[mesa.git] / src / mesa / main / uniform_query.cpp

/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 2004-2008  Brian Paul   All Rights Reserved.
 * Copyright (C) 2009-2010  VMware, Inc.  All Rights Reserved.
 * Copyright © 2010, 2011 Intel Corporation
 *
 * 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
 * BRIAN PAUL 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.
 */

#include <stdlib.h>

#include "main/core.h"
#include "main/context.h"
#include "ir.h"
#include "ir_uniform.h"
#include "program/hash_table.h"
#include "../glsl/program.h"
#include "../glsl/ir_uniform.h"
#include "main/shaderapi.h"
#include "main/shaderobj.h"
#include "uniforms.h"


extern "C" void GLAPIENTRY
_mesa_GetActiveUniform(GLhandleARB program, GLuint index,
                          GLsizei maxLength, GLsizei *length, GLint *size,
                          GLenum *type, GLcharARB *nameOut)
{
   GET_CURRENT_CONTEXT(ctx);
   struct gl_shader_program *shProg =
      _mesa_lookup_shader_program_err(ctx, program, "glGetActiveUniform");

   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (!shProg)
      return;

   if (index >= shProg->NumUserUniformStorage) {
      _mesa_error(ctx, GL_INVALID_VALUE, "glGetActiveUniform(index)");
      return;
   }

   const struct gl_uniform_storage *const uni = &shProg->UniformStorage[index];

   if (nameOut) {
      _mesa_get_uniform_name(uni, maxLength, length, nameOut);
   }

   if (size) {
      /* array_elements is zero for non-arrays, but the API requires that 1 be
       * returned.
       */
      *size = MAX2(1, uni->array_elements);
   }

   if (type) {
      *type = uni->type->gl_type;
   }
}

extern "C" void GLAPIENTRY
_mesa_GetActiveUniformsiv(GLuint program,
                          GLsizei uniformCount,
                          const GLuint *uniformIndices,
                          GLenum pname,
                          GLint *params)
{
   GET_CURRENT_CONTEXT(ctx);
   struct gl_shader_program *shProg;
   GLsizei i;

   shProg = _mesa_lookup_shader_program_err(ctx, program, "glGetActiveUniform");
   if (!shProg)
      return;

   if (uniformCount < 0) {
      _mesa_error(ctx, GL_INVALID_VALUE,
                  "glGetUniformIndices(uniformCount < 0)");
      return;
   }

   for (i = 0; i < uniformCount; i++) {
      GLuint index = uniformIndices[i];

      if (index >= shProg->NumUserUniformStorage) {
         _mesa_error(ctx, GL_INVALID_VALUE, "glGetActiveUniformsiv(index)");
         return;
      }
   }

   for (i = 0; i < uniformCount; i++) {
      GLuint index = uniformIndices[i];
      const struct gl_uniform_storage *uni = &shProg->UniformStorage[index];

      switch (pname) {
      case GL_UNIFORM_TYPE:
         params[i] = uni->type->gl_type;
         break;

      case GL_UNIFORM_SIZE:
         /* array_elements is zero for non-arrays, but the API requires that 1 be
          * returned.
          */
         params[i] = MAX2(1, uni->array_elements);
         break;

      case GL_UNIFORM_NAME_LENGTH:
         params[i] = strlen(uni->name) + 1;

         /* Page 61 (page 73 of the PDF) in section 2.11 of the OpenGL ES 3.0
          * spec says:
          *
          *     "If the active uniform is an array, the uniform name returned
          *     in name will always be the name of the uniform array appended
          *     with "[0]"."
          */
         if (uni->array_elements != 0)
            params[i] += 3;
         break;

      case GL_UNIFORM_BLOCK_INDEX:
         params[i] = uni->block_index;
         break;

      case GL_UNIFORM_OFFSET:
         params[i] = uni->offset;
         break;

      case GL_UNIFORM_ARRAY_STRIDE:
         params[i] = uni->array_stride;
         break;

      case GL_UNIFORM_MATRIX_STRIDE:
         params[i] = uni->matrix_stride;
         break;

      case GL_UNIFORM_IS_ROW_MAJOR:
         params[i] = uni->row_major;
         break;

