GLboolean
_mesa_validate_DrawElementsInstanced(struct gl_context *ctx,
                                     GLenum mode, GLsizei count, GLenum type,
                                     const GLvoid *indices, GLsizei numInstances)
{
   FLUSH_CURRENT(ctx, 0);

   if (numInstances < 0) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glDrawElementsInstanced(numInstances=%d)", numInstances);
      return GL_FALSE;
   }

   return validate_DrawElements_common(ctx, mode, count, type, indices,
                                       "glDrawElementsInstanced")
      && (numInstances > 0);
}

void GLAPIENTRY
_mesa_GetVertexAttribfvARB(GLuint index, GLenum pname, GLfloat *params)
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (index == 0 || index >= MAX_VERTEX_PROGRAM_ATTRIBS) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glGetVertexAttribfvARB(index)");
      return;
   }

   switch (pname) {
      case GL_VERTEX_ATTRIB_ARRAY_ENABLED_ARB:
         params[0] = (GLfloat) ctx->Array.VertexAttrib[index].Enabled;
         break;
      case GL_VERTEX_ATTRIB_ARRAY_SIZE_ARB:
         params[0] = (GLfloat) ctx->Array.VertexAttrib[index].Size;
         break;
      case GL_VERTEX_ATTRIB_ARRAY_STRIDE_ARB:
         params[0] = (GLfloat) ctx->Array.VertexAttrib[index].Stride;
         break;
      case GL_VERTEX_ATTRIB_ARRAY_TYPE_ARB:
         params[0] = (GLfloat) ctx->Array.VertexAttrib[index].Type;
         break;
      case GL_VERTEX_ATTRIB_ARRAY_NORMALIZED_ARB:
         params[0] = ctx->Array.VertexAttrib[index].Normalized;
         break;
      case GL_CURRENT_VERTEX_ATTRIB_ARB:
	 FLUSH_CURRENT(ctx, 0);
         /* XXX should read:
            COPY_4V(params, ctx->Current.Attrib[VERT_ATTRIB_GENERIC0 + index]);
          */
         COPY_4V(params, ctx->Current.Attrib[index]);
         break;
      case GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING_ARB:
         if (!ctx->Extensions.ARB_vertex_buffer_object) {
            _mesa_error(ctx, GL_INVALID_ENUM, "glGetVertexAttribfvARB(pname)");
            return;
         }
         params[0] = (GLfloat) ctx->Array.VertexAttrib[index].BufferObj->Name;
      default:
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetVertexAttribfvARB(pname)");
         return;
   }
}

/**
 * Get a vertex (or vertex array) attribute.
 * \note Not compiled into display lists.
 * \note Called from the GL API dispatcher.
 */
void GLAPIENTRY
_mesa_GetVertexAttribivNV(GLuint index, GLenum pname, GLint *params)
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (index >= MAX_NV_VERTEX_PROGRAM_INPUTS) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glGetVertexAttribdvNV(index)");
      return;
   }

   switch (pname) {
      case GL_ATTRIB_ARRAY_SIZE_NV:
         params[0] = ctx->Array.ArrayObj->VertexAttrib[index].Size;
         break;
      case GL_ATTRIB_ARRAY_STRIDE_NV:
         params[0] = ctx->Array.ArrayObj->VertexAttrib[index].Stride;
         break;
      case GL_ATTRIB_ARRAY_TYPE_NV:
         params[0] = ctx->Array.ArrayObj->VertexAttrib[index].Type;
         break;
      case GL_CURRENT_ATTRIB_NV:
         if (index == 0) {
            _mesa_error(ctx, GL_INVALID_OPERATION,
                        "glGetVertexAttribivNV(index == 0)");
            return;
         }
	 FLUSH_CURRENT(ctx, 0);
         params[0] = (GLint) ctx->Current.Attrib[index][0];
         params[1] = (GLint) ctx->Current.Attrib[index][1];
         params[2] = (GLint) ctx->Current.Attrib[index][2];
         params[3] = (GLint) ctx->Current.Attrib[index][3];
         break;
      case GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING_ARB:
         if (!ctx->Extensions.ARB_vertex_buffer_object) {
            _mesa_error(ctx, GL_INVALID_ENUM, "glGetVertexAttribdvNV");
            return;
         }
         params[0] = ctx->Array.ArrayObj->VertexAttrib[index].BufferObj->Name;
         break;
      default:
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetVertexAttribdvNV");
         return;
   }
}

