// Project64 - A Nintendo 64 emulator
// http://www.pj64-emu.com/
// Copyright(C) 2001-2021 Project64
// Copyright(C) 2007 Hiroshi Morii
// Copyright(C) 2003 Rice1964
// GNU/GPLv2 licensed: https://gnu.org/licenses/gpl-2.0.html

/* use power of 2 texture size
 * (0:disable, 1:enable, 2:3dfx) */
#define POW2_TEXTURES 0

 /* check 8 bytes. use a larger value if needed. */
#define PNG_CHK_BYTES 8

#include "TxImage.h"
#include "TxReSample.h"
#include "TxDbg.h"
#include <stdlib.h>
#include <Project64-video/Renderer/types.h>

bool TxImage::getPNGInfo(FILE *fp, png_structp *png_ptr, png_infop *info_ptr)
{
    unsigned char sig[PNG_CHK_BYTES];

    /* check for valid file pointer */
    if (!fp)
        return 0;

    /* check if file is PNG */
    if (fread(sig, 1, PNG_CHK_BYTES, fp) != PNG_CHK_BYTES)
        return 0;

    if (png_sig_cmp(sig, 0, PNG_CHK_BYTES) != 0)
        return 0;

    /* get PNG file info */
    *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!*png_ptr)
        return 0;

    *info_ptr = png_create_info_struct(*png_ptr);
    if (!*info_ptr) {
        png_destroy_read_struct(png_ptr, NULL, NULL);
        return 0;
    }

    if (setjmp(png_jmpbuf(*png_ptr))) {
        DBG_INFO(80, "error reading png!\n");
        png_destroy_read_struct(png_ptr, info_ptr, NULL);
        return 0;
    }

    png_init_io(*png_ptr, fp);
    png_set_sig_bytes(*png_ptr, PNG_CHK_BYTES);
    png_read_info(*png_ptr, *info_ptr);

    return 1;
}

uint8*
TxImage::readPNG(FILE* fp, int* width, int* height, uint16* format)
{
    /* NOTE: returned image format is GFX_TEXFMT_ARGB_8888 */

    png_structp png_ptr;
    png_infop info_ptr;
    uint8 *image = NULL;
    int bit_depth, color_type, interlace_type, compression_type, filter_type,
        row_bytes, o_width, o_height, num_pas;

    /* initialize */
    *width = 0;
    *height = 0;
    *format = 0;

    /* check if we have a valid png file */
    if (!fp)
        return NULL;

    if (!getPNGInfo(fp, &png_ptr, &info_ptr))
    {
        INFO(80, "error reading png file! png image is corrupt.\n");
        return NULL;
    }

    png_get_IHDR(png_ptr, info_ptr,
        (png_uint_32*)&o_width, (png_uint_32*)&o_height, &bit_depth, &color_type,
        &interlace_type, &compression_type, &filter_type);

    DBG_INFO(80, "png format %d x %d bitdepth:%d color:%x interlace:%x compression:%x filter:%x\n",
        o_width, o_height, bit_depth, color_type,
        interlace_type, compression_type, filter_type);

    /* transformations */

    /* Rice hi-res textures
     * _all.png
     * _rgb.png, _a.png
     * _ciByRGBA.png
     * _allciByRGBA.png
     */

     /* strip if color channel is larger than 8 bits */
    if (bit_depth > 8) {
        png_set_strip_16(png_ptr);
        bit_depth = 8;
    }

#if 1
    /* These are not really required per Rice format spec,
     * but is done just in case someone uses them.
     */
     /* convert palette color to rgb color */
    if (color_type == PNG_COLOR_TYPE_PALETTE) {
        png_set_palette_to_rgb(png_ptr);
        color_type = PNG_COLOR_TYPE_RGB;
    }

    /* expand 1,2,4 bit gray scale to 8 bit gray scale */
    if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
        png_set_expand(png_ptr);

    /* convert gray scale or gray scale + alpha to rgb color */
    if (color_type == PNG_COLOR_TYPE_GRAY ||
        color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
        png_set_gray_to_rgb(png_ptr);
        color_type = PNG_COLOR_TYPE_RGB;
    }
#endif

    /* add alpha channel if any */
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
        png_set_tRNS_to_alpha(png_ptr);
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
    }