      default:
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetActiveUniformsiv(pname)");
         return;
      }
   }
}

static bool
validate_uniform_parameters(struct gl_context *ctx,
                            struct gl_shader_program *shProg,
                            GLint location, GLsizei count,
                            unsigned *loc,
                            unsigned *array_index,
                            const char *caller,
                            bool negative_one_is_not_valid)
{
   if (!shProg || !shProg->LinkStatus) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "%s(program not linked)", caller);
      return false;
   }

   if (location == -1) {
      /* For glGetUniform, page 264 (page 278 of the PDF) of the OpenGL 2.1
       * spec says:
       *
       *     "The error INVALID_OPERATION is generated if program has not been
       *     linked successfully, or if location is not a valid location for
       *     program."
       *
       * For glUniform, page 82 (page 96 of the PDF) of the OpenGL 2.1 spec
       * says:
       *
       *     "If the value of location is -1, the Uniform* commands will
       *     silently ignore the data passed in, and the current uniform
       *     values will not be changed."
       *
       * Allowing -1 for the location parameter of glUniform allows
       * applications to avoid error paths in the case that, for example, some
       * uniform variable is removed by the compiler / linker after
       * optimization.  In this case, the new value of the uniform is dropped
       * on the floor.  For the case of glGetUniform, there is nothing
       * sensible to do for a location of -1.
       *
       * The negative_one_is_not_valid flag selects between the two behaviors.
       */
      if (negative_one_is_not_valid) {
         _mesa_error(ctx, GL_INVALID_OPERATION, "%s(location=%d)",
                     caller, location);
      }

      return false;
   }

   /* From page 12 (page 26 of the PDF) of the OpenGL 2.1 spec:
    *
    *     "If a negative number is provided where an argument of type sizei or
    *     sizeiptr is specified, the error INVALID_VALUE is generated."
    */
   if (count < 0) {
      _mesa_error(ctx, GL_INVALID_VALUE, "%s(count < 0)", caller);
      return false;
   }

   /* Page 82 (page 96 of the PDF) of the OpenGL 2.1 spec says:
    *
    *     "If any of the following conditions occur, an INVALID_OPERATION
    *     error is generated by the Uniform* commands, and no uniform values
    *     are changed:
    *
    *     ...
    *
    *         - if no variable with a location of location exists in the
    *           program object currently in use and location is not -1,
    *         - if count is greater than one, and the uniform declared in the
    *           shader is not an array variable,
    */
   if (location < -1) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "%s(location=%d)",
                  caller, location);
      return false;
   }

   _mesa_uniform_split_location_offset(location, loc, array_index);

   if (*loc >= shProg->NumUserUniformStorage) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "%s(location=%d)",
                  caller, location);
      return false;
   }

   if (shProg->UniformStorage[*loc].array_elements == 0 && count > 1) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "%s(count > 1 for non-array, location=%d)",
                  caller, location);
      return false;
   }

   /* If the uniform is an array, check that array_index is in bounds.
    * If not an array, check that array_index is zero.
    * array_index is unsigned so no need to check for less than zero.
    */
   unsigned limit = shProg->UniformStorage[*loc].array_elements;
   if (limit == 0)
      limit = 1;
   if (*array_index >= limit) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "%s(location=%d)",
                  caller, location);
      return false;
   }
   return true;
}

/**
 * Called via glGetUniform[fiui]v() to get the current value of a uniform.
 */
extern "C" void
_mesa_get_uniform(struct gl_context *ctx, GLuint program, GLint location,
                  GLsizei bufSize, enum glsl_base_type returnType,
                  GLvoid *paramsOut)
{
   struct gl_shader_program *shProg =
      _mesa_lookup_shader_program_err(ctx, program, "glGetUniformfv");
   struct gl_uniform_storage *uni;
   unsigned loc, offset;

   if (!validate_uniform_parameters(ctx, shProg, location, 1,
                                    &loc, &offset, "glGetUniform", true))
      return;

   uni = &shProg->UniformStorage[loc];

   {
      unsigned elements = (uni->type->is_sampler())
         ? 1 : uni->type->components();

