text: /*
   * Mesa 3-D graphics library
   * Version:  6.5.2
   *
   * Copyright (C) 1999-2006  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
   * 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 "glheader.h"
  #include "context.h"
  #include "macros.h"
  #include "imports.h"
  #include "fbobject.h"
  
  #include "s_accum.h"
  #include "s_context.h"
  #include "s_masking.h"
  #include "s_span.h"
  
  
  /* XXX this would have to change for accum buffers with more or less
   * than 16 bits per color channel.
   */
  #define ACCUM_SCALE16 32767.0
  
  
  /*
   * Accumulation buffer notes
   *
   * Normally, accumulation buffer values are GLshorts with values in
   * [-32767, 32767] which represent floating point colors in [-1, 1],
   * as defined by the OpenGL specification.
   *
   * We optimize for the common case used for full-scene antialiasing:
   *    // start with accum buffer cleared to zero
   *    glAccum(GL_LOAD, w);   // or GL_ACCUM the first image
   *    glAccum(GL_ACCUM, w);
   *    ...
   *    glAccum(GL_ACCUM, w);
   *    glAccum(GL_RETURN, 1.0);
   * That is, we start with an empty accumulation buffer and accumulate
   * n images, each with weight w = 1/n.
   * In this scenario, we can simply store unscaled integer values in
   * the accum buffer instead of scaled integers.  We'll also keep track
   * of the w value so when we do GL_RETURN we simply divide the accumulated
   * values by n (n=1/w).
   * This lets us avoid _many_ int->float->int conversions.
   */
  
  
  #if CHAN_BITS == 8
  /* enable the optimization */
  #define USE_OPTIMIZED_ACCUM  1
  #else
  #define USE_OPTIMIZED_ACCUM  0
  #endif
  
  
  /**
   * This is called when we fall out of optimized/unscaled accum buffer mode.
   * That is, we convert each unscaled accum buffer value into a scaled value
   * representing the range[-1, 1].
   */
  static void
  rescale_accum( GLcontext *ctx )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     struct gl_renderbuffer *rb
        = ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer;
     const GLfloat s = swrast->_IntegerAccumScaler * (32767.0F / CHAN_MAXF);
  
     assert(rb);
     assert(rb->_BaseFormat == GL_RGBA);
     /* add other types in future? */
     assert(rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT);
     assert(swrast->_IntegerAccumMode);
  
     if (rb->GetPointer(ctx, rb, 0, 0)) {
        /* directly-addressable memory */
        GLuint y;
        for (y = 0; y < rb->Height; y++) {
           GLuint i;
           GLshort *acc = (GLshort *) rb->GetPointer(ctx, rb, 0, y);
           for (i = 0; i < 4 * rb->Width; i++) {
              acc[i] = (GLshort) (acc[i] * s);
           }
        }
     }
     else {
        /* use get/put row funcs */
        GLuint y;
        for (y = 0; y < rb->Height; y++) {
           GLshort accRow[MAX_WIDTH * 4];
           GLuint i;
           rb->GetRow(ctx, rb, rb->Width, 0, y, accRow);
           for (i = 0; i < 4 * rb->Width; i++) {
              accRow[i] = (GLshort) (accRow[i] * s);
           }
           rb->PutRow(ctx, rb, rb->Width, 0, y, accRow, NULL);
        }
     }
  
     swrast->_IntegerAccumMode = GL_FALSE;
  }
  
  
  
  /**
   * Clear the accumulation Buffer.
   */
  void
  _swrast_clear_accum_buffer( GLcontext *ctx, struct gl_renderbuffer *rb )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     GLuint x, y, width, height;
  
     if (ctx->Visual.accumRedBits == 0) {
        /* No accumulation buffer! Not an error. */
        return;
     }
  
     if (!rb || !rb->Data)
        return;
  
     assert(rb->_BaseFormat == GL_RGBA);
     /* add other types in future? */
     assert(rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT);
  
