text: /*
   * Mesa 3-D graphics library
   *
   * Copyright (C) 2010 LunarG Inc.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included
   * in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS IN THE SOFTWARE.
   *
   * Authors:
   *    Chia-I Wu <olv@lunarg.com>
   */
  
  #include "main/mtypes.h"
  #include "main/extensions.h"
  #include "main/context.h"
  #include "main/texobj.h"
  #include "main/teximage.h"
  #include "main/texstate.h"
  #include "main/errors.h"
  #include "main/framebuffer.h"
  #include "main/fbobject.h"
  #include "main/renderbuffer.h"
  #include "main/version.h"
  #include "st_texture.h"
  
  #include "st_context.h"
  #include "st_extensions.h"
  #include "st_format.h"
  #include "st_cb_fbo.h"
  #include "st_cb_flush.h"
  #include "st_manager.h"
  
  #include "state_tracker/st_gl_api.h"
  
  #include "pipe/p_context.h"
  #include "pipe/p_screen.h"
  #include "util/u_format.h"
  #include "util/u_pointer.h"
  #include "util/u_inlines.h"
  #include "util/u_atomic.h"
  #include "util/u_surface.h"
  
  /**
   * Cast wrapper to convert a struct gl_framebuffer to an st_framebuffer.
   * Return NULL if the struct gl_framebuffer is a user-created framebuffer.
   * We'll only return non-null for window system framebuffers.
   * Note that this function may fail.
   */
  static inline struct st_framebuffer *
  st_ws_framebuffer(struct gl_framebuffer *fb)
  {
     /* FBO cannot be casted.  See st_new_framebuffer */
     if (fb && _mesa_is_winsys_fbo(fb))
        return (struct st_framebuffer *) fb;
     return NULL;
  }
  
  /**
   * Map an attachment to a buffer index.
   */
  static inline gl_buffer_index
  attachment_to_buffer_index(enum st_attachment_type statt)
  {
     gl_buffer_index index;
  
     switch (statt) {
     case ST_ATTACHMENT_FRONT_LEFT:
        index = BUFFER_FRONT_LEFT;
        break;
     case ST_ATTACHMENT_BACK_LEFT:
        index = BUFFER_BACK_LEFT;
        break;
     case ST_ATTACHMENT_FRONT_RIGHT:
        index = BUFFER_FRONT_RIGHT;
        break;
     case ST_ATTACHMENT_BACK_RIGHT:
        index = BUFFER_BACK_RIGHT;
        break;
     case ST_ATTACHMENT_DEPTH_STENCIL:
        index = BUFFER_DEPTH;
        break;
     case ST_ATTACHMENT_ACCUM:
        index = BUFFER_ACCUM;
        break;
     case ST_ATTACHMENT_SAMPLE:
     default:
        index = BUFFER_COUNT;
        break;
     }
  
     return index;
  }
  
  /**
   * Map a buffer index to an attachment.
   */
  static inline enum st_attachment_type
  buffer_index_to_attachment(gl_buffer_index index)
  {
     enum st_attachment_type statt;
  
     switch (index) {
     case BUFFER_FRONT_LEFT:
        statt = ST_ATTACHMENT_FRONT_LEFT;
        break;
     case BUFFER_BACK_LEFT:
        statt = ST_ATTACHMENT_BACK_LEFT;
        break;
     case BUFFER_FRONT_RIGHT:
        statt = ST_ATTACHMENT_FRONT_RIGHT;
        break;
     case BUFFER_BACK_RIGHT:
        statt = ST_ATTACHMENT_BACK_RIGHT;
        break;
     case BUFFER_DEPTH:
        statt = ST_ATTACHMENT_DEPTH_STENCIL;
        break;
     case BUFFER_ACCUM:
        statt = ST_ATTACHMENT_ACCUM;
        break;
     default:
        statt = ST_ATTACHMENT_INVALID;
        break;
     }
  