      /* Calculate the source base address *BEFORE* modifying elements to
       * account for the size of the user's buffer.
       */
      const union gl_constant_value *const src =
         &uni->storage[offset * elements];

      assert(returnType == GLSL_TYPE_FLOAT || returnType == GLSL_TYPE_INT ||
             returnType == GLSL_TYPE_UINT);
      /* The three (currently) supported types all have the same size,
       * which is of course the same as their union. That'll change
       * with glGetUniformdv()...
       */
      unsigned bytes = sizeof(src[0]) * elements;
      if (bufSize < 0 || bytes > (unsigned) bufSize) {
         _mesa_error( ctx, GL_INVALID_OPERATION,
                     "glGetnUniform*vARB(out of bounds: bufSize is %d,"
                     " but %u bytes are required)", bufSize, bytes );
         return;
      }

      /* If the return type and the uniform's native type are "compatible,"
       * just memcpy the data.  If the types are not compatible, perform a
       * slower convert-and-copy process.
       */
      if (returnType == uni->type->base_type
          || ((returnType == GLSL_TYPE_INT
               || returnType == GLSL_TYPE_UINT
               || returnType == GLSL_TYPE_SAMPLER)
              &&
              (uni->type->base_type == GLSL_TYPE_INT
               || uni->type->base_type == GLSL_TYPE_UINT
               || uni->type->base_type == GLSL_TYPE_SAMPLER))) {
         memcpy(paramsOut, src, bytes);
      } else {
         union gl_constant_value *const dst =
            (union gl_constant_value *) paramsOut;

         /* This code could be optimized by putting the loop inside the switch
          * statements.  However, this is not expected to be
          * performance-critical code.
          */
         for (unsigned i = 0; i < elements; i++) {
            switch (returnType) {
            case GLSL_TYPE_FLOAT:
               switch (uni->type->base_type) {
               case GLSL_TYPE_UINT:
                  dst[i].f = (float) src[i].u;
                  break;
               case GLSL_TYPE_INT:
               case GLSL_TYPE_SAMPLER:
                  dst[i].f = (float) src[i].i;
                  break;
               case GLSL_TYPE_BOOL:
                  dst[i].f = src[i].i ? 1.0f : 0.0f;
                  break;
               default:
                  assert(!"Should not get here.");
                  break;
               }
               break;

            case GLSL_TYPE_INT:
            case GLSL_TYPE_UINT:
               switch (uni->type->base_type) {
               case GLSL_TYPE_FLOAT:
                  /* While the GL 3.2 core spec doesn't explicitly
                   * state how conversion of float uniforms to integer
                   * values works, in section 6.2 "State Tables" on
                   * page 267 it says:
                   *
                   *     "Unless otherwise specified, when floating
                   *      point state is returned as integer values or
                   *      integer state is returned as floating-point
                   *      values it is converted in the fashion
                   *      described in section 6.1.2"
                   *
                   * That section, on page 248, says:
                   *
                   *     "If GetIntegerv or GetInteger64v are called,
                   *      a floating-point value is rounded to the
                   *      nearest integer..."
                   */
                  dst[i].i = IROUND(src[i].f);
                  break;
               case GLSL_TYPE_BOOL:
                  dst[i].i = src[i].i ? 1 : 0;
                  break;
               default:
                  assert(!"Should not get here.");
                  break;
               }
               break;

            default:
               assert(!"Should not get here.");
               break;
            }
         }
      }
   }
}

static void
log_uniform(const void *values, enum glsl_base_type basicType,
            unsigned rows, unsigned cols, unsigned count,
            bool transpose,
            const struct gl_shader_program *shProg,
            GLint location,
            const struct gl_uniform_storage *uni)
{

   const union gl_constant_value *v = (const union gl_constant_value *) values;
   const unsigned elems = rows * cols * count;
   const char *const extra = (cols == 1) ? "uniform" : "uniform matrix";

   printf("Mesa: set program %u %s \"%s\" (loc %d, type \"%s\", "
          "transpose = %s) to: ",
          shProg->Name, extra, uni->name, location, uni->type->name,
          transpose ? "true" : "false");
   for (unsigned i = 0; i < elems; i++) {
      if (i != 0 && ((i % rows) == 0))
         printf(", ");

      switch (basicType) {
      case GLSL_TYPE_UINT:
         printf("%u ", v[i].u);
         break;
      case GLSL_TYPE_INT:
         printf("%d ", v[i].i);
         break;
      case GLSL_TYPE_FLOAT:
         printf("%g ", v[i].f);
         break;
      default:
         assert(!"Should not get here.");
         break;
      }
   }
   printf("\n");
   fflush(stdout);
}

