rsx: rasterize font glyphs straight into the texture

The font texture is linear B8 with its pitch its width, the atlas's
own layout, so the atlas is placed in texture memory and is the
texture: the glyph cache rasterizes into it and nothing is copied. A
grown atlas is the texture as it is; the memory it left is retired
until the font goes. Without texture memory for it the atlas stays on
the heap and is copied in as before.

gfx/drivers/rsx_gfx.c

@@ -397,8 +397,9 @@ typedef struct
    unsigned tex_dims;
    /* Texture memory the atlas outgrew: a frame in flight may still
     * draw from it, and freeing it means waiting for the RSX, so it goes
-    * when the font does - the atlas grows at most twice */
-   u32 *retired[2];
+    * when the font does - the atlas grows at most twice, and when it is
+    * kept in texture memory the last of it goes with the font */
+   u32 *retired[4];
    unsigned retired_count;
    u32 fp_offset;
    u32 pos_offset;
@@ -413,6 +414,9 @@ typedef struct
    float font_vertex[2 * 6 * MAX_MSG_LEN_CHUNK];
    float font_tex_coords[2 * 6 * MAX_MSG_LEN_CHUNK];
    float font_color[4 * 6 * MAX_MSG_LEN_CHUNK];
+   /* The atlas is kept in texture memory (rsx_font_storage) and is the
+    * texture: nothing is copied into it */
+   bool atlas_in_place;
 } rsx_font_t;
 
 static const float rsx_vertexes[8] = {
@@ -658,7 +662,9 @@ static void rsx_font_free(void *data,
     * font scale change or context reset. */
    rsxFinish(font->rsx->context, 0);
 
-   if (font->texture.data)
+   /* Kept in texture memory, the atlas's last buffer went to
+    * rsx_font_storage_free with the font driver's */
+   if (font->texture.data && !font->atlas_in_place)
       rsxFree(font->texture.data);
    {
       unsigned i;
@@ -713,7 +719,8 @@ static void rsx_font_copy_dirty(rsx_font_t *font)
 
 static bool rsx_font_upload_atlas(rsx_t *rsx, rsx_font_t *font)
 {
-   rsx_font_copy_dirty(font);
+   if (!font->atlas_in_place)
+      rsx_font_copy_dirty(font);
 
    font->texture.tex.format    = GCM_TEXTURE_FORMAT_B8 | GCM_TEXTURE_FORMAT_LIN;
    font->texture.tex.mipmap    = 1;
@@ -753,6 +760,24 @@ static bool rsx_font_upload_atlas(rsx_t *rsx, rsx_font_t *font)
    return true;
 }
 
+/* Texture memory for the atlas, which the cache rasterizes glyphs
+ * straight into and the RSX samples: the texture is linear B8 with its
+ * pitch its width, the atlas's own layout */
+static void *rsx_font_storage(void *user, size_t size)
+{
+   (void)user;
+   return rsxMemalign(128, (u32)size);
+}
+
+/* Texture memory the atlas moved out of: a frame in flight may still
+ * draw from it, so it goes when the font does */
+static void rsx_font_storage_free(void *user, void *buffer)
+{
+   rsx_font_t *font = (rsx_font_t*)user;
+   if (font->retired_count < sizeof(font->retired) / sizeof(font->retired[0]))
+      font->retired[font->retired_count++] = (u32*)buffer;
+}
+
 static void *rsx_font_init(void *data,
       const char *font_path, float font_size,
       bool is_threaded)
@@ -807,7 +832,14 @@ static void *rsx_font_init(void *data,
    font->atlas->max_dims = VIDEO_SCALE_PACK(2048, 2048);
    font->tex_dims           = VIDEO_SCALE_PACK(font->atlas->width,
          font->atlas->height);
-   if (!(font->texture.data = (u32*)rsxMemalign(128,
+   /* The atlas kept in texture memory, or copied into it */
+   if (font_atlas_place(font->atlas, rsx_font_storage,
+            rsx_font_storage_free, font))
+   {
+      font->atlas_in_place = true;
+      font->texture.data   = (u32*)font->atlas->buffer;
+   }
+   else if (!(font->texture.data = (u32*)rsxMemalign(128,
          VIDEO_SCALE_AREA(font->tex_dims))))
       goto error;
    rsxAddressToOffset(font->texture.data, &font->texture.offset);
@@ -1083,7 +1115,20 @@ static void rsx_font_render_msg(
    if (font->font_driver && font->font_data)
    {
       font->atlas = font->font_driver->get_atlas(font->font_data);
-      if (     font->retired_count < 2
+      /* Kept in texture memory, the grown atlas is the texture already;
+       * the cache handed the memory it left to rsx_font_storage_free */
+      if (     font->atlas_in_place
+            && font->tex_dims != VIDEO_SCALE_PACK(font->atlas->width,
+               font->atlas->height))
+      {
+         font->texture.data = (u32*)font->atlas->buffer;
+         rsxAddressToOffset(font->texture.data, &font->texture.offset);
+         font->tex_dims     = VIDEO_SCALE_PACK(font->atlas->width,
+               font->atlas->height);
+         font->atlas->dirty = true;
+      }
+      else if (!font->atlas_in_place
+            && font->retired_count < 2
             && font->tex_dims != VIDEO_SCALE_PACK(font->atlas->width,
                font->atlas->height))
       {