initial commit, splitting this out from runes

1 files changed, 959 insertions, 0 deletions

diff --git a/src/screen.c b/src/screen.c
new file mode 100644
index 0000000..ea16498
--- /dev/null
+++ b/src/screen.c
@@ -0,0 +1,959 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include <glib.h>
+
+#include "vt100.h"
+#include "parser.h"
+
+static void vt100_screen_ensure_capacity(VT100Screen *vt, int size);
+static struct vt100_row *vt100_screen_row_at(VT100Screen *vt, int row);
+static struct vt100_cell *vt100_screen_cell_at(VT100Screen *vt, int row, int col);
+static void vt100_screen_scroll_down(VT100Screen *vt, int count);
+static void vt100_screen_scroll_up(VT100Screen *vt, int count);
+static int vt100_screen_scroll_region_is_active(VT100Screen *vt);
+static int vt100_screen_loc_is_between(
+    VT100Screen *vt, struct vt100_loc loc,
+    struct vt100_loc start, struct vt100_loc end);
+static int vt100_screen_row_max_col(VT100Screen *vt, int row);
+
+void vt100_screen_init(VT100Screen *vt)
+{
+    vt->grid = calloc(1, sizeof(struct vt100_grid));
+    vt100_parser_yylex_init_extra(vt, &vt->scanner);
+}
+
+void vt100_screen_set_window_size(VT100Screen *vt)
+{
+    struct vt100_loc old_size;
+    int i;
+
+    old_size.row = vt->grid->max.row;
+    old_size.col = vt->grid->max.col;
+
+    /* vt->grid->max.row = vt->display.ypixel / vt->display.fonty; */
+    /* vt->grid->max.col = vt->display.xpixel / vt->display.fontx; */
+    // XXX vt100
+    vt->grid->max.row = 24;
+    vt->grid->max.col = 80;
+
+    if (vt->grid->max.row == 0) {
+        vt->grid->max.row = 1;
+    }
+    if (vt->grid->max.col == 0) {
+        vt->grid->max.col = 1;
+    }
+
+    if (vt->grid->max.row == old_size.row && vt->grid->max.col == old_size.col) {
+        return;
+    }
+
+    if (vt->grid->cur.row >= vt->grid->max.row) {
+        vt->grid->cur.row = vt->grid->max.row - 1;
+    }
+    if (vt->grid->cur.col > vt->grid->max.col) {
+        vt->grid->cur.col = vt->grid->max.col;
+    }
+
+    vt100_screen_ensure_capacity(vt, vt->grid->max.row);
+
+    for (i = 0; i < vt->grid->row_count; ++i) {
+        vt->grid->rows[i].cells = realloc(
+            vt->grid->rows[i].cells,
+            vt->grid->max.col * sizeof(struct vt100_cell));
+        if (old_size.col < vt->grid->max.col) {
+            memset(
+                &vt->grid->rows[i].cells[old_size.col], 0,
+                (vt->grid->max.col - old_size.col) * sizeof(struct vt100_cell));
+        }
+    }
+
+    for (i = vt->grid->row_count; i < vt->grid->max.row; ++i) {
+        vt->grid->rows[i].cells = calloc(
+            vt->grid->max.col, sizeof(struct vt100_cell));
+    }
+
+    if (vt->grid->row_count < vt->grid->max.row) {
+        vt->grid->row_count = vt->grid->max.row;
+        vt->grid->row_top = 0;
+    }
+    else {
+        vt->grid->row_top = vt->grid->row_count - vt->grid->max.row;
+    }
+
+    vt->grid->scroll_top    = 0;
+    vt->grid->scroll_bottom = vt->grid->max.row - 1;
+}
+
+int vt100_screen_process_string(VT100Screen *vt, char *buf, size_t len)
+{
+    int remaining;
+
+    vt->state = vt100_parser_yy_scan_bytes(buf, len, vt->scanner);
+    remaining = vt100_parser_yylex(vt->scanner);
+    vt100_parser_yy_delete_buffer(vt->state, vt->scanner);
+    return len - remaining;
+}
+
+int vt100_screen_loc_is_selected(VT100Screen *vt, struct vt100_loc loc)