/**
 * Get a vertex (or vertex array) attribute.
 * \note Not compiled into display lists.
 * \note Called from the GL API dispatcher.
 */
void GLAPIENTRY
_mesa_GetVertexAttribivNV(GLuint index, GLenum pname, GLint *params)
{
   const struct gl_client_array *array;
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (index >= MAX_NV_VERTEX_PROGRAM_INPUTS) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glGetVertexAttribdvNV(index)");
      return;
   }

   array = &ctx->Array.ArrayObj->VertexAttrib[VERT_ATTRIB_GENERIC(index)];

   switch (pname) {
      case GL_ATTRIB_ARRAY_SIZE_NV:
         params[0] = array->Size;
         break;
      case GL_ATTRIB_ARRAY_STRIDE_NV:
         params[0] = array->Stride;
         break;
      case GL_ATTRIB_ARRAY_TYPE_NV:
         params[0] = array->Type;
         break;
      case GL_CURRENT_ATTRIB_NV:
         if (index == 0) {
            _mesa_error(ctx, GL_INVALID_OPERATION,
                        "glGetVertexAttribivNV(index == 0)");
            return;
         }
	 FLUSH_CURRENT(ctx, 0);
         params[0] = (GLint) ctx->Current.Attrib[index][0];
         params[1] = (GLint) ctx->Current.Attrib[index][1];
         params[2] = (GLint) ctx->Current.Attrib[index][2];
         params[3] = (GLint) ctx->Current.Attrib[index][3];
         break;
      case GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING_ARB:
         params[0] = array->BufferObj->Name;
         break;
      default:
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetVertexAttribdvNV");
         return;
   }
}

/**
 * Helper function for all the RasterPos functions.
 */
static void
rasterpos(GLfloat x, GLfloat y, GLfloat z, GLfloat w)
{
   GET_CURRENT_CONTEXT(ctx);
   GLfloat p[4];

   p[0] = x;
   p[1] = y;
   p[2] = z;
   p[3] = w;

   FLUSH_VERTICES(ctx, 0);
   FLUSH_CURRENT(ctx, 0);

   if (ctx->NewState)
      _mesa_update_state( ctx );

   ctx->Driver.RasterPos(ctx, p);
}

/**
 * Helper function for all the RasterPos functions.
 */
static void
rasterpos(GLfloat x, GLfloat y, GLfloat z, GLfloat w)
{
   GET_CURRENT_CONTEXT(ctx);
   GLfloat p[4];

   p[0] = x;
   p[1] = y;
   p[2] = z;
   p[3] = w;

   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
   FLUSH_CURRENT(ctx, 0);

   if (ctx->NewState)
      _mesa_update_state( ctx );

   ctx->Driver.RasterPos(ctx, p);
}

GLboolean
_mesa_validate_DrawTransformFeedback(struct gl_context *ctx,
                                     GLenum mode,
                                     struct gl_transform_feedback_object *obj,
                                     GLuint stream,
                                     GLsizei numInstances)
{
   FLUSH_CURRENT(ctx, 0);

   if (!_mesa_valid_prim_mode(ctx, mode, "glDrawTransformFeedback*(mode)")) {
      return GL_FALSE;
   }

   if (!obj) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glDrawTransformFeedback*(name)");
      return GL_FALSE;
   }

   if (!obj->EndedAnytime) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawTransformFeedback*");
      return GL_FALSE;
   }

   if (stream >= ctx->Const.MaxVertexStreams) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glDrawTransformFeedbackStream*(index>=MaxVertexStream)");
      return GL_FALSE;
   }

   if (numInstances <= 0) {
      if (numInstances < 0)
         _mesa_error(ctx, GL_INVALID_VALUE,
                     "glDrawTransformFeedback*Instanced(numInstances=%d)",
                     numInstances);
      return GL_FALSE;
   }

   if (!check_valid_to_render(ctx, "glDrawTransformFeedback*")) {
      return GL_FALSE;
   }

   return GL_TRUE;
}

/**
 * All glWindowPosMESA and glWindowPosARB commands call this function to
 * update the current raster position.
 */
static void
window_pos3f(GLfloat x, GLfloat y, GLfloat z)
{
   GET_CURRENT_CONTEXT(ctx);
   GLfloat z2;

   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
   FLUSH_CURRENT(ctx, 0);

   z2 = CLAMP(z, 0.0F, 1.0F) * (ctx->Viewport.Far - ctx->Viewport.Near)
      + ctx->Viewport.Near;

   /* set raster position */
   ctx->Current.RasterPos[0] = x;
   ctx->Current.RasterPos[1] = y;
   ctx->Current.RasterPos[2] = z2;
   ctx->Current.RasterPos[3] = 1.0F;

   ctx->Current.RasterPosValid = GL_TRUE;

   if (ctx->Fog.FogCoordinateSource == GL_FOG_COORDINATE_EXT)
      ctx->Current.RasterDistance = ctx->Current.Attrib[VERT_ATTRIB_FOG][0];
   else
      ctx->Current.RasterDistance = 0.0;

