizeof(VTermLineInfo));
+  state->lineinfo = state->lineinfos[BUFIDX_PRIMARY];
+
+  state->encoding_utf8.enc = vterm_lookup_encoding(ENC_UTF8, 'u');
+  if (*state->encoding_utf8.enc->init) {
+    (*state->encoding_utf8.enc->init)(state->encoding_utf8.enc, state->encoding_utf8.data);
+  }
+
+  for (size_t i = 0; i < ARRAY_SIZE(state->key_encoding_stacks); i++) {
+    struct VTermKeyEncodingStack *stack = &state->key_encoding_stacks[i];
+    for (size_t j = 0; j < ARRAY_SIZE(stack->items); j++) {
+      memset(&stack->items[j], 0, sizeof(stack->items[j]));
+    }
+
+    stack->size = 1;
+  }
+
+  return state;
+}
+
+void vterm_state_free(VTermState *state)
+{
+  vterm_allocator_free(state->vt, state->tabstops);
+  vterm_allocator_free(state->vt, state->lineinfos[BUFIDX_PRIMARY]);
+  if (state->lineinfos[BUFIDX_ALTSCREEN]) {
+    vterm_allocator_free(state->vt, state->lineinfos[BUFIDX_ALTSCREEN]);
+  }
+  vterm_allocator_free(state->vt, state);
+}
+
+static void scroll(VTermState *state, VTermRect rect, int downward, int rightward)
+{
+  if (!downward && !rightward) {
+    return;
+  }
+
+  int rows = rect.end_row - rect.start_row;
+  if (downward > rows) {
+    downward = rows;
+  } else if (downward < -rows) {
+    downward = -rows;
+  }
+
+  int cols = rect.end_col - rect.start_col;
+  if (rightward > cols) {
+    rightward = cols;
+  } else if (rightward < -cols) {
+    rightward = -cols;
+  }
+
+  // Update lineinfo if full line
+  if (rect.start_col == 0 && rect.end_col == state->cols && rightward == 0) {
+    int height = rect.end_row - rect.start_row - abs(downward);
+
+    if (downward > 0) {
+      memmove(state->lineinfo + rect.start_row,
+              state->lineinfo + rect.start_row + downward,
+              (size_t)height * sizeof(state->lineinfo[0]));
+      for (int row = rect.end_row - downward; row < rect.end_row; row++) {
+        state->lineinfo[row] = (VTermLineInfo){ 0 };
+      }
+    } else {
+      memmove(state->lineinfo + rect.start_row - downward,
+              state->lineinfo + rect.start_row,
+              (size_t)height * sizeof(state->lineinfo[0]));
+      for (int row = rect.start_row; row < rect.start_row - downward; row++) {
+        state->lineinfo[row] = (VTermLineInfo){ 0 };
+      }
+    }
+  }
+
+  if (state->callbacks && state->callbacks->scrollrect) {
+    if ((*state->callbacks->scrollrect)(rect, downward, rightward, state->cbdata)) {
+      return;
+    }
+  }
+
+  if (state->callbacks) {
+    vterm_scroll_rect(rect, downward, rightward,
+                      state->callbacks->moverect, state->callbacks->erase, state->cbdata);
+  }
+}
+
+static void linefeed(VTermState *state)
+{
+  if (state->pos.row == SCROLLREGION_BOTTOM(state) - 1) {
+    VTermRect rect = {
+      .start_row = state->scrollregion_top,
+      .end_row = SCROLLREGION_BOTTOM(state),
+      .start_col = SCROLLREGION_LEFT(state),
+      .end_col = SCROLLREGION_RIGHT(state),
+    };
+
+    scroll(state, rect, 1, 0);
+  } else if (state->pos.row < state->rows - 1) {
+    state->pos.row++;
+  }
+}
+
+static void set_col_tabstop(VTermState *state, int col)
+{
+  uint8_t mask = (uint8_t)(1 << (col & 7));
+  state->tabstops[col >> 3] |= mask;
+}
+
+static void clear_col_tabstop(VTermState *state, int col)
+{
+  uint8_t mask = (uint8_t)(1 << (col & 7));
+  state->tabstops[col >> 3] &= ~mask;
+}
+
+static int is_col_tabstop(VTermState *state, int col)
+{
+  uint8_t mask = (uint8_t)(1 << (col & 7));
+  return state->tabstops[col >> 3] & mask;
+}
+
+static int is_cursor_in_scrollregion(const VTermState *state)
+{
+  if (state->pos.row < state->scrollregion_top
+      || state->pos.row >= SCROLLREGION_BOTTOM(state)) {
+    return 0;
+  }
+  if (state->pos.col < SCROLLREGION_LEFT(state)
+      || state->pos.col >= SCROLLREGION_RIGHT(state)) {
+    return 0;
+  }
+
+  return 1;
+}
+
+static void tab(VTermState *state, int count, int direction)
+{
+  while (count > 0) {
+    if (direction > 0) {
+      if (state->pos.col >= THISROWWIDTH(state) - 1) {
+        return;
+      }
+
+      state->pos.col++;
+    } else if (direction < 0) {
+      if (state->pos.col < 1) {
+        return;
+      }
+
+      state->pos.col--;
+    }
+
+    if (is_col_tabstop(state, state->pos.col)) {
+      count--;
+    }
+  }
+}
+
+#define NO_FORCE 0
+#define FORCE    1
+
+#define DWL_OFF 0
+#define DWL_ON  1
+
+#define DHL_OFF    0
+#define DHL_TOP    1
+#define DHL_BOTTOM 2
+
+static void set_lineinfo(VTermState *state, int row, int force, int dwl, int dhl)
+{
+  VTermLineInfo info = state->lineinfo[row];
+
+  if (dwl == DWL_OFF) {
+    info.doublewidth = DWL_OFF;
+  } else if (dwl == DWL_ON) {
+    info.doublewidth = DWL_ON;
+  }
+  // else -1 to ignore
+
+  if (dhl == DHL_OFF) {
+    info.doubleheight = DHL_OFF;
+  } else if (dhl == DHL_TOP) {
+    info.doubleheight = DHL_TOP;
+  } else if (dhl == DHL_BOTTOM) {
+    info.doubleheight = DHL_BOTTOM;
+  }
+
+  if ((state->callbacks
+       && state->callbacks->setlineinfo
+       && (*state->callbacks->setlineinfo)(row, &info, state->lineinfo + row, state->cbdata))
+      || force) {
+    state->lineinfo[row] = info;
+  }
+}
+
+static int on_text(const char bytes[], size_t len, void *user)
+{
+  VTermState *state = user;
+
+  VTermPos oldpos = state->pos;
+
+  uint32_t *codepoints = (uint32_t *)(state->vt->tmpbuffer);
+  size_t maxpoints = (state->vt->tmpbuffer_len) / sizeof(uint32_t);
+
+  int npoints = 0;
+  size_t eaten = 0;
+
+  VTermEncodingInstance *encoding =
+    state->gsingle_set ? &state->encoding[state->gsingle_set]
+                       : !(bytes[eaten] & 0x80) ? &state->encoding[state->gl_set]
+                                                : state->vt->mode.utf8 ? &state->encoding_utf8
+                                                                       : &state->encoding[state->
+                                                                                          gr_set];
+
+  (*encoding->enc->decode)(encoding->enc, encoding->data,
+                           codepoints, &npoints, state->gsingle_set ? 1 : (int)maxpoints,
+                           bytes, &eaten, len);
+
+  // There's a chance an encoding (e.g. UTF-8) hasn't found enough bytes yet for even a single codepoint
+  if (!npoints) {
+    return (int)eaten;
+  }
+
+  if (state->gsingle_set && npoints) {
+    state->gsingle_set = 0;
+  }
+
+  int i = 0;
+  GraphemeState grapheme_state = GRAPHEME_STATE_INIT;
+  size_t grapheme_len = 0;
+  bool recombine = false;
+
+  // See if the cursor has moved since
+  if (state->pos.row == state->combine_pos.row
+      && state->pos.col == state->combine_pos.col + state->combine_width) {
+    // This is a combining char. that needs to be merged with the previous glyph output
+    if (utf_iscomposing((int)state->grapheme_last, (int)codepoints[i], &state->grapheme_state)) {
+      // Find where we need to append these combining chars
+      grapheme_len = state->grapheme_len;
+      grapheme_state = state->grapheme_state;
+      state->pos.col = state->combine_pos.col;
+      recombine = true;
+    } else {
+      DEBUG_LOG("libvterm: TODO: Skip over split char+combining\n");
+    }
+  }
+
+  while (i < npoints) {
+    // Try to find combining characters following this
+    do {
+      if (grapheme_len < sizeof(state->grapheme_buf) - 4) {
+        grapheme_len += (size_t)utf_char2bytes((int)codepoints[i],
+                                               state->grapheme_buf + grapheme_len);
+      }
+      i++;
+    } while (i < npoints && utf_iscomposing((int)codepoints[i - 1], (int)codepoints[i],
+                                            &grapheme_state));
+
+    int width = utf_ptr2cells_len(state->grapheme_buf, (int)grapheme_len);
+
+    if (state->at_phantom || state->pos.col + width > THISROWWIDTH(state)) {
+      linefeed(state);
+      state->pos.col = 0;
+      state->at_phantom = 0;
+      state->lineinfo[state->pos.row].continuation = 1;
+    }
+
+    if (state->mode.insert && !recombine) {