+{
+    struct vt100_loc start = vt->grid->selection_start;
+    struct vt100_loc end = vt->grid->selection_end;
+
+    if (!vt->has_selection) {
+        return 0;
+    }
+
+    if (loc.row == start.row) {
+        int start_max_col;
+
+        start_max_col = vt100_screen_row_max_col(vt, start.row);
+        if (start.col > start_max_col) {
+            start.col = vt->grid->max.col;
+        }
+    }
+
+    if (loc.row == end.row) {
+        int end_max_col;
+
+        end_max_col = vt100_screen_row_max_col(vt, end.row);
+        if (end.col > end_max_col) {
+            end.col = vt->grid->max.col;
+        }
+    }
+
+    return vt100_screen_loc_is_between(vt, loc, start, end);
+}
+
+void vt100_screen_get_string(
+    VT100Screen *vt, struct vt100_loc *start, struct vt100_loc *end,
+    char **strp, size_t *lenp)
+{
+    int row, col;
+    size_t capacity = 8;
+
+    *lenp = 0;
+
+    if (end->row < start->row || (end->row == start->row && end->col <= start->col)) {
+        return;
+    }
+
+    *strp = malloc(capacity);
+
+    for (row = start->row; row <= end->row; ++row) {
+        int start_col, end_col, max_col;
+        struct vt100_row *grid_row = &vt->grid->rows[row];
+
+        max_col = vt100_screen_row_max_col(vt, row);
+
+        if (row == start->row) {
+            if (start->col > max_col) {
+                start_col = vt->grid->max.col;
+            }
+            else {
+                start_col = start->col;
+            }
+        }
+        else {
+            start_col = 0;
+        }
+
+        if (row == end->row) {
+            if (end->col > max_col) {
+                end_col = vt->grid->max.col;
+            }
+            else {
+                end_col = end->col;
+            }
+        }
+        else {
+            end_col = vt->grid->max.col;
+        }
+
+        if (end_col > max_col) {
+            end_col = max_col;
+        }
+
+        for (col = start_col; col < end_col; ++col) {
+            struct vt100_cell *cell = &grid_row->cells[col];
+            char *contents = cell->contents;
+            size_t len = cell->len;
+
+            if (cell->len == 0) {
+                contents = " ";
+                len = 1;
+            }
+
+            if (*lenp + len > capacity) {
+                capacity *= 1.5;
+                *strp = realloc(*strp, capacity);
+            }
+            memcpy(*strp + *lenp, contents, len);
+            *lenp += len;
+        }
+
+        if ((row != end->row || end->col > max_col) && !grid_row->wrapped) {
+            if (*lenp + 1 > capacity) {
+                capacity *= 1.5;
+                *strp = realloc(*strp, capacity);
+            }
+            memcpy(*strp + *lenp, "\n", 1);
+            *lenp += 1;
+        }
+    }
+}
+
+void vt100_screen_audible_bell(VT100Screen *vt)
+{
+    vt->audible_bell = 1;
+}
+
+void vt100_screen_visual_bell(VT100Screen *vt)
+{
+    vt->visual_bell = 1;
+}
+
+void vt100_screen_show_string_ascii(VT100Screen *vt, char *buf, size_t len)
+{
+    size_t i;
+    int col = vt->grid->cur.col;
+
+    for (i = 0; i < len; ++i) {
+        struct vt100_cell *cell;
+
+        if (col >= vt->grid->max.col) {
+            vt100_screen_row_at(vt, vt->grid->cur.row)->wrapped = 1;
+            vt100_screen_move_to(vt, vt->grid->cur.row + 1, 0);