#if 0
static void
log_program_parameters(const struct gl_shader_program *shProg)
{
   static const char *stages[] = {
      "vertex", "fragment", "geometry"
   };

   assert(Elements(stages) == MESA_SHADER_TYPES);

   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
      if (shProg->_LinkedShaders[i] == NULL)
         continue;

      const struct gl_program *const prog = shProg->_LinkedShaders[i]->Program;

      printf("Program %d %s shader parameters:\n",
             shProg->Name, stages[i]);
      for (unsigned j = 0; j < prog->Parameters->NumParameters; j++) {
         printf("%s: %p %f %f %f %f\n",
                prog->Parameters->Parameters[j].Name,
                prog->Parameters->ParameterValues[j],
                prog->Parameters->ParameterValues[j][0].f,
                prog->Parameters->ParameterValues[j][1].f,
                prog->Parameters->ParameterValues[j][2].f,
                prog->Parameters->ParameterValues[j][3].f);
      }
   }
   fflush(stdout);
}
#endif

/**
 * Propagate some values from uniform backing storage to driver storage
 *
 * Values propagated from uniform backing storage to driver storage
 * have all format / type conversions previously requested by the
 * driver applied.  This function is most often called by the
 * implementations of \c glUniform1f, etc. and \c glUniformMatrix2f,
 * etc.
 *
 * \param uni          Uniform whose data is to be propagated to driver storage
 * \param array_index  If \c uni is an array, this is the element of
 *                     the array to be propagated.
 * \param count        Number of array elements to propagate.
 */
extern "C" void
_mesa_propagate_uniforms_to_driver_storage(struct gl_uniform_storage *uni,
                                           unsigned array_index,
                                           unsigned count)
{
   unsigned i;

   /* vector_elements and matrix_columns can be 0 for samplers.
    */
   const unsigned components = MAX2(1, uni->type->vector_elements);
   const unsigned vectors = MAX2(1, uni->type->matrix_columns);

   /* Store the data in the driver's requested type in the driver's storage
    * areas.
    */
   unsigned src_vector_byte_stride = components * 4;

   for (i = 0; i < uni->num_driver_storage; i++) {
      struct gl_uniform_driver_storage *const store = &uni->driver_storage[i];
      uint8_t *dst = (uint8_t *) store->data;
      const unsigned extra_stride =
         store->element_stride - (vectors * store->vector_stride);
      const uint8_t *src =
         (uint8_t *) (&uni->storage[array_index * (components * vectors)].i);

#if 0
      printf("%s: %p[%d] components=%u vectors=%u count=%u vector_stride=%u "
             "extra_stride=%u\n",
             __func__, dst, array_index, components,
             vectors, count, store->vector_stride, extra_stride);
#endif

      dst += array_index * store->element_stride;

      switch (store->format) {
      case uniform_native:
      case uniform_bool_int_0_1: {
         unsigned j;
         unsigned v;

         for (j = 0; j < count; j++) {
            for (v = 0; v < vectors; v++) {
               memcpy(dst, src, src_vector_byte_stride);
               src += src_vector_byte_stride;
               dst += store->vector_stride;
            }

            dst += extra_stride;
         }
         break;
      }

      case uniform_int_float:
      case uniform_bool_float: {
         const int *isrc = (const int *) src;
         unsigned j;
         unsigned v;
         unsigned c;

         for (j = 0; j < count; j++) {
            for (v = 0; v < vectors; v++) {
               for (c = 0; c < components; c++) {
                  ((float *) dst)[c] = (float) *isrc;
                  isrc++;
               }

               dst += store->vector_stride;
            }

            dst += extra_stride;
         }
         break;
      }

      case uniform_bool_int_0_not0: {
         const int *isrc = (const int *) src;
         unsigned j;
         unsigned v;
         unsigned c;

         for (j = 0; j < count; j++) {
            for (v = 0; v < vectors; v++) {
               for (c = 0; c < components; c++) {
                  ((int *) dst)[c] = *isrc == 0 ? 0 : ~0;
                  isrc++;
               }

               dst += store->vector_stride;
            }

            dst += extra_stride;
         }
         break;
      }

      default:
         assert(!"Should not get here.");
         break;
      }
   }
}