     return statt;
  }
  
  /**
   * Make sure a context picks up the latest cached state of the
   * drawables it binds to.
   */
  static void
  st_context_validate(struct st_context *st,
                      struct st_framebuffer *stdraw,
                      struct st_framebuffer *stread)
  {
      if (stdraw && stdraw->stamp != st->draw_stamp) {
         st->dirty.st |= ST_NEW_FRAMEBUFFER;
         _mesa_resize_framebuffer(st->ctx, &stdraw->Base,
                                  stdraw->Base.Width,
                                  stdraw->Base.Height);
         st->draw_stamp = stdraw->stamp;
      }
  
      if (stread && stread->stamp != st->read_stamp) {
         if (stread != stdraw) {
            st->dirty.st |= ST_NEW_FRAMEBUFFER;
            _mesa_resize_framebuffer(st->ctx, &stread->Base,
                                     stread->Base.Width,
                                     stread->Base.Height);
         }
         st->read_stamp = stread->stamp;
      }
  }
  
  /**
   * Validate a framebuffer to make sure up-to-date pipe_textures are used.
   * The context is only used for creating pipe surfaces and for calling
   * _mesa_resize_framebuffer().
   * (That should probably be rethought, since those surfaces become
   * drawable state, not context state, and can be freed by another pipe
   * context).
   */
  static void
  st_framebuffer_validate(struct st_framebuffer *stfb,
                          struct st_context *st)
  {
     struct pipe_resource *textures[ST_ATTACHMENT_COUNT];
     uint width, height;
     unsigned i;
     boolean changed = FALSE;
     int32_t new_stamp;
  
     /* Check for incomplete framebuffers (e.g. EGL_KHR_surfaceless_context) */
     if (!stfb->iface)
        return;
  
     new_stamp = p_atomic_read(&stfb->iface->stamp);
     if (stfb->iface_stamp == new_stamp)
        return;
  
     /* validate the fb */
     do {
        if (!stfb->iface->validate(&st->iface, stfb->iface, stfb->statts,
  				 stfb->num_statts, textures))
  	 return;
  
        stfb->iface_stamp = new_stamp;
        new_stamp = p_atomic_read(&stfb->iface->stamp);
     } while(stfb->iface_stamp != new_stamp);
  
     width = stfb->Base.Width;
     height = stfb->Base.Height;
  
     for (i = 0; i < stfb->num_statts; i++) {
        struct st_renderbuffer *strb;
        struct pipe_surface *ps, surf_tmpl;
        gl_buffer_index idx;
  
        if (!textures[i])
           continue;
  
        idx = attachment_to_buffer_index(stfb->statts[i]);
        if (idx >= BUFFER_COUNT) {
           pipe_resource_reference(&textures[i], NULL);
           continue;
        }
  
        strb = st_renderbuffer(stfb->Base.Attachment[idx].Renderbuffer);
        assert(strb);
        if (strb->texture == textures[i]) {
           pipe_resource_reference(&textures[i], NULL);
           continue;
        }
  
        u_surface_default_template(&surf_tmpl, textures[i]);
        ps = st->pipe->create_surface(st->pipe, textures[i], &surf_tmpl);
        if (ps) {
           pipe_surface_reference(&strb->surface, ps);
           pipe_resource_reference(&strb->texture, ps->texture);
           /* ownership transfered */
           pipe_surface_reference(&ps, NULL);
  
           changed = TRUE;
  
           strb->Base.Width = strb->surface->width;
           strb->Base.Height = strb->surface->height;
  
           width = strb->Base.Width;
           height = strb->Base.Height;
        }
  
        pipe_resource_reference(&textures[i], NULL);
     }
  
     if (changed) {
        ++stfb->stamp;
        _mesa_resize_framebuffer(st->ctx, &stfb->Base, width, height);
     }
  }
  