     /* bounds, with scissor */
     x = ctx->DrawBuffer->_Xmin;
     y = ctx->DrawBuffer->_Ymin;
     width = ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin;
     height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
  
     if (rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT) {
        const GLfloat accScale = 32767.0;
        GLshort clearVal[4];
        GLuint i;
  
        clearVal[0] = (GLshort) (ctx->Accum.ClearColor[0] * accScale);
        clearVal[1] = (GLshort) (ctx->Accum.ClearColor[1] * accScale);
        clearVal[2] = (GLshort) (ctx->Accum.ClearColor[2] * accScale);
        clearVal[3] = (GLshort) (ctx->Accum.ClearColor[3] * accScale);
  
        for (i = 0; i < height; i++) {
           rb->PutMonoRow(ctx, rb, width, x, y + i, clearVal, NULL);
        }
     }
     else {
        /* someday support other sizes */
     }
  
     /* update optimized accum state vars */
     if (ctx->Accum.ClearColor[0] == 0.0 && ctx->Accum.ClearColor[1] == 0.0 &&
         ctx->Accum.ClearColor[2] == 0.0 && ctx->Accum.ClearColor[3] == 0.0) {
  #if USE_OPTIMIZED_ACCUM
        swrast->_IntegerAccumMode = GL_TRUE;
  #else
        swrast->_IntegerAccumMode = GL_FALSE;
  #endif
        swrast->_IntegerAccumScaler = 0.0;  /* denotes empty accum buffer */
     }
     else {
        swrast->_IntegerAccumMode = GL_FALSE;
     }
  }
  
  
  static void
  accum_add(GLcontext *ctx, GLfloat value,
            GLint xpos, GLint ypos, GLint width, GLint height )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     struct gl_renderbuffer *rb
        = ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer;
  
     assert(rb);
  
     /* Leave optimized accum buffer mode */
     if (swrast->_IntegerAccumMode)
        rescale_accum(ctx);
  
     if (rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT) {
        const GLshort incr = (GLshort) (value * ACCUM_SCALE16);
        if (rb->GetPointer(ctx, rb, 0, 0)) {
           GLint i, j;
           for (i = 0; i < height; i++) {
              GLshort *acc = (GLshort *) rb->GetPointer(ctx, rb, xpos, ypos + i);
              for (j = 0; j < 4 * width; j++) {
                 acc[j] += incr;
              }
           }
        }
        else {
           GLint i, j;
           for (i = 0; i < height; i++) {
              GLshort accRow[4 * MAX_WIDTH];
              rb->GetRow(ctx, rb, width, xpos, ypos + i, accRow);
              for (j = 0; j < 4 * width; j++) {
                 accRow[j] += incr;
              }
              rb->PutRow(ctx, rb, width, xpos, ypos + i, accRow, NULL);
           }
        }
     }
     else {
        /* other types someday */
     }
  }
  
  
  static void
  accum_mult(GLcontext *ctx, GLfloat mult,
             GLint xpos, GLint ypos, GLint width, GLint height )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     struct gl_renderbuffer *rb
        = ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer;
  
     assert(rb);
  
     /* Leave optimized accum buffer mode */
     if (swrast->_IntegerAccumMode)
        rescale_accum(ctx);
  
     if (rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT) {
        if (rb->GetPointer(ctx, rb, 0, 0)) {
           GLint i, j;
           for (i = 0; i < height; i++) {
              GLshort *acc = (GLshort *) rb->GetPointer(ctx, rb, xpos, ypos + i);
              for (j = 0; j < 4 * width; j++) {
                 acc[j] = (GLshort) (acc[j] * mult);
              }
           }
        }
        else {
           GLint i, j;
           for (i = 0; i < height; i++) {
              GLshort accRow[4 * MAX_WIDTH];
              rb->GetRow(ctx, rb, width, xpos, ypos + i, accRow);
              for (j = 0; j < 4 * width; j++) {
                 accRow[j] = (GLshort) (accRow[j] * mult);
              }
              rb->PutRow(ctx, rb, width, xpos, ypos + i, accRow, NULL);
           }
        }
     }
     else {
        /* other types someday */
     }
  }
  
