Function read_tga

encoder/basisu_enc.cpp:2435–2815

	};

	uint8_t *read_tga(const uint8_t *pBuf, uint32_t buf_size, int &width, int &height, int &n_chans)
	{
		width = 0;
		height = 0;
		n_chans = 0;

		if (buf_size <= sizeof(tga_header))
			return nullptr;

		const tga_header &hdr = *reinterpret_cast<const tga_header *>(pBuf);

		if ((!hdr.m_width) || (!hdr.m_height) || (hdr.m_width > MAX_TGA_IMAGE_SIZE) || (hdr.m_height > MAX_TGA_IMAGE_SIZE))
			return nullptr;

		if (hdr.m_desc >> 6)
			return nullptr;

		// Simple validation
		if ((hdr.m_cmap != 0) && (hdr.m_cmap != 1))
			return nullptr;
		
		if (hdr.m_cmap)
		{
			if ((hdr.m_cmap_bpp == 0) || (hdr.m_cmap_bpp > 32))
				return nullptr;

			// Nobody implements CMapFirst correctly, so we're not supporting it. Never seen it used, either.
			if (hdr.m_cmap_first != 0)
				return nullptr;
		}

		const bool x_flipped = (hdr.m_desc & 0x10) != 0;
		const bool y_flipped = (hdr.m_desc & 0x20) == 0;

		bool rle_flag = false;
		int file_image_type = hdr.m_type;
		if (file_image_type > 8)
		{
			file_image_type -= 8;
			rle_flag = true;
		}

		const tga_image_type image_type = static_cast<tga_image_type>(file_image_type);

		switch (file_image_type)
		{
		case cITRGB:
			if (hdr.m_depth == 8)
				return nullptr;
			break;
		case cITPalettized:
			if ((hdr.m_depth != 8) || (hdr.m_cmap != 1) || (hdr.m_cmap_len == 0))
				return nullptr;
			break;
		case cITGrayscale:
			if ((hdr.m_cmap != 0) || (hdr.m_cmap_len != 0))
				return nullptr;
			if ((hdr.m_depth != 8) && (hdr.m_depth != 16))