   /* raster color = current color or index */
   ctx->Current.RasterColor[0]
      = CLAMP(ctx->Current.Attrib[VERT_ATTRIB_COLOR][0], 0.0F, 1.0F);
   ctx->Current.RasterColor[1]
      = CLAMP(ctx->Current.Attrib[VERT_ATTRIB_COLOR][1], 0.0F, 1.0F);
   ctx->Current.RasterColor[2]
      = CLAMP(ctx->Current.Attrib[VERT_ATTRIB_COLOR][2], 0.0F, 1.0F);
   ctx->Current.RasterColor[3]
      = CLAMP(ctx->Current.Attrib[VERT_ATTRIB_COLOR][3], 0.0F, 1.0F);

   /* raster texcoord = current texcoord */
   COPY_4FV( ctx->Current.RasterTexCoords, ctx->Current.Attrib[VERT_ATTRIB_TEX] );

   if (ctx->RenderMode==GL_SELECT) {
      _mesa_update_hitflag( ctx, ctx->Current.RasterPos[2] );
   }
}

/**
 * Error checking for glMultiDrawElements().  Includes parameter checking
 * and VBO bounds checking.
 * \return GL_TRUE if OK to render, GL_FALSE if error found
 */
GLboolean
_mesa_validate_MultiDrawElements(struct gl_context *ctx,
                                 GLenum mode, const GLsizei *count,
                                 GLenum type, const GLvoid * const *indices,
                                 GLuint primcount)
{
   unsigned i;

   FLUSH_CURRENT(ctx, 0);

   for (i = 0; i < primcount; i++) {
      if (count[i] < 0) {
         _mesa_error(ctx, GL_INVALID_VALUE,
                     "glMultiDrawElements(count)" );
         return GL_FALSE;
      }
   }

   if (!_mesa_valid_prim_mode(ctx, mode, "glMultiDrawElements")) {
      return GL_FALSE;
   }

   if (!valid_elements_type(ctx, type, "glMultiDrawElements"))
      return GL_FALSE;

   if (!check_valid_to_render(ctx, "glMultiDrawElements"))
      return GL_FALSE;

   /* Not using a VBO for indices, so avoid NULL pointer derefs later.
    */
   if (!_mesa_is_bufferobj(ctx->Array.VAO->IndexBufferObj)) {
      for (i = 0; i < primcount; i++) {
         if (!indices[i])
            return GL_FALSE;
      }
   }

   return GL_TRUE;
}

/**
 * Get a vertex (or vertex array) attribute.
 * \note Not compiled into display lists.
 * \note Called from the GL API dispatcher.
 */
void GLAPIENTRY
_mesa_GetVertexAttribfvNV(GLuint index, GLenum pname, GLfloat *params)
{
   const struct gl_client_array *array;
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (index >= MAX_NV_VERTEX_PROGRAM_INPUTS) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glGetVertexAttribdvNV(index)");
      return;
   }

   array = &ctx->Array.ArrayObj->VertexAttrib[index];

   switch (pname) {
      case GL_ATTRIB_ARRAY_SIZE_NV:
         params[0] = (GLfloat) array->Size;
         break;
      case GL_ATTRIB_ARRAY_STRIDE_NV:
         params[0] = (GLfloat) array->Stride;
         break;
      case GL_ATTRIB_ARRAY_TYPE_NV:
         params[0] = (GLfloat) array->Type;
         break;
      case GL_CURRENT_ATTRIB_NV:
         if (index == 0) {
            _mesa_error(ctx, GL_INVALID_OPERATION,
                        "glGetVertexAttribfvNV(index == 0)");
            return;
         }
	 FLUSH_CURRENT(ctx, 0);
         COPY_4V(params, ctx->Current.Attrib[index]);
         break;
      default:
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetVertexAttribdvNV");
         return;
   }
}

GLboolean
_mesa_validate_DispatchCompute(struct gl_context *ctx,
                               const GLuint *num_groups)
{
   int i;
   FLUSH_CURRENT(ctx, 0);

   if (!check_valid_to_compute(ctx, "glDispatchCompute"))
      return GL_FALSE;

   for (i = 0; i < 3; i++) {
      /* From the OpenGL 4.3 Core Specification, Chapter 19, Compute Shaders:
       *
       * "An INVALID_VALUE error is generated if any of num_groups_x,
       *  num_groups_y and num_groups_z are greater than or equal to the
       *  maximum work group count for the corresponding dimension."
       *
       * However, the "or equal to" portions appears to be a specification
       * bug. In all other areas, the specification appears to indicate that
       * the number of workgroups can match the MAX_COMPUTE_WORK_GROUP_COUNT
       * value. For example, under DispatchComputeIndirect:
       *
       * "If any of num_groups_x, num_groups_y or num_groups_z is greater than
       *  the value of MAX_COMPUTE_WORK_GROUP_COUNT for the corresponding
       *  dimension then the results are undefined."
       *
       * Additionally, the OpenGLES 3.1 specification does not contain "or
       * equal to" as an error condition.
       */
      if (num_groups[i] > ctx->Const.MaxComputeWorkGroupCount[i]) {
         _mesa_error(ctx, GL_INVALID_VALUE,
                     "glDispatchCompute(num_groups_%c)", 'x' + i);
         return GL_FALSE;
      }
   }