+            col = 0;
+        }
+        cell = vt100_screen_cell_at(vt, vt->grid->cur.row, col++);
+
+        cell->len = 1;
+        cell->contents[0] = buf[i];
+        cell->attrs = vt->attrs;
+        cell->is_wide = 0;
+    }
+    vt100_screen_move_to(vt, vt->grid->cur.row, col);
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_show_string_utf8(VT100Screen *vt, char *buf, size_t len)
+{
+    char *c = buf, *next;
+    int col = vt->grid->cur.col;
+
+    /* XXX need to detect combining characters and append them to the previous
+     * cell */
+    while ((next = g_utf8_next_char(c))) {
+        gunichar uc;
+        struct vt100_cell *cell = NULL;
+        int is_wide, is_combining;
+        GUnicodeType ctype;
+
+        uc = g_utf8_get_char(c);
+        /* XXX handle zero width characters */
+        is_wide = g_unichar_iswide(uc);
+        ctype = g_unichar_type(uc);
+        /* XXX should this also include spacing marks? */
+        is_combining = ctype == G_UNICODE_ENCLOSING_MARK
+                    || ctype == G_UNICODE_NON_SPACING_MARK;
+
+        if (is_combining) {
+            if (col > 0) {
+                cell = vt100_screen_cell_at(
+                    vt, vt->grid->cur.row, col - 1);
+            }
+            else if (vt->grid->cur.row > 0 && vt100_screen_row_at(vt, vt->grid->cur.row - 1)->wrapped) {
+                cell = vt100_screen_cell_at(
+                    vt, vt->grid->cur.row - 1, vt->grid->max.col - 1);
+            }
+
+            if (cell) {
+                char *normal;
+
+                memcpy(cell->contents + cell->len, c, next - c);
+                cell->len += next - c;
+                /* some fonts have combined characters but can'vt handle
+                 * combining characters, so try to fix that here */
+                /* XXX it'd be nice if there was a way to do this that didn'vt
+                 * require an allocation */
+                normal = g_utf8_normalize(
+                    cell->contents, cell->len, G_NORMALIZE_NFC);
+                memcpy(cell->contents, normal, cell->len);
+                free(normal);
+            }
+        }
+        else {
+            if (col + (is_wide ? 2 : 1) > vt->grid->max.col) {
+                vt100_screen_row_at(vt, vt->grid->cur.row)->wrapped = 1;
+                vt100_screen_move_to(vt, vt->grid->cur.row + 1, 0);
+                col = 0;
+            }
+            cell = vt100_screen_cell_at(vt, vt->grid->cur.row, col);
+            cell->is_wide = is_wide;
+
+            cell->len = next - c;
+            memcpy(cell->contents, c, cell->len);
+            cell->attrs = vt->attrs;
+
+            col += is_wide ? 2 : 1;
+        }
+
+        c = next;
+        if ((size_t)(c - buf) >= len) {
+            break;
+        }
+    }
+    vt100_screen_move_to(vt, vt->grid->cur.row, col);
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_move_to(VT100Screen *vt, int row, int col)
+{
+    int top = vt->grid->scroll_top, bottom = vt->grid->scroll_bottom;
+
+    if (row > bottom) {
+        vt100_screen_scroll_down(vt, row - bottom);
+        row = bottom;
+    }
+    else if (row < top) {
+        vt100_screen_scroll_up(vt, top - row);
+        row = top;
+    }
+
+    if (col < 0) {
+        col = 0;
+    }
+
+    if (col > vt->grid->max.col) {
