/* ---------------------------------------------------------------------------

 * Truevision Targa Reader/Writer

 * Copyright (C) 2001-2003, Emil Mikulic.

 *

 * Source and binary redistribution of this code, with or without changes, for

 * free or for profit, is allowed as long as this copyright notice is kept

 * intact.  Modified versions must be clearly marked as modified.

 *

 * This code is provided without any warranty.  The copyright holder is

 * not liable for anything bad that might happen as a result of the

 * code.

 * -------------------------------------------------------------------------*/

/*

 * preso da http://dmr.ath.cx/gfx/targa/

 * modificato da gmt

 *

 */

/*@unused@*/ static const char rcsid[] =

    "$Id: targa.c,v 1.7 2003/06/21 09:30:53 emikulic Exp $";

#define TGA_KEEP_MACROS /* BIT, htole16, letoh16 */

#include "targa.h"

#include <stdlib.h></stdlib.h>

#include <string.h> /* memcpy, memcmp */</string.h>

#define SANE_DEPTH(x) ((x) == 8 || (x) == 16 || (x) == 24 || (x) == 32)

#define UNMAP_DEPTH(x) ((x) == 16 || (x) == 24 || (x) == 32)

static const char tga_id[] =

    "\0\0\0\0" /* extension area offset */

    "\0\0\0\0" /* developer directory offset */

    "TRUEVISION-XFILE.";

static const size_t tga_id_length = 26; /* tga_id + \0 */

/* helpers */

static tga_result tga_read_rle(tga_image *dest, FILE *fp);

static tga_result tga_write_row_RLE(FILE *fp, const tga_image *src,

                                    const uint8_t *row);

typedef enum { RAW, RLE } packet_type;

static packet_type rle_packet_type(const uint8_t *row, const uint16_t pos,

                                   const uint16_t width, const uint16_t bpp);

static uint8_t rle_packet_len(const uint8_t *row, const uint16_t pos,

                              const uint16_t width, const uint16_t bpp,

                              const packet_type type);

uint8_t tga_get_attribute_bits(const tga_image *tga) {

  return tga->image_descriptor & TGA_ATTRIB_BITS;

}

int tga_is_right_to_left(const tga_image *tga) {

  return (tga->image_descriptor & TGA_R_TO_L_BIT) != 0;

}

int tga_is_top_to_bottom(const tga_image *tga) {

  return (tga->image_descriptor & TGA_T_TO_B_BIT) != 0;

}

int tga_is_colormapped(const tga_image *tga) {

  return (tga->image_type == TGA_IMAGE_TYPE_COLORMAP ||

          tga->image_type == TGA_IMAGE_TYPE_COLORMAP_RLE);

}

int tga_is_rle(const tga_image *tga) {

  return (tga->image_type == TGA_IMAGE_TYPE_COLORMAP_RLE ||

          tga->image_type == TGA_IMAGE_TYPE_BGR_RLE ||

          tga->image_type == TGA_IMAGE_TYPE_MONO_RLE);

}

int tga_is_mono(const tga_image *tga) {

  return (tga->image_type == TGA_IMAGE_TYPE_MONO ||

          tga->image_type == TGA_IMAGE_TYPE_MONO_RLE);

}

/* ---------------------------------------------------------------------------

 * Convert the numerical <errcode> into a verbose error string.</errcode>

 *

 * Returns: an error string

 */

const char *tga_error(const tga_result errcode) {

  switch (errcode) {

  case TGA_NOERR:

    return "no error";

  case TGAERR_FOPEN:

    return "error opening file";

  case TGAERR_EOF:

    return "premature end of file";

  case TGAERR_WRITE:

    return "error writing to file";

  case TGAERR_CMAP_TYPE:

    return "invalid color map type";

  case TGAERR_IMG_TYPE:

    return "invalid image type";

  case TGAERR_NO_IMG:

    return "no image data included";

  case TGAERR_CMAP_MISSING:

    return "color-mapped image without color map";

  case TGAERR_CMAP_PRESENT:

    return "non-color-mapped image with extraneous color map";

  case TGAERR_CMAP_LENGTH:

    return "color map has zero length";

  case TGAERR_CMAP_DEPTH:

    return "invalid color map depth";

  case TGAERR_ZERO_SIZE:

    return "the image dimensions are zero";

  case TGAERR_PIXEL_DEPTH:

    return "invalid pixel depth";

  case TGAERR_NO_MEM:

    return "out of memory";

  case TGAERR_NOT_CMAP:

    return "image is not color mapped";

  case TGAERR_RLE:

    return "RLE data is corrupt";

  case TGAERR_INDEX_RANGE:

    return "color map index out of range";

  case TGAERR_MONO:

    return "image is mono";

  default:

    return "unknown error code";