    /* convert rgb to rgba */
    if (color_type == PNG_COLOR_TYPE_RGB) {
        png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
    }

    /* punt invalid formats */
    if (color_type != PNG_COLOR_TYPE_RGB_ALPHA) {
        png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
        DBG_INFO(80, "Error: not PNG_COLOR_TYPE_RGB_ALPHA format!\n");
        return NULL;
    }

    /*png_color_8p sig_bit;
    if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
      png_set_shift(png_ptr, sig_bit);*/

      /* convert rgba to bgra */
    png_set_bgr(png_ptr);

    /* turn on interlace handling to cope with the weirdness
     * of texture authors using interlaced format */
    num_pas = png_set_interlace_handling(png_ptr);

    /* update info structure */
    png_read_update_info(png_ptr, info_ptr);

    /* we only get here if ARGB8888 */
    row_bytes = png_get_rowbytes(png_ptr, info_ptr);

    /* allocate memory to read in image */
    image = (uint8*)malloc(row_bytes * o_height);

    /* read in image */
    if (image) {
        int pas, i;
        uint8* tmpimage;

        for (pas = 0; pas < num_pas; pas++) { /* deal with interlacing */
            tmpimage = image;

            for (i = 0; i < o_height; i++) {
                /* copy row */
                png_read_rows(png_ptr, &tmpimage, NULL, 1);
                tmpimage += row_bytes;
            }
        }

        /* read rest of the info structure */
        png_read_end(png_ptr, info_ptr);

        *width = (row_bytes >> 2);
        *height = o_height;
        *format = GFX_TEXFMT_ARGB_8888;

#if POW2_TEXTURES
        /* next power of 2 size conversions */
        /* NOTE: I can do this in the above loop for faster operations, but some
         * texture packs require a workaround. see HACKALERT in nextPow2().
         */

        TxReSample txReSample = new TxReSample; // XXX: temporary. move to a better place.

#if (POW2_TEXTURES == 2)
        if (!txReSample->nextPow2(&image, width, height, 32, 1)) {
#else
        if (!txReSample->nextPow2(&image, width, height, 32, 0)) {
#endif
            if (image) {
                free(image);
                image = NULL;
            }
            *width = 0;
            *height = 0;
            *format = 0;
        }

        delete txReSample;

#endif /* POW2_TEXTURES */
    }

    /* clean up */
    png_destroy_read_struct(&png_ptr, &info_ptr, NULL);

#ifdef DEBUG
    if (!image) {
        DBG_INFO(80, "Error: failed to load png image!\n");
    }
#endif

    return image;
}

bool
TxImage::writePNG(uint8* src, FILE* fp, int width, int height, int rowStride, uint16 format, uint8 *palette)
{
    png_structp png_ptr;
    png_infop info_ptr;
    png_color_8 sig_bit;
    png_colorp palette_ptr;
    png_bytep trans_ptr;//, tex_ptr;
    int bit_depth, color_type, row_bytes, num_palette;
    int i;
    //uint16 srcfmt, destfmt;

    if (!src || !fp)
        return 0;

    png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (png_ptr == NULL)
        return 0;

    info_ptr = png_create_info_struct(png_ptr);
    if (info_ptr == NULL) {
        png_destroy_write_struct(&png_ptr, NULL);
        return 0;
    }

    /*if (setjmp(png_ptr->jmpbuf)) {
      png_destroy_write_struct(&png_ptr, &info_ptr);
      return 0;
    }*/

    png_init_io(png_ptr, fp);

    /* TODO: images must be converted to RGBA8888 or CI8,
     * palettes need to be separated to A and RGB. */

     /* N64 formats
      * Format: 0 - RGBA, 1 - YUV, 2 - CI, 3 - IA, 4 - I
      * Size:   0 - 4bit, 1 - 8bit, 2 - 16bit, 3 - 32 bit
      * format = (Format << 8 | Size);
      */

