diff --git a/_cmptest/bigintdemo/fib.go b/_cmptest/bigintdemo/fib.go
index 9876c2e0..23a3d5a4 100644
--- a/_cmptest/bigintdemo/fib.go
+++ b/_cmptest/bigintdemo/fib.go
@@ -5,7 +5,7 @@ import (
 	"math/big"
 )
 
-func main() {
+func fib() {
 	// Initialize two big ints with the first two numbers in the sequence.
 	a := big.NewInt(0)
 	b := big.NewInt(1)
@@ -23,3 +23,41 @@ func main() {
 	}
 	fmt.Println(a) // 100-digit Fibonacci number
 }
+
+func abs() {
+	a := big.NewInt(64)
+	b := big.NewInt(-52)
+	a.Set(b)
+	a.Abs(a)
+	a.Set(big.NewInt(-164))
+	a.Abs(a)
+	fmt.Println("value: ", a.String())
+}
+
+func neg() {
+	fmt.Println("value: ", big.NewInt(-64).Neg(big.NewInt(-64)))
+	fmt.Println("value: ", big.NewInt(64).Neg(big.NewInt(64)))
+	fmt.Println("value: ", big.NewInt(0).Neg(big.NewInt(0)))
+}
+
+func calc() {
+	a := big.NewInt(64)
+	b := big.NewInt(-52)
+	c := big.NewInt(54)
+	fmt.Println("value:", a.Add(a, b))
+	fmt.Println("value:", a.Sub(b, c))
+	d := big.NewInt(10)
+	e := big.NewInt(4)
+	fmt.Println("value:", d.Mul(d, e))
+}
+
+func bitop() {
+	a := big.NewInt(4)
+	fmt.Println("value:", a.Lsh(a, 1))
+	b := big.NewInt(16)
+	fmt.Println("value:", b.Rsh(b, 2))
+}
+
+func main() {
+	bitop()
+}
diff --git a/c/openssl/bn.go b/c/openssl/bn.go
index 4a765b1c..37cf3452 100644
--- a/c/openssl/bn.go
+++ b/c/openssl/bn.go
@@ -49,8 +49,19 @@ func BN_CTXSecureNew() *BN_CTX
 func (*BN_CTX) Free() {}
 
 // void BN_CTX_start(BN_CTX *ctx);
+//
+// llgo:link (*BN_CTX).Start C.BN_CTX_start
+func (*BN_CTX) Start() {}
+
 // BIGNUM *BN_CTX_get(BN_CTX *ctx);
+//
+// llgo:link (*BN_CTX).Get C.BN_CTX_get
+func (*BN_CTX) Get() *BIGNUM { return nil }
+
 // void BN_CTX_end(BN_CTX *ctx);
+//
+// llgo:link (*BN_CTX).End C.BN_CTX_end
+func (*BN_CTX) End() {}
 
 // -----------------------------------------------------------------------------
 
@@ -191,23 +202,80 @@ func BNDec2bn(a **BIGNUM, str *c.Char) c.Int
 //go:linkname BNAsc2bn C.BN_asc2bn
 func BNAsc2bn(a **BIGNUM, str *c.Char) c.Int
 