  }

}

/* ---------------------------------------------------------------------------

 * Read a Targa image from a file named <filename> to <dest>.  This is just a</dest></filename>

 * wrapper around tga_read_from_FILE().

 *

 * Returns: TGA_NOERR on success, or a matching TGAERR_* code on failure.

 */

tga_result tga_read(tga_image *dest, const char *filename) {

  tga_result result;

  FILE *fp = fopen(filename, "rb");

  if (fp == NULL) return TGAERR_FOPEN;

  result = tga_read_from_FILE(dest, fp);

  fclose(fp);

  return result;

}

/* ---------------------------------------------------------------------------

 * Read a Targa image from <fp> to <dest>.</dest></fp>

 *

 * Returns: TGA_NOERR on success, or a TGAERR_* code on failure.  In the

 *          case of failure, the contents of dest are not guaranteed to be

 *          valid.

 */

tga_result tga_read_from_FILE(tga_image *dest, FILE *fp) {

#define BARF(errcode)                                                          \

  {                                                                            \

    tga_free_buffers(dest);                                                    \

    return errcode;                                                            \

  }

#define READ(destptr, size)                                                    \

  if (fread(destptr, size, 1, fp) != 1) BARF(TGAERR_EOF)

#define READ16(dest)                                                           \

  {                                                                            \

    if (fread(&(dest), 2, 1, fp) != 1) BARF(TGAERR_EOF);                       \

    dest = letoh16(dest);                                                      \

  }

  dest->image_id       = NULL;

  dest->color_map_data = NULL;

  dest->image_data     = NULL;

  READ(&dest->image_id_length, 1);

  READ(&dest->color_map_type, 1);

  if (dest->color_map_type != TGA_COLOR_MAP_ABSENT &&

      dest->color_map_type != TGA_COLOR_MAP_PRESENT)

    BARF(TGAERR_CMAP_TYPE);

  READ(&dest->image_type, 1);

  if (dest->image_type == TGA_IMAGE_TYPE_NONE) BARF(TGAERR_NO_IMG);

  if (dest->image_type != TGA_IMAGE_TYPE_COLORMAP &&

      dest->image_type != TGA_IMAGE_TYPE_BGR &&

      dest->image_type != TGA_IMAGE_TYPE_MONO &&

      dest->image_type != TGA_IMAGE_TYPE_COLORMAP_RLE &&

      dest->image_type != TGA_IMAGE_TYPE_BGR_RLE &&

      dest->image_type != TGA_IMAGE_TYPE_MONO_RLE)

    BARF(TGAERR_IMG_TYPE);

  if (tga_is_colormapped(dest) && dest->color_map_type == TGA_COLOR_MAP_ABSENT)

    BARF(TGAERR_CMAP_MISSING);

  if (!tga_is_colormapped(dest) &&

      dest->color_map_type == TGA_COLOR_MAP_PRESENT)

    BARF(TGAERR_CMAP_PRESENT);

  READ16(dest->color_map_origin);

  READ16(dest->color_map_length);

  READ(&dest->color_map_depth, 1);

  if (dest->color_map_type == TGA_COLOR_MAP_PRESENT) {

    if (dest->color_map_length == 0) BARF(TGAERR_CMAP_LENGTH);

    if (!UNMAP_DEPTH(dest->color_map_depth)) BARF(TGAERR_CMAP_DEPTH);

  }

  READ16(dest->origin_x);

  READ16(dest->origin_y);

  READ16(dest->width);

  READ16(dest->height);

  if (dest->width == 0 || dest->height == 0) BARF(TGAERR_ZERO_SIZE);

