-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;
+const uint8_t BAM_BASECODE_EQUAL = 0;
+const uint8_t BAM_BASECODE_A = 1;
+const uint8_t BAM_BASECODE_C = 2;
+const uint8_t BAM_BASECODE_M = 3;
+const uint8_t BAM_BASECODE_G = 4;
+const uint8_t BAM_BASECODE_R = 5;
+const uint8_t BAM_BASECODE_S = 6;
+const uint8_t BAM_BASECODE_V = 7;
+const uint8_t BAM_BASECODE_T = 8;
+const uint8_t BAM_BASECODE_W = 9;
+const uint8_t BAM_BASECODE_Y = 10;
+const uint8_t BAM_BASECODE_H = 11;
+const uint8_t BAM_BASECODE_K = 12;
+const uint8_t BAM_BASECODE_D = 13;
+const uint8_t BAM_BASECODE_B = 14;
+const uint8_t 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_M = 'M';
+const char BAM_DNA_G = 'G';
+const char BAM_DNA_R = 'R';
+const char BAM_DNA_S = 'S';
+const char BAM_DNA_V = 'V';
+const char BAM_DNA_T = 'T';
+const char BAM_DNA_W = 'W';
+const char BAM_DNA_Y = 'Y';
+const char BAM_DNA_H = 'H';
+const char BAM_DNA_K = 'K';
+const char BAM_DNA_D = 'D';
+const char BAM_DNA_B = 'B';
+const char BAM_DNA_N = 'N';
+const char BAM_DNA_DEL = '-';
+const char BAM_DNA_PAD = '*';
+
+// zlib & BGZF constants
+const char GZIP_ID1 = 31;
+const char GZIP_ID2 = 139;
+const char CM_DEFLATE = 8;
+const char FLG_FEXTRA = 4;
+const char OS_UNKNOWN = 255;
+const char BGZF_XLEN = 6;
+const char BGZF_ID1 = 66;
+const char BGZF_ID2 = 67;
+const char BGZF_LEN = 2;
+
+const int8_t GZIP_WINDOW_BITS = -15;
+const int8_t Z_DEFAULT_MEM_LEVEL = 8;
+const uint8_t BGZF_BLOCK_HEADER_LENGTH = 18;
+const uint8_t BGZF_BLOCK_FOOTER_LENGTH = 8;
+const uint32_t BGZF_MAX_BLOCK_SIZE = 65536;
+const uint32_t BGZF_DEFAULT_BLOCK_SIZE = 65536;