-/*
-BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
-BIGNUM *BN_signed_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
-int BN_bn2bin(const BIGNUM *a, unsigned char *to);
-int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen);
-int BN_signed_bn2bin(const BIGNUM *a, unsigned char *to, int tolen);
-BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
-BIGNUM *BN_signed_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
-int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen);
-int BN_signed_bn2lebin(const BIGNUM *a, unsigned char *to, int tolen);
-BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret);
-BIGNUM *BN_signed_native2bn(const unsigned char *s, int len, BIGNUM *ret);
-int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen);
-int BN_signed_bn2native(const BIGNUM *a, unsigned char *to, int tolen);
-BIGNUM *BN_mpi2bn(const unsigned char *s, int len, BIGNUM *ret);
-int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
-*/
+// BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNBin2bn C.BN_bin2bn
+func BNBin2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// BIGNUM *BN_signed_bin2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNSignedBin2bn C.BN_signed_bin2bn
+func BNSignedBin2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// int BN_bn2bin(const BIGNUM *a, unsigned char *to);
+//
+// llgo:link (*BIGNUM).Bn2bin C.BN_bn2bin
+func (bn *BIGNUM) Bn2bin(to *byte) c.Int { return 0 }
+
+// int BN_bn2binpad(const BIGNUM *a, unsigned char *to, int tolen);
+//
+// llgo:link (*BIGNUM).Bn2binpad C.BN_bn2binpad
+func (bn *BIGNUM) Bn2binpad(to *byte, tolen c.Int) c.Int { return 0 }
+
+// int BN_signed_bn2bin(const BIGNUM *a, unsigned char *to, int tolen);
+//
+// llgo:link (*BIGNUM).SignedBn2bin C.BN_signed_bn2bin
+func (bn *BIGNUM) SignedBn2bin(to *byte, tolen c.Int) c.Int { return 0 }
+
+// BIGNUM *BN_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNLebin2bn C.BN_lebin2bn
+func BNLebin2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// BIGNUM *BN_signed_lebin2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNSignedLebin2bn C.BN_signed_lebin2bn
+func BNSignedLebin2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// int BN_bn2lebinpad(const BIGNUM *a, unsigned char *to, int tolen);
+//
+// llgo:link (*BIGNUM).Bn2lebinpad C.BN_bn2lebinpad
+func (bn *BIGNUM) Bn2lebinpad(to *byte, tolen c.Int) c.Int { return 0 }
+
+// int BN_signed_bn2lebin(const BIGNUM *a, unsigned char *to, int tolen);
+//
+// llgo:link (*BIGNUM).SignedBn2lebin C.BN_signed_bn2lebin
+func (bn *BIGNUM) SignedBn2lebin(to *byte, tolen c.Int) c.Int { return 0 }
+
+// BIGNUM *BN_native2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNNative2bn C.BN_native2bn
+func BNNative2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// BIGNUM *BN_signed_native2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNSignedNative2bn C.BN_signed_native2bn
+func BNSignedNative2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// int BN_bn2nativepad(const BIGNUM *a, unsigned char *to, int tolen);
+//
+// llgo:link (*BIGNUM).Bn2nativepad C.BN_bn2nativepad
+func (bn *BIGNUM) Bn2nativepad(to *byte, tolen c.Int) c.Int { return 0 }
+
+// int BN_signed_bn2native(const BIGNUM *a, unsigned char *to, int tolen);
+//
+// llgo:link (*BIGNUM).SignedBn2native C.BN_signed_bn2native
+func (bn *BIGNUM) SignedBn2native(to *byte, tolen c.Int) c.Int { return 0 }
+
+// BIGNUM *BN_mpi2bn(const unsigned char *s, int len, BIGNUM *ret);
+//
+//go:linkname BNMpi2bn C.BN_mpi2bn
+func BNMpi2bn(s *byte, len c.Int, ret *BIGNUM) *BIGNUM
+
+// int BN_bn2mpi(const BIGNUM *a, unsigned char *to);
+//
+// llgo:link (*BIGNUM).Bn2mpi C.BN_bn2mpi
+func (bn *BIGNUM) Bn2mpi(to *byte) c.Int { return 0 }
 
 // int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b);
 //
diff --git a/internal/lib/math/big/int.go b/internal/lib/math/big/int.go
index f568938b..e0bbbfe1 100644
--- a/internal/lib/math/big/int.go
+++ b/internal/lib/math/big/int.go
@@ -18,6 +18,9 @@ package big
 
 // llgo:skipall
 import (
+	"math/rand"
+
+	"github.com/goplus/llgo/c"
 	"github.com/goplus/llgo/c/openssl"
 )
 
