/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
 * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
 *
 * 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.
 */

/** 
 * \file texenv.c
 *
 * glTexEnv-related functions
 */


#include "main/glheader.h"
#include "main/context.h"
#include "main/blend.h"
#include "main/enums.h"
#include "main/macros.h"
#include "main/mtypes.h"
#include "main/state.h"
#include "main/texenv.h"
#include "main/texstate.h"


#define TE_ERROR(errCode, msg, value)				\
   _mesa_error(ctx, errCode, msg, _mesa_enum_to_string(value));


/** Set texture env mode */
static void
set_env_mode(struct gl_context *ctx,
             struct gl_texture_unit *texUnit,
             GLenum mode)
{
   GLboolean legal;

   if (texUnit->EnvMode == mode)
      return;

   switch (mode) {
   case GL_MODULATE:
   case GL_BLEND:
   case GL_DECAL:
   case GL_REPLACE:
   case GL_ADD:
   case GL_COMBINE:
      legal = GL_TRUE;
      break;
   case GL_REPLACE_EXT:
      mode = GL_REPLACE; /* GL_REPLACE_EXT != GL_REPLACE */
      legal = GL_TRUE;
      break;
   case GL_COMBINE4_NV:
      legal = ctx->Extensions.NV_texture_env_combine4;
      break;
   default:
      legal = GL_FALSE;
   }

   if (legal) {
      FLUSH_VERTICES(ctx, _NEW_TEXTURE);
      texUnit->EnvMode = mode;
   }
   else {
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(param=%s)", mode);
   }
}


static void
set_env_color(struct gl_context *ctx,
              struct gl_texture_unit *texUnit,
              const GLfloat *color)
{
   if (TEST_EQ_4V(color, texUnit->EnvColorUnclamped))
      return;
   FLUSH_VERTICES(ctx, _NEW_TEXTURE);
   COPY_4FV(texUnit->EnvColorUnclamped, color);
   texUnit->EnvColor[0] = CLAMP(color[0], 0.0F, 1.0F);
   texUnit->EnvColor[1] = CLAMP(color[1], 0.0F, 1.0F);
   texUnit->EnvColor[2] = CLAMP(color[2], 0.0F, 1.0F);
   texUnit->EnvColor[3] = CLAMP(color[3], 0.0F, 1.0F);
}


/** Set an RGB or A combiner mode/function */
static void
set_combiner_mode(struct gl_context *ctx,
                  struct gl_texture_unit *texUnit,
                  GLenum pname, GLenum mode)
{
   GLboolean legal;

   switch (mode) {
   case GL_REPLACE:
   case GL_MODULATE:
   case GL_ADD:
   case GL_ADD_SIGNED:
   case GL_INTERPOLATE:
      legal = GL_TRUE;
      break;
   case GL_SUBTRACT:
      legal = ctx->Extensions.ARB_texture_env_combine;
      break;
   case GL_DOT3_RGB_EXT:
   case GL_DOT3_RGBA_EXT:
      legal = (ctx->API == API_OPENGL_COMPAT &&
               ctx->Extensions.EXT_texture_env_dot3 &&
               pname == GL_COMBINE_RGB);
      break;
   case GL_DOT3_RGB:
   case GL_DOT3_RGBA:
      legal = (ctx->Extensions.ARB_texture_env_dot3 &&
               pname == GL_COMBINE_RGB);
      break;
   case GL_MODULATE_ADD_ATI:
   case GL_MODULATE_SIGNED_ADD_ATI:
   case GL_MODULATE_SUBTRACT_ATI:
      legal = (ctx->API == API_OPENGL_COMPAT &&
               ctx->Extensions.ATI_texture_env_combine3);
      break;
   default:
      legal = GL_FALSE;
   }

   if (!legal) {
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(param=%s)", mode);
      return;
   }

   switch (pname) {
   case GL_COMBINE_RGB:
      if (texUnit->Combine.ModeRGB == mode)
         return;
      FLUSH_VERTICES(ctx, _NEW_TEXTURE);
      texUnit->Combine.ModeRGB = mode;
      break;

   case GL_COMBINE_ALPHA:
      if (texUnit->Combine.ModeA == mode)
         return;
      FLUSH_VERTICES(ctx, _NEW_TEXTURE);
      texUnit->Combine.ModeA = mode;
      break;
   default:
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
   }
}