+      // TODO(vterm): This will be a little inefficient for large bodies of text, as it'll have to
+      // 'ICH' effectively before every glyph. We should scan ahead and ICH as many times as
+      // required
+      VTermRect rect = {
+        .start_row = state->pos.row,
+        .end_row = state->pos.row + 1,
+        .start_col = state->pos.col,
+        .end_col = THISROWWIDTH(state),
+      };
+      scroll(state, rect, 0, -1);
+    }
+
+    schar_T sc = schar_from_buf(state->grapheme_buf, grapheme_len);
+    putglyph(state, sc, width, state->pos);
+
+    if (i == npoints) {
+      // End of the buffer. Save the chars in case we have to combine with more on the next call
+      state->grapheme_len = grapheme_len;
+      state->grapheme_last = codepoints[i - 1];
+      state->grapheme_state = grapheme_state;
+      state->combine_width = width;
+      state->combine_pos = state->pos;
+    } else {
+      grapheme_len = 0;
+      recombine = false;
+    }
+
+    if (state->pos.col + width >= THISROWWIDTH(state)) {
+      if (state->mode.autowrap) {
+        state->at_phantom = 1;
+      }
+    } else {
+      state->pos.col += width;
+    }
+  }
+
+  updatecursor(state, &oldpos, 0);
+
+#ifdef DEBUG
+  if (state->pos.row < 0 || state->pos.row >= state->rows
+      || state->pos.col < 0 || state->pos.col >= state->cols) {
+    fprintf(stderr, "Position out of bounds after text: (%d,%d)\n",
+            state->pos.row, state->pos.col);
+    abort();
+  }
+#endif
+
+  return (int)eaten;
+}
+
+static int on_control(uint8_t control, void *user)
+{
+  VTermState *state = user;
+
+  VTermPos oldpos = state->pos;
+
+  switch (control) {
+  case 0x07:  // BEL - ECMA-48 8.3.3
+    if (state->callbacks && state->callbacks->bell) {
+      (*state->callbacks->bell)(state->cbdata);
+    }
+    break;
+
+  case 0x08:  // BS - ECMA-48 8.3.5
+    if (state->pos.col > 0) {
+      state->pos.col--;
+    }
+    break;
+
+  case 0x09:  // HT - ECMA-48 8.3.60
+    tab(state, 1, +1);
+    break;
+
+  case 0x0a:  // LF - ECMA-48 8.3.74
+  case 0x0b:  // VT
+  case 0x0c:  // FF
+    linefeed(state);
+    if (state->mode.newline) {
+      state->pos.col = 0;
+    }
+    break;
+
+  case 0x0d:  // CR - ECMA-48 8.3.15
+    state->pos.col = 0;
+    break;
+
+  case 0x0e:  // LS1 - ECMA-48 8.3.76
+    state->gl_set = 1;
+    break;
+
+  case 0x0f:  // LS0 - ECMA-48 8.3.75
+    state->gl_set = 0;
+    break;
+
+  case 0x84:  // IND - DEPRECATED but implemented for completeness
+    linefeed(state);
+    break;
+
+  case 0x85:  // NEL - ECMA-48 8.3.86
+    linefeed(state);
+    state->pos.col = 0;
+    break;
+
+  case 0x88:  // HTS - ECMA-48 8.3.62
+    set_col_tabstop(state, state->pos.col);
+    break;
+
+  case 0x8d:  // RI - ECMA-48 8.3.104
+    if (state->pos.row == state->scrollregion_top) {
+      VTermRect rect = {
+        .start_row = state->scrollregion_top,
+        .end_row = SCROLLREGION_BOTTOM(state),
+        .start_col = SCROLLREGION_LEFT(state),
+        .end_col = SCROLLREGION_RIGHT(state),
+      };
+
+      scroll(state, rect, -1, 0);
+    } else if (state->pos.row > 0) {
+      state->pos.row--;
+    }
+    break;
+
+  case 0x8e:  // SS2 - ECMA-48 8.3.141
+    state->gsingle_set = 2;
+    break;
+
+  case 0x8f:  // SS3 - ECMA-48 8.3.142
+    state->gsingle_set = 3;
+    break;
+
+  default:
+    if (state->fallbacks && state->fallbacks->control) {
+      if ((*state->fallbacks->control)(control, state->fbdata)) {
+        return 1;
+      }
+    }
+
+    return 0;
+  }
+
+  updatecursor(state, &oldpos, 1);
+
+#ifdef DEBUG
+  if (state->pos.row < 0 || state->pos.row >= state->rows
+      || state->pos.col < 0 || state->pos.col >= state->cols) {
+    fprintf(stderr, "Position out of bounds after Ctrl %02x: (%d,%d)\n",
+            control, state->pos.row, state->pos.col);
+    abort();
+  }
+#endif
+
+  return 1;
+}
+
+static int settermprop_bool(VTermState *state, VTermProp prop, int v)
+{
+  VTermValue val = { .boolean = v };
+  return vterm_state_set_termprop(state, prop, &val);
+}
+
+static int settermprop_int(VTermState *state, VTermProp prop, int v)
+{
+  VTermValue val = { .number = v };
+  return vterm_state_set_termprop(state, prop, &val);
+}
+
+static int settermprop_string(VTermState *state, VTermProp prop, VTermStringFragment frag)
+{
+  VTermValue val = { .string = frag };
+  return vterm_state_set_termprop(state, prop, &val);
+}
+
+static void savecursor(VTermState *state, int save)
+{
+  if (save) {
+    state->saved.pos = state->pos;
+    state->saved.mode.cursor_visible = state->mode.cursor_visible;
+    state->saved.mode.cursor_blink = state->mode.cursor_blink;
+    state->saved.mode.cursor_shape = state->mode.cursor_shape;
+
+    vterm_state_savepen(state, 1);
+  } else {
+    VTermPos oldpos = state->pos;
+
+    state->pos = state->saved.pos;
+
+    settermprop_bool(state, VTERM_PROP_CURSORVISIBLE, state->saved.mode.cursor_visible);
+    settermprop_bool(state, VTERM_PROP_CURSORBLINK,   state->saved.mode.cursor_blink);
+    settermprop_int(state, VTERM_PROP_CURSORSHAPE,   state->saved.mode.cursor_shape);
+
+    vterm_state_savepen(state, 0);
+
+    updatecursor(state, &oldpos, 1);
+  }
+}
+
+static int on_escape(const char *bytes, size_t len, void *user)
+{
+  VTermState *state = user;
+
+  // Easier to decode this from the first byte, even though the final byte terminates it
+  switch (bytes[0]) {
+  case ' ':
+    if (len != 2) {
+      return 0;
+    }
+
+    switch (bytes[1]) {
+    case 'F':  // S7C1T
+      state->vt->mode.ctrl8bit = 0;
+      break;
+
+    case 'G':  // S8C1T
+      state->vt->mode.ctrl8bit = 1;
+      break;
+
+    default:
+      return 0;
+    }
+    return 2;
+
+  case '#':
+    if (len != 2) {
+      return 0;
+    }
+
+    switch (bytes[1]) {
+    case '3':  // DECDHL top
+      if (state->mode.leftrightmargin) {
+        break;
+      }
+      set_lineinfo(state, state->pos.row, NO_FORCE, DWL_ON, DHL_TOP);
+      break;
+
+    case '4':  // DECDHL bottom
+      if (state->mode.leftrightmargin) {
+        break;
+      }
+      set_lineinfo(state, state->pos.row, NO_FORCE, DWL_ON, DHL_BOTTOM);
+      break;
+
+    case '5':  // DECSWL
+      if (state->mode.leftrightmargin) {
+        break;
+      }
+      set_lineinfo(state, state->pos.row, NO_FORCE, DWL_OFF, DHL_OFF);
+      break;
+
+    case '6':  // DECDWL
+      if (state->mode.leftrightmargin) {
+        break;
+      }
+      set_lineinfo(state, state->pos.row, NO_FORCE, DWL_ON, DHL_OFF);
+      break;
+
+    case '8':  // DECALN
+    {
+      VTermPos pos;
+      schar_T E = schar_from_ascii('E');  // E
+      for (pos.row = 0; pos.row < state->rows; pos.row++) {
+        for (pos.col = 0; pos.col < ROWWIDTH(state, pos.row); pos.col++) {
+          putglyph(state, E, 1, pos);
+        }
+      }
+      break;
+    }
+
+    default:
+      return 0;
+    }
+    return 2;
+
+  case '(':
+  case ')':
+  case '*':
+  case '+':  // SCS
+    if (len != 2) {
+      return 0;
+    }
+
+    {
+      int setnum = bytes[0] - 0x28;
+      VTermEncoding *newenc = vterm_lookup_encoding(ENC_SINGLE_94, bytes[1]);
+
+      if (newenc) {
+        state->encoding[setnum].enc = newenc;
+
+        if (newenc->init) {
+          (*newenc->init)(newenc, state->encoding[setnum].data);
+        }
+      }
+    }
+
+    return 2;
+
+  case '7':  // DECSC
+    savecursor(state, 1);
+    return 1;
+
+  case '8':  // DECRC
+    savecursor(state, 0);
+    return 1;
+
+  case '<':  // Ignored by VT100. Used in VT52 mode to switch up to VT100
+    return 1;
+
+  case '=':  // DECKPAM
+    state->mode.keypad = 1;
+    return 1;
+
+  case '>':  // DECKPNM
+    state->mode.keypad = 0;
+    return 1;
+
+  case 'c':  // RIS - ECMA-48 8.3.105
+  {
+    VTermPos oldpos = state->pos;
+    vterm_state_reset(state, 1);
+    if (state->callbacks && state->callbacks->movecursor) {
+      (*state->callbacks->movecursor)(state->pos, oldpos, state->mode.cursor_visible,
+                                      state->cbdata);
+    }
+    return 1;
+  }
+