  
  
  static void
  accum_accum(GLcontext *ctx, GLfloat value,
              GLint xpos, GLint ypos, GLint width, GLint height )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     struct gl_renderbuffer *rb
        = ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer;
     const GLboolean directAccess = (rb->GetPointer(ctx, rb, 0, 0) != NULL);
  
     assert(rb);
  
     if (!ctx->ReadBuffer->_ColorReadBuffer) {
        /* no read buffer - OK */
        return;
     }
  
     /* May have to leave optimized accum buffer mode */
     if (swrast->_IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
        swrast->_IntegerAccumScaler = value;
     if (swrast->_IntegerAccumMode && value != swrast->_IntegerAccumScaler)
        rescale_accum(ctx);
  
     if (rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT) {
        const GLfloat scale = value * ACCUM_SCALE16 / CHAN_MAXF;
        GLshort accumRow[4 * MAX_WIDTH];
        GLchan rgba[MAX_WIDTH][4];
        GLint i;
  
        for (i = 0; i < height; i++) {
           GLshort *acc;
           if (directAccess) {
              acc = (GLshort *) rb->GetPointer(ctx, rb, xpos, ypos + i);
           }
           else {
              rb->GetRow(ctx, rb, width, xpos, ypos + i, accumRow);
              acc = accumRow;
           }
  
           /* read colors from color buffer */
           _swrast_read_rgba_span(ctx, ctx->ReadBuffer->_ColorReadBuffer, width,
                                  xpos, ypos + i, CHAN_TYPE, rgba);
  
           /* do accumulation */
           if (swrast->_IntegerAccumMode) {
              /* simply add integer color values into accum buffer */
              GLint j;
              for (j = 0; j < width; j++) {
                 acc[j * 4 + 0] += rgba[j][RCOMP];
                 acc[j * 4 + 1] += rgba[j][GCOMP];
                 acc[j * 4 + 2] += rgba[j][BCOMP];
                 acc[j * 4 + 3] += rgba[j][ACOMP];
              }
           }
           else {
              /* scaled integer (or float) accum buffer */
              GLint j;
              for (j = 0; j < width; j++) {
                 acc[j * 4 + 0] += (GLshort) ((GLfloat) rgba[j][RCOMP] * scale);
                 acc[j * 4 + 1] += (GLshort) ((GLfloat) rgba[j][GCOMP] * scale);
                 acc[j * 4 + 2] += (GLshort) ((GLfloat) rgba[j][BCOMP] * scale);
                 acc[j * 4 + 3] += (GLshort) ((GLfloat) rgba[j][ACOMP] * scale);
              }
           }
  
           if (!directAccess) {
              rb->PutRow(ctx, rb, width, xpos, ypos + i, accumRow, NULL);
           }
        }
     }
     else {
        /* other types someday */
     }
  }
  
  
  
  static void
  accum_load(GLcontext *ctx, GLfloat value,
             GLint xpos, GLint ypos, GLint width, GLint height )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     struct gl_renderbuffer *rb
        = ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer;
     const GLboolean directAccess = (rb->GetPointer(ctx, rb, 0, 0) != NULL);
  
     assert(rb);
  
     if (!ctx->ReadBuffer->_ColorReadBuffer) {
        /* no read buffer - OK */
        return;
     }
  
     /* This is a change to go into optimized accum buffer mode */
     if (value > 0.0 && value <= 1.0) {
  #if USE_OPTIMIZED_ACCUM
        swrast->_IntegerAccumMode = GL_TRUE;
  #else
        swrast->_IntegerAccumMode = GL_FALSE;
  #endif
        swrast->_IntegerAccumScaler = value;
     }
     else {
        swrast->_IntegerAccumMode = GL_FALSE;
        swrast->_IntegerAccumScaler = 0.0;
     }
  
     if (rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT) {
        const GLfloat scale = value * ACCUM_SCALE16 / CHAN_MAXF;
        GLshort accumRow[4 * MAX_WIDTH];
        GLchan rgba[MAX_WIDTH][4];
        GLint i;
  
        for (i = 0; i < height; i++) {
           GLshort *acc;
           if (directAccess) {
              acc = (GLshort *) rb->GetPointer(ctx, rb, xpos, ypos + i);
           }
           else {
              rb->GetRow(ctx, rb, width, xpos, ypos + i, accumRow);
              acc = accumRow;
           }
  
