1 files changed, 65 insertions, 0 deletions
diff --git a/vgasrc/swcursor.c b/vgasrc/swcursor.c
new file mode 100644
index 0000000..35f857a
--- /dev/null
+++ b/vgasrc/swcursor.c
@@ -0,0 +1,65 @@
+// Virtual software based cursor support
+//
+// Copyright (C) 2014-2016  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU LGPLv3 license.
+
+#include "biosvar.h" // GET_BDA
+#include "vgabios.h" // handle_gfx_op
+
+// Draw/undraw a cursor on the framebuffer by xor'ing the cursor cell
+static void
+gfx_set_swcursor(struct vgamode_s *vmode_g, int enable, struct cursorpos cp)
+{
+    u16 cursor_type = get_cursor_shape();
+    u8 start = cursor_type >> 8, end = cursor_type & 0xff;
+    struct gfx_op op;
+    init_gfx_op(&op, vmode_g);
+    op.x = cp.x * 8;
+    int cheight = GET_BDA(char_height);
+    op.y = cp.y * cheight + start;
+
+    int i;
+    for (i = start; i < cheight && i <= end; i++, op.y++) {
+        op.op = GO_READ8;
+        handle_gfx_op(&op);
+        int j;
+        for (j = 0; j < 8; j++)
+            op.pixels[j] ^= 0x07;
+        op.op = GO_WRITE8;
+        handle_gfx_op(&op);
+    }
+}
+
+// Draw/undraw a cursor on the screen
+void
+vgafb_set_swcursor(int enable)
+{
+    if (!vga_emulate_text())
+        return;
+    u8 flags = GET_BDA_EXT(flags);
+    if (!!(flags & BF_SWCURSOR) == enable)
+        // Already in requested mode.
+        return;
+    struct vgamode_s *vmode_g = get_current_mode();
+    if (!vmode_g)
+        return;
+    struct cursorpos cp = get_cursor_pos(GET_BDA(video_page));
+    if (cp.x >= GET_BDA(video_cols) || cp.y > GET_BDA(video_rows)
+        || GET_BDA(cursor_type) >= 0x2000)
+        // Cursor not visible
+        return;
+
+    SET_BDA_EXT(flags, (flags & ~BF_SWCURSOR) | (enable ? BF_SWCURSOR : 0));
+
+    if (GET_GLOBAL(vmode_g->memmodel) != MM_TEXT) {
+        gfx_set_swcursor(vmode_g, enable, cp);
+        return;
+    }
+
+    // In text mode, swap foreground and background attributes for cursor
+    void *dest_far = text_address(cp) + 1;
+    u8 attr = GET_FARVAR(GET_GLOBAL(vmode_g->sstart), *(u8*)dest_far);
+    attr = (attr >> 4) | (attr << 4);
+    SET_FARVAR(GET_GLOBAL(vmode_g->sstart), *(u8*)dest_far, attr);
+}