+        col = vt->grid->max.col;
+    }
+
+    vt->grid->cur.row = row;
+    vt->grid->cur.col = col;
+}
+
+void vt100_screen_clear_screen(VT100Screen *vt)
+{
+    int r;
+
+    for (r = 0; r < vt->grid->max.row; ++r) {
+        struct vt100_row *row;
+
+        row = vt100_screen_row_at(vt, r);
+        memset(row->cells, 0, vt->grid->max.col * sizeof(struct vt100_cell));
+        row->wrapped = 0;
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_clear_screen_forward(VT100Screen *vt)
+{
+    struct vt100_row *row;
+    int r;
+
+    row = vt100_screen_row_at(vt, vt->grid->cur.row);
+    memset(
+        &row->cells[vt->grid->cur.col], 0,
+        (vt->grid->max.col - vt->grid->cur.col) * sizeof(struct vt100_cell));
+    row->wrapped = 0;
+    for (r = vt->grid->cur.row + 1; r < vt->grid->max.row; ++r) {
+        row = vt100_screen_row_at(vt, r);
+        memset(row->cells, 0, vt->grid->max.col * sizeof(struct vt100_cell));
+        row->wrapped = 0;
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_clear_screen_backward(VT100Screen *vt)
+{
+    struct vt100_row *row;
+    int r;
+
+    for (r = 0; r < vt->grid->cur.row - 1; ++r) {
+        row = vt100_screen_row_at(vt, r);
+        memset(row->cells, 0, vt->grid->max.col * sizeof(struct vt100_cell));
+        row->wrapped = 0;
+    }
+    row = vt100_screen_row_at(vt, vt->grid->cur.row);
+    memset(row->cells, 0, vt->grid->cur.col * sizeof(struct vt100_cell));
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_kill_line(VT100Screen *vt)
+{
+    struct vt100_row *row;
+
+    row = vt100_screen_row_at(vt, vt->grid->cur.row);
+    memset(row->cells, 0, vt->grid->max.col * sizeof(struct vt100_cell));
+    row->wrapped = 0;
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_kill_line_forward(VT100Screen *vt)
+{
+    struct vt100_row *row;
+
+    row = vt100_screen_row_at(vt, vt->grid->cur.row);
+    memset(
+        &row->cells[vt->grid->cur.col], 0,
+        (vt->grid->max.col - vt->grid->cur.col) * sizeof(struct vt100_cell));
+    row->wrapped = 0;
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_kill_line_backward(VT100Screen *vt)
+{
+    struct vt100_row *row;
+
+    row = vt100_screen_row_at(vt, vt->grid->cur.row);
+    memset(row->cells, 0, vt->grid->cur.col * sizeof(struct vt100_cell));
+    if (vt->grid->cur.row > 0) {
+        row = vt100_screen_row_at(vt, vt->grid->cur.row - 1);
+        row->wrapped = 0;
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_insert_characters(VT100Screen *vt, int count)
+{
+    struct vt100_row *row;
+
+    row = vt100_screen_row_at(vt, vt->grid->cur.row);
+    if (count >= vt->grid->max.col - vt->grid->cur.col) {
+        vt100_screen_kill_line_forward(vt);
+    }
+    else {
+        memmove(
+            &row->cells[vt->grid->cur.col + count],
+            &row->cells[vt->grid->cur.col],
+            (vt->grid->max.col - vt->grid->cur.col - count) * sizeof(struct vt100_cell));
+        memset(
+            &row->cells[vt->grid->cur.col], 0,
+            count * sizeof(struct vt100_cell));
+        row->wrapped = 0;
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_insert_lines(VT100Screen *vt, int count)
+{
+    if (count >= vt->grid->max.row - vt->grid->cur.row) {
+        vt100_screen_clear_screen_forward(vt);
+        vt100_screen_kill_line(vt);
+    }
+    else {