/**
 * Called via glUniform*() functions.
 */
extern "C" void
_mesa_uniform(struct gl_context *ctx, struct gl_shader_program *shProg,
              GLint location, GLsizei count,
              const GLvoid *values, GLenum type)
{
   unsigned loc, offset;
   unsigned components;
   unsigned src_components;
   enum glsl_base_type basicType;
   struct gl_uniform_storage *uni;

   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (!validate_uniform_parameters(ctx, shProg, location, count,
                                    &loc, &offset, "glUniform", false))
      return;

   uni = &shProg->UniformStorage[loc];

   /* Verify that the types are compatible.
    */
   switch (type) {
   case GL_FLOAT:
      basicType = GLSL_TYPE_FLOAT;
      src_components = 1;
      break;
   case GL_FLOAT_VEC2:
      basicType = GLSL_TYPE_FLOAT;
      src_components = 2;
      break;
   case GL_FLOAT_VEC3:
      basicType = GLSL_TYPE_FLOAT;
      src_components = 3;
      break;
   case GL_FLOAT_VEC4:
      basicType = GLSL_TYPE_FLOAT;
      src_components = 4;
      break;
   case GL_UNSIGNED_INT:
      basicType = GLSL_TYPE_UINT;
      src_components = 1;
      break;
   case GL_UNSIGNED_INT_VEC2:
      basicType = GLSL_TYPE_UINT;
      src_components = 2;
      break;
   case GL_UNSIGNED_INT_VEC3:
      basicType = GLSL_TYPE_UINT;
      src_components = 3;
      break;
   case GL_UNSIGNED_INT_VEC4:
      basicType = GLSL_TYPE_UINT;
      src_components = 4;
      break;
   case GL_INT:
      basicType = GLSL_TYPE_INT;
      src_components = 1;
      break;
   case GL_INT_VEC2:
      basicType = GLSL_TYPE_INT;
      src_components = 2;
      break;
   case GL_INT_VEC3:
      basicType = GLSL_TYPE_INT;
      src_components = 3;
      break;
   case GL_INT_VEC4:
      basicType = GLSL_TYPE_INT;
      src_components = 4;
      break;
   case GL_BOOL:
   case GL_BOOL_VEC2:
   case GL_BOOL_VEC3:
   case GL_BOOL_VEC4:
   case GL_FLOAT_MAT2:
   case GL_FLOAT_MAT2x3:
   case GL_FLOAT_MAT2x4:
   case GL_FLOAT_MAT3x2:
   case GL_FLOAT_MAT3:
   case GL_FLOAT_MAT3x4:
   case GL_FLOAT_MAT4x2:
   case GL_FLOAT_MAT4x3:
   case GL_FLOAT_MAT4:
   default:
      _mesa_problem(NULL, "Invalid type in %s", __func__);
      return;
   }

   if (uni->type->is_sampler()) {
      components = 1;
   } else {
      components = uni->type->vector_elements;
   }

   bool match;
   switch (uni->type->base_type) {
   case GLSL_TYPE_BOOL:
      match = true;
      break;
   case GLSL_TYPE_SAMPLER:
      match = (basicType == GLSL_TYPE_INT);
      break;
   default:
      match = (basicType == uni->type->base_type);
      break;
   }

   if (uni->type->is_matrix() || components != src_components || !match) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glUniform(type mismatch)");
      return;
   }

   if (ctx->Shader.Flags & GLSL_UNIFORMS) {
      log_uniform(values, basicType, components, 1, count,
                  false, shProg, location, uni);
   }

   /* Page 100 (page 116 of the PDF) of the OpenGL 3.0 spec says:
    *
    *     "Setting a sampler's value to i selects texture image unit number
    *     i. The values of i range from zero to the implementation- dependent
    *     maximum supported number of texture image units."
    *
    * In addition, table 2.3, "Summary of GL errors," on page 17 (page 33 of
    * the PDF) says:
    *
    *     "Error         Description                    Offending command
    *                                                   ignored?
    *     ...
    *     INVALID_VALUE  Numeric argument out of range  Yes"
    *
    * Based on that, when an invalid sampler is specified, we generate a
    * GL_INVALID_VALUE error and ignore the command.
    */
   if (uni->type->is_sampler()) {
      int i;

      for (i = 0; i < count; i++) {
         const unsigned texUnit = ((unsigned *) values)[i];