  READ(&dest->pixel_depth, 1);

  if (!SANE_DEPTH(dest->pixel_depth) ||

      (dest->pixel_depth != 8 && tga_is_colormapped(dest)))

    BARF(TGAERR_PIXEL_DEPTH);

  READ(&dest->image_descriptor, 1);

  if (dest->image_id_length > 0) {

    dest->image_id = (uint8_t *)malloc(dest->image_id_length);

    if (dest->image_id == NULL) BARF(TGAERR_NO_MEM);

    READ(dest->image_id, dest->image_id_length);

  }

  if (dest->color_map_type == TGA_COLOR_MAP_PRESENT) {

    dest->color_map_data =

        (uint8_t *)malloc((dest->color_map_origin + dest->color_map_length) *

                          dest->color_map_depth / 8);

    if (dest->color_map_data == NULL) BARF(TGAERR_NO_MEM);

    READ(dest->color_map_data +

             (dest->color_map_origin * dest->color_map_depth / 8),

         dest->color_map_length * dest->color_map_depth / 8);

  }

  dest->image_data =

      (uint8_t *)malloc(dest->width * dest->height * dest->pixel_depth / 8);

  if (dest->image_data == NULL) BARF(TGAERR_NO_MEM);

  if (tga_is_rle(dest)) {

    /* read RLE */

    tga_result result = tga_read_rle(dest, fp);

    if (result != TGA_NOERR) BARF(result);

  } else {

    /* uncompressed */

    READ(dest->image_data, dest->width * dest->height * dest->pixel_depth / 8);

  }

  return TGA_NOERR;

#undef BARF

#undef READ

#undef READ16

}

/* ---------------------------------------------------------------------------

 * Helper function for tga_read_from_FILE().  Decompresses RLE image data from

 * <fp>.  Assumes <dest> header fields are set correctly.</dest></fp>

 */

static tga_result tga_read_rle(tga_image *dest, FILE *fp) {

#define RLE_BIT BIT(7)

#define READ(dest, size)                                                       \

  if (fread(dest, size, 1, fp) != 1) return TGAERR_EOF

  uint8_t *pos;

  uint32_t p_loaded = 0, p_expected = dest->width * dest->height;

  uint8_t bpp = dest->pixel_depth / 8; /* bytes per pixel */

  pos = dest->image_data;

  while ((p_loaded < p_expected) && !feof(fp)) {

    uint8_t b;

    READ(&b, 1);

    if (b & RLE_BIT) {

      /* is an RLE packet */

      uint8_t count, tmp[4], i;

      count = (b & ~RLE_BIT) + 1;

      READ(tmp, bpp);

      for (i = 0; i < count; i++) {

        p_loaded++;

        if (p_loaded > p_expected) return TGAERR_RLE;

        memcpy(pos, tmp, bpp);

        pos += bpp;

      }

    } else /* RAW packet */

    {

      uint8_t count;

      count = (b & ~RLE_BIT) + 1;

      if (p_loaded + count > p_expected) return TGAERR_RLE;

      p_loaded += count;

      READ(pos, bpp * count);

      pos += count * bpp;

    }

  }

  return TGA_NOERR;

#undef RLE_BIT

#undef READ

}

/* ---------------------------------------------------------------------------

 * Write a Targa image to a file named <filename> from <src>.  This is just a</src></filename>

 * wrapper around tga_write_to_FILE().

 *

 * Returns: TGA_NOERR on success, or a matching TGAERR_* code on failure.

 */

tga_result tga_write(const char *filename, const tga_image *src) {

  tga_result result;

  FILE *fp = fopen(filename, "wb");

  if (fp == NULL) return TGAERR_FOPEN;

  result = tga_write_to_FILE(fp, src);

  fclose(fp);

  return result;

}

/* ---------------------------------------------------------------------------

 * Write one row of an image to <fp> using RLE.  This is a helper function</fp>

 * called from tga_write_to_FILE().  It assumes that <src> has its header</src>

 * fields set up correctly.