+        struct vt100_row *row;
+        int bottom = vt->grid->scroll_bottom + 1;
+        int i;
+
+        for (i = bottom - count; i < bottom; ++i) {
+            row = vt100_screen_row_at(vt, i);
+            free(row->cells);
+        }
+        row = vt100_screen_row_at(vt, vt->grid->cur.row);
+        memmove(
+            row + count, row,
+            (bottom - vt->grid->cur.row - count) * sizeof(struct vt100_row));
+        memset(row, 0, count * sizeof(struct vt100_row));
+        for (i = vt->grid->cur.row; i < vt->grid->cur.row + count; ++i) {
+            row = vt100_screen_row_at(vt, i);
+            row->cells = calloc(vt->grid->max.col, sizeof(struct vt100_cell));
+            row->wrapped = 0;
+        }
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_delete_characters(VT100Screen *vt, int count)
+{
+    if (count >= vt->grid->max.col - vt->grid->cur.col) {
+        vt100_screen_kill_line_forward(vt);
+    }
+    else {
+        struct vt100_row *row;
+
+        row = vt100_screen_row_at(vt, vt->grid->cur.row);
+        memmove(
+            &row->cells[vt->grid->cur.col],
+            &row->cells[vt->grid->cur.col + count],
+            (vt->grid->max.col - vt->grid->cur.col - count) * sizeof(struct vt100_cell));
+        memset(
+            &row->cells[vt->grid->max.col - count], 0,
+            count * sizeof(struct vt100_cell));
+        row->wrapped = 0;
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_delete_lines(VT100Screen *vt, int count)
+{
+    if (count >= vt->grid->max.row - vt->grid->cur.row) {
+        vt100_screen_clear_screen_forward(vt);
+        vt100_screen_kill_line(vt);
+    }
+    else {
+        struct vt100_row *row;
+        int bottom = vt->grid->scroll_bottom + 1;
+        int i;
+
+        for (i = vt->grid->cur.row; i < vt->grid->cur.row + count; ++i) {
+            row = vt100_screen_row_at(vt, i);
+            free(row->cells);
+        }
+        row = vt100_screen_row_at(vt, vt->grid->cur.row);
+        memmove(
+            row, row + count,
+            (bottom - vt->grid->cur.row - count) * sizeof(struct vt100_row));
+        row = vt100_screen_row_at(vt, bottom - count);
+        memset(row, 0, count * sizeof(struct vt100_row));
+        for (i = bottom - count; i < bottom; ++i) {
+            row = vt100_screen_row_at(vt, i);
+            row->cells = calloc(vt->grid->max.col, sizeof(struct vt100_cell));
+            row->wrapped = 0;
+        }
+    }
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_set_scroll_region(
+    VT100Screen *vt, int top, int bottom, int left, int right)
+{
+    if (left > 0 || right < vt->grid->max.col - 1) {
+        fprintf(stderr, "vertical scroll regions not yet implemented\n");
+    }
+
+    if (top > bottom) {
+        return;
+    }
+
+    vt->grid->scroll_top = top < 0
+        ? 0
+        : top;
+    vt->grid->scroll_bottom = bottom >= vt->grid->max.row
+        ? vt->grid->max.row - 1
+        : bottom;
+
+    vt100_screen_move_to(vt, vt->grid->scroll_top, 0);
+}
+
+void vt100_screen_reset_text_attributes(VT100Screen *vt)
+{
+    memset(&vt->attrs, 0, sizeof(struct vt100_cell_attrs));
+}
+
+void vt100_screen_set_fg_color(VT100Screen *vt, int idx)
+{
+    vt->attrs.fgcolor.type = VT100_COLOR_IDX;
+    vt->attrs.fgcolor.idx = idx;
+}
+
+void vt100_screen_set_fg_color_rgb(