         /* check that the sampler (tex unit index) is legal */
         if (texUnit >= ctx->Const.MaxCombinedTextureImageUnits) {
            _mesa_error(ctx, GL_INVALID_VALUE,
                        "glUniform1i(invalid sampler/tex unit index for "
                        "uniform %d)",
                        location);
            return;
         }
      }
   }

   /* Page 82 (page 96 of the PDF) of the OpenGL 2.1 spec says:
    *
    *     "When loading N elements starting at an arbitrary position k in a
    *     uniform declared as an array, elements k through k + N - 1 in the
    *     array will be replaced with the new values. Values for any array
    *     element that exceeds the highest array element index used, as
    *     reported by GetActiveUniform, will be ignored by the GL."
    *
    * Clamp 'count' to a valid value.  Note that for non-arrays a count > 1
    * will have already generated an error.
    */
   if (uni->array_elements != 0) {
      count = MIN2(count, (int) (uni->array_elements - offset));
   }

   FLUSH_VERTICES(ctx, _NEW_PROGRAM_CONSTANTS);

   /* Store the data in the "actual type" backing storage for the uniform.
    */
   if (!uni->type->is_boolean()) {
      memcpy(&uni->storage[components * offset], values,
             sizeof(uni->storage[0]) * components * count);
   } else {
      const union gl_constant_value *src =
         (const union gl_constant_value *) values;
      union gl_constant_value *dst = &uni->storage[components * offset];
      const unsigned elems = components * count;
      unsigned i;

      for (i = 0; i < elems; i++) {
         if (basicType == GLSL_TYPE_FLOAT) {
            dst[i].i = src[i].f != 0.0f ? 1 : 0;
         } else {
            dst[i].i = src[i].i != 0    ? 1 : 0;
         }
      }
   }

   uni->initialized = true;

   _mesa_propagate_uniforms_to_driver_storage(uni, offset, count);

   /* If the uniform is a sampler, do the extra magic necessary to propagate
    * the changes through.
    */
   if (uni->type->is_sampler()) {
      int i;

      for (i = 0; i < count; i++) {
         shProg->SamplerUnits[uni->sampler + offset + i] =
            ((unsigned *) values)[i];
      }

      bool flushed = false;
      for (i = 0; i < MESA_SHADER_TYPES; i++) {
         struct gl_shader *const sh = shProg->_LinkedShaders[i];

         /* If the shader stage doesn't use any samplers, don't bother
          * checking if any samplers have changed.
          */
         if (sh == NULL || sh->active_samplers == 0)
            continue;

         struct gl_program *const prog = sh->Program;

         assert(sizeof(prog->SamplerUnits) == sizeof(shProg->SamplerUnits));

         /* Determine if any of the samplers used by this shader stage have
          * been modified.
          */
         bool changed = false;
         for (unsigned j = 0; j < Elements(prog->SamplerUnits); j++) {
            if ((sh->active_samplers & (1U << j)) != 0
                && (prog->SamplerUnits[j] != shProg->SamplerUnits[j])) {
               changed = true;
               break;
            }
         }

         if (changed) {
            if (!flushed) {
               FLUSH_VERTICES(ctx, _NEW_TEXTURE | _NEW_PROGRAM);
               flushed = true;
            }

            memcpy(prog->SamplerUnits,
                   shProg->SamplerUnits,
                   sizeof(shProg->SamplerUnits));

            _mesa_update_shader_textures_used(shProg, prog);
            if (ctx->Driver.SamplerUniformChange)
               ctx->Driver.SamplerUniformChange(ctx, prog->Target, prog);
         }
      }
   }
}

