Mini C BMP Loader

bmploader.cpp

// mini bmp loader written by HSU YOU-LUN
unsigned char *load_bmp(const char *bmp, unsigned int *width, unsigned int *height, unsigned short int *bits)
{
	unsigned char *result=nullptr;
	FILE *fp = fopen(bmp, "rb");
	if(!fp)
		return nullptr;
	char type[2];
	unsigned int size, offset;
	// check for magic signature	
	fread(type, sizeof(type), 1, fp);
	if(type[0]==0x42 || type[1]==0x4d){
		fread(&size, sizeof(size), 1, fp);
		// ignore 2 two-byte reversed fields
		fseek(fp, 4, SEEK_CUR);
		fread(&offset, sizeof(offset), 1, fp);
		// ignore size of bmpinfoheader field
		fseek(fp, 4, SEEK_CUR);
		fread(width, sizeof(*width), 1, fp);
		fread(height, sizeof(*height), 1, fp);
		// ignore planes field
		fseek(fp, 2, SEEK_CUR);
		fread(bits, sizeof(*bits), 1, fp);
		unsigned char *pos = result = new unsigned char[size-offset];
		fseek(fp, offset, SEEK_SET);
		while(size-ftell(fp)>0)
			pos+=fread(pos, 1, size-ftell(fp), fp);
	}
	fclose(fp);
	return result;
}