+  case 'n':  // LS2 - ECMA-48 8.3.78
+    state->gl_set = 2;
+    return 1;
+
+  case 'o':  // LS3 - ECMA-48 8.3.80
+    state->gl_set = 3;
+    return 1;
+
+  case '~':  // LS1R - ECMA-48 8.3.77
+    state->gr_set = 1;
+    return 1;
+
+  case '}':  // LS2R - ECMA-48 8.3.79
+    state->gr_set = 2;
+    return 1;
+
+  case '|':  // LS3R - ECMA-48 8.3.81
+    state->gr_set = 3;
+    return 1;
+
+  default:
+    return 0;
+  }
+}
+
+static void set_mode(VTermState *state, int num, int val)
+{
+  switch (num) {
+  case 4:  // IRM - ECMA-48 7.2.10
+    state->mode.insert = (unsigned)val;
+    break;
+
+  case 20:  // LNM - ANSI X3.4-1977
+    state->mode.newline = (unsigned)val;
+    break;
+
+  default:
+    DEBUG_LOG("libvterm: Unknown mode %d\n", num);
+    return;
+  }
+}
+
+static void set_dec_mode(VTermState *state, int num, int val)
+{
+  switch (num) {
+  case 1:
+    state->mode.cursor = (unsigned)val;
+    break;
+
+  case 5:  // DECSCNM - screen mode
+    settermprop_bool(state, VTERM_PROP_REVERSE, val);
+    break;
+
+  case 6:  // DECOM - origin mode
+  {
+    VTermPos oldpos = state->pos;
+    state->mode.origin = (unsigned)val;
+    state->pos.row = state->mode.origin ? state->scrollregion_top : 0;
+    state->pos.col = state->mode.origin ? SCROLLREGION_LEFT(state) : 0;
+    updatecursor(state, &oldpos, 1);
+  }
+  break;
+
+  case 7:
+    state->mode.autowrap = (unsigned)val;
+    break;
+
+  case 12:
+    settermprop_bool(state, VTERM_PROP_CURSORBLINK, val);
+    break;
+
+  case 25:
+    settermprop_bool(state, VTERM_PROP_CURSORVISIBLE, val);
+    break;
+
+  case 69:  // DECVSSM - vertical split screen mode
+            // DECLRMM - left/right margin mode
+    state->mode.leftrightmargin = (unsigned)val;
+    if (val) {
+      // Setting DECVSSM must clear doublewidth/doubleheight state of every line
+      for (int row = 0; row < state->rows; row++) {
+        set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
+      }
+    }
+
+    break;
+
+  case 1000:
+  case 1002:
+  case 1003:
+    settermprop_int(state, VTERM_PROP_MOUSE,
+                    !val ? VTERM_PROP_MOUSE_NONE
+                         : (num == 1000) ? VTERM_PROP_MOUSE_CLICK
+                                         : (num == 1002) ? VTERM_PROP_MOUSE_DRAG
+                                                         : VTERM_PROP_MOUSE_MOVE);
+    break;
+
+  case 1004:
+    settermprop_bool(state, VTERM_PROP_FOCUSREPORT, val);
+    state->mode.report_focus = (unsigned)val;
+    break;
+
+  case 1005:
+    state->mouse_protocol = val ? MOUSE_UTF8 : MOUSE_X10;
+    break;
+
+  case 1006:
+    state->mouse_protocol = val ? MOUSE_SGR : MOUSE_X10;
+    break;
+
+  case 1015:
+    state->mouse_protocol = val ? MOUSE_RXVT : MOUSE_X10;
+    break;
+
+  case 1047:
+    settermprop_bool(state, VTERM_PROP_ALTSCREEN, val);
+    break;
+
+  case 1048:
+    savecursor(state, val);
+    break;
+
+  case 1049:
+    settermprop_bool(state, VTERM_PROP_ALTSCREEN, val);
+    savecursor(state, val);
+    break;
+
+  case 2004:
+    state->mode.bracketpaste = (unsigned)val;
+    break;
+
+  case 2031:
+    settermprop_bool(state, VTERM_PROP_THEMEUPDATES, val);
+    break;
+
+  default:
+    DEBUG_LOG("libvterm: Unknown DEC mode %d\n", num);
+    return;
+  }
+}
+
+static void request_dec_mode(VTermState *state, int num)
+{
+  int reply;
+
+  switch (num) {
+  case 1:
+    reply = state->mode.cursor;
+    break;
+
+  case 5:
+    reply = state->mode.screen;
+    break;
+
+  case 6:
+    reply = state->mode.origin;
+    break;
+
+  case 7:
+    reply = state->mode.autowrap;
+    break;
+
+  case 12:
+    reply = state->mode.cursor_blink;
+    break;
+
+  case 25:
+    reply = state->mode.cursor_visible;
+    break;
+
+  case 69:
+    reply = state->mode.leftrightmargin;
+    break;
+
+  case 1000:
+    reply = state->mouse_flags == MOUSE_WANT_CLICK;
+    break;
+
+  case 1002:
+    reply = state->mouse_flags == (MOUSE_WANT_CLICK|MOUSE_WANT_DRAG);
+    break;
+
+  case 1003:
+    reply = state->mouse_flags == (MOUSE_WANT_CLICK|MOUSE_WANT_MOVE);
+    break;
+
+  case 1004:
+    reply = state->mode.report_focus;
+    break;
+
+  case 1005:
+    reply = state->mouse_protocol == MOUSE_UTF8;
+    break;
+
+  case 1006:
+    reply = state->mouse_protocol == MOUSE_SGR;
+    break;
+
+  case 1015:
+    reply = state->mouse_protocol == MOUSE_RXVT;
+    break;
+
+  case 1047:
+    reply = state->mode.alt_screen;
+    break;
+
+  case 2004:
+    reply = state->mode.bracketpaste;
+    break;
+
+  case 2031:
+    reply = state->mode.theme_updates;
+    break;
+
+  default:
+    vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?%d;%d$y", num, 0);
+    return;
+  }
+
+  vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?%d;%d$y", num, reply ? 1 : 2);
+}
+
+static void request_version_string(VTermState *state)
+{
+  vterm_push_output_sprintf_str(state->vt, C1_DCS, true, ">|libvterm(%d.%d)",
+                                VTERM_VERSION_MAJOR, VTERM_VERSION_MINOR);
+}
+
+static void request_key_encoding_flags(VTermState *state)
+{
+  int screen = state->mode.alt_screen ? BUFIDX_ALTSCREEN : BUFIDX_PRIMARY;
+  struct VTermKeyEncodingStack *stack = &state->key_encoding_stacks[screen];
+
+  int reply = 0;
+
+  assert(stack->size > 0);
+  VTermKeyEncodingFlags flags = stack->items[stack->size - 1];
+
+  if (flags.disambiguate) {
+    reply |= KEY_ENCODING_DISAMBIGUATE;
+  }
+
+  if (flags.report_events) {
+    reply |= KEY_ENCODING_REPORT_EVENTS;
+  }
+
+  if (flags.report_alternate) {
+    reply |= KEY_ENCODING_REPORT_ALTERNATE;
+  }
+
+  if (flags.report_all_keys) {
+    reply |= KEY_ENCODING_REPORT_ALL_KEYS;
+  }
+
+  if (flags.report_associated) {
+    reply |= KEY_ENCODING_REPORT_ASSOCIATED;
+  }
+
+  vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?%du", reply);
+}
+
+static void set_key_encoding_flags(VTermState *state, int arg, int mode)
+{
+  // When mode is 3, bits set in arg reset the corresponding mode
+  bool set = mode != 3;
+
+  // When mode is 1, unset bits are reset
+  bool reset_unset = mode == 1;
+
+  struct VTermKeyEncodingFlags flags = { 0 };
+  if (arg & KEY_ENCODING_DISAMBIGUATE) {
+    flags.disambiguate = set;
+  } else if (reset_unset) {
+    flags.disambiguate = false;
+  }
+
+  if (arg & KEY_ENCODING_REPORT_EVENTS) {
+    flags.report_events = set;
+  } else if (reset_unset) {
+    flags.report_events = false;
+  }
+
+  if (arg & KEY_ENCODING_REPORT_ALTERNATE) {
+    flags.report_alternate = set;
+  } else if (reset_unset) {
+    flags.report_alternate = false;
+  }
+  if (arg & KEY_ENCODING_REPORT_ALL_KEYS) {
+    flags.report_all_keys = set;
+  } else if (reset_unset) {
+    flags.report_all_keys = false;
+  }
+
+  if (arg & KEY_ENCODING_REPORT_ASSOCIATED) {
+    flags.report_associated = set;
+  } else if (reset_unset) {
+    flags.report_associated = false;
+  }
+
+  int screen = state->mode.alt_screen ? BUFIDX_ALTSCREEN : BUFIDX_PRIMARY;
+  struct VTermKeyEncodingStack *stack = &state->key_encoding_stacks[screen];
+  assert(stack->size > 0);
+  stack->items[stack->size - 1] = flags;
+}
+
+static void push_key_encoding_flags(VTermState *state, int arg)
+{
+  int screen = state->mode.alt_screen ? BUFIDX_ALTSCREEN : BUFIDX_PRIMARY;
+  struct VTermKeyEncodingStack *stack = &state->key_encoding_stacks[screen];
+  assert(stack->size <= ARRAY_SIZE(stack->items));
+
+  if (stack->size == ARRAY_SIZE(stack->items)) {
+    // Evict oldest entry when stack is full
+    for (size_t i = 0; i < ARRAY_SIZE(stack->items) - 1; i++) {
+      stack->items[i] = stack->items[i + 1];
+    }
+  } else {
+    stack->size++;
+  }
+
+  set_key_encoding_flags(state, arg, 1);
+}
+
+static void pop_key_encoding_flags(VTermState *state, int arg)
+{
+  int screen = state->mode.alt_screen ? BUFIDX_ALTSCREEN : BUFIDX_PRIMARY;
+  struct VTermKeyEncodingStack *stack = &state->key_encoding_stacks[screen];
+  if (arg >= stack->size) {
+    stack->size = 1;
+
+    // If a pop request is received that empties the stack, all flags are reset.