   return GL_TRUE;
}

GLboolean
_mesa_validate_DrawArraysInstanced(struct gl_context *ctx, GLenum mode, GLint first,
                                   GLsizei count, GLsizei numInstances)
{
   struct gl_transform_feedback_object *xfb_obj
      = ctx->TransformFeedback.CurrentObject;
   FLUSH_CURRENT(ctx, 0);

   if (count < 0) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glDrawArraysInstanced(count=%d)", count);
      return GL_FALSE;
   }

   if (first < 0) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glDrawArraysInstanced(start=%d)", first);
      return GL_FALSE;
   }

   if (!_mesa_valid_prim_mode(ctx, mode, "glDrawArraysInstanced")) {
      return GL_FALSE;
   }

   if (numInstances <= 0) {
      if (numInstances < 0)
         _mesa_error(ctx, GL_INVALID_VALUE,
                     "glDrawArraysInstanced(numInstances=%d)", numInstances);
      return GL_FALSE;
   }

   if (!check_valid_to_render(ctx, "glDrawArraysInstanced(invalid to render)"))
      return GL_FALSE;

   /* From the GLES3 specification, section 2.14.2 (Transform Feedback
    * Primitive Capture):
    *
    *   The error INVALID_OPERATION is generated by DrawArrays and
    *   DrawArraysInstanced if recording the vertices of a primitive to the
    *   buffer objects being used for transform feedback purposes would result
    *   in either exceeding the limits of any buffer object’s size, or in
    *   exceeding the end position offset + size − 1, as set by
    *   BindBufferRange.
    *
    * This is in contrast to the behaviour of desktop GL, where the extra
    * primitives are silently dropped from the transform feedback buffer.
    */
   if (_mesa_is_gles3(ctx) && _mesa_is_xfb_active_and_unpaused(ctx)) {
      size_t prim_count
         = vbo_count_tessellated_primitives(mode, count, numInstances);
      if (xfb_obj->GlesRemainingPrims < prim_count) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glDrawArraysInstanced(exceeds transform feedback size)");
         return GL_FALSE;
      }
      xfb_obj->GlesRemainingPrims -= prim_count;
   }

   if (count == 0)
      return GL_FALSE;

   return GL_TRUE;
}

//.........这里部分代码省略.........
    * to a lack of defined mapping from integer data to gl_Color fragment shader
    * input), NVIDIA's implementation also just returns this error despite
    * exposing GL_EXT_texture_integer, just return an error regardless.
    */
   if (_mesa_is_enum_format_integer(format)) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glDrawPixels(integer format)");
      goto end;
   }

   err = _mesa_error_check_format_and_type(ctx, format, type);
   if (err != GL_NO_ERROR) {
      _mesa_error(ctx, err, "glDrawPixels(invalid format %s and/or type %s)",
                  _mesa_lookup_enum_by_nr(format),
                  _mesa_lookup_enum_by_nr(type));
      goto end;
   }

   /* do special format-related checks */
   switch (format) {
   case GL_STENCIL_INDEX:
   case GL_DEPTH_COMPONENT:
   case GL_DEPTH_STENCIL_EXT:
      /* these buffers must exist */
      if (!_mesa_dest_buffer_exists(ctx, format)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glDrawPixels(missing deest buffer)");
         goto end;
      }
      break;
   case GL_COLOR_INDEX:
      if (ctx->PixelMaps.ItoR.Size == 0 ||
          ctx->PixelMaps.ItoG.Size == 0 ||
          ctx->PixelMaps.ItoB.Size == 0) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                "glDrawPixels(drawing color index pixels into RGB buffer)");
         goto end;
      }
      break;
   default:
      /* for color formats it's not an error if the destination color
       * buffer doesn't exist.
       */
      break;
   }

   if (ctx->RasterDiscard) {
      goto end;
   }

   if (!ctx->Current.RasterPosValid) {
      goto end;  /* no-op, not an error */
   }

   if (ctx->RenderMode == GL_RENDER) {
      if (width > 0 && height > 0) {
         /* Round, to satisfy conformance tests (matches SGI's OpenGL) */
         GLint x = IROUND(ctx->Current.RasterPos[0]);
         GLint y = IROUND(ctx->Current.RasterPos[1]);