/**
 * Called by glUniformMatrix*() functions.
 * Note: cols=2, rows=4  ==>  array[2] of vec4
 */
extern "C" void
_mesa_uniform_matrix(struct gl_context *ctx, struct gl_shader_program *shProg,
                     GLuint cols, GLuint rows,
                     GLint location, GLsizei count,
                     GLboolean transpose, const GLfloat *values)
{
   unsigned loc, offset;
   unsigned vectors;
   unsigned components;
   unsigned elements;
   struct gl_uniform_storage *uni;

   ASSERT_OUTSIDE_BEGIN_END(ctx);

   if (!validate_uniform_parameters(ctx, shProg, location, count,
                                    &loc, &offset, "glUniformMatrix", false))
      return;

   uni = &shProg->UniformStorage[loc];
   if (!uni->type->is_matrix()) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glUniformMatrix(non-matrix uniform)");
      return;
   }

   assert(!uni->type->is_sampler());
   vectors = uni->type->matrix_columns;
   components = uni->type->vector_elements;

   /* Verify that the types are compatible.  This is greatly simplified for
    * matrices because they can only have a float base type.
    */
   if (vectors != cols || components != rows) {
      _mesa_error(ctx, GL_INVALID_OPERATION,
                  "glUniformMatrix(matrix size mismatch)");
      return;
   }

   /* GL_INVALID_VALUE is generated if `transpose' is not GL_FALSE.
    * http://www.khronos.org/opengles/sdk/docs/man/xhtml/glUniform.xml */
   if (ctx->API == API_OPENGLES
       || (ctx->API == API_OPENGLES2 && ctx->Version < 30)) {
      if (transpose) {
         _mesa_error(ctx, GL_INVALID_VALUE,
                     "glUniformMatrix(matrix transpose is not GL_FALSE)");
         return;
      }
   }

   if (ctx->Shader.Flags & GLSL_UNIFORMS) {
      log_uniform(values, GLSL_TYPE_FLOAT, components, vectors, count,
                  bool(transpose), shProg, location, uni);
   }

   /* Page 82 (page 96 of the PDF) of the OpenGL 2.1 spec says:
    *
    *     "When loading N elements starting at an arbitrary position k in a
    *     uniform declared as an array, elements k through k + N - 1 in the
    *     array will be replaced with the new values. Values for any array
    *     element that exceeds the highest array element index used, as
    *     reported by GetActiveUniform, will be ignored by the GL."
    *
    * Clamp 'count' to a valid value.  Note that for non-arrays a count > 1
    * will have already generated an error.
    */
   if (uni->array_elements != 0) {
      count = MIN2(count, (int) (uni->array_elements - offset));
   }

   FLUSH_VERTICES(ctx, _NEW_PROGRAM_CONSTANTS);

   /* Store the data in the "actual type" backing storage for the uniform.
    */
   elements = components * vectors;

   if (!transpose) {
      memcpy(&uni->storage[elements * offset], values,
             sizeof(uni->storage[0]) * elements * count);
   } else {
      /* Copy and transpose the matrix.
       */
      const float *src = values;
      float *dst = &uni->storage[elements * offset].f;

      for (int i = 0; i < count; i++) {
         for (unsigned r = 0; r < rows; r++) {
            for (unsigned c = 0; c < cols; c++) {
               dst[(c * components) + r] = src[c + (r * vectors)];
            }
         }

         dst += elements;
         src += elements;
      }
   }

   uni->initialized = true;

   _mesa_propagate_uniforms_to_driver_storage(uni, offset, count);
}

/**
 * Called via glGetUniformLocation().
 *
 * Returns the uniform index into UniformStorage (also the
 * glGetActiveUniformsiv uniform index), and stores the referenced
 * array offset in *offset, or GL_INVALID_INDEX (-1).  Those two
 * return values can be encoded into a uniform location for
 * glUniform* using _mesa_uniform_merge_location_offset(index, offset).
 */
extern "C" unsigned
_mesa_get_uniform_location(struct gl_context *ctx,
                           struct gl_shader_program *shProg,
                           const GLchar *name,
                           unsigned *out_offset)
{
   const size_t len = strlen(name);
   long offset;
   bool array_lookup;
   char *name_copy;

   /* If the name ends with a ']', assume that it refers to some element of an
    * array.  Malformed array references will fail the hash table look up
    * below, so it doesn't matter that they are not caught here.  This code
    * only wants to catch the "leaf" array references so that arrays of
    * structures containing arrays will be handled correctly.
    */
   if (name[len-1] == ']') {
      unsigned i;