+    memset(&stack->items[0], 0, sizeof(stack->items[0]));
+  } else if (arg > 0) {
+    stack->size -= arg;
+  }
+}
+
+static int on_csi(const char *leader, const long args[], int argcount, const char *intermed,
+                  char command, void *user)
+{
+  VTermState *state = user;
+  int leader_byte = 0;
+  int intermed_byte = 0;
+  int cancel_phantom = 1;
+
+  if (leader && leader[0]) {
+    if (leader[1]) {  // longer than 1 char
+      return 0;
+    }
+
+    switch (leader[0]) {
+    case '?':
+    case '>':
+    case '<':
+    case '=':
+      leader_byte = (int)leader[0];
+      break;
+    default:
+      return 0;
+    }
+  }
+
+  if (intermed && intermed[0]) {
+    if (intermed[1]) {  // longer than 1 char
+      return 0;
+    }
+
+    switch (intermed[0]) {
+    case ' ':
+    case '!':
+    case '"':
+    case '$':
+    case '\'':
+      intermed_byte = (int)intermed[0];
+      break;
+    default:
+      return 0;
+    }
+  }
+
+  VTermPos oldpos = state->pos;
+
+  // Some temporaries for later code
+  int count, val;
+  int row, col;
+  VTermRect rect;
+  int selective;
+
+#define LBOUND(v, min) if ((v) < (min))(v) = (min)
+#define UBOUND(v, max) if ((v) > (max))(v) = (max)
+
+#define LEADER(l, b) ((l << 8) | b)
+#define INTERMED(i, b) ((i << 16) | b)
+
+  switch (intermed_byte << 16 | leader_byte << 8 | command) {
+  case 0x40:  // ICH - ECMA-48 8.3.64
+    count = CSI_ARG_COUNT(args[0]);
+
+    if (!is_cursor_in_scrollregion(state)) {
+      break;
+    }
+
+    rect.start_row = state->pos.row;
+    rect.end_row = state->pos.row + 1;
+    rect.start_col = state->pos.col;
+    if (state->mode.leftrightmargin) {
+      rect.end_col = SCROLLREGION_RIGHT(state);
+    } else {
+      rect.end_col = THISROWWIDTH(state);
+    }
+
+    scroll(state, rect, 0, -count);
+
+    break;
+
+  case 0x41:  // CUU - ECMA-48 8.3.22
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.row -= count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x42:  // CUD - ECMA-48 8.3.19
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.row += count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x43:  // CUF - ECMA-48 8.3.20
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.col += count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x44:  // CUB - ECMA-48 8.3.18
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.col -= count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x45:  // CNL - ECMA-48 8.3.12
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.col = 0;
+    state->pos.row += count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x46:  // CPL - ECMA-48 8.3.13
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.col = 0;
+    state->pos.row -= count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x47:  // CHA - ECMA-48 8.3.9
+    val = CSI_ARG_OR(args[0], 1);
+    state->pos.col = val - 1;
+    state->at_phantom = 0;
+    break;
+
+  case 0x48:  // CUP - ECMA-48 8.3.21
+    row = CSI_ARG_OR(args[0], 1);
+    col = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? 1 : CSI_ARG(args[1]);
+    // zero-based
+    state->pos.row = row - 1;
+    state->pos.col = col - 1;
+    if (state->mode.origin) {
+      state->pos.row += state->scrollregion_top;
+      state->pos.col += SCROLLREGION_LEFT(state);
+    }
+    state->at_phantom = 0;
+    break;
+
+  case 0x49:  // CHT - ECMA-48 8.3.10
+    count = CSI_ARG_COUNT(args[0]);
+    tab(state, count, +1);
+    break;
+
+  case 0x4a:  // ED - ECMA-48 8.3.39
+  case LEADER('?', 0x4a):  // DECSED - Selective Erase in Display
+    selective = (leader_byte == '?');
+    switch (CSI_ARG(args[0])) {
+    case CSI_ARG_MISSING:
+    case 0:
+      rect.start_row = state->pos.row; rect.end_row = state->pos.row + 1;
+      rect.start_col = state->pos.col; rect.end_col = state->cols;
+      if (rect.end_col > rect.start_col) {
+        erase(state, rect, selective);
+      }
+
+      rect.start_row = state->pos.row + 1; rect.end_row = state->rows;
+      rect.start_col = 0;
+      for (int row_ = rect.start_row; row_ < rect.end_row; row_++) {
+        set_lineinfo(state, row_, FORCE, DWL_OFF, DHL_OFF);
+      }
+      if (rect.end_row > rect.start_row) {
+        erase(state, rect, selective);
+      }
+      break;
+
+    case 1:
+      rect.start_row = 0; rect.end_row = state->pos.row;
+      rect.start_col = 0; rect.end_col = state->cols;
+      for (int row_ = rect.start_row; row_ < rect.end_row; row_++) {
+        set_lineinfo(state, row_, FORCE, DWL_OFF, DHL_OFF);
+      }
+      if (rect.end_col > rect.start_col) {
+        erase(state, rect, selective);
+      }
+
+      rect.start_row = state->pos.row; rect.end_row = state->pos.row + 1;
+      rect.end_col = state->pos.col + 1;
+      if (rect.end_row > rect.start_row) {
+        erase(state, rect, selective);
+      }
+      break;
+
+    case 2:
+      rect.start_row = 0; rect.end_row = state->rows;
+      rect.start_col = 0; rect.end_col = state->cols;
+      for (int row_ = rect.start_row; row_ < rect.end_row; row_++) {
+        set_lineinfo(state, row_, FORCE, DWL_OFF, DHL_OFF);
+      }
+      erase(state, rect, selective);
+      break;
+
+    case 3:
+      if (state->callbacks && state->callbacks->sb_clear) {
+        if ((*state->callbacks->sb_clear)(state->cbdata)) {
+          return 1;
+        }
+      }
+      break;
+    }
+    break;
+
+  case 0x4b:  // EL - ECMA-48 8.3.41
+  case LEADER('?', 0x4b):  // DECSEL - Selective Erase in Line
+    selective = (leader_byte == '?');
+    rect.start_row = state->pos.row;
+    rect.end_row = state->pos.row + 1;
+
+    switch (CSI_ARG(args[0])) {
+    case CSI_ARG_MISSING:
+    case 0:
+      rect.start_col = state->pos.col; rect.end_col = THISROWWIDTH(state); break;
+    case 1:
+      rect.start_col = 0; rect.end_col = state->pos.col + 1; break;
+    case 2:
+      rect.start_col = 0; rect.end_col = THISROWWIDTH(state); break;
+    default:
+      return 0;
+    }
+
+    if (rect.end_col > rect.start_col) {
+      erase(state, rect, selective);
+    }
+
+    break;
+
+  case 0x4c:  // IL - ECMA-48 8.3.67
+    count = CSI_ARG_COUNT(args[0]);
+
+    if (!is_cursor_in_scrollregion(state)) {
+      break;
+    }
+
+    rect.start_row = state->pos.row;
+    rect.end_row = SCROLLREGION_BOTTOM(state);
+    rect.start_col = SCROLLREGION_LEFT(state);
+    rect.end_col = SCROLLREGION_RIGHT(state);
+
+    scroll(state, rect, -count, 0);
+
+    break;
+
+  case 0x4d:  // DL - ECMA-48 8.3.32
+    count = CSI_ARG_COUNT(args[0]);
+
+    if (!is_cursor_in_scrollregion(state)) {
+      break;
+    }
+
+    rect.start_row = state->pos.row;
+    rect.end_row = SCROLLREGION_BOTTOM(state);
+    rect.start_col = SCROLLREGION_LEFT(state);
+    rect.end_col = SCROLLREGION_RIGHT(state);
+
+    scroll(state, rect, count, 0);
+
+    break;
+
+  case 0x50:  // DCH - ECMA-48 8.3.26
+    count = CSI_ARG_COUNT(args[0]);
+
+    if (!is_cursor_in_scrollregion(state)) {
+      break;
+    }
+
+    rect.start_row = state->pos.row;
+    rect.end_row = state->pos.row + 1;
+    rect.start_col = state->pos.col;
+    if (state->mode.leftrightmargin) {
+      rect.end_col = SCROLLREGION_RIGHT(state);
+    } else {
+      rect.end_col = THISROWWIDTH(state);
+    }
+
+    scroll(state, rect, 0, count);
+
+    break;
+
+  case 0x53:  // SU - ECMA-48 8.3.147
+    count = CSI_ARG_COUNT(args[0]);
+
+    rect.start_row = state->scrollregion_top;
+    rect.end_row = SCROLLREGION_BOTTOM(state);
+    rect.start_col = SCROLLREGION_LEFT(state);
+    rect.end_col = SCROLLREGION_RIGHT(state);
+
+    scroll(state, rect, count, 0);
+
+    break;
+
+  case 0x54:  // SD - ECMA-48 8.3.113
+    count = CSI_ARG_COUNT(args[0]);
+
+    rect.start_row = state->scrollregion_top;
+    rect.end_row = SCROLLREGION_BOTTOM(state);