      /* each channel is saved in 8bits for consistency */
    switch (format) {
    case 0x0002:/* RGBA5551 */
        bit_depth = 8;
        sig_bit.red = 5;
        sig_bit.green = 5;
        sig_bit.blue = 5;
        sig_bit.alpha = 1;
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
        break;
    case 0x0003:/* RGBA8888 */
    case 0x0302:/* IA88 */
        bit_depth = 8;
        sig_bit.red = 8;
        sig_bit.green = 8;
        sig_bit.blue = 8;
        sig_bit.alpha = 8;
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
        break;
    case 0x0300:/* IA31 */
        bit_depth = 8;
        sig_bit.red = 3;
        sig_bit.green = 3;
        sig_bit.blue = 3;
        sig_bit.alpha = 1;
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
        break;
    case 0x0301:/* IA44 */
        bit_depth = 8;
        sig_bit.red = 4;
        sig_bit.green = 4;
        sig_bit.blue = 4;
        sig_bit.alpha = 4;
        color_type = PNG_COLOR_TYPE_RGB_ALPHA;
        break;
    case 0x0400:/* I4 */
        bit_depth = 8;
        sig_bit.red = 4;
        sig_bit.green = 4;
        sig_bit.blue = 4;
        color_type = PNG_COLOR_TYPE_RGB;
        break;
    case 0x0401:/* I8 */
    case 0x0402:/* I16 */
        bit_depth = 8;
        sig_bit.red = 8;
        sig_bit.green = 8;
        sig_bit.blue = 8;
        color_type = PNG_COLOR_TYPE_RGB;
        break;
    case 0x0200:/* CI4 */
        bit_depth = 8;
        num_palette = 16;
        color_type = PNG_COLOR_TYPE_PALETTE;
        break;
    case 0x0201:/* CI8 */
        bit_depth = 8;
        num_palette = 256;
        color_type = PNG_COLOR_TYPE_PALETTE;
        break;
    case 0x0102:/* YUV ? */
    case 0x0103:
    default:
        /* unsupported format */
        png_destroy_write_struct(&png_ptr, &info_ptr);
        return 0;
    }

    switch (color_type) {
    case PNG_COLOR_TYPE_RGB_ALPHA:
    case PNG_COLOR_TYPE_RGB:
        //row_bytes = (bit_depth * width) >> 1;
        row_bytes = rowStride;
        png_set_bgr(png_ptr);
        png_set_sBIT(png_ptr, info_ptr, &sig_bit);
        break;
    case PNG_COLOR_TYPE_PALETTE:
        //row_bytes = (bit_depth * width) >> 3;
        row_bytes = rowStride;
        png_set_PLTE(png_ptr, info_ptr, palette_ptr, num_palette);
        png_set_tRNS(png_ptr, info_ptr, trans_ptr, num_palette, 0);
    }

    //png_set_filter(png_ptr, 0, PNG_ALL_FILTERS);

    //if (bit_depth == 16)
    //  png_set_swap(png_ptr);

    //if (bit_depth < 8)
    //  png_set_packswap(png_ptr);

    png_set_IHDR(png_ptr, info_ptr, width, height,
        bit_depth, color_type, PNG_INTERLACE_NONE,
        PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

    //png_set_gAMA(png_ptr, info_ptr, 1.0);

    png_write_info(png_ptr, info_ptr);
    for (i = 0; i < height; i++) {
        png_write_row(png_ptr, (png_bytep)src);
        src += row_bytes;
    }
    png_write_end(png_ptr, info_ptr);

    png_destroy_write_struct(&png_ptr, &info_ptr);

    //if (tex_ptr) delete [] tex_ptr;

    return 1;
}

bool
TxImage::getBMPInfo(FILE* fp, BITMAPFILEHEADER* bmp_fhdr, BITMAPINFOHEADER* bmp_ihdr)
{
    /*
     * read in BITMAPFILEHEADER
     */

     /* is this a BMP file? */
    if (fread(&bmp_fhdr->bfType, 2, 1, fp) != 1)
        return 0;

    if (memcmp(&bmp_fhdr->bfType, "BM", 2) != 0)
        return 0;

    /* get file size */
    if (fread(&bmp_fhdr->bfSize, 4, 1, fp) != 1)
        return 0;

    /* reserved 1 */
    if (fread(&bmp_fhdr->bfReserved1, 2, 1, fp) != 1)
        return 0;

    /* reserved 2 */
    if (fread(&bmp_fhdr->bfReserved2, 2, 1, fp) != 1)
        return 0;

    /* offset to the image data */
    if (fread(&bmp_fhdr->bfOffBits, 4, 1, fp) != 1)
        return 0;