  /**
   * Update the attachments to validate by looping the existing renderbuffers.
   */
  static void
  st_framebuffer_update_attachments(struct st_framebuffer *stfb)
  {
     gl_buffer_index idx;
  
     stfb->num_statts = 0;
     for (idx = 0; idx < BUFFER_COUNT; idx++) {
        struct st_renderbuffer *strb;
        enum st_attachment_type statt;
  
        strb = st_renderbuffer(stfb->Base.Attachment[idx].Renderbuffer);
        if (!strb || strb->software)
           continue;
  
        statt = buffer_index_to_attachment(idx);
        if (statt != ST_ATTACHMENT_INVALID &&
            st_visual_have_buffers(stfb->iface->visual, 1 << statt))
           stfb->statts[stfb->num_statts++] = statt;
     }
     stfb->stamp++;
  }
  
  /**
   * Add a renderbuffer to the framebuffer.
   */
  static boolean
  st_framebuffer_add_renderbuffer(struct st_framebuffer *stfb,
                                  gl_buffer_index idx)
  {
     struct gl_renderbuffer *rb;
     enum pipe_format format;
     boolean sw;
  
     if (!stfb->iface)
        return FALSE;
  
     /* do not distinguish depth/stencil buffers */
     if (idx == BUFFER_STENCIL)
        idx = BUFFER_DEPTH;
  
     switch (idx) {
     case BUFFER_DEPTH:
        format = stfb->iface->visual->depth_stencil_format;
        sw = FALSE;
        break;
     case BUFFER_ACCUM:
        format = stfb->iface->visual->accum_format;
        sw = TRUE;
        break;
     default:
        format = stfb->iface->visual->color_format;
        if (stfb->Base.Visual.sRGBCapable)
           format = util_format_srgb(format);
        sw = FALSE;
        break;
     }
  
     if (format == PIPE_FORMAT_NONE)
        return FALSE;
  
     rb = st_new_renderbuffer_fb(format, stfb->iface->visual->samples, sw);
     if (!rb)
        return FALSE;
  
     if (idx != BUFFER_DEPTH) {
        _mesa_add_renderbuffer(&stfb->Base, idx, rb);
     }
     else {
        if (util_format_get_component_bits(format, UTIL_FORMAT_COLORSPACE_ZS, 0))
           _mesa_add_renderbuffer(&stfb->Base, BUFFER_DEPTH, rb);
        if (util_format_get_component_bits(format, UTIL_FORMAT_COLORSPACE_ZS, 1))
           _mesa_add_renderbuffer(&stfb->Base, BUFFER_STENCIL, rb);
     }
  
     return TRUE;
  }
  
  /**
   * Intialize a struct gl_config from a visual.
   */
  static void
  st_visual_to_context_mode(const struct st_visual *visual,
                            struct gl_config *mode)
  {
     memset(mode, 0, sizeof(*mode));
  
     if (st_visual_have_buffers(visual, ST_ATTACHMENT_BACK_LEFT_MASK))
        mode->doubleBufferMode = GL_TRUE;
     if (st_visual_have_buffers(visual,
              ST_ATTACHMENT_FRONT_RIGHT_MASK | ST_ATTACHMENT_BACK_RIGHT_MASK))
        mode->stereoMode = GL_TRUE;
  
     if (visual->color_format != PIPE_FORMAT_NONE) {
        mode->rgbMode = GL_TRUE;
  
        mode->redBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 0);
        mode->greenBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 1);
        mode->blueBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 2);
        mode->alphaBits =
           util_format_get_component_bits(visual->color_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 3);
  
        mode->rgbBits = mode->redBits +
           mode->greenBits + mode->blueBits + mode->alphaBits;
     }
  
     if (visual->depth_stencil_format != PIPE_FORMAT_NONE) {
        mode->depthBits =
           util_format_get_component_bits(visual->depth_stencil_format,
                 UTIL_FORMAT_COLORSPACE_ZS, 0);
        mode->stencilBits =
           util_format_get_component_bits(visual->depth_stencil_format,
                 UTIL_FORMAT_COLORSPACE_ZS, 1);
  
        mode->haveDepthBuffer = mode->depthBits > 0;
        mode->haveStencilBuffer = mode->stencilBits > 0;
     }
  
     if (visual->accum_format != PIPE_FORMAT_NONE) {
        mode->haveAccumBuffer = GL_TRUE;
  
        mode->accumRedBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 0);
        mode->accumGreenBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 1);
        mode->accumBlueBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 2);
        mode->accumAlphaBits =
           util_format_get_component_bits(visual->accum_format,
                 UTIL_FORMAT_COLORSPACE_RGB, 3);
     }
  
     if (visual->samples > 1) {
        mode->sampleBuffers = 1;
        mode->samples = visual->samples;
     }
  }
  