         if (_mesa_is_bufferobj(ctx->Unpack.BufferObj)) {
            /* unpack from PBO */
            if (!_mesa_validate_pbo_access(2, &ctx->Unpack, width, height,
                                           1, format, type, INT_MAX, pixels)) {
               _mesa_error(ctx, GL_INVALID_OPERATION,
                           "glDrawPixels(invalid PBO access)");
               goto end;
            }
            if (_mesa_bufferobj_mapped(ctx->Unpack.BufferObj)) {
               /* buffer is mapped - that's an error */
               _mesa_error(ctx, GL_INVALID_OPERATION,
                           "glDrawPixels(PBO is mapped)");
               goto end;
            }
         }

         ctx->Driver.DrawPixels(ctx, x, y, width, height, format, type,
                                &ctx->Unpack, pixels);
      }
   }
   else if (ctx->RenderMode == GL_FEEDBACK) {
      /* Feedback the current raster pos info */
      FLUSH_CURRENT( ctx, 0 );
      _mesa_feedback_token( ctx, (GLfloat) (GLint) GL_DRAW_PIXEL_TOKEN );
      _mesa_feedback_vertex( ctx,
                             ctx->Current.RasterPos,
                             ctx->Current.RasterColor,
                             ctx->Current.RasterTexCoords[0] );
   }
   else {
      ASSERT(ctx->RenderMode == GL_SELECT);
      /* Do nothing.  See OpenGL Spec, Appendix B, Corollary 6. */
   }

end:
   _mesa_set_vp_override(ctx, GL_FALSE);

   if (MESA_DEBUG_FLAGS & DEBUG_ALWAYS_FLUSH) {
      _mesa_flush(ctx);
   }
}

static void GLAPIENTRY
_mesa_Bitmap( GLsizei width, GLsizei height,
              GLfloat xorig, GLfloat yorig, GLfloat xmove, GLfloat ymove,
              const GLubyte *bitmap )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);

   if (width < 0 || height < 0) {
      _mesa_error( ctx, GL_INVALID_VALUE, "glBitmap(width or height < 0)" );
      return;
   }

   if (!ctx->Current.RasterPosValid) {
      return;    /* do nothing */
   }

   /* Note: this call does state validation */
   if (!_mesa_valid_to_render(ctx, "glBitmap")) {
      /* the error code was recorded */
      return;
   }

   if (ctx->RasterDiscard)
      return;

   if (ctx->RenderMode == GL_RENDER) {
      /* Truncate, to satisfy conformance tests (matches SGI's OpenGL). */
      if (width > 0 && height > 0) {
         const GLfloat epsilon = 0.0001F;
         GLint x = IFLOOR(ctx->Current.RasterPos[0] + epsilon - xorig);
         GLint y = IFLOOR(ctx->Current.RasterPos[1] + epsilon - yorig);

         if (_mesa_is_bufferobj(ctx->Unpack.BufferObj)) {
            /* unpack from PBO */
            if (!_mesa_validate_pbo_access(2, &ctx->Unpack, width, height,
                                           1, GL_COLOR_INDEX, GL_BITMAP,
                                           INT_MAX, (const GLvoid *) bitmap)) {
               _mesa_error(ctx, GL_INVALID_OPERATION,
                           "glBitmap(invalid PBO access)");
               return;
            }
            if (_mesa_bufferobj_mapped(ctx->Unpack.BufferObj)) {
               /* buffer is mapped - that's an error */
               _mesa_error(ctx, GL_INVALID_OPERATION,
                           "glBitmap(PBO is mapped)");
               return;
            }
         }

         ctx->Driver.Bitmap( ctx, x, y, width, height, &ctx->Unpack, bitmap );
      }
   }
#if _HAVE_FULL_GL
   else if (ctx->RenderMode == GL_FEEDBACK) {
      FLUSH_CURRENT(ctx, 0);
      _mesa_feedback_token( ctx, (GLfloat) (GLint) GL_BITMAP_TOKEN );
      _mesa_feedback_vertex( ctx,
                             ctx->Current.RasterPos,
                             ctx->Current.RasterColor,
                             ctx->Current.RasterTexCoords[0] );
   }
   else {
      ASSERT(ctx->RenderMode == GL_SELECT);
      /* Do nothing.  See OpenGL Spec, Appendix B, Corollary 6. */
   }
#endif