      /* Walk backwards over the string looking for a non-digit character.
       * This had better be the opening bracket for an array index.
       *
       * Initially, i specifies the location of the ']'.  Since the string may
       * contain only the ']' charcater, walk backwards very carefully.
       */
      for (i = len - 1; (i > 0) && isdigit(name[i-1]); --i)
         /* empty */ ;

      /* Page 80 (page 94 of the PDF) of the OpenGL 2.1 spec says:
       *
       *     "The first element of a uniform array is identified using the
       *     name of the uniform array appended with "[0]". Except if the last
       *     part of the string name indicates a uniform array, then the
       *     location of the first element of that array can be retrieved by
       *     either using the name of the uniform array, or the name of the
       *     uniform array appended with "[0]"."
       *
       * Page 79 (page 93 of the PDF) of the OpenGL 2.1 spec says:
       *
       *     "name must be a null terminated string, without white space."
       *
       * Return an error if there is no opening '[' to match the closing ']'.
       * An error will also be returned if there is intervening white space
       * (or other non-digit characters) before the opening '['.
       */
      if ((i == 0) || name[i-1] != '[')
         return GL_INVALID_INDEX;

      /* Return an error if there are no digits between the opening '[' to
       * match the closing ']'.
       */
      if (i == (len - 1))
         return GL_INVALID_INDEX;

      /* Make a new string that is a copy of the old string up to (but not
       * including) the '[' character.
       */
      name_copy = (char *) malloc(i);
      memcpy(name_copy, name, i - 1);
      name_copy[i-1] = '\0';

      offset = strtol(&name[i], NULL, 10);
      if (offset < 0) {
         free(name_copy);
         return GL_INVALID_INDEX;
      }

      array_lookup = true;
   } else {
      name_copy = (char *) name;
      offset = 0;
      array_lookup = false;
   }

   unsigned location = 0;
   const bool found = shProg->UniformHash->get(location, name_copy);

   assert(!found
          || strcmp(name_copy, shProg->UniformStorage[location].name) == 0);

   /* Free the temporary buffer *before* possibly returning an error.
    */
   if (name_copy != name)
      free(name_copy);

   if (!found)
      return GL_INVALID_INDEX;

   /* If the uniform is an array, fail if the index is out of bounds.
    * (A negative index is caught above.)  This also fails if the uniform
    * is not an array, but the user is trying to index it, because
    * array_elements is zero and offset >= 0.
    */
   if (array_lookup
       && offset >= (long) shProg->UniformStorage[location].array_elements) {
      return GL_INVALID_INDEX;
   }

   *out_offset = offset;
   return location;
}

extern "C" bool
_mesa_sampler_uniforms_are_valid(const struct gl_shader_program *shProg,
                                 char *errMsg, size_t errMsgLength)
{
   const glsl_type *unit_types[MAX_COMBINED_TEXTURE_IMAGE_UNITS];

   memset(unit_types, 0, sizeof(unit_types));

   for (unsigned i = 0; i < shProg->NumUserUniformStorage; i++) {
      const struct gl_uniform_storage *const storage =
         &shProg->UniformStorage[i];
      const glsl_type *const t = (storage->type->is_array())
         ? storage->type->fields.array : storage->type;

      if (!t->is_sampler())
         continue;

      const unsigned count = MAX2(1, storage->type->array_size());
      for (unsigned j = 0; j < count; j++) {
         const unsigned unit = storage->storage[j].i;

         /* The types of the samplers associated with a particular texture
          * unit must be an exact match.  Page 74 (page 89 of the PDF) of the
          * OpenGL 3.3 core spec says:
          *
          *     "It is not allowed to have variables of different sampler
          *     types pointing to the same texture image unit within a program
          *     object."
          */
         if (unit_types[unit] == NULL) {
            unit_types[unit] = t;
         } else if (unit_types[unit] != t) {
            _mesa_snprintf(errMsg, errMsgLength,
                           "Texture unit %d is accessed both as %s and %s",
                           unit, unit_types[unit]->name, t->name);
            return false;
         }
      }
   }

   return true;
}