Add big integer implementation

include/bh/internal/bigint.h

@@ -0,0 +1,31 @@
+#ifndef BH_INTERNAL_BIGINT_H
+#define BH_INTERNAL_BIGINT_H
+
+#include "bh.h"
+#include <bh/bigint.h>
+
+#if defined(BH_BIGINT_LONG)
+#define BH_BIGINT_BITS  31
+#define BH_BIGINT_MASK  0x7FFFFFFF
+#define BH_BIGINT_TYPE  bh_uint32_t
+#define BH_BIGINT_TMP   bh_uint64_t
+#else
+#define BH_BIGINT_BITS  15
+#define BH_BIGINT_MASK  0x7FFF
+#define BH_BIGINT_TYPE  bh_uint16_t
+#define BH_BIGINT_TMP   bh_uint32_t
+#endif
+
+struct bh_bigint_s
+{
+    BH_BIGINT_TYPE *data;
+    size_t size;
+    size_t capacity;
+    int type;
+    int error;
+};
+
+void bh_bigint_init(bh_bigint_t *bigint);
+void bh_bigint_destroy(bh_bigint_t *bigint);
+
+#endif /* BH_INTERNAL_BIGINT_H */