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scalebit.cpp

/*
 * This file is part of the Scale2x project.
 *
 * Copyright (C) 2003 Andrea Mazzoleni
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 * This file contains an example implementation of the Scale effect
 * applyed to a generic bitmap.
 *
 * You can find an high level description of the effect at :
 *
 * http://scale2x.sourceforge.net/
 *
 * Alternatively at the previous license terms, you are allowed to use this
 * code in your program with these conditions:
 * - the program is not used in commercial activities.
 * - the whole source code of the program is released with the binary.
 * - derivative works of the program are allowed.
 */

#if defined(HAVE_CONFIG_H)
#include <config.h>
#endif

#include "common/scaler/intern.h"

#include "scale2x.h"
#include "scale3x.h"

#if defined(HAVE_ALLOCA_H)
#include <alloca.h>
#endif

#include <assert.h>
#include <stdlib.h>

#define DST(bits, num)  (scale2x_uint ## bits *)dst ## num
#define SRC(bits, num)  (const scale2x_uint ## bits *)src ## num

/**
 * Apply the Scale2x effect on a group of rows. Used internally.
 */
static inline void stage_scale2x(void* dst0, void* dst1, const void* src0, const void* src1, const void* src2, unsigned pixel, unsigned pixel_per_row)
{
      switch (pixel) {
#if defined(__GNUC__) && defined(__i386__)
            case 1 : scale2x_8_mmx(DST(8,0), DST(8,1), SRC(8,0), SRC(8,1), SRC(8,2), pixel_per_row); break;
            case 2 : scale2x_16_mmx(DST(16,0), DST(16,1), SRC(16,0), SRC(16,1), SRC(16,2), pixel_per_row); break;
            case 4 : scale2x_32_mmx(DST(32,0), DST(32,1), SRC(32,0), SRC(32,1), SRC(32,2), pixel_per_row); break;
#else
            case 1 : scale2x_8_def(DST(8,0), DST(8,1), SRC(8,0), SRC(8,1), SRC(8,2), pixel_per_row); break;
            case 2 : scale2x_16_def(DST(16,0), DST(16,1), SRC(16,0), SRC(16,1), SRC(16,2), pixel_per_row); break;
            case 4 : scale2x_32_def(DST(32,0), DST(32,1), SRC(32,0), SRC(32,1), SRC(32,2), pixel_per_row); break;
#endif
      }
}

/**
 * Apply the Scale3x effect on a group of rows. Used internally.
 */
static inline void stage_scale3x(void* dst0, void* dst1, void* dst2, const void* src0, const void* src1, const void* src2, unsigned pixel, unsigned pixel_per_row)
{
      switch (pixel) {
            case 1 : scale3x_8_def(DST(8,0), DST(8,1), DST(8,2), SRC(8,0), SRC(8,1), SRC(8,2), pixel_per_row); break;
            case 2 : scale3x_16_def(DST(16,0), DST(16,1), DST(16,2), SRC(16,0), SRC(16,1), SRC(16,2), pixel_per_row); break;
            case 4 : scale3x_32_def(DST(32,0), DST(32,1), DST(32,2), SRC(32,0), SRC(32,1), SRC(32,2), pixel_per_row); break;
      }
}

/**
 * Apply the Scale4x effect on a group of rows. Used internally.
 */
static inline void stage_scale4x(void* dst0, void* dst1, void* dst2, void* dst3, const void* src0, const void* src1, const void* src2, const void* src3, unsigned pixel, unsigned pixel_per_row)
{
      stage_scale2x(dst0, dst1, src0, src1, src2, pixel, 2 * pixel_per_row);
      stage_scale2x(dst2, dst3, src1, src2, src3, pixel, 2 * pixel_per_row);
}

#define SCDST(i) (dst+(i)*dst_slice)
#define SCSRC(i) (src+(i)*src_slice)
#define SCMID(i) (mid[(i)])

/**
 * Apply the Scale2x effect on a bitmap.
 * The destination bitmap is filled with the scaled version of the source bitmap.
 * The source bitmap isn't modified.
 * The destination bitmap must be manually allocated before calling the function,
 * note that the resulting size is exactly 2x2 times the size of the source bitmap.
 * \param void_dst Pointer at the first pixel of the destination bitmap.
 * \param dst_slice Size in bytes of a destination bitmap row.
 * \param void_src Pointer at the first pixel of the source bitmap.
 * \param src_slice Size in bytes of a source bitmap row.
 * \param pixel Bytes per pixel of the source and destination bitmap.
 * \param width Horizontal size in pixels of the source bitmap.
 * \param height Vertical size in pixels of the source bitmap.
 */
static void scale2x(void* void_dst, unsigned dst_slice, const void* void_src, unsigned src_slice, unsigned pixel, unsigned width, unsigned height)
{
      unsigned char* dst = (unsigned char*)void_dst;
      const unsigned char* src = (const unsigned char*)void_src;
      unsigned count;

      assert(height >= 2);

      count = height;

      while (count) {
            stage_scale2x(SCDST(0), SCDST(1), SCSRC(0), SCSRC(1), SCSRC(2), pixel, width);

            dst = SCDST(2);
            src = SCSRC(1);