           /* read colors from color buffer */
           _swrast_read_rgba_span(ctx, ctx->ReadBuffer->_ColorReadBuffer, width,
                                  xpos, ypos + i, CHAN_TYPE, rgba);
  
           /* do load */
           if (swrast->_IntegerAccumMode) {
              /* just copy values in */
              GLint j;
              assert(swrast->_IntegerAccumScaler > 0.0);
              assert(swrast->_IntegerAccumScaler <= 1.0);
              for (j = 0; j < width; j++) {
                 acc[j * 4 + 0] = rgba[j][RCOMP];
                 acc[j * 4 + 1] = rgba[j][GCOMP];
                 acc[j * 4 + 2] = rgba[j][BCOMP];
                 acc[j * 4 + 3] = rgba[j][ACOMP];
              }
           }
           else {
              /* scaled integer (or float) accum buffer */
              GLint j;
              for (j = 0; j < width; j++) {
                 acc[j * 4 + 0] = (GLshort) ((GLfloat) rgba[j][RCOMP] * scale);
                 acc[j * 4 + 1] = (GLshort) ((GLfloat) rgba[j][GCOMP] * scale);
                 acc[j * 4 + 2] = (GLshort) ((GLfloat) rgba[j][BCOMP] * scale);
                 acc[j * 4 + 3] = (GLshort) ((GLfloat) rgba[j][ACOMP] * scale);
              }
           }
  
           if (!directAccess) {
              rb->PutRow(ctx, rb, width, xpos, ypos + i, accumRow, NULL);
           }
        }
     }
  }
  
  
  static void
  accum_return(GLcontext *ctx, GLfloat value,
               GLint xpos, GLint ypos, GLint width, GLint height )
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     struct gl_framebuffer *fb = ctx->DrawBuffer;
     struct gl_renderbuffer *accumRb = fb->Attachment[BUFFER_ACCUM].Renderbuffer;
     const GLboolean directAccess
        = (accumRb->GetPointer(ctx, accumRb, 0, 0) != NULL);
     const GLboolean masking = (!ctx->Color.ColorMask[RCOMP] ||
                                !ctx->Color.ColorMask[GCOMP] ||
                                !ctx->Color.ColorMask[BCOMP] ||
                                !ctx->Color.ColorMask[ACOMP]);
  
     static GLchan multTable[32768];
     static GLfloat prevMult = 0.0;
     const GLfloat mult = swrast->_IntegerAccumScaler;
     const GLint max = MIN2((GLint) (256 / mult), 32767);
  
     /* May have to leave optimized accum buffer mode */
     if (swrast->_IntegerAccumMode && value != 1.0)
        rescale_accum(ctx);
  
     if (swrast->_IntegerAccumMode && swrast->_IntegerAccumScaler > 0) {
        /* build lookup table to avoid many floating point multiplies */
        GLint j;
        assert(swrast->_IntegerAccumScaler <= 1.0);
        if (mult != prevMult) {
           for (j = 0; j < max; j++)
              multTable[j] = IROUND((GLfloat) j * mult);
           prevMult = mult;
        }
     }
  
     if (accumRb->DataType == GL_SHORT ||
         accumRb->DataType == GL_UNSIGNED_SHORT) {
        const GLfloat scale = value * CHAN_MAXF / ACCUM_SCALE16;
        GLuint buffer;
        GLint i;
  
        /* XXX maybe transpose the 'i' and 'buffer' loops??? */
        for (i = 0; i < height; i++) {
           GLshort accumRow[4 * MAX_WIDTH];
           GLshort *acc;
           SWspan span;
  
           /* init color span */
           INIT_SPAN(span, GL_BITMAP);
           span.end = width;
           span.arrayMask = SPAN_RGBA;
           span.x = xpos;
           span.y = ypos + i;
  
           if (directAccess) {
              acc = (GLshort *) accumRb->GetPointer(ctx, accumRb, xpos, ypos +i);
           }
           else {
              accumRb->GetRow(ctx, accumRb, width, xpos, ypos + i, accumRow);
              acc = accumRow;
           }
  