 */

#define PIXEL(ofs) (row + (ofs)*bpp)

static tga_result tga_write_row_RLE(FILE *fp, const tga_image *src,

                                    const uint8_t *row) {

#define WRITE(src, size)                                                       \

  if (fwrite(src, size, 1, fp) != 1) return TGAERR_WRITE

  uint16_t pos = 0;

  uint16_t bpp = src->pixel_depth / 8;

  while (pos < src->width) {

    packet_type type = rle_packet_type(row, pos, src->width, bpp);

    uint8_t len      = rle_packet_len(row, pos, src->width, bpp, type);

    uint8_t packet_header;

    packet_header = len - 1;

    if (type == RLE) packet_header |= BIT(7);

    WRITE(&packet_header, 1);

    if (type == RLE) {

      WRITE(PIXEL(pos), bpp);

    } else /* type == RAW */

    {

      WRITE(PIXEL(pos), bpp * len);

    }

    pos += len;

  }

  return TGA_NOERR;

#undef WRITE

}

/* ---------------------------------------------------------------------------

 * Determine whether the next packet should be RAW or RLE for maximum

 * efficiency.  This is a helper function called from rle_packet_len() and

 * tga_write_row_RLE().

 */

#define SAME(ofs1, ofs2) (memcmp(PIXEL(ofs1), PIXEL(ofs2), bpp) == 0)

static packet_type rle_packet_type(const uint8_t *row, const uint16_t pos,

                                   const uint16_t width, const uint16_t bpp) {

  if (pos == width - 1) return RAW; /* one pixel */

  if (SAME(pos, pos + 1))           /* dupe pixel */

  {

    if (bpp > 1) return RLE; /* inefficient for bpp=1 */

    /* three repeats makes the bpp=1 case efficient enough */

    if ((pos < width - 2) && SAME(pos + 1, pos + 2)) return RLE;

  }

  return RAW;

}

/* ---------------------------------------------------------------------------

 * Find the length of the current RLE packet.  This is a helper function

 * called from tga_write_row_RLE().

 */

static uint8_t rle_packet_len(const uint8_t *row, const uint16_t pos,

                              const uint16_t width, const uint16_t bpp,

                              const packet_type type) {

  uint8_t len = 2;

  if (pos == width - 1) return 1;

  if (pos == width - 2) return 2;

  if (type == RLE) {

    while (pos + len < width) {

      if (SAME(pos, pos + len))

        len++;

      else

        return len;

      if (len == 128) return 128;

    }

  } else /* type == RAW */

  {

    while (pos + len < width) {

      if (rle_packet_type(row, pos + len, width, bpp) == RAW)

        len++;

      else

        return len;

      if (len == 128) return 128;

    }

  }

  return len; /* hit end of row (width) */

}

#undef SAME

#undef PIXEL

/* ---------------------------------------------------------------------------

 * Writes a Targa image to <fp> from <src>.</src></fp>

 *

 * Returns: TGA_NOERR on success, or a TGAERR_* code on failure.

 *          On failure, the contents of the file are not guaranteed

 *          to be valid.

 */

tga_result tga_write_to_FILE(FILE *fp, const tga_image *src) {

#define WRITE(srcptr, size)                                                    \

  if (fwrite(srcptr, size, 1, fp) != 1) return TGAERR_WRITE

#define WRITE16(src)                                                           \

  {                                                                            \

    uint16_t _temp = htole16(src);                                             \

    if (fwrite(&_temp, 2, 1, fp) != 1) return TGAERR_WRITE;                    \

  }

  WRITE(&src->image_id_length, 1);

  if (src->color_map_type != TGA_COLOR_MAP_ABSENT &&

      src->color_map_type != TGA_COLOR_MAP_PRESENT)

    return TGAERR_CMAP_TYPE;

  WRITE(&src->color_map_type, 1);

  if (src->image_type == TGA_IMAGE_TYPE_NONE) return TGAERR_NO_IMG;

  if (src->image_type != TGA_IMAGE_TYPE_COLORMAP &&

      src->image_type != TGA_IMAGE_TYPE_BGR &&

      src->image_type != TGA_IMAGE_TYPE_MONO &&

      src->image_type != TGA_IMAGE_TYPE_COLORMAP_RLE &&

      src->image_type != TGA_IMAGE_TYPE_BGR_RLE &&

      src->image_type != TGA_IMAGE_TYPE_MONO_RLE)

    return TGAERR_IMG_TYPE;