   /* update raster position */
   ctx->Current.RasterPos[0] += xmove;
   ctx->Current.RasterPos[1] += ymove;

   if (MESA_DEBUG_FLAGS & DEBUG_ALWAYS_FLUSH) {
      _mesa_flush(ctx);
   }
}

void GLAPIENTRY
_mesa_CopyPixels( GLint srcx, GLint srcy, GLsizei width, GLsizei height,
                  GLenum type )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);

   if (ctx->NewState) {
      _mesa_update_state(ctx);
   }

   if (ctx->FragmentProgram.Enabled && !ctx->FragmentProgram._Enabled) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glCopyPixels (invalid fragment program)");
      return;
   }

   if (width < 0 || height < 0) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glCopyPixels(width or height < 0)");
      return;
   }

   if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT ||
       ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
                  "glCopyPixels(incomplete framebuffer)" );
      return;
   }

   if (!_mesa_source_buffer_exists(ctx, type) ||
       !_mesa_dest_buffer_exists(ctx, type)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glCopyPixels(missing source or dest buffer)");
      return;
   }

   if (!ctx->Current.RasterPosValid) {
      return;
   }

   if (ctx->RenderMode == GL_RENDER) {
      /* Round to satisfy conformance tests (matches SGI's OpenGL) */
      GLint destx = IROUND(ctx->Current.RasterPos[0]);
      GLint desty = IROUND(ctx->Current.RasterPos[1]);
      ctx->Driver.CopyPixels( ctx, srcx, srcy, width, height, destx, desty,
			      type );
   }
   else if (ctx->RenderMode == GL_FEEDBACK) {
      FLUSH_CURRENT( ctx, 0 );
      FEEDBACK_TOKEN( ctx, (GLfloat) (GLint) GL_COPY_PIXEL_TOKEN );
      _mesa_feedback_vertex( ctx, 
                             ctx->Current.RasterPos,
                             ctx->Current.RasterColor,
                             ctx->Current.RasterIndex,
                             ctx->Current.RasterTexCoords[0] );
   }
   else {
      ASSERT(ctx->RenderMode == GL_SELECT);
      /* Do nothing.  See OpenGL Spec, Appendix B, Corollary 6. */
   }
}

/**
 * New in GL 3.0
 * Clear unsigned integer color buffer (not depth, not stencil).
 */
void GLAPIENTRY
_mesa_ClearBufferuiv(GLenum buffer, GLint drawbuffer, const GLuint *value)
{
    GET_CURRENT_CONTEXT(ctx);

    FLUSH_VERTICES(ctx, 0);
    FLUSH_CURRENT(ctx, 0);

    if (ctx->NewState) {
        _mesa_update_state( ctx );
    }

    switch (buffer) {
    case GL_COLOR:
    {
        const GLbitfield mask = make_color_buffer_mask(ctx, drawbuffer);
        if (mask == INVALID_MASK) {
            _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferuiv(drawbuffer=%d)",
                        drawbuffer);
            return;
        }
        else if (mask && !ctx->RasterDiscard) {
            union gl_color_union clearSave;

            /* save color */
            clearSave = ctx->Color.ClearColor;
            /* set color */
            COPY_4V(ctx->Color.ClearColor.ui, value);
            /* clear buffer(s) */
            ctx->Driver.Clear(ctx, mask);
            /* restore color */
            ctx->Color.ClearColor = clearSave;
        }
    }
    break;
    case GL_DEPTH:
    case GL_STENCIL:
        /* Page 264 (page 280 of the PDF) of the OpenGL 3.0 spec says:
         *
         *     "The result of ClearBuffer is undefined if no conversion between
         *     the type of the specified value and the type of the buffer being
         *     cleared is defined (for example, if ClearBufferiv is called for a
         *     fixed- or floating-point buffer, or if ClearBufferfv is called
         *     for a signed or unsigned integer buffer). This is not an error."
         *
         * In this case we take "undefined" and "not an error" to mean "ignore."
         * Even though we could do something sensible for GL_STENCIL, page 263
         * (page 279 of the PDF) says:
         *
         *     "Only ClearBufferiv should be used to clear stencil buffers."
         *
         * Note that we still need to generate an error for the invalid
         * drawbuffer case (see the GL_STENCIL case in _mesa_ClearBufferiv).
         */
        if (drawbuffer != 0) {
            _mesa_error(ctx, GL_INVALID_VALUE, "glClearBufferuiv(drawbuffer=%d)",
                        drawbuffer);
            return;
        }
        return;
    default:
        _mesa_error(ctx, GL_INVALID_ENUM, "glClearBufferuiv(buffer=%s)",
                    _mesa_lookup_enum_by_nr(buffer));
        return;
    }
}

void GLAPIENTRY
_mesa_Bitmap( GLsizei width, GLsizei height,
              GLfloat xorig, GLfloat yorig, GLfloat xmove, GLfloat ymove,
              const GLubyte *bitmap )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);

   if (width < 0 || height < 0) {
      _mesa_error( ctx, GL_INVALID_VALUE, "glBitmap(width or height < 0)" );
      return;
   }

   if (!ctx->Current.RasterPosValid) {
      return;    /* do nothing */
   }

   if (ctx->NewState) {
      _mesa_update_state(ctx);
   }

   if (ctx->FragmentProgram.Enabled && !ctx->FragmentProgram._Enabled) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glBitmap (invalid fragment program)");
      return;
   }

   if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
                  "glBitmap(incomplete framebuffer)");
      return;
   }

