/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 1999-2007  Brian Paul   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.
 */

#include "main/glheader.h"
#include "main/colormac.h"
#include "main/samplerobj.h"
#include "program/prog_instruction.h"

#include "s_context.h"
#include "s_fragprog.h"
#include "s_span.h"

/**
 * \brief Should swrast use a fragment program?
 *
 * \return true if the current fragment program exists and is not the fixed
 *         function fragment program
 */
GLboolean
_swrast_use_fragment_program(struct gl_context *ctx)
{
   struct gl_fragment_program *fp = ctx->FragmentProgram._Current;
   return fp && !(fp == ctx->FragmentProgram._TexEnvProgram
                  && fp->Base.NumInstructions == 0);
}

/**
 * Apply texture object's swizzle (X/Y/Z/W/0/1) to incoming 'texel'
 * and return results in 'colorOut'.
 */
static inline void
swizzle_texel(const GLfloat texel[4], GLfloat colorOut[4], GLuint swizzle)
{
   if (swizzle == SWIZZLE_NOOP) {
      COPY_4V(colorOut, texel);
   }
   else {
      GLfloat vector[6];
      vector[SWIZZLE_X] = texel[0];
      vector[SWIZZLE_Y] = texel[1];
      vector[SWIZZLE_Z] = texel[2];
      vector[SWIZZLE_W] = texel[3];
      vector[SWIZZLE_ZERO] = 0.0F;
      vector[SWIZZLE_ONE] = 1.0F;
      colorOut[0] = vector[GET_SWZ(swizzle, 0)];
      colorOut[1] = vector[GET_SWZ(swizzle, 1)];
      colorOut[2] = vector[GET_SWZ(swizzle, 2)];
      colorOut[3] = vector[GET_SWZ(swizzle, 3)];
   }
}


/**
 * Fetch a texel with given lod.
 * Called via machine->FetchTexelLod()
 */
static void
fetch_texel_lod( struct gl_context *ctx, const GLfloat texcoord[4], GLfloat lambda,
                 GLuint unit, GLfloat color[4] )
{
   const struct gl_texture_object *texObj = ctx->Texture.Unit[unit]._Current;

   if (texObj) {
      SWcontext *swrast = SWRAST_CONTEXT(ctx);
      GLfloat rgba[4];
      const struct gl_sampler_object *samp = _mesa_get_samplerobj(ctx, unit);

      lambda = CLAMP(lambda, samp->MinLod, samp->MaxLod);

      swrast->TextureSample[unit](ctx, samp, ctx->Texture.Unit[unit]._Current,
                                  1, (const GLfloat (*)[4]) texcoord,
                                  &lambda, &rgba);
      swizzle_texel(rgba, color, texObj->_Swizzle);
   }
   else {
      ASSIGN_4V(color, 0.0F, 0.0F, 0.0F, 1.0F);
   }
}


/**
 * Fetch a texel with the given partial derivatives to compute a level
 * of detail in the mipmap.
 * Called via machine->FetchTexelDeriv()
 * \param lodBias  the lod bias which may be specified by a TXB instruction,
 *                 otherwise zero.
 */
static void
fetch_texel_deriv( struct gl_context *ctx, const GLfloat texcoord[4],
                   const GLfloat texdx[4], const GLfloat texdy[4],
                   GLfloat lodBias, GLuint unit, GLfloat color[4] )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   const struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
   const struct gl_texture_object *texObj = texUnit->_Current;

   if (texObj) {
      const struct gl_texture_image *texImg =
         texObj->Image[0][texObj->BaseLevel];
      const struct swrast_texture_image *swImg =
         swrast_texture_image_const(texImg);
      const struct gl_sampler_object *samp = _mesa_get_samplerobj(ctx, unit);
      const GLfloat texW = (GLfloat) swImg->WidthScale;
      const GLfloat texH = (GLfloat) swImg->HeightScale;
      GLfloat lambda;
      GLfloat rgba[4];

      lambda = _swrast_compute_lambda(texdx[0], texdy[0], /* ds/dx, ds/dy */
                                      texdx[1], texdy[1], /* dt/dx, dt/dy */
                                      texdx[3], texdy[3], /* dq/dx, dq/dy */
                                      texW, texH,
                                      texcoord[0], texcoord[1], texcoord[3],
                                      1.0F / texcoord[3]);

      lambda += lodBias + texUnit->LodBias + samp->LodBias;

      lambda = CLAMP(lambda, samp->MinLod, samp->MaxLod);

      swrast->TextureSample[unit](ctx, samp, ctx->Texture.Unit[unit]._Current,
                                  1, (const GLfloat (*)[4]) texcoord,
                                  &lambda, &rgba);
      swizzle_texel(rgba, color, texObj->_Swizzle);
   }
   else {
      ASSIGN_4V(color, 0.0F, 0.0F, 0.0F, 1.0F);
   }
}