  WRITE(&src->image_type, 1);

  if (tga_is_colormapped(src) && src->color_map_type == TGA_COLOR_MAP_ABSENT)

    return TGAERR_CMAP_MISSING;

  if (!tga_is_colormapped(src) && src->color_map_type == TGA_COLOR_MAP_PRESENT)

    return TGAERR_CMAP_PRESENT;

  if (src->color_map_type == TGA_COLOR_MAP_PRESENT) {

    if (src->color_map_length == 0) return TGAERR_CMAP_LENGTH;

    if (!UNMAP_DEPTH(src->color_map_depth)) return TGAERR_CMAP_DEPTH;

  }

  WRITE16(src->color_map_origin);

  WRITE16(src->color_map_length);

  WRITE(&src->color_map_depth, 1);

  WRITE16(src->origin_x);

  WRITE16(src->origin_y);

  if (src->width == 0 || src->height == 0) return TGAERR_ZERO_SIZE;

  WRITE16(src->width);

  WRITE16(src->height);

  if (!SANE_DEPTH(src->pixel_depth) ||

      (src->pixel_depth != 8 && tga_is_colormapped(src)))

    return TGAERR_PIXEL_DEPTH;

  WRITE(&src->pixel_depth, 1);

  WRITE(&src->image_descriptor, 1);

  if (src->image_id_length > 0) WRITE(&src->image_id, src->image_id_length);

  if (src->color_map_type == TGA_COLOR_MAP_PRESENT)

    WRITE(src->color_map_data +

              (src->color_map_origin * src->color_map_depth / 8),

          src->color_map_length * src->color_map_depth / 8);

  if (tga_is_rle(src)) {

    uint16_t row;

    for (row = 0; row < src->height; row++) {

      tga_result result = tga_write_row_RLE(

          fp, src, src->image_data + row * src->width * src->pixel_depth / 8);

      if (result != TGA_NOERR) return result;

    }

  } else {

    /* uncompressed */

    WRITE(src->image_data, src->width * src->height * src->pixel_depth / 8);

  }

  WRITE(tga_id, tga_id_length);

  return TGA_NOERR;

#undef WRITE

#undef WRITE16

}

/* Convenient writing functions --------------------------------------------*/

/*

 * This is just a helper function to initialise the header fields in a

 * tga_image struct.

 */

static void init_tga_image(tga_image *img, uint8_t *image, const uint16_t width,

                           const uint16_t height, const uint8_t depth) {

  img->image_id_length  = 0;

  img->color_map_type   = TGA_COLOR_MAP_ABSENT;

  img->image_type       = TGA_IMAGE_TYPE_NONE; /* override this below! */

  img->color_map_origin = 0;

  img->color_map_length = 0;

  img->color_map_depth  = 0;

  img->origin_x         = 0;

  img->origin_y         = 0;

  img->width            = width;

  img->height           = height;

  img->pixel_depth      = depth;

  img->image_descriptor = TGA_T_TO_B_BIT;

  img->image_id         = NULL;

  img->color_map_data   = NULL;

  img->image_data       = image;

}

tga_result tga_write_mono(const char *filename, uint8_t *image,

                          const uint16_t width, const uint16_t height) {

  tga_image img;

  init_tga_image(&img, image, width, height, 8);

  img.image_type = TGA_IMAGE_TYPE_MONO;

  return tga_write(filename, &img);

}

tga_result tga_write_mono_rle(const char *filename, uint8_t *image,

                              const uint16_t width, const uint16_t height) {

  tga_image img;

  init_tga_image(&img, image, width, height, 8);

  img.image_type = TGA_IMAGE_TYPE_MONO_RLE;

  return tga_write(filename, &img);

}

tga_result tga_write_bgr(const char *filename, uint8_t *image,

                         const uint16_t width, const uint16_t height,

                         const uint8_t depth) {

  tga_image img;

  init_tga_image(&img, image, width, height, depth);

  img.image_type = TGA_IMAGE_TYPE_BGR;

  return tga_write(filename, &img);