   if (ctx->RenderMode == GL_RENDER) {
      if (bitmap) {
         /* Truncate, to satisfy conformance tests (matches SGI's OpenGL). */
         GLint x = IFLOOR(ctx->Current.RasterPos[0] - xorig);
         GLint y = IFLOOR(ctx->Current.RasterPos[1] - yorig);
         ctx->Driver.Bitmap( ctx, x, y, width, height, &ctx->Unpack, bitmap );
      }
   }
#if _HAVE_FULL_GL
   else if (ctx->RenderMode == GL_FEEDBACK) {
      FLUSH_CURRENT(ctx, 0);
      FEEDBACK_TOKEN( ctx, (GLfloat) (GLint) GL_BITMAP_TOKEN );
      _mesa_feedback_vertex( ctx,
                             ctx->Current.RasterPos,
                             ctx->Current.RasterColor,
                             ctx->Current.RasterIndex, 
                             ctx->Current.RasterTexCoords[0] );
   }
   else {
      ASSERT(ctx->RenderMode == GL_SELECT);
      /* Do nothing.  See OpenGL Spec, Appendix B, Corollary 6. */
   }
#endif

   /* update raster position */
   ctx->Current.RasterPos[0] += xmove;
   ctx->Current.RasterPos[1] += ymove;
}

GLboolean
_mesa_validate_DrawElementsInstanced(struct gl_context *ctx,
                                     GLenum mode, GLsizei count, GLenum type,
                                     const GLvoid *indices, GLsizei numInstances,
                                     GLint basevertex)
{
   FLUSH_CURRENT(ctx, 0);

   /* From the GLES3 specification, section 2.14.2 (Transform Feedback
    * Primitive Capture):
    *
    *   The error INVALID_OPERATION is also generated by DrawElements,
    *   DrawElementsInstanced, and DrawRangeElements while transform feedback
    *   is active and not paused, regardless of mode.
    */
   if (_mesa_is_gles3(ctx) && _mesa_is_xfb_active_and_unpaused(ctx)) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glDrawElements(transform feedback active)");
      return GL_FALSE;
   }

   if (count <= 0) {
      if (count < 0)
	 _mesa_error(ctx, GL_INVALID_VALUE,
                     "glDrawElementsInstanced(count=%d)", count);
      return GL_FALSE;
   }

   if (!_mesa_valid_prim_mode(ctx, mode, "glDrawElementsInstanced")) {
      return GL_FALSE;
   }

   if (!valid_elements_type(ctx, type, "glDrawElementsInstanced"))
      return GL_FALSE;

   if (numInstances <= 0) {
      if (numInstances < 0)
         _mesa_error(ctx, GL_INVALID_VALUE,
                     "glDrawElementsInstanced(numInstances=%d)", numInstances);
      return GL_FALSE;
   }

   if (!check_valid_to_render(ctx, "glDrawElementsInstanced"))
      return GL_FALSE;

   /* Vertex buffer object tests */
   if (_mesa_is_bufferobj(ctx->Array.ArrayObj->ElementArrayBufferObj)) {
      /* use indices in the buffer object */
      /* make sure count doesn't go outside buffer bounds */
      if (index_bytes(type, count) > ctx->Array.ArrayObj->ElementArrayBufferObj->Size) {
         _mesa_warning(ctx,
                       "glDrawElementsInstanced index out of buffer bounds");
         return GL_FALSE;
      }
   }
   else {
      /* not using a VBO */
      if (!indices)
         return GL_FALSE;
   }

   if (!check_index_bounds(ctx, count, type, indices, basevertex))
      return GL_FALSE;

   return GL_TRUE;
}

void GLAPIENTRY
_mesa_ReadnPixelsARB( GLint x, GLint y, GLsizei width, GLsizei height,
		      GLenum format, GLenum type, GLsizei bufSize,
                      GLvoid *pixels )
{
   GET_CURRENT_CONTEXT(ctx);
   ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);

   FLUSH_CURRENT(ctx, 0);

   if (MESA_VERBOSE & VERBOSE_API)
      _mesa_debug(ctx, "glReadPixels(%d, %d, %s, %s, %p)\n",
                  width, height,
                  _mesa_lookup_enum_by_nr(format),
                  _mesa_lookup_enum_by_nr(type),
                  pixels);

   if (width < 0 || height < 0) {
      _mesa_error( ctx, GL_INVALID_VALUE,
                   "glReadPixels(width=%d height=%d)", width, height );
      return;
   }

   if (ctx->NewState)
      _mesa_update_state(ctx);

   if (_mesa_error_check_format_type(ctx, format, type, GL_FALSE)) {
      /* found an error */
      return;
   }