            --count;
      }

#if defined(__GNUC__) && defined(__i386__)
      scale2x_mmx_emms();
#endif
}

/**
 * Apply the Scale32x effect on a bitmap.
 * The destination bitmap is filled with the scaled version of the source bitmap.
 * The source bitmap isn't modified.
 * The destination bitmap must be manually allocated before calling the function,
 * note that the resulting size is exactly 3x3 times the size of the source bitmap.
 * \param void_dst Pointer at the first pixel of the destination bitmap.
 * \param dst_slice Size in bytes of a destination bitmap row.
 * \param void_src Pointer at the first pixel of the source bitmap.
 * \param src_slice Size in bytes of a source bitmap row.
 * \param pixel Bytes per pixel of the source and destination bitmap.
 * \param width Horizontal size in pixels of the source bitmap.
 * \param height Vertical size in pixels of the source bitmap.
 */
static void scale3x(void* void_dst, unsigned dst_slice, const void* void_src, unsigned src_slice, unsigned pixel, unsigned width, unsigned height)
{
      unsigned char* dst = (unsigned char*)void_dst;
      const unsigned char* src = (const unsigned char*)void_src;
      unsigned count;

      assert(height >= 2);

      count = height;

      while (count) {
            stage_scale3x(SCDST(0), SCDST(1), SCDST(2), SCSRC(0), SCSRC(1), SCSRC(2), pixel, width);

            dst = SCDST(3);
            src = SCSRC(1);

            --count;
      }
}

/**
 * Apply the Scale4x effect on a bitmap.
 * The destination bitmap is filled with the scaled version of the source bitmap.
 * The source bitmap isn't modified.
 * The destination bitmap must be manually allocated before calling the function,
 * note that the resulting size is exactly 4x4 times the size of the source bitmap.
 * \note This function requires also a small buffer bitmap used internally to store
 * intermediate results. This bitmap must have at least an horizontal size in bytes of 2*width*pixel,
 * and a vertical size of 6 rows. The memory of this buffer must not be allocated
 * in video memory because it's also read and not only written. Generally
 * a heap (malloc) or a stack (alloca) buffer is the best choices.
 * \param void_dst Pointer at the first pixel of the destination bitmap.
 * \param dst_slice Size in bytes of a destination bitmap row.
 * \param void_mid Pointer at the first pixel of the buffer bitmap.
 * \param mid_slice Size in bytes of a buffer bitmap row.
 * \param void_src Pointer at the first pixel of the source bitmap.
 * \param src_slice Size in bytes of a source bitmap row.
 * \param pixel Bytes per pixel of the source and destination bitmap.
 * \param width Horizontal size in pixels of the source bitmap.
 * \param height Vertical size in pixels of the source bitmap.
 */
static void scale4x_buf(void* void_dst, unsigned dst_slice, void* void_mid, unsigned mid_slice, const void* void_src, unsigned src_slice, unsigned pixel, unsigned width, unsigned height)
{
      unsigned char* dst = (unsigned char*)void_dst;
      const unsigned char* src = (const unsigned char*)void_src;
      unsigned count;
      unsigned char* mid[6];

      assert(height >= 4);

      count = height;

      /* set the 6 buffer pointers */
      mid[0] = (unsigned char*)void_mid;
      mid[1] = mid[0] + mid_slice;
      mid[2] = mid[1] + mid_slice;
      mid[3] = mid[2] + mid_slice;
      mid[4] = mid[3] + mid_slice;
      mid[5] = mid[4] + mid_slice;

      while (count) {
            unsigned char* tmp;

            stage_scale2x(SCMID(4), SCMID(5), SCSRC(2), SCSRC(3), SCSRC(4), pixel, width);
            stage_scale4x(SCDST(0), SCDST(1), SCDST(2), SCDST(3), SCMID(1), SCMID(2), SCMID(3), SCMID(4), pixel, width);

            dst = SCDST(4);
            src = SCSRC(1);

            tmp = SCMID(0); /* shift by 2 position */
            SCMID(0) = SCMID(2);
            SCMID(2) = SCMID(4);
            SCMID(4) = tmp;
            tmp = SCMID(1);
            SCMID(1) = SCMID(3);
            SCMID(3) = SCMID(5);
            SCMID(5) = tmp;