}

tga_result tga_write_bgr_rle(const char *filename, uint8_t *image,

                             const uint16_t width, const uint16_t height,

                             const uint8_t depth) {

  tga_image img;

  init_tga_image(&img, image, width, height, depth);

  img.image_type = TGA_IMAGE_TYPE_BGR_RLE;

  return tga_write(filename, &img);

}

/* Note: this function will MODIFY  */

tga_result tga_write_rgb(const char *filename, uint8_t *image,

                         const uint16_t width, const uint16_t height,

                         const uint8_t depth) {

  tga_image img;

  init_tga_image(&img, image, width, height, depth);

  img.image_type = TGA_IMAGE_TYPE_BGR;

  (void)tga_swap_red_blue(&img);

  return tga_write(filename, &img);

}

/* Note: this function will MODIFY  */

tga_result tga_write_rgb_rle(const char *filename, uint8_t *image,

                             const uint16_t width, const uint16_t height,

                             const uint8_t depth) {

  tga_image img;

  init_tga_image(&img, image, width, height, depth);

  img.image_type = TGA_IMAGE_TYPE_BGR_RLE;

  (void)tga_swap_red_blue(&img);

  return tga_write(filename, &img);

}

/* Convenient manipulation functions ---------------------------------------*/

/* ---------------------------------------------------------------------------

 * Horizontally flip the image in place.  Reverses the right-to-left bit in

 * the image descriptor.

 */

tga_result tga_flip_horiz(tga_image *img) {

  uint16_t row;

  size_t bpp;

  uint8_t *left, *right;

  int r_to_l;

  if (!SANE_DEPTH(img->pixel_depth)) return TGAERR_PIXEL_DEPTH;

  bpp = (size_t)(img->pixel_depth / 8); /* bytes per pixel */

  for (row = 0; row < img->height; row++) {

    left  = img->image_data + row * img->width * bpp;

    right = left + (img->width - 1) * bpp;

    /* reverse from left to right */

    while (left < right) {

      uint8_t buffer[4];

      /* swap */

      memcpy(buffer, left, bpp);

      memcpy(left, right, bpp);

      memcpy(right, buffer, bpp);

      left += bpp;

      right -= bpp;

    }

  }

  /* Correct image_descriptor's left-to-right-ness. */

  r_to_l = tga_is_right_to_left(img);

  img->image_descriptor &= ~TGA_R_TO_L_BIT; /* mask out r-to-l bit */

  if (!r_to_l)                              /* was l-to-r, need to set r_to_l */

    img->image_descriptor |= TGA_R_TO_L_BIT;

  /* else bit is already rubbed out */

  return TGA_NOERR;

}

/* ---------------------------------------------------------------------------

 * Vertically flip the image in place.  Reverses the top-to-bottom bit in

 * the image descriptor.

 */

tga_result tga_flip_vert(tga_image *img) {

  uint16_t col;

  size_t bpp, line;

  uint8_t *top, *bottom;

  int t_to_b;

  if (!SANE_DEPTH(img->pixel_depth)) return TGAERR_PIXEL_DEPTH;

  bpp  = (size_t)(img->pixel_depth / 8); /* bytes per pixel */

  line = bpp * img->width;               /* bytes per line */

  for (col = 0; col < img->width; col++) {

    top    = img->image_data + col * bpp;

    bottom = top + (img->height - 1) * line;

    /* reverse from top to bottom */

    while (top < bottom) {

      uint8_t buffer[4];

      /* swap */

      memcpy(buffer, top, bpp);

      memcpy(top, bottom, bpp);

      memcpy(bottom, buffer, bpp);

      top += line;

      bottom -= line;

    }

  }

  /* Correct image_descriptor's top-to-bottom-ness. */

  t_to_b = tga_is_top_to_bottom(img);

  img->image_descriptor &= ~TGA_T_TO_B_BIT; /* mask out t-to-b bit */

  if (!t_to_b)                              /* was b-to-t, need to set t_to_b */

    img->image_descriptor |= TGA_T_TO_B_BIT;

  /* else bit is already rubbed out */

  return TGA_NOERR;

}

/* ---------------------------------------------------------------------------

 * Convert a color-mapped image to unmapped BGR.  Reallocates image_data to a

 * bigger size, then converts the image backwards to avoid using a secondary

 * buffer.  Alters the necessary header fields and deallocates the color map.