           /* get the colors to return */
           if (swrast->_IntegerAccumMode) {
              GLint j;
              for (j = 0; j < width; j++) {
                 ASSERT(acc[j * 4 + 0] < max);
                 ASSERT(acc[j * 4 + 1] < max);
                 ASSERT(acc[j * 4 + 2] < max);
                 ASSERT(acc[j * 4 + 3] < max);
                 span.array->rgba[j][RCOMP] = multTable[acc[j * 4 + 0]];
                 span.array->rgba[j][GCOMP] = multTable[acc[j * 4 + 1]];
                 span.array->rgba[j][BCOMP] = multTable[acc[j * 4 + 2]];
                 span.array->rgba[j][ACOMP] = multTable[acc[j * 4 + 3]];
              }
           }
           else {
              /* scaled integer (or float) accum buffer */
              GLint j;
              for (j = 0; j < width; j++) {
  #if CHAN_BITS==32
                 GLchan r = acc[j * 4 + 0] * scale;
                 GLchan g = acc[j * 4 + 1] * scale;
                 GLchan b = acc[j * 4 + 2] * scale;
                 GLchan a = acc[j * 4 + 3] * scale;
  #else
                 GLint r = IROUND( (GLfloat) (acc[j * 4 + 0]) * scale );
                 GLint g = IROUND( (GLfloat) (acc[j * 4 + 1]) * scale );
                 GLint b = IROUND( (GLfloat) (acc[j * 4 + 2]) * scale );
                 GLint a = IROUND( (GLfloat) (acc[j * 4 + 3]) * scale );
  #endif
                 span.array->rgba[j][RCOMP] = CLAMP( r, 0, CHAN_MAX );
                 span.array->rgba[j][GCOMP] = CLAMP( g, 0, CHAN_MAX );
                 span.array->rgba[j][BCOMP] = CLAMP( b, 0, CHAN_MAX );
                 span.array->rgba[j][ACOMP] = CLAMP( a, 0, CHAN_MAX );
              }
           }
  
           /* store colors */
           for (buffer = 0; buffer < fb->_NumColorDrawBuffers; buffer++) {
              struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buffer];
              if (masking) {
                 _swrast_mask_rgba_span(ctx, rb, &span);
              }
              rb->PutRow(ctx, rb, width, xpos, ypos + i, span.array->rgba, NULL);
           }
        }
     }
     else {
        /* other types someday */
     }
  }
  
  
  
  /**
   * Software fallback for glAccum.
   */
  void
  _swrast_Accum(GLcontext *ctx, GLenum op, GLfloat value)
  {
     SWcontext *swrast = SWRAST_CONTEXT(ctx);
     GLint xpos, ypos, width, height;
  
     if (SWRAST_CONTEXT(ctx)->NewState)
        _swrast_validate_derived( ctx );
  
     if (!ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer) {
        _mesa_warning(ctx, "Calling glAccum() without an accumulation buffer");
        return;
     }
  
     RENDER_START(swrast, ctx);
  
     /* Compute region after calling RENDER_START so that we know the
      * drawbuffer's size/bounds are up to date.
      */
     xpos = ctx->DrawBuffer->_Xmin;
     ypos = ctx->DrawBuffer->_Ymin;
     width =  ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin;
     height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;
  
     switch (op) {
        case GL_ADD:
           if (value != 0.0F) {
              accum_add(ctx, value, xpos, ypos, width, height);
  	 }
  	 break;
        case GL_MULT:
           if (value != 1.0F) {
              accum_mult(ctx, value, xpos, ypos, width, height);
  	 }
  	 break;
        case GL_ACCUM:
           if (value != 0.0F) {
              accum_accum(ctx, value, xpos, ypos, width, height);
           }
  	 break;
        case GL_LOAD:
           accum_load(ctx, value, xpos, ypos, width, height);
  	 break;
        case GL_RETURN:
           accum_return(ctx, value, xpos, ypos, width, height);
  	 break;
        default:
           _mesa_problem(ctx, "invalid mode in _swrast_Accum()");
           break;
     }
  
     RENDER_FINISH(swrast, ctx);
  }
  