/**
 * Initialize the virtual fragment program machine state prior to running
 * fragment program on a fragment.  This involves initializing the input
 * registers, condition codes, etc.
 * \param machine  the virtual machine state to init
 * \param program  the fragment program we're about to run
 * \param span  the span of pixels we'll operate on
 * \param col  which element (column) of the span we'll operate on
 */
static void
init_machine(struct gl_context *ctx, struct gl_program_machine *machine,
             const struct gl_fragment_program *program,
             const SWspan *span, GLuint col)
{
   GLfloat *wpos = span->array->attribs[VARYING_SLOT_POS][col];

   /* ARB_fragment_coord_conventions */
   if (program->OriginUpperLeft)
      wpos[1] = ctx->DrawBuffer->Height - 1 - wpos[1];
   if (!program->PixelCenterInteger) {
      wpos[0] += 0.5F;
      wpos[1] += 0.5F;
   }

   /* Setup pointer to input attributes */
   machine->Attribs = span->array->attribs;

   machine->DerivX = (GLfloat (*)[4]) span->attrStepX;
   machine->DerivY = (GLfloat (*)[4]) span->attrStepY;
   machine->NumDeriv = VARYING_SLOT_MAX;

   machine->Samplers = program->Base.SamplerUnits;

   /* if running a GLSL program (not ARB_fragment_program) */
   if (ctx->_Shader->CurrentProgram[MESA_SHADER_FRAGMENT]) {
      /* Store front/back facing value */
      machine->Attribs[VARYING_SLOT_FACE][col][0] = 1.0F - span->facing;
   }

   machine->CurElement = col;

   /* init condition codes */
   machine->CondCodes[0] = COND_EQ;
   machine->CondCodes[1] = COND_EQ;
   machine->CondCodes[2] = COND_EQ;
   machine->CondCodes[3] = COND_EQ;

   /* init call stack */
   machine->StackDepth = 0;

   machine->FetchTexelLod = fetch_texel_lod;
   machine->FetchTexelDeriv = fetch_texel_deriv;
}


/**
 * Run fragment program on the pixels in span from 'start' to 'end' - 1.
 */
static void
run_program(struct gl_context *ctx, SWspan *span, GLuint start, GLuint end)
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   const struct gl_fragment_program *program = ctx->FragmentProgram._Current;
   const GLbitfield64 outputsWritten = program->Base.OutputsWritten;
   struct gl_program_machine *machine = &swrast->FragProgMachine;
   GLuint i;

   for (i = start; i < end; i++) {
      if (span->array->mask[i]) {
         init_machine(ctx, machine, program, span, i);

         if (_mesa_execute_program(ctx, &program->Base, machine)) {

            /* Store result color */
	    if (outputsWritten & BITFIELD64_BIT(FRAG_RESULT_COLOR)) {
               COPY_4V(span->array->attribs[VARYING_SLOT_COL0][i],
                       machine->Outputs[FRAG_RESULT_COLOR]);
            }
            else {
               /* Multiple drawbuffers / render targets
                * Note that colors beyond 0 and 1 will overwrite other
                * attributes, such as FOGC, TEX0, TEX1, etc.  That's OK.
                */
               GLuint buf;
               for (buf = 0; buf < ctx->DrawBuffer->_NumColorDrawBuffers; buf++) {
                  if (outputsWritten & BITFIELD64_BIT(FRAG_RESULT_DATA0 + buf)) {
                     COPY_4V(span->array->attribs[VARYING_SLOT_COL0 + buf][i],
                             machine->Outputs[FRAG_RESULT_DATA0 + buf]);
                  }
               }
            }

            /* Store result depth/z */
            if (outputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) {
               const GLfloat depth = machine->Outputs[FRAG_RESULT_DEPTH][2];
               if (depth <= 0.0)
                  span->array->z[i] = 0;
               else if (depth >= 1.0)
                  span->array->z[i] = ctx->DrawBuffer->_DepthMax;
               else
                  span->array->z[i] =
                     (GLuint) (depth * ctx->DrawBuffer->_DepthMaxF + 0.5F);
            }
         }
         else {
            /* killed fragment */
            span->array->mask[i] = GL_FALSE;
            span->writeAll = GL_FALSE;
         }
      }
   }
}


/**
 * Execute the current fragment program for all the fragments
 * in the given span.
 */
void
_swrast_exec_fragment_program( struct gl_context *ctx, SWspan *span )
{
   const struct gl_fragment_program *program = ctx->FragmentProgram._Current;

   /* incoming colors should be floats */
   if (program->Base.InputsRead & VARYING_BIT_COL0) {
      ASSERT(span->array->ChanType == GL_FLOAT);
   }

   run_program(ctx, span, 0, span->end);

   if (program->Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_COLOR)) {
      span->interpMask &= ~SPAN_RGBA;
      span->arrayMask |= SPAN_RGBA;
   }

   if (program->Base.OutputsWritten & BITFIELD64_BIT(FRAG_RESULT_DEPTH)) {
      span->interpMask &= ~SPAN_Z;
      span->arrayMask |= SPAN_Z;
   }
}

