+const unsigned char BAM_BASECODE_EQUAL = 0;
+const unsigned char BAM_BASECODE_A = 1;
+const unsigned char BAM_BASECODE_C = 2;
+const unsigned char BAM_BASECODE_G = 4;
+const unsigned char BAM_BASECODE_T = 8;
+const unsigned char BAM_BASECODE_N = 15;
+
+const char BAM_DNA_EQUAL = '=';
+const char BAM_DNA_A = 'A';
+const char BAM_DNA_C = 'C';
+const char BAM_DNA_G = 'G';
+const char BAM_DNA_T = 'T';
+const char BAM_DNA_N = 'N';
+const char BAM_DNA_DEL = '-';
+const char BAM_DNA_PAD = '*';
+
+// zlib constants
+const int GZIP_ID1 = 31;
+const int GZIP_ID2 = 139;
+const int CM_DEFLATE = 8;
+const int FLG_FEXTRA = 4;
+const int OS_UNKNOWN = 255;
+const int BGZF_XLEN = 6;
+const int BGZF_ID1 = 66;
+const int BGZF_ID2 = 67;
+const int BGZF_LEN = 2;
+const int GZIP_WINDOW_BITS = -15;
+const int Z_DEFAULT_MEM_LEVEL = 8;
+
+// BZGF constants
+const int BGZF_BLOCK_HEADER_LENGTH = 18;
+const int BGZF_BLOCK_FOOTER_LENGTH = 8;
+const int BGZF_MAX_BLOCK_SIZE = 65536;
+const int BGZF_DEFAULT_BLOCK_SIZE = 65536;