aboutsummaryrefslogtreecommitdiff
path: root/src/bignum.h
diff options
context:
space:
mode:
Diffstat (limited to 'src/bignum.h')
-rw-r--r--src/bignum.h65
1 files changed, 0 insertions, 65 deletions
diff --git a/src/bignum.h b/src/bignum.h
index 0259338b31..6b77462d83 100644
--- a/src/bignum.h
+++ b/src/bignum.h
@@ -269,71 +269,6 @@ public:
return vch;
}
- // The "compact" format is a representation of a whole
- // number N using an unsigned 32bit number similar to a
- // floating point format.
- // The most significant 8 bits are the unsigned exponent of base 256.
- // This exponent can be thought of as "number of bytes of N".
- // The lower 23 bits are the mantissa.
- // Bit number 24 (0x800000) represents the sign of N.
- // N = (-1^sign) * mantissa * 256^(exponent-3)
- //
- // Satoshi's original implementation used BN_bn2mpi() and BN_mpi2bn().
- // MPI uses the most significant bit of the first byte as sign.
- // Thus 0x1234560000 is compact (0x05123456)
- // and 0xc0de000000 is compact (0x0600c0de)
- // (0x05c0de00) would be -0x40de000000
- //
- // Bitcoin only uses this "compact" format for encoding difficulty
- // targets, which are unsigned 256bit quantities. Thus, all the
- // complexities of the sign bit and using base 256 are probably an
- // implementation accident.
- //
- // This implementation directly uses shifts instead of going
- // through an intermediate MPI representation.
- CBigNum& SetCompact(unsigned int nCompact)
- {
- unsigned int nSize = nCompact >> 24;
- bool fNegative =(nCompact & 0x00800000) != 0;
- unsigned int nWord = nCompact & 0x007fffff;
- if (nSize <= 3)
- {
- nWord >>= 8*(3-nSize);
- BN_set_word(this, nWord);
- }
- else
- {
- BN_set_word(this, nWord);
- BN_lshift(this, this, 8*(nSize-3));
- }
- BN_set_negative(this, fNegative);
- return *this;
- }
-
- unsigned int GetCompact() const
- {
- unsigned int nSize = BN_num_bytes(this);
- unsigned int nCompact = 0;
- if (nSize <= 3)
- nCompact = BN_get_word(this) << 8*(3-nSize);
- else
- {
- CBigNum bn;
- BN_rshift(&bn, this, 8*(nSize-3));
- nCompact = BN_get_word(&bn);
- }
- // The 0x00800000 bit denotes the sign.
- // Thus, if it is already set, divide the mantissa by 256 and increase the exponent.
- if (nCompact & 0x00800000)
- {
- nCompact >>= 8;
- nSize++;
- }
- nCompact |= nSize << 24;
- nCompact |= (BN_is_negative(this) ? 0x00800000 : 0);
- return nCompact;
- }
-
void SetHex(const std::string& str)
{
// skip 0x