    /*
     * read in BITMAPINFOHEADER
     */

     /* size of BITMAPINFOHEADER */
    if (fread(&bmp_ihdr->biSize, 4, 1, fp) != 1)
        return 0;

    /* is this a Windows BMP? */
    if (bmp_ihdr->biSize != 40)
        return 0;

    /* width of the bitmap in pixels */
    if (fread(&bmp_ihdr->biWidth, 4, 1, fp) != 1)
        return 0;

    /* height of the bitmap in pixels */
    if (fread(&bmp_ihdr->biHeight, 4, 1, fp) != 1)
        return 0;

    /* number of planes (always 1) */
    if (fread(&bmp_ihdr->biPlanes, 2, 1, fp) != 1)
        return 0;

    /* number of bits-per-pixel. (1, 4, 8, 16, 24, 32) */
    if (fread(&bmp_ihdr->biBitCount, 2, 1, fp) != 1)
        return 0;

    /* compression for a compressed bottom-up bitmap
     *   0 : uncompressed format
     *   1 : run-length encoded 4 bpp format
     *   2 : run-length encoded 8 bpp format
     *   3 : bitfield
     */
    if (fread(&bmp_ihdr->biCompression, 4, 1, fp) != 1)
        return 0;

    /* size of the image in bytes */
    if (fread(&bmp_ihdr->biSizeImage, 4, 1, fp) != 1)
        return 0;

    /* horizontal resolution in pixels-per-meter */
    if (fread(&bmp_ihdr->biXPelsPerMeter, 4, 1, fp) != 1)
        return 0;

    /* vertical resolution in pixels-per-meter */
    if (fread(&bmp_ihdr->biYPelsPerMeter, 4, 1, fp) != 1)
        return 0;

    /* number of color indexes in the color table that are actually used */
    if (fread(&bmp_ihdr->biClrUsed, 4, 1, fp) != 1)
        return 0;

    /*  the number of color indexes that are required for displaying */
    if (fread(&bmp_ihdr->biClrImportant, 4, 1, fp) != 1)
        return 0;

    return 1;
}

uint8*
TxImage::readBMP(FILE* fp, int* width, int* height, uint16* format)
{
    /* NOTE: returned image format;
     *       4, 8bit palette bmp -> GFX_TEXFMT_P_8
     *       24, 32bit bmp -> GFX_TEXFMT_ARGB_8888
     */

    uint8 *image = NULL;
    uint8 *image_row = NULL;
    uint8 *tmpimage = NULL;
    unsigned int row_bytes, pos;
    int i, j;
    /* Windows Bitmap */
    BITMAPFILEHEADER bmp_fhdr;
    BITMAPINFOHEADER bmp_ihdr;

    /* initialize */
    *width = 0;
    *height = 0;
    *format = 0;

    /* check if we have a valid bmp file */
    if (!fp)
        return NULL;

    if (!getBMPInfo(fp, &bmp_fhdr, &bmp_ihdr)) {
        INFO(80, "error reading bitmap file! bitmap image is corrupt.\n");
        return NULL;
    }

    DBG_INFO(80, "bmp format %d x %d bitdepth:%d compression:%x offset:%d\n",
        bmp_ihdr.biWidth, bmp_ihdr.biHeight, bmp_ihdr.biBitCount,
        bmp_ihdr.biCompression, bmp_fhdr.bfOffBits);

    /* rowStride in bytes */
    row_bytes = (bmp_ihdr.biWidth * bmp_ihdr.biBitCount) >> 3;
    /* align to 4bytes boundary */
    row_bytes = (row_bytes + 3) & ~3;

    /* Rice hi-res textures */
    if (!(bmp_ihdr.biBitCount == 8 || bmp_ihdr.biBitCount == 4 || bmp_ihdr.biBitCount == 32 || bmp_ihdr.biBitCount == 24) ||
        bmp_ihdr.biCompression != 0) {
        DBG_INFO(80, "Error: incompatible bitmap format!\n");
        return NULL;
    }