            --count;
      }

#if defined(__GNUC__) && defined(__i386__)
      scale2x_mmx_emms();
#endif
}

/**
 * Apply the Scale4x effect on a bitmap.
 * The destination bitmap is filled with the scaled version of the source bitmap.
 * The source bitmap isn't modified.
 * The destination bitmap must be manually allocated before calling the function,
 * note that the resulting size is exactly 4x4 times the size of the source bitmap.
 * \note This function operates like ::scale4x_buf() but the intermediate buffer is
 * automatically allocated in the stack.
 * \param void_dst Pointer at the first pixel of the destination bitmap.
 * \param dst_slice Size in bytes of a destination bitmap row.
 * \param void_src Pointer at the first pixel of the source bitmap.
 * \param src_slice Size in bytes of a source bitmap row.
 * \param pixel Bytes per pixel of the source and destination bitmap.
 * \param width Horizontal size in pixels of the source bitmap.
 * \param height Vertical size in pixels of the source bitmap.
 */
static void scale4x(void* void_dst, unsigned dst_slice, const void* void_src, unsigned src_slice, unsigned pixel, unsigned width, unsigned height)
{
      unsigned mid_slice;
      void* mid;

      mid_slice = 2 * pixel * width; /* required space for 1 row buffer */

      mid_slice = (mid_slice + 0x7) & ~0x7; /* align to 8 bytes */

#if defined(HAVE_ALLOCA)
      mid = alloca(6 * mid_slice); /* allocate space for 6 row buffers */

      assert(mid != 0); /* alloca should never fails */
#else
      mid = malloc(6 * mid_slice); /* allocate space for 6 row buffers */

      if (!mid)
            return;
#endif

      scale4x_buf(void_dst, dst_slice, mid, mid_slice, void_src, src_slice, pixel, width, height);

#if !defined(HAVE_ALLOCA)
      free(mid);
#endif
}

/**
 * Check if the scale implementation is applicable at the given arguments.
 * \param scale Scale factor. 2, 3 or 4.
 * \param pixel Bytes per pixel of the source and destination bitmap.
 * \param width Horizontal size in pixels of the source bitmap.
 * \param height Vertical size in pixels of the source bitmap.
 * \return
 *   - -1 on precondition violated.
 *   - 0 on success.
 */
int scale_precondition(unsigned scale, unsigned pixel, unsigned width, unsigned height)
{
      if (scale != 2 && scale != 3 && scale != 4)
            return -1;

      if (pixel != 1 && pixel != 2 && pixel != 4)
            return -1;

      switch (scale) {
      case 2 :
      case 3 :
            if (height < 2)
                  return -1;
            break;
      case 4 :
            if (height < 4)
                  return -1;
            break;
      }

#if defined(__GNUC__) && defined(__i386__)
      switch (scale) {
      case 2 :
      case 4 :
            if (width < (16 / pixel))
                  return -1;
            if (width % (8 / pixel) != 0)
                  return -1;
            break;
      case 3 :
            if (width < 2)
                  return -1;
            break;
      }
#else
      if (width < 2)
            return -1;
#endif

      return 0;
}

/**
 * Apply the Scale effect on a bitmap.
 * This function is simply a common interface for ::scale2x(), ::scale3x() and ::scale4x().
 * \param scale Scale factor. 2, 3 or 4.
 * \param void_dst Pointer at the first pixel of the destination bitmap.
 * \param dst_slice Size in bytes of a destination bitmap row.
 * \param void_src Pointer at the first pixel of the source bitmap.
 * \param src_slice Size in bytes of a source bitmap row.
 * \param pixel Bytes per pixel of the source and destination bitmap.
 * \param width Horizontal size in pixels of the source bitmap.
 * \param height Vertical size in pixels of the source bitmap.
 */
void scale(unsigned scale, void* void_dst, unsigned dst_slice, const void* void_src, unsigned src_slice, unsigned pixel, unsigned width, unsigned height)
{
      switch (scale) {
      case 2 :
            scale2x(void_dst, dst_slice, void_src, src_slice, pixel, width, height);
            break;
      case 3 :
            scale3x(void_dst, dst_slice, void_src, src_slice, pixel, width, height);
            break;
      case 4 :
            scale4x(void_dst, dst_slice, void_src, src_slice, pixel, width, height);
            break;
      }
}


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