+    VT100Screen *vt, unsigned char r, unsigned char g, unsigned char b)
+{
+    vt->attrs.fgcolor.type = VT100_COLOR_RGB;
+    vt->attrs.fgcolor.r = r;
+    vt->attrs.fgcolor.g = g;
+    vt->attrs.fgcolor.b = b;
+}
+
+void vt100_screen_reset_fg_color(VT100Screen *vt)
+{
+    vt->attrs.fgcolor.type = VT100_COLOR_DEFAULT;
+}
+
+void vt100_screen_set_bg_color(VT100Screen *vt, int idx)
+{
+    vt->attrs.bgcolor.type = VT100_COLOR_IDX;
+    vt->attrs.bgcolor.idx = idx;
+}
+
+void vt100_screen_set_bg_color_rgb(
+    VT100Screen *vt, unsigned char r, unsigned char g, unsigned char b)
+{
+    vt->attrs.bgcolor.type = VT100_COLOR_RGB;
+    vt->attrs.bgcolor.r = r;
+    vt->attrs.bgcolor.g = g;
+    vt->attrs.bgcolor.b = b;
+}
+
+void vt100_screen_reset_bg_color(VT100Screen *vt)
+{
+    vt->attrs.bgcolor.type = VT100_COLOR_DEFAULT;
+}
+
+void vt100_screen_set_bold(VT100Screen *vt)
+{
+    vt->attrs.bold = 1;
+}
+
+void vt100_screen_set_italic(VT100Screen *vt)
+{
+    vt->attrs.italic = 1;
+}
+
+void vt100_screen_set_underline(VT100Screen *vt)
+{
+    vt->attrs.underline = 1;
+}
+
+void vt100_screen_set_inverse(VT100Screen *vt)
+{
+    vt->attrs.inverse = 1;
+}
+
+void vt100_screen_reset_bold(VT100Screen *vt)
+{
+    vt->attrs.bold = 0;
+}
+
+void vt100_screen_reset_italic(VT100Screen *vt)
+{
+    vt->attrs.italic = 0;
+}
+
+void vt100_screen_reset_underline(VT100Screen *vt)
+{
+    vt->attrs.underline = 0;
+}
+
+void vt100_screen_reset_inverse(VT100Screen *vt)
+{
+    vt->attrs.inverse = 0;
+}
+
+void vt100_screen_use_alternate_buffer(VT100Screen *vt)
+{
+    if (vt->alternate) {
+        return;
+    }
+
+    vt->alternate = vt->grid;
+    vt->grid = calloc(1, sizeof(struct vt100_grid));
+    vt100_screen_set_window_size(vt);
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_use_normal_buffer(VT100Screen *vt)
+{
+    int i;
+
+    if (!vt->alternate) {
+        return;
+    }
+
+    for (i = 0; i < vt->grid->row_count; ++i) {
+        free(vt->grid->rows[i].cells);
+    }
+    free(vt->grid->rows);
+    free(vt->grid);
+
+    vt->grid = vt->alternate;
+    vt->alternate = NULL;
+
+    vt100_screen_set_window_size(vt);
+
+    vt->dirty = 1;
+}
+
+void vt100_screen_save_cursor(VT100Screen *vt)
+{
+    vt->grid->saved = vt->grid->cur;
+}
+
+void vt100_screen_restore_cursor(VT100Screen *vt)
+{
+    vt->grid->cur = vt->grid->saved;
+}
+
+void vt100_screen_show_cursor(VT100Screen *vt)
+{
+    vt->hide_cursor = 0;
+}
+
+void vt100_screen_hide_cursor(VT100Screen *vt)
+{
+    vt->hide_cursor = 1;
+}
+
+void vt100_screen_set_application_keypad(VT100Screen *vt)
+{
+    vt->application_keypad = 1;
+}
+
+void vt100_screen_reset_application_keypad(VT100Screen *vt)
+{
+    vt->application_keypad = 0;
+}
+
+void vt100_screen_set_application_cursor(VT100Screen *vt)
+{
+    vt->application_cursor = 1;
+}
+
+void vt100_screen_reset_application_cursor(VT100Screen *vt)
+{
+    vt->application_cursor = 0;
+}
+
+void vt100_screen_set_mouse_reporting_press(VT100Screen *vt)
+{
+    vt->mouse_reporting_press = 1;
+}
+
+void vt100_screen_reset_mouse_reporting_press(VT100Screen *vt)
+{
+    vt->mouse_reporting_press = 0;
+}
+
+void vt100_screen_set_mouse_reporting_press_release(VT100Screen *vt)
+{
+    vt->mouse_reporting_press_release = 1;
+}
+
+void vt100_screen_reset_mouse_reporting_press_release(VT100Screen *vt)