/** Set an RGB or A combiner source term */
static void
set_combiner_source(struct gl_context *ctx,
                    struct gl_texture_unit *texUnit,
                    GLenum pname, GLenum param)
{
   GLuint term;
   GLboolean alpha, legal;

   /*
    * Translate pname to (term, alpha).
    *
    * The enums were given sequential values for a reason.
    */
   switch (pname) {
   case GL_SOURCE0_RGB:
   case GL_SOURCE1_RGB:
   case GL_SOURCE2_RGB:
   case GL_SOURCE3_RGB_NV:
      term = pname - GL_SOURCE0_RGB;
      alpha = GL_FALSE;
      break;
   case GL_SOURCE0_ALPHA:
   case GL_SOURCE1_ALPHA:
   case GL_SOURCE2_ALPHA:
   case GL_SOURCE3_ALPHA_NV:
      term = pname - GL_SOURCE0_ALPHA;
      alpha = GL_TRUE;
      break;
   default:
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
      return;
   }

   if ((term == 3) && (ctx->API != API_OPENGL_COMPAT
                       || !ctx->Extensions.NV_texture_env_combine4)) {
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
      return;
   }

   assert(term < MAX_COMBINER_TERMS);

   /*
    * Error-check param (the source term)
    */
   switch (param) {
   case GL_TEXTURE:
   case GL_CONSTANT:
   case GL_PRIMARY_COLOR:
   case GL_PREVIOUS:
      legal = GL_TRUE;
      break;
   case GL_TEXTURE0:
   case GL_TEXTURE1:
   case GL_TEXTURE2:
   case GL_TEXTURE3:
   case GL_TEXTURE4:
   case GL_TEXTURE5:
   case GL_TEXTURE6:
   case GL_TEXTURE7:
      legal = (ctx->Extensions.ARB_texture_env_crossbar &&
               param - GL_TEXTURE0 < ctx->Const.MaxTextureUnits);
      break;
   case GL_ZERO:
      legal = (ctx->API == API_OPENGL_COMPAT &&
               (ctx->Extensions.ATI_texture_env_combine3 ||
                ctx->Extensions.NV_texture_env_combine4));
      break;
   case GL_ONE:
      legal = (ctx->API == API_OPENGL_COMPAT &&
               ctx->Extensions.ATI_texture_env_combine3);
      break;
   default:
      legal = GL_FALSE;
   }

   if (!legal) {
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(param=%s)", param);
      return;
   }

   FLUSH_VERTICES(ctx, _NEW_TEXTURE);

   if (alpha)
      texUnit->Combine.SourceA[term] = param;
   else
      texUnit->Combine.SourceRGB[term] = param;
}


/** Set an RGB or A combiner operand term */
static void
set_combiner_operand(struct gl_context *ctx,
                     struct gl_texture_unit *texUnit,
                     GLenum pname, GLenum param)
{
   GLuint term;
   GLboolean alpha, legal;

   /* The enums were given sequential values for a reason.
    */
   switch (pname) {
   case GL_OPERAND0_RGB:
   case GL_OPERAND1_RGB:
   case GL_OPERAND2_RGB:
   case GL_OPERAND3_RGB_NV:
      term = pname - GL_OPERAND0_RGB;
      alpha = GL_FALSE;
      break;
   case GL_OPERAND0_ALPHA:
   case GL_OPERAND1_ALPHA:
   case GL_OPERAND2_ALPHA:
   case GL_OPERAND3_ALPHA_NV:
      term = pname - GL_OPERAND0_ALPHA;
      alpha = GL_TRUE;
      break;
   default:
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
      return;
   }

   if ((term == 3) && (ctx->API != API_OPENGL_COMPAT
                       || !ctx->Extensions.NV_texture_env_combine4)) {
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
      return;
   }

   assert(term < MAX_COMBINER_TERMS);