@@ -81,9 +84,34 @@ func NewInt(x int64) *Int {
 	return z.SetInt64(x)
 }
 
-/*
 // Set sets z to x and returns z.
 func (z *Int) Set(x *Int) *Int {
+	if z != x {
+		a := (*openssl.BIGNUM)(z)
+		b := (*openssl.BIGNUM)(x)
+		a.Copy(b)
+	}
+	return z
+}
+
+// Abs sets z to |x| (the absolute value of x) and returns z.
+func (z *Int) Abs(x *Int) *Int {
+	z.Set(x)
+	a := (*openssl.BIGNUM)(z)
+	a.SetNegative(0)
+	return z
+}
+
+// Neg sets z to -x and returns z.
+func (z *Int) Neg(x *Int) *Int {
+	z.Set(x)
+	a := (*openssl.BIGNUM)(z)
+	if a.IsNegative() != 0 {
+		a.SetNegative(0)
+	} else {
+		a.SetNegative(1)
+	}
+	return z
 }
 
 // Bits provides raw (unchecked but fast) access to x by returning its
@@ -92,6 +120,7 @@ func (z *Int) Set(x *Int) *Int {
 // Bits is intended to support implementation of missing low-level Int
 // functionality outside this package; it should be avoided otherwise.
 func (x *Int) Bits() []Word {
+	panic("todo big.Bits")
 }
 
 // SetBits provides raw (unchecked but fast) access to z by setting its
@@ -100,17 +129,9 @@ func (x *Int) Bits() []Word {
 // SetBits is intended to support implementation of missing low-level Int
 // functionality outside this package; it should be avoided otherwise.
 func (z *Int) SetBits(abs []Word) *Int {
+	panic("todo big.SetBits")
 }
 
-// Abs sets z to |x| (the absolute value of x) and returns z.
-func (z *Int) Abs(x *Int) *Int {
-}
-
-// Neg sets z to -x and returns z.
-func (z *Int) Neg(x *Int) *Int {
-}
-*/
-
 // Add sets z to the sum x+y and returns z.
 func (z *Int) Add(x, y *Int) *Int {
 	(*openssl.BIGNUM)(z).Add((*openssl.BIGNUM)(x), (*openssl.BIGNUM)(y))
@@ -123,31 +144,35 @@ func (z *Int) Sub(x, y *Int) *Int {
 	return z
 }
 
-/*
 // Mul sets z to the product x*y and returns z.
 func (z *Int) Mul(x, y *Int) *Int {
+	panic("todo big.Mul")
 }
 
 // MulRange sets z to the product of all integers
 // in the range [a, b] inclusively and returns z.
 // If a > b (empty range), the result is 1.
 func (z *Int) MulRange(a, b int64) *Int {
+	panic("todo big.MulRange")
 }
 
 // Binomial sets z to the binomial coefficient C(n, k) and returns z.
 func (z *Int) Binomial(n, k int64) *Int {
+	panic("todo big.Binomial")
 }
 
 // Quo sets z to the quotient x/y for y != 0 and returns z.
 // If y == 0, a division-by-zero run-time panic occurs.
 // Quo implements truncated division (like Go); see QuoRem for more details.
 func (z *Int) Quo(x, y *Int) *Int {
+	panic("todo big.Quo")
 }
 
 // Rem sets z to the remainder x%y for y != 0 and returns z.
 // If y == 0, a division-by-zero run-time panic occurs.
 // Rem implements truncated modulus (like Go); see QuoRem for more details.
 func (z *Int) Rem(x, y *Int) *Int {
+	panic("todo big.Rem")
 }
 
 // QuoRem sets z to the quotient x/y and r to the remainder x%y
@@ -162,18 +187,21 @@ func (z *Int) Rem(x, y *Int) *Int {
 // (See Daan Leijen, “Division and Modulus for Computer Scientists”.)
 // See DivMod for Euclidean division and modulus (unlike Go).
 func (z *Int) QuoRem(x, y, r *Int) (*Int, *Int) {
+	panic("todo big.QuoRem")
 }
 
 // Div sets z to the quotient x/y for y != 0 and returns z.
 // If y == 0, a division-by-zero run-time panic occurs.
 // Div implements Euclidean division (unlike Go); see DivMod for more details.
 func (z *Int) Div(x, y *Int) *Int {
+	panic("todo big.Div")
 }
 