    switch (bmp_ihdr.biBitCount) {
    case 8:
    case 32:
        /* 8 bit, 32 bit bitmap */
        image = (uint8*)malloc(row_bytes * bmp_ihdr.biHeight);
        if (image) {
            tmpimage = image;
            pos = bmp_fhdr.bfOffBits + row_bytes * (bmp_ihdr.biHeight - 1);
            for (i = 0; i < bmp_ihdr.biHeight; i++) {
                /* read in image */
                fseek(fp, pos, SEEK_SET);
                fread(tmpimage, row_bytes, 1, fp);
                tmpimage += row_bytes;
                pos -= row_bytes;
            }
        }
        break;
    case 4:
        /* 4bit bitmap */
        image = (uint8*)malloc((row_bytes * bmp_ihdr.biHeight) << 1);
        image_row = (uint8*)malloc(row_bytes);
        if (image && image_row) {
            tmpimage = image;
            pos = bmp_fhdr.bfOffBits + row_bytes * (bmp_ihdr.biHeight - 1);
            for (i = 0; i < bmp_ihdr.biHeight; i++) {
                /* read in image */
                fseek(fp, pos, SEEK_SET);
                fread(image_row, row_bytes, 1, fp);
                /* expand 4bpp to 8bpp. stuff 4bit values into 8bit comps. */
                for (j = 0; j < (int)row_bytes; j++) {
                    tmpimage[j << 1] = image_row[j] & 0x0f;
                    tmpimage[(j << 1) + 1] = (image_row[j] & 0xf0) >> 4;
                }
                tmpimage += (row_bytes << 1);
                pos -= row_bytes;
            }
            free(image_row);
        }
        else {
            if (image_row) free(image_row);
            if (image) free(image);
            image = NULL;
        }
        break;
    case 24:
        /* 24 bit bitmap */
        image = (uint8*)malloc((bmp_ihdr.biWidth * bmp_ihdr.biHeight) << 2);
        image_row = (uint8*)malloc(row_bytes);
        if (image && image_row) {
            tmpimage = image;
            pos = bmp_fhdr.bfOffBits + row_bytes * (bmp_ihdr.biHeight - 1);
            for (i = 0; i < bmp_ihdr.biHeight; i++) {
                /* read in image */
                fseek(fp, pos, SEEK_SET);
                fread(image_row, row_bytes, 1, fp);
                /* convert 24bpp to 32bpp. */
                for (j = 0; j < bmp_ihdr.biWidth; j++) {
                    tmpimage[(j << 2)] = image_row[j * 3];
                    tmpimage[(j << 2) + 1] = image_row[j * 3 + 1];
                    tmpimage[(j << 2) + 2] = image_row[j * 3 + 2];
                    tmpimage[(j << 2) + 3] = 0xFF;
                }
                tmpimage += (bmp_ihdr.biWidth << 2);
                pos -= row_bytes;
            }
            free(image_row);
        }
        else {
            if (image_row) free(image_row);
            if (image) free(image);
            image = NULL;
        }
    }

    if (image) {
        *width = (row_bytes << 3) / bmp_ihdr.biBitCount;
        *height = bmp_ihdr.biHeight;

        switch (bmp_ihdr.biBitCount) {
        case 8:
        case 4:
            *format = GFX_TEXFMT_P_8;
            break;
        case 32:
        case 24:
            *format = GFX_TEXFMT_ARGB_8888;
        }

#if POW2_TEXTURES
        /* next power of 2 size conversions */
        /* NOTE: I can do this in the above loop for faster operations, but some
         * texture packs require a workaround. see HACKALERT in nextPow2().
         */

        TxReSample txReSample = new TxReSample; // XXX: temporary. move to a better place.

#if (POW2_TEXTURES == 2)
        if (!txReSample->nextPow2(&image, width, height, 8, 1)) {
#else
        if (!txReSample->nextPow2(&image, width, height, 8, 0)) {
#endif
            if (image) {
                free(image);
                image = NULL;
            }
            *width = 0;
            *height = 0;
            *format = 0;
        }

        delete txReSample;

#endif /* POW2_TEXTURES */
    }

#ifdef DEBUG
    if (!image) {
        DBG_INFO(80, "Error: failed to load bmp image!\n");
    }
#endif

    return image;
}

bool
TxImage::getDDSInfo(FILE *fp, DDSFILEHEADER *dds_fhdr)
{
    /*
     * read in DDSFILEHEADER
     */

     /* is this a DDS file? */
    if (fread(&dds_fhdr->dwMagic, 4, 1, fp) != 1)
        return 0;

    if (memcmp(&dds_fhdr->dwMagic, "DDS ", 4) != 0)
        return 0;

    if (fread(&dds_fhdr->dwSize, 4, 1, fp) != 1)
        return 0;