   /*
    * Error-check param (the source operand)
    */
   switch (param) {
   case GL_SRC_COLOR:
   case GL_ONE_MINUS_SRC_COLOR:
      /* The color input can only be used with GL_OPERAND[01]_RGB in the EXT
       * version.  In the ARB and NV versions and OpenGL ES 1.x they can be
       * used for any RGB operand.
       */
      legal = !alpha
	 && ((term < 2) || ctx->Extensions.ARB_texture_env_combine
	     || ctx->Extensions.NV_texture_env_combine4);
      break;
   case GL_ONE_MINUS_SRC_ALPHA:
      /* GL_ONE_MINUS_SRC_ALPHA can only be used with
       * GL_OPERAND[01]_(RGB|ALPHA) in the EXT version.  In the ARB and NV
       * versions and OpenGL ES 1.x it can be used for any operand.
       */
      legal = (term < 2) || ctx->Extensions.ARB_texture_env_combine
	 || ctx->Extensions.NV_texture_env_combine4;
      break;
   case GL_SRC_ALPHA:
      legal = GL_TRUE;
      break;
   default:
      legal = GL_FALSE;
   }

   if (!legal) {
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(param=%s)", param);
      return;
   }

   FLUSH_VERTICES(ctx, _NEW_TEXTURE);

   if (alpha)
      texUnit->Combine.OperandA[term] = param;
   else
      texUnit->Combine.OperandRGB[term] = param;
}


static void
set_combiner_scale(struct gl_context *ctx,
                   struct gl_texture_unit *texUnit,
                   GLenum pname, GLfloat scale)
{
   GLuint shift;

   if (scale == 1.0F) {
      shift = 0;
   }
   else if (scale == 2.0F) {
      shift = 1;
   }
   else if (scale == 4.0F) {
      shift = 2;
   }
   else {
      _mesa_error( ctx, GL_INVALID_VALUE,
                   "glTexEnv(GL_RGB_SCALE not 1, 2 or 4)" );
      return;
   }

   switch (pname) {
   case GL_RGB_SCALE:
      if (texUnit->Combine.ScaleShiftRGB == shift)
         return;
      FLUSH_VERTICES(ctx, _NEW_TEXTURE);
      texUnit->Combine.ScaleShiftRGB = shift;
      break;
   case GL_ALPHA_SCALE:
      if (texUnit->Combine.ScaleShiftA == shift)
         return;
      FLUSH_VERTICES(ctx, _NEW_TEXTURE);
      texUnit->Combine.ScaleShiftA = shift;
      break;
   default:
      TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
   }
}



void GLAPIENTRY
_mesa_TexEnvfv( GLenum target, GLenum pname, const GLfloat *param )
{
   const GLint iparam0 = (GLint) param[0];
   struct gl_texture_unit *texUnit;
   GLuint maxUnit;
   GET_CURRENT_CONTEXT(ctx);

   maxUnit = (target == GL_POINT_SPRITE_NV && pname == GL_COORD_REPLACE_NV)
      ? ctx->Const.MaxTextureCoordUnits : ctx->Const.MaxCombinedTextureImageUnits;
   if (ctx->Texture.CurrentUnit >= maxUnit) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glTexEnvfv(current unit)");
      return;
   }

   texUnit = _mesa_get_current_tex_unit(ctx);