 // Mod sets z to the modulus x%y for y != 0 and returns z.
 // If y == 0, a division-by-zero run-time panic occurs.
 // Mod implements Euclidean modulus (unlike Go); see DivMod for more details.
 func (z *Int) Mod(x, y *Int) *Int {
+	panic("todo big.Mod")
 }
 
 // DivMod sets z to the quotient x div y and m to the modulus x mod y
@@ -191,8 +219,8 @@ func (z *Int) Mod(x, y *Int) *Int {
 // ACM press.)
 // See QuoRem for T-division and modulus (like Go).
 func (z *Int) DivMod(x, y, m *Int) (*Int, *Int) {
+	panic("big.DivMod")
 }
-*/
 
 // Cmp compares x and y and returns:
 //
@@ -212,29 +240,35 @@ func (x *Int) CmpAbs(y *Int) int {
 	return int((*openssl.BIGNUM)(x).Ucmp((*openssl.BIGNUM)(y)))
 }
 
-/*
 // Int64 returns the int64 representation of x.
 // If x cannot be represented in an int64, the result is undefined.
 func (x *Int) Int64() int64 {
+	panic("todo big.Int64")
 }
 
 // Uint64 returns the uint64 representation of x.
 // If x cannot be represented in a uint64, the result is undefined.
 func (x *Int) Uint64() uint64 {
+	panic("todo big.Uint64")
 }
 
 // IsInt64 reports whether x can be represented as an int64.
 func (x *Int) IsInt64() bool {
+	panic("todo big.IsInt64")
 }
 
 // IsUint64 reports whether x can be represented as a uint64.
 func (x *Int) IsUint64() bool {
+	panic("todo big.IsUint64")
 }
 
 // Float64 returns the float64 value nearest x,
 // and an indication of any rounding that occurred.
 // TODO(xsw):
-// func (x *Int) Float64() (float64, Accuracy)
+/*
+func (x *Int) Float64() (float64, Accuracy) {
+	panic("todo big.Float64")
+}*/
 
 // SetString sets z to the value of s, interpreted in the given base,
 // and returns z and a boolean indicating success. The entire string
@@ -259,17 +293,20 @@ func (x *Int) IsUint64() bool {
 // are no other errors. If base != 0, underscores are not recognized
 // and act like any other character that is not a valid digit.
 func (z *Int) SetString(s string, base int) (*Int, bool) {
+	panic("todo big.SetString")
 }
 
 // SetBytes interprets buf as the bytes of a big-endian unsigned
 // integer, sets z to that value, and returns z.
 func (z *Int) SetBytes(buf []byte) *Int {
+	panic("todo big.SetBytes")
 }
 
 // Bytes returns the absolute value of x as a big-endian byte slice.
 //
 // To use a fixed length slice, or a preallocated one, use FillBytes.
 func (x *Int) Bytes() []byte {
+	panic("todo big.Bytes")
 }
 
 // FillBytes sets buf to the absolute value of x, storing it as a zero-extended
@@ -277,18 +314,20 @@ func (x *Int) Bytes() []byte {
 //
 // If the absolute value of x doesn't fit in buf, FillBytes will panic.
 func (x *Int) FillBytes(buf []byte) []byte {
+	panic("todo big.FillBytes")
 }
 
 // BitLen returns the length of the absolute value of x in bits.
 // The bit length of 0 is 0.
 func (x *Int) BitLen() int {
+	panic("todo big.BitLen")
 }
 
 // TrailingZeroBits returns the number of consecutive least significant zero
 // bits of |x|.
 func (x *Int) TrailingZeroBits() uint {
+	panic("todo big.TrailingZeroBits")
 }
-*/
 
 // Exp sets z = x**y mod |m| (i.e. the sign of m is ignored), and returns z.
 // If m == nil or m == 0, z = x**y unless y <= 0 then z = 1. If m != 0, y < 0,
@@ -308,7 +347,6 @@ func (z *Int) Exp(x, y, m *Int) *Int {
 	return z
 }
 