+    rect.start_col = SCROLLREGION_LEFT(state);
+    rect.end_col = SCROLLREGION_RIGHT(state);
+
+    scroll(state, rect, -count, 0);
+
+    break;
+
+  case 0x58:  // ECH - ECMA-48 8.3.38
+    count = CSI_ARG_COUNT(args[0]);
+
+    rect.start_row = state->pos.row;
+    rect.end_row = state->pos.row + 1;
+    rect.start_col = state->pos.col;
+    rect.end_col = state->pos.col + count;
+    UBOUND(rect.end_col, THISROWWIDTH(state));
+
+    erase(state, rect, 0);
+    break;
+
+  case 0x5a:  // CBT - ECMA-48 8.3.7
+    count = CSI_ARG_COUNT(args[0]);
+    tab(state, count, -1);
+    break;
+
+  case 0x60:  // HPA - ECMA-48 8.3.57
+    col = CSI_ARG_OR(args[0], 1);
+    state->pos.col = col - 1;
+    state->at_phantom = 0;
+    break;
+
+  case 0x61:  // HPR - ECMA-48 8.3.59
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.col += count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x62: {  // REP - ECMA-48 8.3.103
+    const int row_width = THISROWWIDTH(state);
+    count = CSI_ARG_COUNT(args[0]);
+    col = state->pos.col + count;
+    UBOUND(col, row_width);
+    schar_T sc = schar_from_buf(state->grapheme_buf, state->grapheme_len);
+    while (state->pos.col < col) {
+      putglyph(state, sc, state->combine_width, state->pos);
+      state->pos.col += state->combine_width;
+    }
+    if (state->pos.col + state->combine_width >= row_width) {
+      if (state->mode.autowrap) {
+        state->at_phantom = 1;
+        cancel_phantom = 0;
+      }
+    }
+    break;
+  }
+
+  case 0x63:  // DA - ECMA-48 8.3.24
+    val = CSI_ARG_OR(args[0], 0);
+    if (val == 0) {
+      // DEC VT100 response
+      vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?1;2c");
+    }
+    break;
+
+  case LEADER('>', 0x63):  // DEC secondary Device Attributes
+    vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, ">%d;%d;%dc", 0, 100, 0);
+    break;
+
+  case 0x64:  // VPA - ECMA-48 8.3.158
+    row = CSI_ARG_OR(args[0], 1);
+    state->pos.row = row - 1;
+    if (state->mode.origin) {
+      state->pos.row += state->scrollregion_top;
+    }
+    state->at_phantom = 0;
+    break;
+
+  case 0x65:  // VPR - ECMA-48 8.3.160
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.row += count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x66:  // HVP - ECMA-48 8.3.63
+    row = CSI_ARG_OR(args[0], 1);
+    col = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? 1 : CSI_ARG(args[1]);
+    // zero-based
+    state->pos.row = row - 1;
+    state->pos.col = col - 1;
+    if (state->mode.origin) {
+      state->pos.row += state->scrollregion_top;
+      state->pos.col += SCROLLREGION_LEFT(state);
+    }
+    state->at_phantom = 0;
+    break;
+
+  case 0x67:  // TBC - ECMA-48 8.3.154
+    val = CSI_ARG_OR(args[0], 0);
+
+    switch (val) {
+    case 0:
+      clear_col_tabstop(state, state->pos.col);
+      break;
+    case 3:
+    case 5:
+      for (col = 0; col < state->cols; col++) {
+        clear_col_tabstop(state, col);
+      }
+      break;
+    case 1:
+    case 2:
+    case 4:
+      break;
+    // TODO(vterm): 1, 2 and 4 aren't meaningful yet without line tab stops
+    default:
+      return 0;
+    }
+    break;
+
+  case 0x68:  // SM - ECMA-48 8.3.125
+    if (!CSI_ARG_IS_MISSING(args[0])) {
+      set_mode(state, CSI_ARG(args[0]), 1);
+    }
+    break;
+
+  case LEADER('?', 0x68):  // DEC private mode set
+    for (int i = 0; i < argcount; i++) {
+      if (!CSI_ARG_IS_MISSING(args[i])) {
+        set_dec_mode(state, CSI_ARG(args[i]), 1);
+      }
+    }
+    break;
+
+  case 0x6a:  // HPB - ECMA-48 8.3.58
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.col -= count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x6b:  // VPB - ECMA-48 8.3.159
+    count = CSI_ARG_COUNT(args[0]);
+    state->pos.row -= count;
+    state->at_phantom = 0;
+    break;
+
+  case 0x6c:  // RM - ECMA-48 8.3.106
+    if (!CSI_ARG_IS_MISSING(args[0])) {
+      set_mode(state, CSI_ARG(args[0]), 0);
+    }
+    break;
+
+  case LEADER('?', 0x6c):  // DEC private mode reset
+    for (int i = 0; i < argcount; i++) {
+      if (!CSI_ARG_IS_MISSING(args[i])) {
+        set_dec_mode(state, CSI_ARG(args[i]), 0);
+      }
+    }
+    break;
+
+  case 0x6d:  // SGR - ECMA-48 8.3.117
+    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);
+
+    {
+      char *qmark = (leader_byte == '?') ? "?" : "";
+      bool dark = false;
+
+      switch (val) {
+      case 0:
+      case 1:
+      case 2:
+      case 3:
+      case 4:
+        // ignore - these are replies
+        break;
+      case 5:
+        vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "%s0n", qmark);
+        break;
+      case 6:  // CPR - cursor position report
+        vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "%s%d;%dR", qmark, state->pos.row + 1,
+                                       state->pos.col + 1);
+        break;
+      case 996:
+        if (state->callbacks && state->callbacks->theme) {
+          if (state->callbacks->theme(&dark, state->cbdata)) {
+            vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "?997;%cn", dark ? '1' : '2');
+          }
+        }
+        break;
+      }
+    }
+    break;
+
+  case INTERMED('!', 0x70):  // DECSTR - DEC soft terminal reset
+    vterm_state_reset(state, 0);
+    break;
+
+  case LEADER('?', INTERMED('$', 0x70)):
+    request_dec_mode(state, CSI_ARG(args[0]));
+    break;
+
+  case LEADER('>', 0x71):  // XTVERSION - xterm query version string
+    request_version_string(state);
+    break;
+
+  case INTERMED(' ', 0x71):  // DECSCUSR - DEC set cursor shape
+    val = CSI_ARG_OR(args[0], 1);
+
+    switch (val) {
+    case 0:
+    case 1:
+      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 1);
+      settermprop_int(state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BLOCK);
+      break;
+    case 2:
+      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 0);
+      settermprop_int(state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BLOCK);
+      break;
+    case 3:
+      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 1);
+      settermprop_int(state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_UNDERLINE);
+      break;
+    case 4:
+      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 0);
+      settermprop_int(state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_UNDERLINE);
+      break;
+    case 5:
+      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 1);
+      settermprop_int(state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BAR_LEFT);
+      break;
+    case 6:
+      settermprop_bool(state, VTERM_PROP_CURSORBLINK, 0);
+      settermprop_int(state, VTERM_PROP_CURSORSHAPE, VTERM_PROP_CURSORSHAPE_BAR_LEFT);
+      break;
+    }
+
+    break;
+
+  case INTERMED('"', 0x71):  // DECSCA - DEC select character protection attribute
+    val = CSI_ARG_OR(args[0], 0);
+
+    switch (val) {
+    case 0:
+    case 2:
+      state->protected_cell = 0;
+      break;
+    case 1:
+      state->protected_cell = 1;
+      break;
+    }
+
+    break;
+
+  case 0x72:  // DECSTBM - DEC custom
+    state->scrollregion_top = CSI_ARG_OR(args[0], 1) - 1;
+    state->scrollregion_bottom = argcount < 2
+                                 || CSI_ARG_IS_MISSING(args[1]) ? -1 : CSI_ARG(args[1]);
+    LBOUND(state->scrollregion_top, 0);
+    UBOUND(state->scrollregion_top, state->rows);
+    LBOUND(state->scrollregion_bottom, -1);
+    if (state->scrollregion_top == 0 && state->scrollregion_bottom == state->rows) {
+      state->scrollregion_bottom = -1;
+    } else {
+      UBOUND(state->scrollregion_bottom, state->rows);
+    }
+
+    if (SCROLLREGION_BOTTOM(state) <= state->scrollregion_top) {
+      // Invalid
+      state->scrollregion_top = 0;