   if (target == GL_TEXTURE_ENV) {
      switch (pname) {
      case GL_TEXTURE_ENV_MODE:
         set_env_mode(ctx, texUnit, (GLenum) iparam0);
         break;
      case GL_TEXTURE_ENV_COLOR:
         set_env_color(ctx, texUnit, param);
         break;
      case GL_COMBINE_RGB:
      case GL_COMBINE_ALPHA:
         set_combiner_mode(ctx, texUnit, pname, (GLenum) iparam0);
	 break;
      case GL_SOURCE0_RGB:
      case GL_SOURCE1_RGB:
      case GL_SOURCE2_RGB:
      case GL_SOURCE3_RGB_NV:
      case GL_SOURCE0_ALPHA:
      case GL_SOURCE1_ALPHA:
      case GL_SOURCE2_ALPHA:
      case GL_SOURCE3_ALPHA_NV:
         set_combiner_source(ctx, texUnit, pname, (GLenum) iparam0);
	 break;
      case GL_OPERAND0_RGB:
      case GL_OPERAND1_RGB:
      case GL_OPERAND2_RGB:
      case GL_OPERAND3_RGB_NV:
      case GL_OPERAND0_ALPHA:
      case GL_OPERAND1_ALPHA:
      case GL_OPERAND2_ALPHA:
      case GL_OPERAND3_ALPHA_NV:
         set_combiner_operand(ctx, texUnit, pname, (GLenum) iparam0);
	 break;
      case GL_RGB_SCALE:
      case GL_ALPHA_SCALE:
         set_combiner_scale(ctx, texUnit, pname, param[0]);
	 break;
      default:
	 _mesa_error( ctx, GL_INVALID_ENUM, "glTexEnv(pname)" );
	 return;
      }
   }
   else if (target == GL_TEXTURE_FILTER_CONTROL_EXT) {
      if (pname == GL_TEXTURE_LOD_BIAS_EXT) {
	 if (texUnit->LodBias == param[0])
	    return;
	 FLUSH_VERTICES(ctx, _NEW_TEXTURE);
         texUnit->LodBias = param[0];
      }
      else {
         TE_ERROR(GL_INVALID_ENUM, "glTexEnv(pname=%s)", pname);
	 return;
      }
   }
   else if (target == GL_POINT_SPRITE_NV) {
      /* GL_ARB_point_sprite / GL_NV_point_sprite */
      if (!ctx->Extensions.NV_point_sprite
	  && !ctx->Extensions.ARB_point_sprite) {
	 _mesa_error( ctx, GL_INVALID_ENUM, "glTexEnv(target=0x%x)", target );
	 return;
      }
      if (pname == GL_COORD_REPLACE_NV) {
         /* It's kind of weird to set point state via glTexEnv,
          * but that's what the spec calls for.
          */
         if (iparam0 == GL_TRUE) {
            if (ctx->Point.CoordReplaceBits & (1u << ctx->Texture.CurrentUnit))
               return;
            ctx->Point.CoordReplaceBits |= (1u << ctx->Texture.CurrentUnit);
         } else if (iparam0 == GL_FALSE) {
            if (~(ctx->Point.CoordReplaceBits) & (1u << ctx->Texture.CurrentUnit))
               return;
            ctx->Point.CoordReplaceBits &= ~(1u << ctx->Texture.CurrentUnit);
         } else {
            _mesa_error( ctx, GL_INVALID_VALUE, "glTexEnv(param=0x%x)", iparam0);
            return;
         }
         FLUSH_VERTICES(ctx, _NEW_POINT);
      }
      else {
         _mesa_error( ctx, GL_INVALID_ENUM, "glTexEnv(pname=0x%x)", pname );
         return;
      }
   }
   else {
      _mesa_error(ctx, GL_INVALID_ENUM, "glTexEnv(target=%s)",
                  _mesa_enum_to_string(target));
      return;
   }

   if (MESA_VERBOSE&(VERBOSE_API|VERBOSE_TEXTURE))
      _mesa_debug(ctx, "glTexEnv %s %s %.1f(%s) ...\n",
                  _mesa_enum_to_string(target),
                  _mesa_enum_to_string(pname),
                  *param,
                  _mesa_enum_to_string((GLenum) iparam0));

   /* Tell device driver about the new texture environment */
   if (ctx->Driver.TexEnv) {
      ctx->Driver.TexEnv(ctx, target, pname, param);
   }
}


void GLAPIENTRY
_mesa_TexEnvf( GLenum target, GLenum pname, GLfloat param )
{
   GLfloat p[4];
   p[0] = param;
   p[1] = p[2] = p[3] = 0.0;
   _mesa_TexEnvfv( target, pname, p );
}



void GLAPIENTRY
_mesa_TexEnvi( GLenum target, GLenum pname, GLint param )
{
   GLfloat p[4];
   p[0] = (GLfloat) param;
   p[1] = p[2] = p[3] = 0.0;
   _mesa_TexEnvfv( target, pname, p );
}


void GLAPIENTRY
_mesa_TexEnviv( GLenum target, GLenum pname, const GLint *param )
{
   GLfloat p[4];
   if (pname == GL_TEXTURE_ENV_COLOR) {
      p[0] = INT_TO_FLOAT( param[0] );
      p[1] = INT_TO_FLOAT( param[1] );
      p[2] = INT_TO_FLOAT( param[2] );
      p[3] = INT_TO_FLOAT( param[3] );
   }
   else {
      p[0] = (GLfloat) param[0];
      p[1] = p[2] = p[3] = 0;  /* init to zero, just to be safe */
   }
   _mesa_TexEnvfv( target, pname, p );
}



