diff options
| -rw-r--r-- | src/main.cpp | 54 | ||||
| -rw-r--r-- | src/main.h | 17 | ||||
| -rw-r--r-- | src/test/compress_tests.cpp | 62 |
3 files changed, 130 insertions, 3 deletions
diff --git a/src/main.cpp b/src/main.cpp index 43bb4b1793..ed677f31c8 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -4058,3 +4058,57 @@ void GenerateBitcoins(bool fGenerate, CWallet* pwallet) } } } + +// Amount compression: +// * If the amount is 0, output 0 +// * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9) +// * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10) +// * call the result n +// * output 1 + 10*(9*n + d - 1) + e +// * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9 +// (this is decodable, as d is in [1-9] and e is in [0-9]) + +uint64 CTxOutCompressor::CompressAmount(uint64 n) +{ + if (n == 0) + return 0; + int e = 0; + while (((n % 10) == 0) && e < 9) { + n /= 10; + e++; + } + if (e < 9) { + int d = (n % 10); + assert(d >= 1 && d <= 9); + n /= 10; + return 1 + (n*9 + d - 1)*10 + e; + } else { + return 1 + (n - 1)*10 + 9; + } +} + +uint64 CTxOutCompressor::DecompressAmount(uint64 x) +{ + // x = 0 OR x = 1+10*(9*n + d - 1) + e OR x = 1+10*(n - 1) + 9 + if (x == 0) + return 0; + x--; + // x = 10*(9*n + d - 1) + e + int e = x % 10; + x /= 10; + uint64 n = 0; + if (e < 9) { + // x = 9*n + d - 1 + int d = (x % 9) + 1; + x /= 9; + // x = n + n = x*10 + d; + } else { + n = x+1; + } + while (e) { + n *= 10; + e--; + } + return n; +} diff --git a/src/main.h b/src/main.h index 1af781f45c..4286880c9f 100644 --- a/src/main.h +++ b/src/main.h @@ -652,14 +652,25 @@ class CTxOutCompressor { private: CTxOut &txout; + public: + static uint64 CompressAmount(uint64 nAmount); + static uint64 DecompressAmount(uint64 nAmount); + CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { } - IMPLEMENT_SERIALIZE( - READWRITE(VARINT(txout.nValue)); + IMPLEMENT_SERIALIZE(({ + if (!fRead) { + uint64 nVal = CompressAmount(txout.nValue); + READWRITE(VARINT(nVal)); + } else { + uint64 nVal = 0; + READWRITE(VARINT(nVal)); + txout.nValue = DecompressAmount(nVal); + } CScriptCompressor cscript(REF(txout.scriptPubKey)); READWRITE(cscript); - ) + });) }; diff --git a/src/test/compress_tests.cpp b/src/test/compress_tests.cpp new file mode 100644 index 0000000000..71b86bcb41 --- /dev/null +++ b/src/test/compress_tests.cpp @@ -0,0 +1,62 @@ +#include <boost/test/unit_test.hpp> + +#include <string> +#include <vector> + +#include "main.h" + +// amounts 0.00000001 .. 0.00100000 +#define NUM_MULTIPLES_UNIT 100000 + +// amounts 0.01 .. 100.00 +#define NUM_MULTIPLES_CENT 10000 + +// amounts 1 .. 10000 +#define NUM_MULTIPLES_1BTC 10000 + +// amounts 50 .. 21000000 +#define NUM_MULTIPLES_50BTC 420000 + +using namespace std; + +BOOST_AUTO_TEST_SUITE(compress_tests) + +bool static TestEncode(uint64 in) { + return in == CTxOutCompressor::DecompressAmount(CTxOutCompressor::CompressAmount(in)); +} + +bool static TestDecode(uint64 in) { + return in == CTxOutCompressor::CompressAmount(CTxOutCompressor::DecompressAmount(in)); +} + +bool static TestPair(uint64 dec, uint64 enc) { + return CTxOutCompressor::CompressAmount(dec) == enc && + CTxOutCompressor::DecompressAmount(enc) == dec; +} + +BOOST_AUTO_TEST_CASE(compress_amounts) +{ + BOOST_CHECK(TestPair( 0, 0x0)); + BOOST_CHECK(TestPair( 1, 0x1)); + BOOST_CHECK(TestPair( CENT, 0x7)); + BOOST_CHECK(TestPair( COIN, 0x9)); + BOOST_CHECK(TestPair( 50*COIN, 0x32)); + BOOST_CHECK(TestPair(21000000*COIN, 0x1406f40)); + + for (uint64 i = 1; i <= NUM_MULTIPLES_UNIT; i++) + BOOST_CHECK(TestEncode(i)); + + for (uint64 i = 1; i <= NUM_MULTIPLES_CENT; i++) + BOOST_CHECK(TestEncode(i * CENT)); + + for (uint64 i = 1; i <= NUM_MULTIPLES_1BTC; i++) + BOOST_CHECK(TestEncode(i * COIN)); + + for (uint64 i = 1; i <= NUM_MULTIPLES_50BTC; i++) + BOOST_CHECK(TestEncode(i * 50 * COIN)); + + for (uint64 i = 0; i < 100000; i++) + BOOST_CHECK(TestDecode(i)); +} + +BOOST_AUTO_TEST_SUITE_END() |