+      state->scrollregion_bottom = -1;
+    }
+
+    // Setting the scrolling region restores the cursor to the home position
+    state->pos.row = 0;
+    state->pos.col = 0;
+    if (state->mode.origin) {
+      state->pos.row += state->scrollregion_top;
+      state->pos.col += SCROLLREGION_LEFT(state);
+    }
+
+    break;
+
+  case 0x73:  // DECSLRM - DEC custom
+    // Always allow setting these margins, just they won't take effect without DECVSSM
+    state->scrollregion_left = CSI_ARG_OR(args[0], 1) - 1;
+    state->scrollregion_right = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? -1 : CSI_ARG(args[1]);
+    LBOUND(state->scrollregion_left, 0);
+    UBOUND(state->scrollregion_left, state->cols);
+    LBOUND(state->scrollregion_right, -1);
+    if (state->scrollregion_left == 0 && state->scrollregion_right == state->cols) {
+      state->scrollregion_right = -1;
+    } else {
+      UBOUND(state->scrollregion_right, state->cols);
+    }
+
+    if (state->scrollregion_right > -1
+        && state->scrollregion_right <= state->scrollregion_left) {
+      // Invalid
+      state->scrollregion_left = 0;
+      state->scrollregion_right = -1;
+    }
+
+    // Setting the scrolling region restores the cursor to the home position
+    state->pos.row = 0;
+    state->pos.col = 0;
+    if (state->mode.origin) {
+      state->pos.row += state->scrollregion_top;
+      state->pos.col += SCROLLREGION_LEFT(state);
+    }
+
+    break;
+
+  case LEADER('?', 0x75):  // Kitty query
+    request_key_encoding_flags(state);
+    break;
+
+  case LEADER('>', 0x75):  // Kitty push flags
+    push_key_encoding_flags(state, CSI_ARG_OR(args[0], 0));
+    break;
+
+  case LEADER('<', 0x75):  // Kitty pop flags
+    pop_key_encoding_flags(state, CSI_ARG_OR(args[0], 1));
+    break;
+
+  case LEADER('=', 0x75):  // Kitty set flags
+    val = argcount < 2 || CSI_ARG_IS_MISSING(args[1]) ? 1 : CSI_ARG(args[1]);
+    set_key_encoding_flags(state, CSI_ARG_OR(args[0], 0), val);
+    break;
+
+  case INTERMED('\'', 0x7D):  // DECIC
+    count = CSI_ARG_COUNT(args[0]);
+
+    if (!is_cursor_in_scrollregion(state)) {
+      break;
+    }
+
+    rect.start_row = state->scrollregion_top;
+    rect.end_row = SCROLLREGION_BOTTOM(state);
+    rect.start_col = state->pos.col;
+    rect.end_col = SCROLLREGION_RIGHT(state);
+
+    scroll(state, rect, 0, -count);
+
+    break;
+
+  case INTERMED('\'', 0x7E):  // DECDC
+    count = CSI_ARG_COUNT(args[0]);
+
+    if (!is_cursor_in_scrollregion(state)) {
+      break;
+    }
+
+    rect.start_row = state->scrollregion_top;
+    rect.end_row = SCROLLREGION_BOTTOM(state);
+    rect.start_col = state->pos.col;
+    rect.end_col = SCROLLREGION_RIGHT(state);
+
+    scroll(state, rect, 0, count);
+
+    break;
+
+  default:
+    if (state->fallbacks && state->fallbacks->csi) {
+      if ((*state->fallbacks->csi)(leader, args, argcount, intermed, command, state->fbdata)) {
+        return 1;
+      }
+    }
+
+    return 0;
+  }
+
+  if (state->mode.origin) {
+    LBOUND(state->pos.row, state->scrollregion_top);
+    UBOUND(state->pos.row, SCROLLREGION_BOTTOM(state) - 1);
+    LBOUND(state->pos.col, SCROLLREGION_LEFT(state));
+    UBOUND(state->pos.col, SCROLLREGION_RIGHT(state) - 1);
+  } else {
+    LBOUND(state->pos.row, 0);
+    UBOUND(state->pos.row, state->rows - 1);
+    LBOUND(state->pos.col, 0);
+    UBOUND(state->pos.col, THISROWWIDTH(state) - 1);
+  }
+
+  updatecursor(state, &oldpos, cancel_phantom);
+
+#ifdef DEBUG
+  if (state->pos.row < 0 || state->pos.row >= state->rows
+      || state->pos.col < 0 || state->pos.col >= state->cols) {
+    fprintf(stderr, "Position out of bounds after CSI %c: (%d,%d)\n",
+            command, state->pos.row, state->pos.col);
+    abort();
+  }
+
+  if (SCROLLREGION_BOTTOM(state) <= state->scrollregion_top) {
+    fprintf(stderr, "Scroll region height out of bounds after CSI %c: %d <= %d\n",
+            command, SCROLLREGION_BOTTOM(state), state->scrollregion_top);
+    abort();
+  }
+
+  if (SCROLLREGION_RIGHT(state) <= SCROLLREGION_LEFT(state)) {
+    fprintf(stderr, "Scroll region width out of bounds after CSI %c: %d <= %d\n",
+            command, SCROLLREGION_RIGHT(state), SCROLLREGION_LEFT(state));
+    abort();
+  }
+#endif
+
+  return 1;
+}
+
+static uint8_t unbase64one(char c)
+{
+  if (c >= 'A' && c <= 'Z') {
+    return (uint8_t)c - 'A';
+  } else if (c >= 'a' && c <= 'z') {
+    return (uint8_t)c - 'a' + 26;
+  } else if (c >= '0' && c <= '9') {
+    return (uint8_t)c - '0' + 52;
+  } else if (c == '+') {
+    return 62;
+  } else if (c == '/') {
+    return 63;
+  }
+
+  return 0xFF;
+}
+
+static void osc_selection(VTermState *state, VTermStringFragment frag)
+{
+  if (frag.initial) {
+    state->tmp.selection.mask = 0;
+    state->tmp.selection.state = SELECTION_INITIAL;
+  }
+
+  while (!state->tmp.selection.state && frag.len) {
+    // Parse selection parameter
+    switch (frag.str[0]) {
+    case 'c':
+      state->tmp.selection.mask |= VTERM_SELECTION_CLIPBOARD;
+      break;
+    case 'p':
+      state->tmp.selection.mask |= VTERM_SELECTION_PRIMARY;
+      break;
+    case 'q':
+      state->tmp.selection.mask |= VTERM_SELECTION_SECONDARY;
+      break;
+    case 's':
+      state->tmp.selection.mask |= VTERM_SELECTION_SELECT;
+      break;
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+      state->tmp.selection.mask |= (VTERM_SELECTION_CUT0 << (frag.str[0] - '0'));
+      break;
+
+    case ';':
+      state->tmp.selection.state = SELECTION_SELECTED;
+      if (!state->tmp.selection.mask) {
+        state->tmp.selection.mask = VTERM_SELECTION_SELECT|VTERM_SELECTION_CUT0;
+      }
+      break;
+    }
+
+    frag.str++;
+    frag.len--;
+  }
+
+  if (!frag.len) {
+    // Clear selection if we're already finished but didn't do anything
+    if (frag.final && state->selection.callbacks->set) {
+      (*state->selection.callbacks->set)(state->tmp.selection.mask, (VTermStringFragment){
+        .str = NULL,
+        .len = 0,
+        .initial = state->tmp.selection.state != SELECTION_SET,
+        .final = true,
+      }, state->selection.user);
+    }
+    return;
+  }
+
+  if (state->tmp.selection.state == SELECTION_SELECTED) {
+    if (frag.str[0] == '?') {
+      state->tmp.selection.state = SELECTION_QUERY;
+    } else {
+      state->tmp.selection.state = SELECTION_SET_INITIAL;
+      state->tmp.selection.recvpartial = 0;
+    }
+  }
+
+  if (state->tmp.selection.state == SELECTION_QUERY) {
+    if (state->selection.callbacks->query) {
+      (*state->selection.callbacks->query)(state->tmp.selection.mask, state->selection.user);
+    }
+    return;
+  }
+
+  if (state->tmp.selection.state == SELECTION_INVALID) {
+    return;
+  }
+
+  if (state->selection.callbacks->set) {
+    size_t bufcur = 0;
+    char *buffer = state->selection.buffer;
+
+    uint32_t x = 0;  // Current decoding value
+    int n = 0;      // Number of sextets consumed
+
+    if (state->tmp.selection.recvpartial) {
+      n = state->tmp.selection.recvpartial >> 24;
+      x = state->tmp.selection.recvpartial & 0x03FFFF;  // could be up to 18 bits of state in here
+
+      state->tmp.selection.recvpartial = 0;
+    }
+
+    while ((state->selection.buflen - bufcur) >= 3 && frag.len) {
+      if (frag.str[0] == '=') {
+        if (n == 2) {
+          buffer[0] = (char)(x >> 4 & 0xFF);
+          buffer += 1, bufcur += 1;
+        }
+        if (n == 3) {
+          buffer[0] = (char)(x >> 10 & 0xFF);
+          buffer[1] = (char)(x >>  2 & 0xFF);
+          buffer += 2, bufcur += 2;
+        }
+
+        while (frag.len && frag.str[0] == '=') {
+          frag.str++, frag.len--;
+        }
+
+        n = 0;
+      } else {
+        uint8_t b = unbase64one(frag.str[0]);
+        if (b == 0xFF) {