/**
 * Helper for glGetTexEnvi/f()
 * \return  value of queried pname or -1 if error.
 */
static GLint
get_texenvi(struct gl_context *ctx, const struct gl_texture_unit *texUnit,
            GLenum pname)
{
   switch (pname) {
   case GL_TEXTURE_ENV_MODE:
      return texUnit->EnvMode;
      break;
   case GL_COMBINE_RGB:
      return texUnit->Combine.ModeRGB;
   case GL_COMBINE_ALPHA:
      return texUnit->Combine.ModeA;
   case GL_SOURCE0_RGB:
   case GL_SOURCE1_RGB:
   case GL_SOURCE2_RGB: {
      const unsigned rgb_idx = pname - GL_SOURCE0_RGB;
      return texUnit->Combine.SourceRGB[rgb_idx];
   }
   case GL_SOURCE3_RGB_NV:
      if (ctx->API == API_OPENGL_COMPAT && ctx->Extensions.NV_texture_env_combine4) {
         return texUnit->Combine.SourceRGB[3];
      }
      else {
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)");
      }
      break;
   case GL_SOURCE0_ALPHA:
   case GL_SOURCE1_ALPHA:
   case GL_SOURCE2_ALPHA: {
      const unsigned alpha_idx = pname - GL_SOURCE0_ALPHA;
      return texUnit->Combine.SourceA[alpha_idx];
   }
   case GL_SOURCE3_ALPHA_NV:
      if (ctx->API == API_OPENGL_COMPAT && ctx->Extensions.NV_texture_env_combine4) {
         return texUnit->Combine.SourceA[3];
      }
      else {
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)");
      }
      break;
   case GL_OPERAND0_RGB:
   case GL_OPERAND1_RGB:
   case GL_OPERAND2_RGB: {
      const unsigned op_rgb = pname - GL_OPERAND0_RGB;
      return texUnit->Combine.OperandRGB[op_rgb];
   }
   case GL_OPERAND3_RGB_NV:
      if (ctx->API == API_OPENGL_COMPAT && ctx->Extensions.NV_texture_env_combine4) {
         return texUnit->Combine.OperandRGB[3];
      }
      else {
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)");
      }
      break;
   case GL_OPERAND0_ALPHA:
   case GL_OPERAND1_ALPHA:
   case GL_OPERAND2_ALPHA: {
      const unsigned op_alpha = pname - GL_OPERAND0_ALPHA;
      return texUnit->Combine.OperandA[op_alpha];
   }
   case GL_OPERAND3_ALPHA_NV:
      if (ctx->API == API_OPENGL_COMPAT && ctx->Extensions.NV_texture_env_combine4) {
         return texUnit->Combine.OperandA[3];
      }
      else {
         _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)");
      }
      break;
   case GL_RGB_SCALE:
      return 1 << texUnit->Combine.ScaleShiftRGB;
   case GL_ALPHA_SCALE:
      return 1 << texUnit->Combine.ScaleShiftA;
   default:
      _mesa_error(ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)");
      break;
   }

   return -1; /* error */
}



void GLAPIENTRY
_mesa_GetTexEnvfv( GLenum target, GLenum pname, GLfloat *params )
{
   GLuint maxUnit;
   const struct gl_texture_unit *texUnit;
   GET_CURRENT_CONTEXT(ctx);

   maxUnit = (target == GL_POINT_SPRITE_NV && pname == GL_COORD_REPLACE_NV)
      ? ctx->Const.MaxTextureCoordUnits : ctx->Const.MaxCombinedTextureImageUnits;
   if (ctx->Texture.CurrentUnit >= maxUnit) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexEnvfv(current unit)");
      return;
   }