+{
+    vt->mouse_reporting_press_release = 0;
+}
+
+void vt100_screen_set_bracketed_paste(VT100Screen *vt)
+{
+    vt->bracketed_paste = 1;
+}
+
+void vt100_screen_reset_bracketed_paste(VT100Screen *vt)
+{
+    vt->bracketed_paste = 0;
+}
+
+void vt100_screen_set_window_title(VT100Screen *vt, char *buf, size_t len)
+{
+    free(vt->title);
+    vt->title_len = len;
+    vt->title = malloc(vt->title_len);
+    memcpy(vt->title, buf, vt->title_len);
+    vt->update_title = 1;
+}
+
+void vt100_screen_set_icon_name(VT100Screen *vt, char *buf, size_t len)
+{
+    free(vt->icon_name);
+    vt->icon_name_len = len;
+    vt->icon_name = malloc(vt->icon_name_len);
+    memcpy(vt->icon_name, buf, vt->icon_name_len);
+    vt->update_icon_name = 1;
+}
+
+void vt100_screen_cleanup(VT100Screen *vt)
+{
+    int i;
+
+    for (i = 0; i < vt->grid->row_count; ++i) {
+        free(vt->grid->rows[i].cells);
+    }
+    free(vt->grid->rows);
+    free(vt->grid);
+
+    free(vt->title);
+    free(vt->icon_name);
+
+    vt100_parser_yylex_destroy(vt->scanner);
+}
+
+static void vt100_screen_ensure_capacity(VT100Screen *vt, int size)
+{
+    int old_capacity = vt->grid->row_capacity;
+
+    if (vt->grid->row_capacity >= size) {
+        return;
+    }
+
+    if (vt->grid->row_capacity == 0) {
+        vt->grid->row_capacity = vt->grid->max.row;
+    }
+
+    while (vt->grid->row_capacity < size) {
+        vt->grid->row_capacity *= 1.5;
+    }
+
+    vt->grid->rows = realloc(
+        vt->grid->rows, vt->grid->row_capacity * sizeof(struct vt100_row));
+    memset(
+        &vt->grid->rows[old_capacity], 0,
+        (vt->grid->row_capacity - old_capacity) * sizeof(struct vt100_row));
+}
+
+static struct vt100_row *vt100_screen_row_at(VT100Screen *vt, int row)
+{
+    return &vt->grid->rows[row + vt->grid->row_top];
+}
+
+static struct vt100_cell *vt100_screen_cell_at(VT100Screen *vt, int row, int col)
+{
+    return &vt->grid->rows[row + vt->grid->row_top].cells[col];
+}
+
+static void vt100_screen_scroll_down(VT100Screen *vt, int count)
+{
+    struct vt100_row *row;
+    int i;
+
+    if (vt100_screen_scroll_region_is_active(vt) || vt->alternate) {
+        int bottom = vt->grid->scroll_bottom, top = vt->grid->scroll_top;
+
+        if (bottom - top + 1 > count) {
+            for (i = 0; i < count; ++i) {
+                row = vt100_screen_row_at(vt, top + i);
+                free(row->cells);
+            }
+            row = vt100_screen_row_at(vt, top);
+            memmove(
+                row, row + count,
+                (bottom - top + 1 - count) * sizeof(struct vt100_row));
+            for (i = 0; i < count; ++i) {
+                row = vt100_screen_row_at(vt, bottom - i);
+                row->cells = calloc(
+                    vt->grid->max.col, sizeof(struct vt100_cell));
+                row->wrapped = 0;
+            }
+        }
+        else {
+            for (i = 0; i < bottom - top + 1; ++i) {
+                row = vt100_screen_row_at(vt, top + i);
+                memset(
+                    row->cells, 0,
+                    vt->grid->max.col * sizeof(struct vt100_cell));
+                row->wrapped = 0;
+            }
+        }
+    }
+    else {
+        /* int scrollback = vt->config.scrollback_length; */
+        int scrollback = 4096; // XXX vt100