  /**
   * Create a framebuffer from a manager interface.
   */
  static struct st_framebuffer *
  st_framebuffer_create(struct st_context *st,
                        struct st_framebuffer_iface *stfbi)
  {
     struct st_framebuffer *stfb;
     struct gl_config mode;
     gl_buffer_index idx;
  
     if (!stfbi)
        return NULL;
  
     stfb = CALLOC_STRUCT(st_framebuffer);
     if (!stfb)
        return NULL;
  
     st_visual_to_context_mode(stfbi->visual, &mode);
  
     /*
      * For desktop GL, sRGB framebuffer write is controlled by both the
      * capability of the framebuffer and GL_FRAMEBUFFER_SRGB.  We should
      * advertise the capability when the pipe driver (and core Mesa) supports
      * it so that applications can enable sRGB write when they want to.
      *
      * This is not to be confused with GLX_FRAMEBUFFER_SRGB_CAPABLE_ARB.  When
      * the attribute is GLX_TRUE, it tells the st manager to pick a color
      * format such that util_format_srgb(visual->color_format) can be supported
      * by the pipe driver.  We still need to advertise the capability here.
      *
      * For GLES, however, sRGB framebuffer write is controlled only by the
      * capability of the framebuffer.  There is GL_EXT_sRGB_write_control to
      * give applications the control back, but sRGB write is still enabled by
      * default.  To avoid unexpected results, we should not advertise the
      * capability.  This could change when we add support for
      * EGL_KHR_gl_colorspace.
      */
     if (_mesa_is_desktop_gl(st->ctx)) {
        struct pipe_screen *screen = st->pipe->screen;
        const enum pipe_format srgb_format =
           util_format_srgb(stfbi->visual->color_format);
  
        if (srgb_format != PIPE_FORMAT_NONE &&
            st_pipe_format_to_mesa_format(srgb_format) != MESA_FORMAT_NONE &&
            screen->is_format_supported(screen, srgb_format,
                                        PIPE_TEXTURE_2D, stfbi->visual->samples,
                                        (PIPE_BIND_DISPLAY_TARGET |
                                         PIPE_BIND_RENDER_TARGET)))
           mode.sRGBCapable = GL_TRUE;
     }
  
     _mesa_initialize_window_framebuffer(&stfb->Base, &mode);
  
     stfb->iface = stfbi;
     stfb->iface_stamp = p_atomic_read(&stfbi->stamp) - 1;
  
     /* add the color buffer */
     idx = stfb->Base._ColorDrawBufferIndexes[0];
     if (!st_framebuffer_add_renderbuffer(stfb, idx)) {
        free(stfb);
        return NULL;
     }
  
     st_framebuffer_add_renderbuffer(stfb, BUFFER_DEPTH);
     st_framebuffer_add_renderbuffer(stfb, BUFFER_ACCUM);
  
     stfb->stamp = 0;
     st_framebuffer_update_attachments(stfb);
  
     return stfb;
  }
  
  /**
   * Reference a framebuffer.
   */
  static void
  st_framebuffer_reference(struct st_framebuffer **ptr,
                           struct st_framebuffer *stfb)
  {
     struct gl_framebuffer *fb = &stfb->Base;
     _mesa_reference_framebuffer((struct gl_framebuffer **) ptr, fb);
  }
  
  static void
  st_context_flush(struct st_context_iface *stctxi, unsigned flags,
                   struct pipe_fence_handle **fence)
  {
     struct st_context *st = (struct st_context *) stctxi;
     unsigned pipe_flags = 0;
  