-/*
 // GCD sets z to the greatest common divisor of a and b and returns z.
 // If x or y are not nil, GCD sets their value such that z = a*x + b*y.
 //
@@ -321,6 +359,7 @@ func (z *Int) Exp(x, y, m *Int) *Int {
 //
 // If a != 0 and b == 0, GCD sets z = |a|, x = sign(a) * 1, y = 0.
 func (z *Int) GCD(x, y, a, b *Int) *Int {
+	panic("todo big.GCD")
 }
 
 // Rand sets z to a pseudo-random number in [0, n) and returns z.
@@ -328,6 +367,7 @@ func (z *Int) GCD(x, y, a, b *Int) *Int {
 // As this uses the math/rand package, it must not be used for
 // security-sensitive work. Use crypto/rand.Int instead.
 func (z *Int) Rand(rnd *rand.Rand, n *Int) *Int {
+	panic("todo big.Rand")
 }
 
 // ModInverse sets z to the multiplicative inverse of g in the ring ℤ/nℤ
@@ -335,11 +375,13 @@ func (z *Int) Rand(rnd *rand.Rand, n *Int) *Int {
 // inverse in the ring ℤ/nℤ.  In this case, z is unchanged and the return value
 // is nil. If n == 0, a division-by-zero run-time panic occurs.
 func (z *Int) ModInverse(g, n *Int) *Int {
+	panic("todo big.ModInverse")
 }
 
 // Jacobi returns the Jacobi symbol (x/y), either +1, -1, or 0.
 // The y argument must be an odd integer.
 func Jacobi(x, y *Int) int {
+	panic("todo big.Jacobi")
 }
 
 // ModSqrt sets z to a square root of x mod p if such a square root exists, and
@@ -347,19 +389,29 @@ func Jacobi(x, y *Int) int {
 // ModSqrt leaves z unchanged and returns nil. This function panics if p is
 // not an odd integer, its behavior is undefined if p is odd but not prime.
 func (z *Int) ModSqrt(x, p *Int) *Int {
+	panic("todo big.ModSqrt")
 }
 
 // Lsh sets z = x << n and returns z.
 func (z *Int) Lsh(x *Int, n uint) *Int {
+	a := (*openssl.BIGNUM)(z)
+	b := (*openssl.BIGNUM)(x)
+	a.Lshift(b, c.Int(n))
+	return z
 }
 
 // Rsh sets z = x >> n and returns z.
 func (z *Int) Rsh(x *Int, n uint) *Int {
+	a := (*openssl.BIGNUM)(z)
+	b := (*openssl.BIGNUM)(x)
+	a.Rshift(b, c.Int(n))
+	return z
 }
 
 // Bit returns the value of the i'th bit of x. That is, it
 // returns (x>>i)&1. The bit index i must be >= 0.
 func (x *Int) Bit(i int) uint {
+	panic("todo big.Bit")
 }
 
 // SetBit sets z to x, with x's i'th bit set to b (0 or 1).
@@ -367,32 +419,38 @@ func (x *Int) Bit(i int) uint {
 // if b is 0 SetBit sets z = x &^ (1 << i). If b is not 0 or 1,
 // SetBit will panic.
 func (z *Int) SetBit(x *Int, i int, b uint) *Int {
+	panic("todo big.SetBit")
 }
 
 // And sets z = x & y and returns z.
 func (z *Int) And(x, y *Int) *Int {
+	panic("todo big.And")
 }
 
 // AndNot sets z = x &^ y and returns z.
 func (z *Int) AndNot(x, y *Int) *Int {
+	panic("todo big.AndNot")
 }
 
 // Or sets z = x | y and returns z.
 func (z *Int) Or(x, y *Int) *Int {
+	panic("todo big.Or")
 }
 
 // Xor sets z = x ^ y and returns z.
 func (z *Int) Xor(x, y *Int) *Int {
+	panic("todo big.Xor")
 }
 
 // Not sets z = ^x and returns z.
 func (z *Int) Not(x *Int) *Int {
+	panic("todo big.Not")
 }
 
 // Sqrt sets z to ⌊√x⌋, the largest integer such that z² ≤ x, and returns z.
 // It panics if x is negative.
 func (z *Int) Sqrt(x *Int) *Int {
+	panic("todo big.Sqrt")
 }
-*/
 
 // -----------------------------------------------------------------------------