   texUnit = _mesa_get_current_tex_unit(ctx);

   if (target == GL_TEXTURE_ENV) {
      if (pname == GL_TEXTURE_ENV_COLOR) {
         if(ctx->NewState & (_NEW_BUFFERS | _NEW_FRAG_CLAMP))
            _mesa_update_state(ctx);
         if (_mesa_get_clamp_fragment_color(ctx, ctx->DrawBuffer))
            COPY_4FV( params, texUnit->EnvColor );
         else
            COPY_4FV( params, texUnit->EnvColorUnclamped );
      }
      else {
         GLint val = get_texenvi(ctx, texUnit, pname);
         if (val >= 0) {
            *params = (GLfloat) val;
         }
      }
   }
   else if (target == GL_TEXTURE_FILTER_CONTROL_EXT) {
      if (pname == GL_TEXTURE_LOD_BIAS_EXT) {
         *params = texUnit->LodBias;
      }
      else {
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)" );
	 return;
      }
   }
   else if (target == GL_POINT_SPRITE_NV) {
      /* GL_ARB_point_sprite / GL_NV_point_sprite */
      if (!ctx->Extensions.NV_point_sprite
	  && !ctx->Extensions.ARB_point_sprite) {
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnvfv(target)" );
         return;
      }
      if (pname == GL_COORD_REPLACE_NV) {
         if (ctx->Point.CoordReplaceBits & (1u << ctx->Texture.CurrentUnit))
            *params = 1.0f;
         else
            *params = 0.0f;
      }
      else {
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnvfv(pname)" );
         return;
      }
   }
   else {
      _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnvfv(target)" );
      return;
   }
}


void GLAPIENTRY
_mesa_GetTexEnviv( GLenum target, GLenum pname, GLint *params )
{
   GLuint maxUnit;
   const struct gl_texture_unit *texUnit;
   GET_CURRENT_CONTEXT(ctx);

   maxUnit = (target == GL_POINT_SPRITE_NV && pname == GL_COORD_REPLACE_NV)
      ? ctx->Const.MaxTextureCoordUnits : ctx->Const.MaxCombinedTextureImageUnits;
   if (ctx->Texture.CurrentUnit >= maxUnit) {
      _mesa_error(ctx, GL_INVALID_OPERATION, "glGetTexEnviv(current unit)");
      return;
   }

   texUnit = _mesa_get_current_tex_unit(ctx);

   if (target == GL_TEXTURE_ENV) {
      if (pname == GL_TEXTURE_ENV_COLOR) {
         params[0] = FLOAT_TO_INT( texUnit->EnvColor[0] );
         params[1] = FLOAT_TO_INT( texUnit->EnvColor[1] );
         params[2] = FLOAT_TO_INT( texUnit->EnvColor[2] );
         params[3] = FLOAT_TO_INT( texUnit->EnvColor[3] );
      }
      else {
         GLint val = get_texenvi(ctx, texUnit, pname);
         if (val >= 0) {
            *params = val;
         }
      }
   }
   else if (target == GL_TEXTURE_FILTER_CONTROL_EXT) {
      if (pname == GL_TEXTURE_LOD_BIAS_EXT) {
         *params = (GLint) texUnit->LodBias;
      }
      else {
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnviv(pname)" );
	 return;
      }
   }
   else if (target == GL_POINT_SPRITE_NV) {
      /* GL_ARB_point_sprite / GL_NV_point_sprite */
      if (!ctx->Extensions.NV_point_sprite
	  && !ctx->Extensions.ARB_point_sprite) {
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnviv(target)" );
         return;
      }
      if (pname == GL_COORD_REPLACE_NV) {
         if (ctx->Point.CoordReplaceBits & (1u << ctx->Texture.CurrentUnit))
            *params = GL_TRUE;
         else
            *params = GL_FALSE;
      }
      else {
         _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnviv(pname)" );
         return;
      }
   }
   else {
      _mesa_error( ctx, GL_INVALID_ENUM, "glGetTexEnviv(target)" );
      return;
   }
}