+          DEBUG_LOG("base64decode bad input %02X\n", (uint8_t)frag.str[0]);
+
+          state->tmp.selection.state = SELECTION_INVALID;
+          if (state->selection.callbacks->set) {
+            (*state->selection.callbacks->set)(state->tmp.selection.mask, (VTermStringFragment){
+              .str = NULL,
+              .len = 0,
+              .initial = true,
+              .final = true,
+            }, state->selection.user);
+          }
+          break;
+        }
+
+        x = (x << 6) | b;
+        n++;
+        frag.str++, frag.len--;
+
+        if (n == 4) {
+          buffer[0] = (char)(x >> 16 & 0xFF);
+          buffer[1] = (char)(x >>  8 & 0xFF);
+          buffer[2] = (char)(x >>  0 & 0xFF);
+
+          buffer += 3, bufcur += 3;
+          x = 0;
+          n = 0;
+        }
+      }
+
+      if (!frag.len || (state->selection.buflen - bufcur) < 3) {
+        if (bufcur) {
+          (*state->selection.callbacks->set)(state->tmp.selection.mask, (VTermStringFragment){
+            .str = state->selection.buffer,
+            .len = bufcur,
+            .initial = state->tmp.selection.state == SELECTION_SET_INITIAL,
+            .final = frag.final && !frag.len,
+          }, state->selection.user);
+          state->tmp.selection.state = SELECTION_SET;
+        }
+
+        buffer = state->selection.buffer;
+        bufcur = 0;
+      }
+    }
+
+    if (n) {
+      state->tmp.selection.recvpartial = (uint32_t)(n << 24) | x;
+    }
+  }
+}
+
+static int on_osc(int command, VTermStringFragment frag, void *user)
+{
+  VTermState *state = user;
+
+  switch (command) {
+  case 0:
+    settermprop_string(state, VTERM_PROP_ICONNAME, frag);
+    settermprop_string(state, VTERM_PROP_TITLE, frag);
+    return 1;
+
+  case 1:
+    settermprop_string(state, VTERM_PROP_ICONNAME, frag);
+    return 1;
+
+  case 2:
+    settermprop_string(state, VTERM_PROP_TITLE, frag);
+    return 1;
+
+  case 52:
+    if (state->selection.callbacks) {
+      osc_selection(state, frag);
+    }
+
+    return 1;
+
+  default:
+    if (state->fallbacks && state->fallbacks->osc) {
+      if ((*state->fallbacks->osc)(command, frag, state->fbdata)) {
+        return 1;
+      }
+    }
+  }
+
+  return 0;
+}
+
+static void request_status_string(VTermState *state, VTermStringFragment frag)
+{
+  VTerm *vt = state->vt;
+
+  char *tmp = state->tmp.decrqss;
+
+  if (frag.initial) {
+    tmp[0] = tmp[1] = tmp[2] = tmp[3] = 0;
+  }
+
+  size_t i = 0;
+  while (i < sizeof(state->tmp.decrqss) - 1 && tmp[i]) {
+    i++;
+  }
+  while (i < sizeof(state->tmp.decrqss) - 1 && frag.len--) {
+    tmp[i++] = (frag.str++)[0];
+  }
+  tmp[i] = 0;
+
+  if (!frag.final) {
+    return;
+  }
+
+  switch (tmp[0] | tmp[1] << 8 | tmp[2] << 16) {
+  case 'm': {
+    // Query SGR
+    long args[20];
+    int argc = vterm_state_getpen(state, args, sizeof(args)/sizeof(args[0]));
+    size_t cur = 0;
+
+    cur += (size_t)snprintf(vt->tmpbuffer + cur, vt->tmpbuffer_len - cur,
+                            vt->mode.ctrl8bit ? "\x90" "1$r" : ESC_S "P" "1$r");  // DCS 1$r ...
+    if (cur >= vt->tmpbuffer_len) {
+      return;
+    }
+
+    for (int argi = 0; argi < argc; argi++) {
+      cur += (size_t)snprintf(vt->tmpbuffer + cur, vt->tmpbuffer_len - cur,
+                              argi == argc - 1 ? "%ld"
+                                               : CSI_ARG_HAS_MORE(args[argi]) ? "%ld:"
+                                                                              : "%ld;",
+                              CSI_ARG(args[argi]));
+      if (cur >= vt->tmpbuffer_len) {
+        return;
+      }
+    }
+
+    cur += (size_t)snprintf(vt->tmpbuffer + cur, vt->tmpbuffer_len - cur,
+                            vt->mode.ctrl8bit ? "m" "\x9C" : "m" ESC_S "\\");  // ... m ST
+    if (cur >= vt->tmpbuffer_len) {
+      return;
+    }
+
+    vterm_push_output_bytes(vt, vt->tmpbuffer, cur);
+    return;
+  }
+
+  case 'r':
+    // Query DECSTBM
+    vterm_push_output_sprintf_str(vt, C1_DCS, true,
+                                  "1$r%d;%dr", state->scrollregion_top + 1,
+                                  SCROLLREGION_BOTTOM(state));
+    return;
+
+  case 's':
+    // Query DECSLRM
+    vterm_push_output_sprintf_str(vt, C1_DCS, true,
+                                  "1$r%d;%ds", SCROLLREGION_LEFT(state) + 1,
+                                  SCROLLREGION_RIGHT(state));
+    return;
+
+  case ' '|('q' << 8): {
+    // Query DECSCUSR
+    int reply = 0;
+    switch (state->mode.cursor_shape) {
+    case VTERM_PROP_CURSORSHAPE_BLOCK:
+      reply = 2; break;
+    case VTERM_PROP_CURSORSHAPE_UNDERLINE:
+      reply = 4; break;
+    case VTERM_PROP_CURSORSHAPE_BAR_LEFT:
+      reply = 6; break;
+    }
+    if (state->mode.cursor_blink) {
+      reply--;
+    }
+    vterm_push_output_sprintf_str(vt, C1_DCS, true,
+                                  "1$r%d q", reply);
+    return;
+  }
+
+  case '\"'|('q' << 8):
+    // Query DECSCA
+    vterm_push_output_sprintf_str(vt, C1_DCS, true,
+                                  "1$r%d\"q", state->protected_cell ? 1 : 2);
+    return;
+  }
+
+  vterm_push_output_sprintf_str(state->vt, C1_DCS, true, "0$r");
+}
+
+static int on_dcs(const char *command, size_t commandlen, VTermStringFragment frag, void *user)
+{
+  VTermState *state = user;
+
+  if (commandlen == 2 && strneq(command, "$q", 2)) {
+    request_status_string(state, frag);
+    return 1;
+  } else if (state->fallbacks && state->fallbacks->dcs) {
+    if ((*state->fallbacks->dcs)(command, commandlen, frag, state->fbdata)) {
+      return 1;
+    }
+  }
+
+  DEBUG_LOG("libvterm: Unhandled DCS %.*s\n", (int)commandlen, command);
+  return 0;
+}
+
+static int on_apc(VTermStringFragment frag, void *user)
+{
+  VTermState *state = user;
+
+  if (state->fallbacks && state->fallbacks->apc) {
+    if ((*state->fallbacks->apc)(frag, state->fbdata)) {
+      return 1;
+    }
+  }
+
+  // No DEBUG_LOG because all APCs are unhandled
+  return 0;
+}
+
+static int on_pm(VTermStringFragment frag, void *user)
+{
+  VTermState *state = user;
+
+  if (state->fallbacks && state->fallbacks->pm) {
+    if ((*state->fallbacks->pm)(frag, state->fbdata)) {
+      return 1;
+    }
+  }
+
+  // No DEBUG_LOG because all PMs are unhandled
+  return 0;
+}
+
+static int on_sos(VTermStringFragment frag, void *user)
+{
+  VTermState *state = user;
+
+  if (state->fallbacks && state->fallbacks->sos) {
+    if ((*state->fallbacks->sos)(frag, state->fbdata)) {
+      return 1;
+    }
+  }
+
+  // No DEBUG_LOG because all SOSs are unhandled
+  return 0;
+}
+
+static int on_resize(int rows, int cols, void *user)
+{
+  VTermState *state = user;
+  VTermPos oldpos = state->pos;
+
+  if (cols != state->cols) {
+    uint8_t *newtabstops = vterm_allocator_malloc(state->vt, ((size_t)cols + 7) / 8);
+
+    // TODO(vterm): This can all be done much more efficiently bytewise
+    int col;
+    for (col = 0; col < state->cols && col < cols; col++) {
+      uint8_t mask = (uint8_t)(1 << (col & 7));
+      if (state->tabstops[col >> 3] & mask) {
+        newtabstops[col >> 3] |= mask;
+      } else {
+        newtabstops[col >> 3] &= ~mask;
+      }
+    }
+
+    for (; col < cols; col++) {
+      uint8_t mask = (uint8_t)(1 << (col & 7));
+      if (col % 8 == 0) {
+        newtabstops[col >> 3] |= mask;
+      } else {
+        newtabstops[col >> 3] &= ~mask;
+      }
+    }
+
+    vterm_allocator_free(state->vt, state->tabstops);
+    state->tabstops = newtabstops;
+  }
+
+  state->rows = rows;
+  state->cols = cols;
+
+  if (state->scrollregion_bottom > -1) {
+    UBOUND(state->scrollregion_bottom, state->rows);
+  }
+  if (state->scrollregion_right > -1) {
+    UBOUND(state->scrollregion_right, state->cols);
+  }
+