    /* get file flags */
    if (fread(&dds_fhdr->dwFlags, 4, 1, fp) != 1)
        return 0;

    /* height of dds in pixels */
    if (fread(&dds_fhdr->dwHeight, 4, 1, fp) != 1)
        return 0;

    /* width of dds in pixels */
    if (fread(&dds_fhdr->dwWidth, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->dwLinearSize, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->dwDepth, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->dwMipMapCount, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->dwReserved1, 4 * 11, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwSize, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwFlags, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwFourCC, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwRGBBitCount, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwRBitMask, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwGBitMask, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwBBitMask, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->ddpf.dwRGBAlphaBitMask, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->dwCaps1, 4, 1, fp) != 1)
        return 0;

    if (fread(&dds_fhdr->dwCaps2, 4, 1, fp) != 1)
        return 0;

    return 1;
}

uint8*
TxImage::readDDS(FILE* fp, int* width, int* height, uint16* format)
{
    uint8 *image = NULL;
    DDSFILEHEADER dds_fhdr;
    uint16 tmpformat = 0;

    /* initialize */
    *width = 0;
    *height = 0;
    *format = 0;

    /* check if we have a valid dds file */
    if (!fp)
        return NULL;

    if (!getDDSInfo(fp, &dds_fhdr)) {
        INFO(80, "error reading dds file! dds image is corrupt.\n");
        return NULL;
    }

    DBG_INFO(80, "dds format %d x %d HeaderSize %d LinearSize %d\n",
        dds_fhdr.dwWidth, dds_fhdr.dwHeight, dds_fhdr.dwSize, dds_fhdr.dwLinearSize);

    if (!(dds_fhdr.dwFlags & (DDSD_CAPS | DDSD_WIDTH | DDSD_HEIGHT | DDSD_PIXELFORMAT | DDSD_LINEARSIZE))) {
        DBG_INFO(80, "Error: incompatible dds format!\n");
        return NULL;
    }

    if ((dds_fhdr.dwFlags & DDSD_MIPMAPCOUNT) && dds_fhdr.dwMipMapCount != 1) {
        DBG_INFO(80, "Error: mipmapped dds not supported!\n");
        return NULL;
    }

    if (!((dds_fhdr.ddpf.dwFlags & DDPF_FOURCC) && dds_fhdr.dwCaps2 == 0)) {
        DBG_INFO(80, "Error: not fourcc standard texture!\n");
        return NULL;
    }

    if (memcmp(&dds_fhdr.ddpf.dwFourCC, "DXT1", 4) == 0) {
        DBG_INFO(80, "DXT1 format\n");
        /* compensate for missing LinearSize */
        dds_fhdr.dwLinearSize = (dds_fhdr.dwWidth * dds_fhdr.dwHeight) >> 1;
        tmpformat = GFX_TEXFMT_ARGB_CMP_DXT1;
    }
    else if (memcmp(&dds_fhdr.ddpf.dwFourCC, "DXT3", 4) == 0) {
        DBG_INFO(80, "DXT3 format\n");
        dds_fhdr.dwLinearSize = dds_fhdr.dwWidth * dds_fhdr.dwHeight;
        tmpformat = GFX_TEXFMT_ARGB_CMP_DXT3;
    }
    else if (memcmp(&dds_fhdr.ddpf.dwFourCC, "DXT5", 4) == 0) {
        DBG_INFO(80, "DXT5 format\n");
        dds_fhdr.dwLinearSize = dds_fhdr.dwWidth * dds_fhdr.dwHeight;
        tmpformat = GFX_TEXFMT_ARGB_CMP_DXT5;
    }
    else {
        DBG_INFO(80, "Error: not DXT1 or DXT3 or DXT5 format!\n");
        return NULL;
    }

    /* read in image */
    image = (uint8*)malloc(dds_fhdr.dwLinearSize);
    if (image) {
        *width = dds_fhdr.dwWidth;
        *height = dds_fhdr.dwHeight;
        *format = tmpformat;

        fseek(fp, 128, SEEK_SET); /* size of header is 128 bytes */
        fread(image, dds_fhdr.dwLinearSize, 1, fp);
    }

    return image;
}