     if (flags & ST_FLUSH_END_OF_FRAME) {
        pipe_flags |= PIPE_FLUSH_END_OF_FRAME;
     }
  
     st_flush(st, fence, pipe_flags);
     if (flags & ST_FLUSH_FRONT)
        st_manager_flush_frontbuffer(st);
  }
  
  static boolean
  st_context_teximage(struct st_context_iface *stctxi,
                      enum st_texture_type tex_type,
                      int level, enum pipe_format pipe_format,
                      struct pipe_resource *tex, boolean mipmap)
  {
     struct st_context *st = (struct st_context *) stctxi;
     struct gl_context *ctx = st->ctx;
     struct gl_texture_object *texObj;
     struct gl_texture_image *texImage;
     struct st_texture_object *stObj;
     struct st_texture_image *stImage;
     GLenum internalFormat;
     GLuint width, height, depth;
     GLenum target;
  
     switch (tex_type) {
     case ST_TEXTURE_1D:
        target = GL_TEXTURE_1D;
        break;
     case ST_TEXTURE_2D:
        target = GL_TEXTURE_2D;
        break;
     case ST_TEXTURE_3D:
        target = GL_TEXTURE_3D;
        break;
     case ST_TEXTURE_RECT:
        target = GL_TEXTURE_RECTANGLE_ARB;
        break;
     default:
        return FALSE;
     }
  
     texObj = _mesa_get_current_tex_object(ctx, target);
  
     _mesa_lock_texture(ctx, texObj);
  
     stObj = st_texture_object(texObj);
     /* switch to surface based */
     if (!stObj->surface_based) {
        _mesa_clear_texture_object(ctx, texObj);
        stObj->surface_based = GL_TRUE;
     }
  
     texImage = _mesa_get_tex_image(ctx, texObj, target, level);
     stImage = st_texture_image(texImage);
     if (tex) {
        mesa_format texFormat = st_pipe_format_to_mesa_format(pipe_format);
  
        if (util_format_has_alpha(tex->format))
           internalFormat = GL_RGBA;
        else
           internalFormat = GL_RGB;
  
        _mesa_init_teximage_fields(ctx, texImage,
                                   tex->width0, tex->height0, 1, 0,
                                   internalFormat, texFormat);
  
        width = tex->width0;
        height = tex->height0;
        depth = tex->depth0;
  
        /* grow the image size until we hit level = 0 */
        while (level > 0) {
           if (width != 1)
              width <<= 1;
           if (height != 1)
              height <<= 1;
           if (depth != 1)
              depth <<= 1;
           level--;
        }
     }
     else {
        _mesa_clear_texture_image(ctx, texImage);
        width = height = depth = 0;
     }
  
     pipe_resource_reference(&stImage->pt, tex);
     stObj->width0 = width;
     stObj->height0 = height;
     stObj->depth0 = depth;
     stObj->surface_format = pipe_format;
  
     _mesa_dirty_texobj(ctx, texObj);
     _mesa_unlock_texture(ctx, texObj);
     
     return TRUE;
  }
  
  static void
  st_context_copy(struct st_context_iface *stctxi,
                  struct st_context_iface *stsrci, unsigned mask)
  {
     struct st_context *st = (struct st_context *) stctxi;
     struct st_context *src = (struct st_context *) stsrci;
  