+
+        if (vt->grid->row_count + count > scrollback) {
+            int overflow = vt->grid->row_count + count - scrollback;
+
+            vt100_screen_ensure_capacity(vt, scrollback);
+            for (i = 0; i < overflow; ++i) {
+                free(vt->grid->rows[i].cells);
+            }
+            memmove(
+                &vt->grid->rows[0], &vt->grid->rows[overflow],
+                (scrollback - overflow) * sizeof(struct vt100_row));
+            for (i = scrollback - count; i < scrollback; ++i) {
+                vt->grid->rows[i].cells = calloc(
+                    vt->grid->max.col, sizeof(struct vt100_cell));
+            }
+            vt->grid->row_count = scrollback;
+            vt->grid->row_top = scrollback - vt->grid->max.row;
+        }
+        else {
+            vt100_screen_ensure_capacity(vt, vt->grid->row_count + count);
+            for (i = 0; i < count; ++i) {
+                row = vt100_screen_row_at(vt, i + vt->grid->max.row);
+                row->cells = calloc(
+                    vt->grid->max.col, sizeof(struct vt100_cell));
+            }
+            vt->grid->row_count += count;
+            vt->grid->row_top += count;
+        }
+    }
+
+    vt->dirty = 1;
+}
+
+static void vt100_screen_scroll_up(VT100Screen *vt, int count)
+{
+    struct vt100_row *row;
+    int bottom = vt->grid->scroll_bottom, top = vt->grid->scroll_top;
+    int i;
+
+    if (bottom - top + 1 > count) {
+        for (i = 0; i < count; ++i) {
+            row = vt100_screen_row_at(vt, bottom - i);
+            free(row->cells);
+        }
+        row = vt100_screen_row_at(vt, top);
+        memmove(
+            row + count, row,
+            (bottom - top + 1 - count) * sizeof(struct vt100_row));
+        for (i = 0; i < count; ++i) {
+            row = vt100_screen_row_at(vt, top + i);
+            row->cells = calloc(vt->grid->max.col, sizeof(struct vt100_cell));
+            row->wrapped = 0;
+        }
+    }
+    else {
+        for (i = 0; i < bottom - top + 1; ++i) {
+            row = vt100_screen_row_at(vt, top + i);
+            memset(
+                row->cells, 0, vt->grid->max.col * sizeof(struct vt100_cell));
+            row->wrapped = 0;
+        }
+    }
+
+    vt->dirty = 1;
+}
+
+static int vt100_screen_scroll_region_is_active(VT100Screen *vt)
+{
+    return vt->grid->scroll_top != 0
+        || vt->grid->scroll_bottom != vt->grid->max.row - 1;
+}
+
+static int vt100_screen_loc_is_between(
+    VT100Screen *vt, struct vt100_loc loc,
+    struct vt100_loc start, struct vt100_loc end)
+{
+    UNUSED(vt);
+
+    if (end.row < start.row || (end.row == start.row && end.col < start.col)) {
+        struct vt100_loc tmp;
+
+        tmp = start;
+        start = end;
+        end = tmp;
+    }
+
+    if (loc.row < start.row || loc.row > end.row) {
+        return 0;
+    }
+
+    if (loc.row == start.row && loc.col < start.col) {
+        return 0;
+    }
+
+    if (loc.row == end.row && loc.col >= end.col) {
+        return 0;
+    }
+
+    return 1;
+}
+
+static int vt100_screen_row_max_col(VT100Screen *vt, int row)
+{
+    struct vt100_cell *cells = vt->grid->rows[row].cells;
+    int i, max = -1;
+
+    for (i = 0; i < vt->grid->max.col; ++i) {
+        if (cells[i].len) {
+            max = i;
+        }
+    }
+
+    return max + 1;
+}