 */

tga_result tga_color_unmap(tga_image *img) {

  uint8_t bpp = img->color_map_depth / 8; /* bytes per pixel */

  int pos;

  void *tmp;

  if (!tga_is_colormapped(img)) return TGAERR_NOT_CMAP;

  if (img->pixel_depth != 8) return TGAERR_PIXEL_DEPTH;

  if (!SANE_DEPTH(img->color_map_depth)) return TGAERR_CMAP_DEPTH;

  tmp = realloc(img->image_data, img->width * img->height * bpp);

  if (tmp == NULL) return TGAERR_NO_MEM;

  img->image_data = (uint8_t *)tmp;

  for (pos = img->width * img->height - 1; pos >= 0; pos--) {

    uint8_t c_index = img->image_data[pos];

    uint8_t *c_bgr  = img->color_map_data + (c_index * bpp);

    if (c_index >= img->color_map_origin + img->color_map_length)

      return TGAERR_INDEX_RANGE;

    memcpy(img->image_data + (pos * bpp), c_bgr, (size_t)bpp);

  }

  /* clean up */

  img->image_type  = TGA_IMAGE_TYPE_BGR;

  img->pixel_depth = img->color_map_depth;

  free(img->color_map_data);

  img->color_map_data   = NULL;

  img->color_map_type   = TGA_COLOR_MAP_ABSENT;

  img->color_map_origin = 0;

  img->color_map_length = 0;

  img->color_map_depth  = 0;

  return TGA_NOERR;

}

/* ---------------------------------------------------------------------------

 * Return a pointer to a given pixel.  Accounts for image orientation (T_TO_B,

 * R_TO_L, etc).  Returns NULL if the pixel is out of range.

 */

uint8_t *tga_find_pixel(const tga_image *img, uint16_t x, uint16_t y) {

  if (x >= img->width || y >= img->height) return NULL;

  if (!tga_is_top_to_bottom(img)) y = img->height - 1 - y;

  if (tga_is_right_to_left(img)) x  = img->width - 1 - x;

  return img->image_data + (x + y * img->width) * img->pixel_depth / 8;

}

/* ---------------------------------------------------------------------------

 * Unpack the pixel at the src pointer according to bits.  Any of b,g,r,a can

 * be set to NULL if not wanted.  Returns TGAERR_PIXEL_DEPTH if a stupid

 * number of bits is given.

 */

tga_result tga_unpack_pixel(const uint8_t *src, const uint8_t bits, uint8_t *b,

                            uint8_t *g, uint8_t *r, uint8_t *a) {

  switch (bits) {

  case 32:

    if (b) *b = src[0];

    if (g) *g = src[1];

    if (r) *r = src[2];

    if (a) *a = src[3];

    break;

  case 24:

    if (b) *b = src[0];

    if (g) *g = src[1];

    if (r) *r = src[2];

    if (a) *a = 0;

    break;

  case 16: {

    uint16_t src16 = (uint16_t)(src[1] << 8) | (uint16_t)src[0];

#define FIVE_BITS (BIT(0) | BIT(1) | BIT(2) | BIT(3) | BIT(4))

    if (b) *b = ((src16)&FIVE_BITS) << 3;

    if (g) *g = ((src16 >> 5) & FIVE_BITS) << 3;

    if (r) *r = ((src16 >> 10) & FIVE_BITS) << 3;

    if (a) *a = (uint8_t)((src16 & BIT(15)) ? 255 : 0);

#undef FIVE_BITS

    break;

  }

  case 8:

    if (b) *b = *src;

    if (g) *g = *src;

    if (r) *r = *src;

    if (a) *a = 0;

    break;

  default:

    return TGAERR_PIXEL_DEPTH;

  }

  return TGA_NOERR;

}

/* ---------------------------------------------------------------------------

 * Pack the pixel at the dest pointer according to bits.  Returns

 * TGAERR_PIXEL_DEPTH if a stupid number of bits is given.