     _mesa_copy_context(src->ctx, st->ctx, mask);
  }
  
  static boolean
  st_context_share(struct st_context_iface *stctxi,
                   struct st_context_iface *stsrci)
  {
     struct st_context *st = (struct st_context *) stctxi;
     struct st_context *src = (struct st_context *) stsrci;
  
     return _mesa_share_state(st->ctx, src->ctx);
  }
  
  static void
  st_context_destroy(struct st_context_iface *stctxi)
  {
     struct st_context *st = (struct st_context *) stctxi;
     st_destroy_context(st);
  }
  
  static struct st_context_iface *
  st_api_create_context(struct st_api *stapi, struct st_manager *smapi,
                        const struct st_context_attribs *attribs,
                        enum st_context_error *error,
                        struct st_context_iface *shared_stctxi)
  {
     struct st_context *shared_ctx = (struct st_context *) shared_stctxi;
     struct st_context *st;
     struct pipe_context *pipe;
     struct gl_config mode;
     gl_api api;
  
     if (!(stapi->profile_mask & (1 << attribs->profile)))
        return NULL;
  
     switch (attribs->profile) {
     case ST_PROFILE_DEFAULT:
        api = API_OPENGL_COMPAT;
        break;
     case ST_PROFILE_OPENGL_ES1:
        api = API_OPENGLES;
        break;
     case ST_PROFILE_OPENGL_ES2:
        api = API_OPENGLES2;
        break;
     case ST_PROFILE_OPENGL_CORE:
        api = API_OPENGL_CORE;
        break;
     default:
        *error = ST_CONTEXT_ERROR_BAD_API;
        return NULL;
        break;
     }
  
     pipe = smapi->screen->context_create(smapi->screen, NULL);
     if (!pipe) {
        *error = ST_CONTEXT_ERROR_NO_MEMORY;
        return NULL;
     }
  
     st_visual_to_context_mode(&attribs->visual, &mode);
     st = st_create_context(api, pipe, &mode, shared_ctx, &attribs->options);
     if (!st) {
        *error = ST_CONTEXT_ERROR_NO_MEMORY;
        pipe->destroy(pipe);
        return NULL;
     }
  
     if (attribs->flags & ST_CONTEXT_FLAG_DEBUG){
        if (!_mesa_set_debug_state_int(st->ctx, GL_DEBUG_OUTPUT, GL_TRUE)) {
           *error = ST_CONTEXT_ERROR_NO_MEMORY;
           return NULL;
        }
        st->ctx->Const.ContextFlags |= GL_CONTEXT_FLAG_DEBUG_BIT;
     }
  
     if (attribs->flags & ST_CONTEXT_FLAG_FORWARD_COMPATIBLE)
        st->ctx->Const.ContextFlags |= GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT;
  
     /* need to perform version check */
     if (attribs->major > 1 || attribs->minor > 0) {
        /* Is the actual version less than the requested version?
         */
        if (st->ctx->Version < attribs->major * 10U + attribs->minor) {
  	 *error = ST_CONTEXT_ERROR_BAD_VERSION;
           st_destroy_context(st);
           return NULL;
        }
     }
  
     st->invalidate_on_gl_viewport =
        smapi->get_param(smapi, ST_MANAGER_BROKEN_INVALIDATE);
  
     st->iface.destroy = st_context_destroy;
     st->iface.flush = st_context_flush;
     st->iface.teximage = st_context_teximage;
     st->iface.copy = st_context_copy;
     st->iface.share = st_context_share;
     st->iface.st_context_private = (void *) smapi;
     st->iface.cso_context = st->cso_context;
     st->iface.pipe = st->pipe;
  
     *error = ST_CONTEXT_SUCCESS;
     return &st->iface;
  }
  
  static struct st_context_iface *
  st_api_get_current(struct st_api *stapi)
  {
     GET_CURRENT_CONTEXT(ctx);
     struct st_context *st = (ctx) ? ctx->st : NULL;
  
     return (st) ? &st->iface : NULL;
  }
  
  static struct st_framebuffer *
  st_framebuffer_reuse_or_create(struct st_context *st,
                                 struct gl_framebuffer *fb,
                                 struct st_framebuffer_iface *stfbi)
  {
     struct st_framebuffer *cur = st_ws_framebuffer(fb), *stfb = NULL;
  