+  VTermStateFields fields = {
+    .pos = state->pos,
+    .lineinfos = {[0] = state->lineinfos[0], [1] = state->lineinfos[1] },
+  };
+
+  if (state->callbacks && state->callbacks->resize) {
+    (*state->callbacks->resize)(rows, cols, &fields, state->cbdata);
+    state->pos = fields.pos;
+
+    state->lineinfos[0] = fields.lineinfos[0];
+    state->lineinfos[1] = fields.lineinfos[1];
+  } else {
+    if (rows != state->rows) {
+      for (int bufidx = BUFIDX_PRIMARY; bufidx <= BUFIDX_ALTSCREEN; bufidx++) {
+        VTermLineInfo *oldlineinfo = state->lineinfos[bufidx];
+        if (!oldlineinfo) {
+          continue;
+        }
+
+        VTermLineInfo *newlineinfo = vterm_allocator_malloc(state->vt,
+                                                            (size_t)rows * sizeof(VTermLineInfo));
+
+        int row;
+        for (row = 0; row < state->rows && row < rows; row++) {
+          newlineinfo[row] = oldlineinfo[row];
+        }
+
+        for (; row < rows; row++) {
+          newlineinfo[row] = (VTermLineInfo){
+            .doublewidth = 0,
+          };
+        }
+
+        vterm_allocator_free(state->vt, state->lineinfos[bufidx]);
+        state->lineinfos[bufidx] = newlineinfo;
+      }
+    }
+  }
+
+  state->lineinfo = state->lineinfos[state->mode.alt_screen ? BUFIDX_ALTSCREEN : BUFIDX_PRIMARY];
+
+  if (state->at_phantom && state->pos.col < cols - 1) {
+    state->at_phantom = 0;
+    state->pos.col++;
+  }
+
+  if (state->pos.row < 0) {
+    state->pos.row = 0;
+  }
+  if (state->pos.row >= rows) {
+    state->pos.row = rows - 1;
+  }
+  if (state->pos.col < 0) {
+    state->pos.col = 0;
+  }
+  if (state->pos.col >= cols) {
+    state->pos.col = cols - 1;
+  }
+
+  updatecursor(state, &oldpos, 1);
+
+  return 1;
+}
+
+static const VTermParserCallbacks parser_callbacks = {
+  .text = on_text,
+  .control = on_control,
+  .escape = on_escape,
+  .csi = on_csi,
+  .osc = on_osc,
+  .dcs = on_dcs,
+  .apc = on_apc,
+  .pm = on_pm,
+  .sos = on_sos,
+  .resize = on_resize,
+};
+
+VTermState *vterm_obtain_state(VTerm *vt)
+{
+  if (vt->state) {
+    return vt->state;
+  }
+
+  VTermState *state = vterm_state_new(vt);
+  vt->state = state;
+
+  vterm_parser_set_callbacks(vt, &parser_callbacks, state);
+
+  return state;
+}
+
+void vterm_state_reset(VTermState *state, int hard)
+{
+  state->scrollregion_top = 0;
+  state->scrollregion_bottom = -1;
+  state->scrollregion_left = 0;
+  state->scrollregion_right = -1;
+
+  state->mode.keypad = 0;
+  state->mode.cursor = 0;
+  state->mode.autowrap = 1;
+  state->mode.insert = 0;
+  state->mode.newline = 0;
+  state->mode.alt_screen = 0;
+  state->mode.origin = 0;
+  state->mode.leftrightmargin = 0;
+  state->mode.bracketpaste = 0;
+  state->mode.report_focus = 0;
+
+  state->mouse_flags = 0;
+
+  state->vt->mode.ctrl8bit = 0;
+
+  for (int col = 0; col < state->cols; col++) {
+    if (col % 8 == 0) {
+      set_col_tabstop(state, col);
+    } else {
+      clear_col_tabstop(state, col);
+    }
+  }
+
+  for (int row = 0; row < state->rows; row++) {
+    set_lineinfo(state, row, FORCE, DWL_OFF, DHL_OFF);
+  }
+
+  if (state->callbacks && state->callbacks->initpen) {
+    (*state->callbacks->initpen)(state->cbdata);
+  }
+
+  vterm_state_resetpen(state);
+
+  VTermEncoding *default_enc = state->vt->mode.utf8
+                               ? vterm_lookup_encoding(ENC_UTF8,      'u')
+                               : vterm_lookup_encoding(ENC_SINGLE_94, 'B');
+
+  for (int i = 0; i < 4; i++) {
+    state->encoding[i].enc = default_enc;
+    if (default_enc->init) {
+      (*default_enc->init)(default_enc, state->encoding[i].data);
+    }
+  }
+
+  state->gl_set = 0;
+  state->gr_set = 1;
+  state->gsingle_set = 0;
+
+  state->protected_cell = 0;
+
+  // Initialise the props
+  settermprop_bool(state, VTERM_PROP_CURSORVISIBLE, 1);
+  settermprop_bool(state, VTERM_PROP_CURSORBLINK,   1);
+  settermprop_int(state, VTERM_PROP_CURSORSHAPE,   VTERM_PROP_CURSORSHAPE_BLOCK);
+
+  if (hard) {
+    state->pos.row = 0;
+    state->pos.col = 0;
+    state->at_phantom = 0;
+
+    VTermRect rect = { 0, state->rows, 0, state->cols };
+    erase(state, rect, 0);
+  }
+}
+
+void vterm_state_set_callbacks(VTermState *state, const VTermStateCallbacks *callbacks, void *user)
+{
+  if (callbacks) {
+    state->callbacks = callbacks;
+    state->cbdata = user;
+
+    if (state->callbacks && state->callbacks->initpen) {
+      (*state->callbacks->initpen)(state->cbdata);
+    }
+  } else {
+    state->callbacks = NULL;
+    state->cbdata = NULL;
+  }
+}
+
+void vterm_state_set_unrecognised_fallbacks(VTermState *state, const VTermStateFallbacks *fallbacks,
+                                            void *user)
+{
+  if (fallbacks) {
+    state->fallbacks = fallbacks;
+    state->fbdata = user;
+  } else {
+    state->fallbacks = NULL;
+    state->fbdata = NULL;
+  }
+}
+
+int vterm_state_set_termprop(VTermState *state, VTermProp prop, VTermValue *val)
+{
+  // Only store the new value of the property if usercode said it was happy. This is especially
+  // important for altscreen switching
+  if (state->callbacks && state->callbacks->settermprop) {
+    if (!(*state->callbacks->settermprop)(prop, val, state->cbdata)) {
+      return 0;
+    }
+  }
+
+  switch (prop) {
+  case VTERM_PROP_TITLE:
+  case VTERM_PROP_ICONNAME:
+    // we don't store these, just transparently pass through
+    return 1;
+  case VTERM_PROP_CURSORVISIBLE:
+    state->mode.cursor_visible = (unsigned)val->boolean;
+    return 1;
+  case VTERM_PROP_CURSORBLINK:
+    state->mode.cursor_blink = (unsigned)val->boolean;
+    return 1;
+  case VTERM_PROP_CURSORSHAPE:
+    state->mode.cursor_shape = (unsigned)val->number;
+    return 1;
+  case VTERM_PROP_REVERSE:
+    state->mode.screen = (unsigned)val->boolean;
+    return 1;
+  case VTERM_PROP_ALTSCREEN:
+    state->mode.alt_screen = (unsigned)val->boolean;
+    state->lineinfo = state->lineinfos[state->mode.alt_screen ? BUFIDX_ALTSCREEN : BUFIDX_PRIMARY];
+    if (state->mode.alt_screen) {
+      VTermRect rect = {
+        .start_row = 0,
+        .start_col = 0,
+        .end_row = state->rows,
+        .end_col = state->cols,
+      };
+      erase(state, rect, 0);
+    }
+    return 1;
+  case VTERM_PROP_MOUSE:
+    state->mouse_flags = 0;
+    if (val->number) {
+      state->mouse_flags |= MOUSE_WANT_CLICK;
+    }
+    if (val->number == VTERM_PROP_MOUSE_DRAG) {
+      state->mouse_flags |= MOUSE_WANT_DRAG;
+    }
+    if (val->number == VTERM_PROP_MOUSE_MOVE) {
+      state->mouse_flags |= MOUSE_WANT_MOVE;
+    }
+    return 1;
+  case VTERM_PROP_FOCUSREPORT:
+    state->mode.report_focus = (unsigned)val->boolean;
+    return 1;
+  case VTERM_PROP_THEMEUPDATES:
+    state->mode.theme_updates = (unsigned)val->boolean;
+    return 1;
+
+  case VTERM_N_PROPS:
+    return 0;
+  }
+
+  return 0;
+}
+
+void vterm_state_focus_in(VTermState *state)
+{
+  if (state->mode.report_focus) {
+    vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "I");
+  }
+}
+
+void vterm_state_focus_out(VTermState *state)
+{
+  if (state->mode.report_focus) {
+    vterm_push_output_sprintf_ctrl(state->vt, C1_CSI, "O");
+  }
+}
+
+const VTermLineInfo *vterm_state_get_lineinfo(const VTermState *state, int row)
+{
+  return state->lineinfo + row;
+}
+
+void vterm_state_set_selection_callbacks(VTermState *state,
+                                         const VTermSelectionCallbacks *callbacks, void *user,
+                                         char *buffer, size_t buflen)
+{
+  if (buflen && !buffer) {
+    buffer = vterm_allocator_malloc(state->vt, buflen);
+  }
+
+  state->selection.callbacks = callbacks;
+  state->selection.user = user;
+  state->selection.buffer = buffer;
+  state->selection.buflen = buflen;
+}