 */

tga_result tga_pack_pixel(uint8_t *dest, const uint8_t bits, const uint8_t b,

                          const uint8_t g, const uint8_t r, const uint8_t a) {

  switch (bits) {

  case 32:

    dest[0] = b;

    dest[1] = g;

    dest[2] = r;

    dest[3] = a;

    break;

  case 24:

    dest[0] = b;

    dest[1] = g;

    dest[2] = r;

    break;

  case 16: {

    uint16_t tmp;

#define FIVE_BITS (BIT(0) | BIT(1) | BIT(2) | BIT(3) | BIT(4))

    tmp = (b >> 3) & FIVE_BITS;

    tmp |= ((g >> 3) & FIVE_BITS) << 5;

    tmp |= ((r >> 3) & FIVE_BITS) << 10;

    if (a > 127) tmp |= BIT(15);

#undef FIVE_BITS

    dest[0] = (uint8_t)(tmp & 0x00FF);

    dest[1] = (uint8_t)((tmp & 0xFF00) >> 8);

    break;

  }

  default:

    return TGAERR_PIXEL_DEPTH;

  }

  return TGA_NOERR;

}

/* ---------------------------------------------------------------------------

 * Desaturate the specified Targa using the specified coefficients:

 *      output = ( red * cr + green * cg + blue * cb ) / dv

 */

tga_result tga_desaturate(tga_image *img, const int cr, const int cg,

                          const int cb, const int dv) {

  uint8_t bpp = img->pixel_depth / 8; /* bytes per pixel */

  uint8_t *dest, *src, *tmp;

  if (tga_is_mono(img)) return TGAERR_MONO;

  if (tga_is_colormapped(img)) {

    tga_result result = tga_color_unmap(img);

    if (result != TGA_NOERR) return result;

  }

  if (!UNMAP_DEPTH(img->pixel_depth)) return TGAERR_PIXEL_DEPTH;

  dest = img->image_data;

  for (src = img->image_data;

       src < img->image_data + img->width * img->height * bpp; src += bpp) {

    uint8_t b, g, r;

    (void)tga_unpack_pixel(src, img->pixel_depth, &b, &g, &r, NULL);

    *dest = (uint8_t)(((int)b * cb + (int)g * cg + (int)r * cr) / dv);

    dest++;

  }

  /* shrink */

  tmp = realloc(img->image_data, img->width * img->height);

  if (tmp == NULL) return TGAERR_NO_MEM;

  img->image_data = tmp;

  img->pixel_depth = 8;

  img->image_type  = TGA_IMAGE_TYPE_MONO;

  return TGA_NOERR;

}

tga_result tga_desaturate_rec_601_1(tga_image *img) {

  return tga_desaturate(img, 2989, 5866, 1145, 10000);

}

tga_result tga_desaturate_rec_709(tga_image *img) {

  return tga_desaturate(img, 2126, 7152, 722, 10000);

}

tga_result tga_desaturate_itu(tga_image *img) {

  return tga_desaturate(img, 2220, 7067, 713, 10000);

}

tga_result tga_desaturate_avg(tga_image *img) {

  return tga_desaturate(img, 1, 1, 1, 3);

}

/* ---------------------------------------------------------------------------

 * Convert an image to the given pixel depth. (one of 32, 24, 16)  Avoids

 * using a secondary buffer to do the conversion.

 */

tga_result tga_convert_depth(tga_image *img, const uint8_t bits) {

  size_t src_size, dest_size;

  uint8_t src_bpp, dest_bpp;

  uint8_t *src, *dest;

  if (!UNMAP_DEPTH(bits) || !SANE_DEPTH(img->pixel_depth))

    return TGAERR_PIXEL_DEPTH;

  if (tga_is_colormapped(img)) {

    tga_result result = tga_color_unmap(img);

    if (result != TGA_NOERR) return result;

  }

  if (img->pixel_depth == bits) return TGA_NOERR; /* no op, no err */

  src_bpp  = img->pixel_depth / 8;

  dest_bpp = bits / 8;

  src_size  = (size_t)(img->width * img->height * src_bpp);

  dest_size = (size_t)(img->width * img->height * dest_bpp);