     /* dummy framebuffers cant be used as st_framebuffer */
     if (cur && &cur->Base != _mesa_get_incomplete_framebuffer() &&
         cur->iface == stfbi) {
        /* reuse the current stfb */
        st_framebuffer_reference(&stfb, cur);
     }
     else {
        /* create a new one */
        stfb = st_framebuffer_create(st, stfbi);
     }
  
     return stfb;
  }
  
  static boolean
  st_api_make_current(struct st_api *stapi, struct st_context_iface *stctxi,
                      struct st_framebuffer_iface *stdrawi,
                      struct st_framebuffer_iface *streadi)
  {
     struct st_context *st = (struct st_context *) stctxi;
     struct st_framebuffer *stdraw, *stread;
     boolean ret;
  
     _glapi_check_multithread();
  
     if (st) {
        /* reuse or create the draw fb */
        stdraw = st_framebuffer_reuse_or_create(st,
              st->ctx->WinSysDrawBuffer, stdrawi);
        if (streadi != stdrawi) {
           /* do the same for the read fb */
           stread = st_framebuffer_reuse_or_create(st,
                 st->ctx->WinSysReadBuffer, streadi);
        }
        else {
           stread = NULL;
           /* reuse the draw fb for the read fb */
           if (stdraw)
              st_framebuffer_reference(&stread, stdraw);
        }
  
        if (stdraw && stread) {
           st_framebuffer_validate(stdraw, st);
           if (stread != stdraw)
              st_framebuffer_validate(stread, st);
  
           ret = _mesa_make_current(st->ctx, &stdraw->Base, &stread->Base);
  
           st->draw_stamp = stdraw->stamp - 1;
           st->read_stamp = stread->stamp - 1;
           st_context_validate(st, stdraw, stread);
        }
        else {
           struct gl_framebuffer *incomplete = _mesa_get_incomplete_framebuffer();
           ret = _mesa_make_current(st->ctx, incomplete, incomplete);
        }
  
        st_framebuffer_reference(&stdraw, NULL);
        st_framebuffer_reference(&stread, NULL);
     }
     else {
        ret = _mesa_make_current(NULL, NULL, NULL);
     }
  
     return ret;
  }
  
  static st_proc_t
  st_api_get_proc_address(struct st_api *stapi, const char *procname)
  {
     return (st_proc_t) _glapi_get_proc_address(procname);
  }
  
  static void
  st_api_destroy(struct st_api *stapi)
  {
  }
  
  /**
   * Flush the front buffer if the current context renders to the front buffer.
   */
  void
  st_manager_flush_frontbuffer(struct st_context *st)
  {
     struct st_framebuffer *stfb = st_ws_framebuffer(st->ctx->DrawBuffer);
     struct st_renderbuffer *strb = NULL;
  
     if (stfb)
        strb = st_renderbuffer(stfb->Base.Attachment[BUFFER_FRONT_LEFT].Renderbuffer);
     if (!strb)
        return;
  
     /* never a dummy fb */
     assert(&stfb->Base != _mesa_get_incomplete_framebuffer());
     stfb->iface->flush_front(&st->iface, stfb->iface, ST_ATTACHMENT_FRONT_LEFT);
  }
  
  /**
   * Return the surface of an EGLImage.
   * FIXME: I think this should operate on resources, not surfaces
   */
  struct pipe_surface *
  st_manager_get_egl_image_surface(struct st_context *st, void *eglimg)
  {
     struct st_manager *smapi =
        (struct st_manager *) st->iface.st_context_private;
     struct st_egl_image stimg;
     struct pipe_surface *ps, surf_tmpl;
  
     if (!smapi || !smapi->get_egl_image)
        return NULL;
  
     memset(&stimg, 0, sizeof(stimg));
     if (!smapi->get_egl_image(smapi, eglimg, &stimg))
        return NULL;
  
     u_surface_default_template(&surf_tmpl, stimg.texture);
     surf_tmpl.u.tex.level = stimg.level;
     surf_tmpl.u.tex.first_layer = stimg.layer;
     surf_tmpl.u.tex.last_layer = stimg.layer;
     ps = st->pipe->create_surface(st->pipe, stimg.texture, &surf_tmpl);
     pipe_resource_reference(&stimg.texture, NULL);
  