   /* Check that the destination format and source buffer are both
    * integer-valued or both non-integer-valued.
    */
   if (ctx->Extensions.EXT_texture_integer && _mesa_is_color_format(format)) {
      const struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
      const GLboolean srcInteger = _mesa_is_format_integer_color(rb->Format);
      const GLboolean dstInteger = _mesa_is_integer_format(format);
      if (dstInteger != srcInteger) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glReadPixels(integer / non-integer format mismatch");
         return;
      }
   }

   if (ctx->ReadBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
      _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
                  "glReadPixels(incomplete framebuffer)" );
      return;
   }

   if (ctx->ReadBuffer->Name != 0 && ctx->ReadBuffer->Visual.samples > 0) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glReadPixels(multisample FBO)");
      return;
   }

   if (!_mesa_source_buffer_exists(ctx, format)) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glReadPixels(no readbuffer)");
      return;
   }

   if (width == 0 || height == 0)
      return; /* nothing to do */

   if (!_mesa_validate_pbo_access(2, &ctx->Pack, width, height, 1,
                                  format, type, bufSize, pixels)) {
      if (_mesa_is_bufferobj(ctx->Pack.BufferObj)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glReadPixels(out of bounds PBO access)");
      } else {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glReadnPixelsARB(out of bounds access:"
                     " bufSize (%d) is too small)", bufSize);
      }
      return;
   }

   if (_mesa_is_bufferobj(ctx->Pack.BufferObj) &&
       _mesa_bufferobj_mapped(ctx->Pack.BufferObj)) {
      /* buffer is mapped - that's an error */
      _mesa_error(ctx, GL_INVALID_OPERATION, "glReadPixels(PBO is mapped)");
      return;
   }

   ctx->Driver.ReadPixels(ctx, x, y, width, height,
			  format, type, &ctx->Pack, pixels);
}

/**
 * Clear buffers.
 *
 * \param mask bit-mask indicating the buffers to be cleared.
 *
 * Flushes the vertices and verifies the parameter. If __struct gl_contextRec::NewState
 * is set then calls _mesa_update_state() to update gl_frame_buffer::_Xmin,
 * etc. If the rasterization mode is set to GL_RENDER then requests the driver
 * to clear the buffers, via the dd_function_table::Clear callback.
 */
void GLAPIENTRY
_mesa_Clear( GLbitfield mask )
{
    GET_CURRENT_CONTEXT(ctx);
    FLUSH_VERTICES(ctx, 0);

    FLUSH_CURRENT(ctx, 0);

    if (MESA_VERBOSE & VERBOSE_API)
        _mesa_debug(ctx, "glClear 0x%x\n", mask);

    if (mask & ~(GL_COLOR_BUFFER_BIT |
                 GL_DEPTH_BUFFER_BIT |
                 GL_STENCIL_BUFFER_BIT |
                 GL_ACCUM_BUFFER_BIT)) {
        /* invalid bit set */
        _mesa_error( ctx, GL_INVALID_VALUE, "glClear(0x%x)", mask);
        return;
    }

    /* Accumulation buffers were removed in core contexts, and they never
     * existed in OpenGL ES.
     */
    if ((mask & GL_ACCUM_BUFFER_BIT) != 0
            && (ctx->API == API_OPENGL_CORE || _mesa_is_gles(ctx))) {
        _mesa_error( ctx, GL_INVALID_VALUE, "glClear(GL_ACCUM_BUFFER_BIT)");
        return;
    }

    if (ctx->NewState) {
        _mesa_update_state( ctx );	/* update _Xmin, etc */
    }

    if (ctx->DrawBuffer->_Status != GL_FRAMEBUFFER_COMPLETE_EXT) {
        _mesa_error(ctx, GL_INVALID_FRAMEBUFFER_OPERATION_EXT,
                    "glClear(incomplete framebuffer)");
        return;
    }

    if (ctx->DrawBuffer->Width == 0 || ctx->DrawBuffer->Height == 0 ||
            ctx->DrawBuffer->_Xmin >= ctx->DrawBuffer->_Xmax ||
            ctx->DrawBuffer->_Ymin >= ctx->DrawBuffer->_Ymax)
        return;

    if (ctx->RasterDiscard)
        return;

    if (ctx->RenderMode == GL_RENDER) {
        GLbitfield bufferMask;

        /* don't clear depth buffer if depth writing disabled */
        if (!ctx->Depth.Mask)
            mask &= ~GL_DEPTH_BUFFER_BIT;

        /* Build the bitmask to send to device driver's Clear function.
         * Note that the GL_COLOR_BUFFER_BIT flag will expand to 0, 1, 2 or 4
         * of the BUFFER_BIT_FRONT/BACK_LEFT/RIGHT flags, or one of the
         * BUFFER_BIT_COLORn flags.
         */
        bufferMask = 0;
        if (mask & GL_COLOR_BUFFER_BIT) {
            GLuint i;
            for (i = 0; i < ctx->