     return ps;
  }
  
  /**
   * Re-validate the framebuffers.
   */
  void
  st_manager_validate_framebuffers(struct st_context *st)
  {
     struct st_framebuffer *stdraw = st_ws_framebuffer(st->ctx->DrawBuffer);
     struct st_framebuffer *stread = st_ws_framebuffer(st->ctx->ReadBuffer);
  
     if (stdraw)
        st_framebuffer_validate(stdraw, st);
     if (stread && stread != stdraw)
        st_framebuffer_validate(stread, st);
  
     st_context_validate(st, stdraw, stread);
  }
  
  /**
   * Add a color renderbuffer on demand.
   */
  boolean
  st_manager_add_color_renderbuffer(struct st_context *st,
                                    struct gl_framebuffer *fb,
                                    gl_buffer_index idx)
  {
     struct st_framebuffer *stfb = st_ws_framebuffer(fb);
  
     /* FBO */
     if (!stfb)
        return FALSE;
  
     if (stfb->Base.Attachment[idx].Renderbuffer)
        return TRUE;
  
     switch (idx) {
     case BUFFER_FRONT_LEFT:
     case BUFFER_BACK_LEFT:
     case BUFFER_FRONT_RIGHT:
     case BUFFER_BACK_RIGHT:
        break;
     default:
        return FALSE;
        break;
     }
  
     if (!st_framebuffer_add_renderbuffer(stfb, idx))
        return FALSE;
  
     st_framebuffer_update_attachments(stfb);
  
     /*
      * Force a call to the state tracker manager to validate the
      * new renderbuffer. It might be that there is a window system
      * renderbuffer available.
      */
     if(stfb->iface)
        stfb->iface_stamp = p_atomic_read(&stfb->iface->stamp) - 1;
  
     st_invalidate_state(st->ctx, _NEW_BUFFERS);
  
     return TRUE;
  }
  
  static unsigned get_version(struct pipe_screen *screen,
                              struct st_config_options *options, gl_api api)
  {
     struct gl_constants consts = {0};
     struct gl_extensions extensions = {0};
     GLuint version;
  
     if ((api == API_OPENGL_COMPAT || api == API_OPENGL_CORE) &&
         _mesa_override_gl_version_contextless(&consts, &api, &version)) {
        return version;
     }
  
     _mesa_init_constants(&consts, api);
     _mesa_init_extensions(&extensions);
  
     st_init_limits(screen, &consts, &extensions);
     st_init_extensions(screen, &consts, &extensions, options, GL_TRUE);
  
     return _mesa_get_version(&extensions, &consts, api);
  }
  
  static void
  st_api_query_versions(struct st_api *stapi, struct st_manager *sm,
                        struct st_config_options *options,
                        int *gl_core_version,
                        int *gl_compat_version,
                        int *gl_es1_version,
                        int *gl_es2_version)
  {
     *gl_core_version = get_version(sm->screen, options, API_OPENGL_CORE);
     *gl_compat_version = get_version(sm->screen, options, API_OPENGL_COMPAT);
     *gl_es1_version = get_version(sm->screen, options, API_OPENGLES);
     *gl_es2_version = get_version(sm->screen, options, API_OPENGLES2);
  }
  
  static const struct st_api st_gl_api = {
     "Mesa " PACKAGE_VERSION,
     ST_API_OPENGL,
     ST_PROFILE_DEFAULT_MASK |
     ST_PROFILE_OPENGL_CORE_MASK |
     ST_PROFILE_OPENGL_ES1_MASK |
     ST_PROFILE_OPENGL_ES2_MASK |
     0,
     ST_API_FEATURE_MS_VISUALS_MASK,
     st_api_destroy,
     st_api_query_versions,
     st_api_get_proc_address,
     st_api_create_context,
     st_api_make_current,
     st_api_get_current,
  };
  
  struct st_api *
  st_gl_api_create(void)
  {
     return (struct st_api *) &st_gl_api;
  }
  